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The conversion of British Columbian softwoods into hardwoods, by the methylol ureas; and The preparation… Robertson, Roderick Francis 1946

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t i n fl% THE CONVERSION OF BRITISH COLUMBIAN SOFTWOODS INTO HARDWOODS BY THE METHYLOL UREAS AND THE PREPARATION OF METHYL TRIMETHYLOL METHANE Roderick Francis Robertson, B.A. / A Thesis Submitted i n P a r t i a l F u l f i l l m e n t / • j of the Requirements f o r the Degree .of / Master of Arts I / ^ i n V i/3 The Department of Chemistry | / i ^ 4 ' University of B r i t i s h Columbia October, 1946. /•W jTZL fittf ^ M J ^ ^ THE CONVERSION OF BRITISH COLUMBIAN SOFTWOODS INTO HARDWOODS BY THE METHYLOL UREAS ACKUOWXEDGrEMEE'T I wish to acknowledge my appreciation to Dr. R. H. Clarik, who directed this research; to R. A. MacLeod and A. N. C^Neill, who shared the many difficulties of this problem with me; to the staff of the Forest Products Laboratory, who so willingly gave of their assistance; and to the British Columbia Industrial and Scientific Research Council who assumed the financial burden for the quantity of necessary equipment. TABLE OF CONTENTS I. Purpose. Page 1 II Introduction. " 1 III The Chief. Limitations of Natural Woods " 2 IV The Improvement of Eatuxal Woods By Methods Other Than Impregnation With Synthetic Resins. 11 2 V The Impregnation Of Wood With Synthetic Resins. " 5 VI The- E f f e c t of Synthetic Resins on Natural Wood. " 5 VII Types of Resin Treated Wood. " 6 VIII The Methods of Impregnating Woods with Synthetic Resins. 11 7 IX The Impregnation of Bulk Wood with Synthetic Resins. " 8 X Chief D i f f i c u l t i e s to he Overcome i n the Impregnating .of Wood on a Bulk Wood Basis " 8 XI The Proposed Method f o r the Impregnation of Bulk Wood. " 9 XII Equipment and I n s t a l l a t i o n . " 10 1. The Solution Storage Tank 10 2 . The Impregnation Unit '-' 11 3 . The Hydraulic Press and Heating unit " 12 XIII The Impregnation of Bulk Wood with Urea Formaldehyde Type Resins. H 12 1. The Wood ? 12 2* The Impregnating Resin " 15 3 . The Impregnation Process 17 4. The Drying of the Wood Samples After Impregnation " 21 5. Curing and Pressing 11 22 XIV The Product A r i s i n g From the Impregnation of Softwoods "by Dimethylol Urea 1 1 23. t> TABLE OF CONTENTS - Cont'd. XV General Summary XVI Conclusion Bibliography DIAGRAMS The Impregnation Unit The Heating and Pressing Unit ABSTRACT. The l i t e r a t u r e on Wood Impregnation has been reviewed. The i n s t a l l a t i o n of a wood has "been completed. The Impregnation of Wood "by the Vacuum Pressure Technique, and tne subsequent curing of the samples "by Radio Frequency F i e l d s , and Hydraulic Pressure, has "been t r i e d . Dimethylol Urea has proven l a r g e l y unsatisfactory f o r the Impregnation of Wood by t h i s method. treatment of 1. THE CONVERSION OF BRITISH COLUMBIAN SOFTWOODS INTO HARDWOODS BY THE METHYLOL UREAS I : PURPOSE The Department of Chemistry of the University of B r i t i s h Columbia, i n co-operation with the B r i t i s h Columbia I n d u s t r i a l and S c i e n t i f i c Research Council and the Forest Products Laboratory, embarked on a long range program of studies on the chemical hardening of B r i t i s h Columbia softwoods. The research was so designed as to determine the p o s s i b i l i t y of e s t a b l i s h i n g a post-war industry i n the chemical hardening of wood i n t h i s Province. This report gives the background,and summarizes the work done on t h i s project, from September, 1944 to January 1946, with special reference to the a f f e c t of DImethylol Urea type resins on wood. II INTRODUCTION The extent to which man has drawn upon the natural woods as a source of raw materials for a large range of a r t i c l e s , from small pieces of furniture and toys, to large e d i f i c e s , i s well known to a l l . The various pieces of wood were relegated to d i f f e r e n t s p e c i f i c tasks which best suited t h e i r own p a r t i c u l a r c h a r a c t e r i s t i c s . The hardwoods were used where high resistance against wear was necessary, such as i n f l o o r -ing, and the softwoods were used extensively i n general construction, where economy and reasonable strength were the only prerequisites. There were, however, certain.inherent disadvantages of wood, which necessitated the use of other more expensive materials for p a r t i c u l a r purposes, i n which the c h a r a c t e r i s t i c s of natural woods f a i l e d to meet a l l the requirements of the tasks i n question. As already mentioned, each type, species, and grade.of wood had c h a r a c t e r i s t i c properties which made i t s use for various s p e c i f i c purposes highly desirable, but i t often had other unique c h a r a c t e r i s t i c s which made i t s use for these purposes impossible. Perhaps the desired wood was not available i n the required abundance and was, consequently, too expensive; or further, the physical l i m i t a t i o n s owing to the size and shape of the natural wood made i t s use impractical. 2. To the general user of wood, i t became obvious that i f the natural defects of wood could be overcome,and un-suitable woods could have t h e i r fundamental physical and chemical properties so improved that they could be safely used for purposes hitherto thought impractical, the con-servation of e x i s t i n g wood stocks, the u t i l i z a t i o n of waste products, and the subsequent economic gain, would be enormous. I l l THE CHIEF LIMITATIONS OF NATURAL Y/OODS Before any adequate consideration could be given to the improvement of wood, i t would be necessary to review the chief l i m i t a t i o n s of the natural woods. The d i f f i c u l t y of si z e , shape and abundance has already been noted, and t h i s problem has caused much concern i n the industry. Wood, before use, had to be drie d . Unless the drying was carried out c a r e f u l l y , large wastage from warping, checking and s p l i t t i n g occurred. In order to avoid t h i s l o s s , slow, expensive, .carefully controlled,drying schedules, 1 i n s p e c i a l l y constructed k i l n s , had to be carried out. Many micro-organisms and insects made a prey of wood; the former, r o t t i n g i t and destroying i t s body and strength, the l a t t e r , boring i t and making i t generally unsuitable for most purposes. Wood was inflammable, was not impervious to water, and was r e a d i l y acted upon by many chemicals. Wood had not the desired strength for many purposes and could not be used for those purposes even though c e r t a i n i f i t s other properties made i t s use most desirable.. This deficiency i n strength was a very serious primary defect of natural wood; often the natural beauty of the wood could not be u t i l i z e d because of t h i s d i f f i c u l t y . But perhaps the greatest drawback to wood was i t s tendency to shrink and swell with changes i n the moisture content of i t s immediate environment. This f a u l t was the most d i f f i c u l t to overcome and lead to many attempts to improve the natural q u a l i t i e s ofthe woods i n order to minimize the swelling and shrinking. IV THE IMPROVEMENT OF NATURAL WOODS BY METHODS OTHER THAN  IMPREGNATION WITH SYNTHETIC RESINS. The d i f f i c u l t y of the size and shape of the natural woods has not been overcome even to t h i s day. Veneers and plywoods have been widely used to compensate fo r t h i s d i f f i c u l t y , but i n thick sections, plywoods have been ex-pensive substitutes. 3 Warping, checking,and s p l i t t i n g ^ have been largely-overcome by the use of well controlled, highly specialized methods of k i l n drying. E s s e n t i a l l y , the woods v/ere subjected to reasonably elevated temperatures under atmospheres i n which the moisture content was only s l i g h t l y displaced from the equilibrium for the moisture content of the wood being dried.. The technology, of k i l n drying has now become we l l standardized and the methods have reached about maximum e f f i c i e n c y . As a further check to warping and splitting^W. ?/ood (35) impregnated natural wood veneers with a hot concentrated s o l u t i o n of MgSO^. This treatment resulted i n a d e f i n i t e decrease i n checking, warping and s p l i t t i n g and also f a c i l i t a t e d handling. Various inorganic s a l t s have been t r i e d as a means of preserving wood. Nowotny (/£*) impregnated wood stocks with a paste of HaF and dinitrophenol to act as a preservative. The impregnation of woods with ZnClg for t h i s purpose has been long successfully c a r r i e d out. Ruber. 7 ( 9 ) impregnated wood with solutions of f l u o r i n e s a l t s and a c i d reacting a l k a l i or a l k a l i earth polyphosphates and noted increased resistance to decay and s l i g h t l y increased dimensional s t a b i l i t y . Many natural organic substances have also been used as preservatives. Waste products of the petroleum industry, and coumarone derivatives, were used by Nowak C*?-) for wood preservation with some success;' The impregnation of woods with the cresoles has long been c a r r i e d out on a commercial scale. Solutions of carbohydrates, such as the pentoses and t h e i r anhydrides, naphthenic or petroleum sulphonic acids, or sulfonic acids of saturated and unsaturated hydrocarbons, which may be emulsified,were applied to wood stocks and found to enhance the resistance to decay and dimensional s t a b i l i t y (//" ). Sanna ( ' 8 ) noted that woods, when impregnated with a mixture of c y c l i c carbon compounds or a mixture of hydroxy toluenes, formaldehyde and acetone, showed', on heating and pressing, marked resistance to f i r e , moisture, and chemicals. . The work done to combat the effects of swelling and shrinking of wood has been so widespread as to be d i f f i c u l t to summarize. The f i r s t most obvious way of overcoming, at l e a s t i n part, the tendency of wood to shrink and swell, and consequently to s p l i t and warp,was by the a p p l i c a t i o n of surface coatings. Surface coats were by f a r the simplest form of antishrink protection and were very e f f e c t i v e for small humidity ranges. The effectiveness 4. of these surface coats has "been studied i n d e t a i l by Browne (*f ) Hunt ('°). These men agreed that with pro-longed exposure and mechanical wear, the effectiveness of the surface coatings decreased most appreciably. Surface impregnation has also been t r i e d and found only moderately e f f e c t i v e . The tendency of the wood i t s e l f , to absorb water, was in.no wise decreased by the a p p l i c a t i o n of such surface coats. The surface coats presented merely a mechanical b a r r i e r to prevent the water -vapour from entering the wood. Stamm (*o) t r i e d various hygroscopic s a l t s to preserve the green state within the wood. This process was only moderately successful. The process was slow, but green wood,so treated, could be k i l n dried at 75$ r e l a t i v e humidity without the surface of the wood tending.to shrink at a l l . The wood tended to r e t a i n i t s green dimensions. Attempts to minimize the swelling and shrinking of wood by the deposition of water r e s i s t a n t materials, such as waxes, within the wood, has been made by Nowak (AS) (A3 ) , and Stamm and Hansen ( 2-0) . This process had value only i n shedding water and s t a b i l i z i n g the dimensions under, rapid l y o s c i l l a t i n g r e l a t i v e humidity conditions. (33) Stammand Hansen showed that the deposition of water insoluble waxes ( car r i e d i n an intermediate solvent completely miscible with both water and the waxes) within the c e l l wall structure, by the replacement .method*improved the dimensional s t a b i l i t y but did not a f f e c t the moisture equilibrium. The reason put forward by Stamm (34-) for the f a i l u r e of the waxes, was. that though the waxes were highly water resistant,•they did not bond the wood. For t h i s reason, the water could work i t s way up between the wax and the wood f i b e r structure. Permanent reduction*of the dimensional i n s t a b i l i t i e s were effected by the heating of dry wood,for short periods of time, at temperatures of 200*- 300° .F, or for longer . periods at 100* F (25"). By t h i s method, the mechanical strength of the wood.was only s l i g h t l y reduced. The i d e a l method for assuring dimensional s t a b i l i t y would have been to impregnate the wood with some substance which had a greater a f f i n i t y f o r wood than i t had for water. The d i f f i c u l t y here, however, was that such substances were a l l very hygroscopic. I f materials were made available which had a higher a f f i n i t y for wood than water and then converted over to some form which was non-hygroscopic, the problem of s t a b i l i z i n g the dimensions of wood, i n a large measure, would be solved. Fortunately, such materials have been made available now i n the form of the Synthetic Resins. V THE IMPREGNATION Off WOOD WITH SYNTHETIC RESINS 5. In attempts to change the appearance, density, mechanical properties, resistance to decay, resistance to chemicals, and to increase the dimensional s t a b i l i t y , several workers have studied the impregnation of wood with synthetic resins (3.) (/9.) (/3J (7) . The most fundamental contributions i n this f i e l d have' been made by A . J.. Stamm and his co-workers. Stamm (2/) (22) suggested that i f a synthetic r e s i n , i n the unpolymerized state, could be forced into the wood, the polar molecules of the r e s i n , upon polymerization, could bond with the free c e l l u l o s e hydroxyl groups (which account for the hygroscopicity of cellulose) and create a product having a high degree of dimensional s t a b i l i t y . The data submitted by Stamm and S.eborg- (2'6), showed t h i s reasoning to be i n a large measure correct. Swelling and shrinking were, reduced to 25$ of normal by the use of phenol formaldehyde r e s i n s . 71 THE EFFECT OF SYNTHETIC RESINS ON NATURAL WOOD • Synthetic resins have been applied to wood as protective coatings and as adhesives f o r plywood manufacture^ A further application of these p l a s t i c materials!has been the impregnation of natural wood to enhance the q u a l i t i e s of the wood, and t o create wood products,so unique i n t h e i r c h a r a c t e r i s t i c s , as to be v i r t u a l l y new substances. The e f f e c t s of these synthetic resins on wood have been shown to be manifold. Some of the most important points i n t h i s conneetipn are worth summarizing here. 1. The dimensional s t a b i l i t y of the wood has been greatly enhanced by treatment with synthetic resins {27) by the interference with the rate of moisture absorption and penetration. This was probably because: (a) the r e s i n closed the paths or channels i n the wood structure, (b) the r e s i n may have reacted with constituents of the wood to produce a material less permeable to moisture, (c) the r e s i n , i f cured under pressure, would render the densified wood very impervious to moisture, (d) the dimensional s t a b i l i t y would have increased the mechanical properties of the wood since the equilibrium moisture content at a given r e l a t i v e humidity was appreciably decreased (e.g. Birch with an E.M.C. of 8$, would carry only 4$ when treated with 30$ of the proper s t a b i l i z i n g £esin( &.) ) % 2. Resistance to decay and chemicals has b.een greatly increased by the use of synthetic resins ( » 7 ) . 6. 3. The r e s i n p l a s t i c i z e d the wood and thus made i t ' possible to compress i t at reasonable pressures to higher densities (28). 4. The resins would bond the wood f i b e r s a f t e r compression, holding them i n t h e i r compressed state, thus preventing spring back when the pressure was released or when moisture was added (28) (29). 5. The resins increased the hardness of the wood. 6. The resins imparted a f i n i s h to the wood which could be e a s i l y brought out by simple treatment. VII TYPES Off RESIN TREATED WOOD. Three p r i n c i p a l types of r e s i n t r e a t e d wood have been developed: A. Impregnated Wood B. .Resin treated Compressed Woods C. Impregnated and compressed bulk wood or "Chemically Transmuted Woods?*. A. Impregnated Wood In the manufacture of Impregnated Wood, wood i n the form of veneers was impregnated with synthetic r e s i n solutions,then dried. The veneers were then baked at from 200°- 250° C to cure the r e s i n . The veneers were then bonded as i n the production of ordinary plywood, or laminated wood. The density of t h i s product was very close to that of natural wood. B. Compressed Woods Before describing the so c a l l e d Compregnated Wood, two other non-resin treated Compressed Woods deserve mention: (1) Densified Wood' Densified Wood was normal untreated wood which had been compressed under non-flow conditions for the l i g n i n . It has been made from s o l i d bulk wood («o ) (/6) and from veneers assembled with a synthetic glue (2 ) (32). This product was not dimensionally stable. (2) "Staypak" One further type of non-resin treated compressed wood has been developed. By compressing wood under conditions which cause the l i g n i n to flow within the wood, i t has been found possible to eliminate the spring back tendency. This product has been named "Staypak". "Staypak" i s heated, s t a b i l i z e d , compressed wood • that has been heated during the pressing process under conditions such that the compression i s not l o s t .when the wood i s subsequently swollen. Although i t w i l l swell appreciably, i t w i l l return to p r a c t i c a l l y the o r i g i n a l compressed thickness on drying to the o r i g i n a l • moisture content" ( 3 0 ) . . Compregnate,d Wood . Wood i n the form of veneers was f i r s t impregnated with synthetic resins, dried, and then assembled and "densified under heat and pressure, with steam platen pressures of 900 - 28.00 p . s . i . , and at • temperatures of 260*- 320° F. The pressing time was from 20 - 100 minutes. The product of greatest current i n t e r e s t had a s p e c i f i c gravity of 1.3-1.4, about the maximum obtainable with wood and synthetic r e s i n s . As the d e n s i f i c a t i o n increased, the mechanical properties changed almost i n proportion. C. Impregnated and Compressed S o l i d Bulk Wood - "Chemically Transmuted Wood". In t h i s process, the synthetic resins were f i r s t impregnated into the s o l i d bulk wood. The product was then heated to render the resins f u s i b l e , then pressed to the. desired dimensions. The heating was then continued to cure the resins and form a dimensionally stable product. This l a t t e r type of r e s i n treated wood was the type chosen for t h i s investigation.' VIII THE METHODS OF IMPREGNATIffG WOODS WITH SYNTHETIC RESINS The process of impregnating woods with preservatives has been c a r r i e d out i n four general ways. The f i r s t method permitted the d i f f u s i o n of chemicals into green wood by simple immersion of the wood i n the impregnating solution. This method has not met wide use because of two reasons. F i r s t , the process of impregnation i s very slow, and second, the wood must be green.' However, i t has the advantage of g i v i n g deeper and more'uniform treatment i n the cross f i b e r d i r e c t i o n than has be'en obtained by the penetration methods. In the second method of impregnation, advantage was taken of the fact that i t i s possible t o replace water i n the green wood with an aqueous s o l u t i o n by the application of, e i t h e r , a hydrostatic head of pressure, or, an e l e c t r i c a l p o t e n t i a l . This was a very slow method of . impregnation. 8. As a t h i r d general method, the c a p i l l i a r y r i s e technique of impregnation has "been applied. In t h i s process, the solution was able to enter the wood by c a p i l l i a r y r i s e , upon the immersion of the dry or p a r t i a l l y dry wood i n the impregnating solution: 1. The fourth and most generally used method, was the so c a l l e d Vacuum Pressure technique of impregnation. C a p i l l i a r y r i s e was aided by the use of a treating cylinder, i n which the wood and impregnating solution • could both be held. By t h i s method, i t was possible to further force the impregnating s o l u t i o n into the . wood, by the application of a i r pressure. I t was t h i s method of impregnation, since i t was the most e f f i c i e n t , and most suitable, that was chosen f o r t h i s research. IX THE IMPREGNATION OF BULK WOOD WITH SYNTHETIC RESINS ' The only f a i r l y complete account of a process for "the impregnation of s o l i d sections of wood was found i n the address published i n pamphlet form by J.F.T. B e r l i n e r , for the du Pont Company (/ ). In that address, was outlined a general process for impregnation. A water s o l u t i o n of an uncondensed methylol urea r e s i n was forced into the wood structure. The methylol urea was there converted into the r e s i n by the natural acid constituents of the wood. Heat, such as i n normal k i l n drying, sped the conversion of the methylol urea i n the wood to the water insoluble r e s i n s . This process, however, took place with s u f f i c i e n t r a p i d i t y at normal temperatures to be completed i n the usual a i r drying period. A permanent r e s i n , both hard and insoluble, was developed i n the wood structure at either, normal, or k i l n temperatures. I f the k i l n temperatures were not too high, or drying was not too rapid, the r e s i n i f i c a t i o n would proceed to the insoluble but s t i l l f u s i b l e stage, and would remain so, for a period of time. I f the wood, so dried, was heated to 240° F (115.5°C) or higher, and subjected to pressure, the r e s i n fused, flowed under the pressure, and the r e s i n i f i c a t i o n was rap i d l y completed t o the i n f u s i b l e state. The wood would permanently r e t a i n the surface and physical dimensions produced during the process. This process was the basis of the method used i n t h i s research. X CHIEF DIFFICULTIES TO BE OVERCOME IN THE IMPREGNATION  OF WOOD ON A BULK WOOD BASIS": Before a p r a c t i c a l procedure for the impregnation of bulk wood could be developed, i t was necessary t o consider the main d i f f i c u l t i e s of such a procedure. A. J". Stamm (3/) has outlined what he considered the three main d i f f i c u l t i e s i n the impregnation of bulk wood. 1. A l l species of wood could not be re a d i l y treated, the common softwoods, or the sapwoods of hardwoods, impregnated f a i r l y e a s i l y , but oak, walnut and the heartwood of maple, did not respond to the cylinder method of impregnation. 2. D i f f i c u l t y i n properly d i s t r i b u t i n g the " chemicals through large pieces of wood was encountered} a very intimate treatment was necessary to assure dimensional s t a b i l i t y . Then the size of the specimens which .could be treated was lim i t e d . The larger the pieces, the longer had to be the time of impregnation. With very large pieces, the treatment time was p r o h i b i t i v e l y long. 3. The cost of the treatment of bulk wood on a commercial scale would be too high. Two further d i f f i c u l t i e s had to be considered. F i r s t , the chemically treated wood was too b r i t t l e after treatment. Second, the curing of the resins within the wood required higher temperatures than the usual k i l n temperatures. I f only k i l n temperatures were used, p a r t i a l polymerization of the p l a s t i c material would occur, and the product would be but a poor substitute f o r the properly treated wood. Because of these l i m i t a t i o n s , the treatment of lumber by t h i s procedure, has been r e s t r i c t e d to small expensive specimens where cost of production was not -all-important, With these d i f f i c u l t i e s c l e a r l y i n mind, a basic procedure for the impregnation of wood of bulk wood dimensions,was developed THE PROPOSED METHOD FOR THE IMPREGNATION OF BULK WOOD The proposed scheme for the impregnation of s o l i d sections of wood involved the general procedure outlined below, and based, l a r g e l y , on the method of Berliner ( / ). The wood samples to be impregnated were f i r s t brought to a moisture content of 10$ - 12$. These sample were then placed i n the tr e a t i n g cylinder and a 28" vacuum was drawn. This vacuum served to remove enclosed a i r from the wood and some moisture. The vacuum tank was then f i l l e d with an aqueous so l u t i o n of the unpolymerized chemicals,in s u f f i c i e n t quantity to cover 10. the wood completely, and allow f o r the volume of the solution absorbed by the wood. A i r pressure was then applied to force the solution into the wood. When s u f f i c i e n t take up of the solution had occurred, the pressure was released, the solut i o n run o f f , and the im-pregnated woods dried to moisture content of about 6$.. After impregnation and drying, the wood was then transferred to the press and heated, then pressed>under varying pressures and temperatures, to determine the optimum conditions. The former method of heating the treated wood between steam or e l e c t r i c a l l y heated platens of the press, resulted i n a temperature gradient between the outside surface and the central core of the wood. Such a condition would cause the chemicals to polymerize to d i f f e r e n t extents throughout the wood, according to the temperature, giving r i s e to a b r i t t l e product. Further, for thicker sections, the platen temperatures required f o r s u f f i c i e n t heat at the center o f the sample, to assure polymerization, came very close to the charring temperature of the wood. The outside surfaces were then i n a great danger of charring. In the past, p l a s t i c s have been l i m i t e d to comparatively t h i n sections for the same reasons. P l a s t i c s are l a r g e l y s o l i d solutions and for these solutions to have mechanical strength, past experience has shown that the constituents must have a very si m i l a r structure amd molecular size throughout. By the use of short-wave d i e l e c t r i c heating, i t has been found possible to heat wood many feet i n thickness almost uniformly throughout the.mass, Having the temperature almost the same throughout the wood, should cause the polymerization to take place to the same extent a l l through the sample. It was hoped that the uniform heating and subsequent uniform polymerization would tend to eliminate, at lea s t to some extent, the tendency of the f i n a l product to be b r i t t l e . XII EQUIPMENT AND INSTALLATION In order to carry out t h i s research, i t was necessary to equip and i n s t a l l a small scale plant for wood impregnation. A description of the various units i n s t a l l e d , follows: 1. . The Solution Storage Tank. This tank was a 38 l i t e r stock pot equipped at the base with a tap. This tap was removed and i n the f i t t i n g was cemented, u p r i g h t a 50 ml burette. 11. Once calibrated, t h i s burette gave a measure of the volume of solution absorbed on each impregnation run. The solution i n the tank was heated by knife edge heaters. Local temperature gradients, due to the heaters, was minimized by the use of an e f f i c i e n t s t i r r i n g apparatus. 2. The Impregnation Unit The impregnation tank consisted of a §•" s t e e l cylinder, 23" deep and 13^t! i n diameter. This tank was arranged on a wooden frame so designed as to cause the tank to slope forward s l i g h t l y toward the cylinder door. This door consisted of a 2" block of s t e e l , machined and f i t t e d with a copper gasket. This door was fixed to the tank by a hinge and :.six large b o l t s . The seal of the door to the tank Was accomplished by a neoprene gasket. At the front and bottom of the impregnating cylinder, a 1" pipe lead over to the solution storage tank. This pipe served t o f i l l and empty the tank with the impregnating solution by the application of p o s i t i v e or negative pressures i n the c y l i n d e r . From the top rear of the cylinder, a §" pipe and f i t t i n g joined the main cylinder to a small over-flow vessel. The overflow vessel was also constructed of i" s t e e l and was f i t t e d with a glass l e v e l gauge to follow the drop i n l e v e l of the solution during impregnation.. At the top of the overflow, a f i t t i n g lead to a vacuum-pressure gauge,and to two pipes. The f i r s t pipe was equipped with a bleed off valve, and the second pipe lead through b a f f l e s to the pressure and vacuum pumps. Because of the possible c a t a l y t i c activity., of the iron i n the impregnating unit, a l l parts which came • i n d i r e c t contact with the r e s i n solution were n i c k e l -plated, This p l a t i n g had to be done at the University by those engaged i n t h i s problem because of the then prevalent wartime r e s t r i c t i o n s . A good p l a t i n g of copper, and then of n i c k e l , was deposited on a l l the required surfaces. Much time was consumed i n t h i s task. The vacuum and a i r pressure was supplied to the impregnating cylinder by e l e c t r i c a l l y driven vacuum and pressure pumps. The pressure pump was a product of the Qjiincey Compressor Company, and driven by a Robins and Myers 2 H.P. D.C-A.C. motor (Type N.EMA.) The vacuum pump was also a-.product of the Quincey 12. Company, and i t was driven by a Robins and Myers 1 H.P. A.C.-D.C. motor (Type NEMA.) A diagramatic representation of the impregnation unit can be found on page 13. 3. The Hydraulic Press and Heating Unit. The press i n s t a l l e d was a manually controlled 75 ton Elmes Hydraulic Press. This type press offered the widest range of pressures compatible with the li m i t e d space at the disposal of t h i s project. E l e c t r i c a l l y heated hot plate platens for hot plate pressing were also included i n the press assembly. The temperature of the platens could be brought to 325" F with t h i s heating u n i t . The heating unit a c t u a l l y used i n t h i s project, was a short wave d i e l e c t r i c heater. A short wave generator was purchased from the Girdler Corporation Thermex Di v i s i o n . This unit was designated "The Gir d l e r Corporation 8 Kilowatt Thermex Heater. I t had a p r a c t i c a l frequency range of from 1.75 to 8.9 megacycles. il The i n s t a l l a t i o n of t h i s unit was done by an I n s t a l l a t i o n Engineer, sent out by the Gir d l e r Corporation. The attaching of the short wave generator to the press, for hot plate pressing, posed a problem. This was solved i n the following way: The Thermex and Press were set side by side on a large sheet of 1/16" copper. The chassis of the Thermex was then connected by 3 ground straps to the copper plate. The press platens were then covered with sheaths of the 1/16" copper plate. These sheets were screwed into the tra n s i t e i n s u l a t i o n between the platens and the body of the press. The ground lead of the Thermex unit was^then connected to these two copper sheaths. This served'as the ground sides of the ultimate heating condenser. The high frequency lead was attached to a t h i r d 1/8" copper plate and t h i s plate was placed equidistantly between the two ground platens by adjusting the shape and amount of the charge being heated. This arrangement gave the eff e c t of two condensers connected i n p a r a l l e l . Diagram 2, page 14, best i l l u s t r a t e s t h i s heating and pressing unit . XIII THE IMPREGNATION OF BULK WOOD WITH UREA FORMALDEHYDE \ TYPE RESINS. 1 ~"~! 1. The Wood It was proposed to investigate the impregnation of DIAGRAM 1 IMPREGNATION UNIT A Solution Tank B Hoait.fi C Sh'rar D ImpMAootim} TOTJH wcoori) Pressure. Got/9« BlctfL-off vbltKE. NfoCOOft) Porrjp Vacuum ?urnp Motor 3a{fle PntSSart pump Baffle Rrvttwe Pomp Motor. D I A G R A M Z. P R E S S A D A P T E D ^ T H E R M E X S B A 8 c D E Copper Sj}«vU?ed Platen* Ground Relorrj.t6 R"F-G«n-Kjgh Frequency Electrode HujVi Frajutncu Lead framGrtn-Oiftlcctn'c - Vwod-15. Hemlock, Spruce, Balsam and Cottonwood. The dimensions of the samples were 15" x 3" x 3/4". The samples were so chosen as to contain no knots. They were k i l n dried to 10-12$ M.C. before each run. To overcome deviations i n the physical properties of i n d i v i d u a l samples, twenty such samples comprised a s i n g l e run. Generally, sapwood samples were chosen. 2. The Impregnating Resin. The r e s i n chosen for the impregnant i n thi s research, was Urea Formaldehyde. This type r e s i n was chosen primarily since the natural colour of the wood was not as seriously a l t e r e d as i n the case of the phenolic r e s i n s . Also, very few a r t i c l e s had been published on the use of t h i s r e s i n so that i t s e f f i c a c y as an impregnating agent was l a r g e l y unknown. (a) The Chemistry of the Urea Formaldehyde Resin. As a r e s u l t of the work of many investigators, i t -i s now believed that urea and formaldehyde react reversibly, under the influence of e i t h e r a c i d i c or basic Catalysts, to produce methylol urea and Ibhen dimethylol urea. NHg NHCHgOH NHCHgOH 0=0 + CH20 -» C-0 + CHgO -> C=0 NHg NHg NHCHgOH Methylol urea Dimethylol urea This Dimethylol Urea i s the water soluble unpolymerized form of the r e s i n as supplied commercially. When t h i s material i s subjected to further heat, the polymerization into the i n f u s i b l e r e s i n occurs. A cross-linked polymer i s produced by the loss of water between various dimethylol urea u n i t s . One possible route of the reaction to form the cross-linked polymer, may be represented as follows: Ho-cHg-NH HN-ciHg'eHv;;;r/;.'.".'.i|NH 0=0 C=0 C=0 HN-cH^av.:;;;jEgi-^".. . HN-CH 2 OH HNH HN-CHg-A NHCHgOH C=0 C-0 C-0 • » t HNCH^OH ;; ; ; ; . H j N - c H g p a " J S H H 16. The resultant polymer has the formula: -CHgNH t HN-CHg--NH T C<=0 i H N-CHo - NH t a t -0 0=0 t c=o t HN-CHg-NHCHg-G=0 t HN-CHg- N-CHg- NH The formation of a c y c l i c derivative of the monamers also i l l u s t r a t e s a possible route: HN c-H -N. H-C-Hc > 2 •N I C-NH-CHpOH -N* H ; CH, H • N \ / N ' H C- N - CH: II < 0 -OH n as: In t h i s polymerization,the linkage may take place ' 9 • -N p - IT' C-NH-CH /CH » 2 C - N 0 0 /N - C . HgC-NH -C - N - C Ho C-NH-CHp-I^  0 C - N % -~N" . 6 H 2 CHQ C - 'N Hg c - NH-CHg 0 * Ft C - N H 2 ' Urea Formaldehyde polymers can be made which are water soluble. On heating these products, the formation of the hard i n f u s i b l e Urea Formaldehyde P l a s t i c Material r e s u l t s , due to the exothermic polymerization r e a c t i o n going on. When methylol urea i s heated, formaldehyde i s l i b e r a t e d . Then, when Dimethylol Urea i s ased, a quantity of free Urea i s added. This free Urea reacts with the l i b e r a t e d formaldehyde to form Methylol, and Dimethylol,Ureas which then polymerize as above. (b) The Urea Formaldehyde Solution Used. The usual•solution used throughout most of the runs, 17. was a solution of 1 part of Urea, 6 parts of Dimethylol Urea and 20 parts of water. This gave approximately a 28% solution of r e s i n by weight. The solution was made up i n 32 l i t e r l o t s . Y/hen freshly prepared, these r e s i n solutions had a pH of about 8.4. Qn impregnation, the pH dropped to about 6.5, due, presumably, to the absorption of natural wood acids during the impregnation. I f the s o l u t i o n was to 1 be.stored, the pH was adjusted to pH 7.6 and the l i q u i d stored i n a cool place. After 48 hours, however, polymerization had' proceeded to such an extent as to make further use of the s o l u t i o n for impregnation impractical. In an e f f o r t to check the v i s c o s i t y of the r e s i n , a method was developed using the c a p i l l i a r y flow method of v i s c o s i t y determination. Because of the constant formation of insoluble p a r t i c l e s i n the s o l u t i o n , on standing, and. the subsequent change i n concentration of the r e s i n , a method of concentration measurement had to be devised. The s p e c i f i c gravity, and the Hitrogen concentration, were both used as a measure of the concentration of the s o l u t i o n . However, the information given by t h i s procedure was so d i f f i c u l t to correlate with the other experimental data, that t h i s process was abandoned. Before impregnation, the solution was adjusted to pH 8. and the solution was warmed to 65°C and kept at.that temperature during the whole impregnation period. Rough preliminary experiments indicated that several species of B r i t i s h Columbia woods could be uniformly impregnated with dyestuffs. Since the chemicals.being used i n the unpolymerized solution were no larger than the dyestuffs i n molecular s i z e , i t was assumed that a f a i r l y uniform impregnation of these same woods by unpolymerized monamers would be possible. 3- The Impregnation Process. (a) Theoretical Considerations The flow of l i q u i d s under pressure through c e l l u l o s i c materials, depends l a r g e l y upon the square of the e f f e c t i v e radius and the e f f e c t i v e c a p i l l i a r y cross section. The average e f f e c t i v e c a p i l l i a r y radius was given by the equation developed by Stamm (23) as r - /TU41P. * l.gP i n which r a and 1. are the radius, and length, respectively, of a standard reference glass 18. c a p i l l i a r y , 1 i s the ef f e c t i v e length of the path thru the membrane,q i s th e . e f f e c t i v e c a p i l l i a r y cross section of the membrane,and P 0 and P are the pressure drops thru the standard glass c a p i l l i a r y , and the membrane, respectively, when connected i n se r i e s . The quantity q could be got from electroosmos measurements by use of the equation F- (300)2 4-ft 17 a E Kq " (300)2 , 4-ft -it E P.K. i n which i s t n e v i s c o s i t y , K.the d i l e c t r i c constant of the l i q u i d , E,the p o t e n t i a l drop over the section, P,the applied hydrostatic pressure, k ,the s p e c i f i c e l e c t r i c a l conductivity of the l i q u i d In the c a p i l l i a r y structure,and q,the e f f e c t i v e c a p i l l i a r y cross section. 'J* i s the streaming p o t e n t i a l . These relationships lead to the following equations for the flow of l i q u i d through wood: (1) i n the fiber d i r e c t i o n (2) i n the cross f i b e r d i r e c t i o n \ I P lr* i n which A m i s the f r a c t i o n a l cross sectional area of the swollen f i b e r c a v i t i e s , qx and q t are the ef f e c t i v e f r a c t i o n a l p i t membrane pore cross sections i n the longitudinal and transverse d i r e c t i o n . Q x and Q,t are the f r a c t i o n a l cross sections of the transient c e l l wall c a p i l l l a r i e s e f f e c t i v e i n the long i t u d i n a l and transverse directions. x4 rP and r„ are the average e f f e c t i v e r a d i i of the f i b e r c a v i t i e s , pit membrane pores,and transient c e l l wall c a p i l l i a r i e s , respectively; 1A ~Lf lp and 1„ are the average e f f e c t i v e f i b e r cavity length, average f i b e r length, average p i t membrane thickness,and average c e l l wall double thick-ness, respectively; and p^ and p*, are the pressure drops through the f i b e r c a v i t i e s and through the communicating opening. These'equations reduce t o (53,000 p / ) = (3.140.0007) p^; P / = 6 x 10"5 p^ for l o n g i t u d i n a l direction, and p* = 1.7 x 10~10 p^, i n the transverse d i r e c t i o n . 19. Then nearly a l l the pressure drop occurs through the p i t membranes,and for t h i s reason, the s p e c i f i c gravity of the wood i s a n e g l i g i b l e factor i n the flow of l i q u i d s through the wood.. The combined p i t membrane pore cross section,and the eff e c t i v e p i t membrane pore size,control' the treatment of wood with l i q u i d s under pressure. The large v a r i a b i l i t y of these values with d i f f e r e n t species of wood,and even with d i f f e r e n t annular rings on the same wood, accounts for the i r r e g u l a r l i n e of advance of a treating solution into the wood i n a l l three. s t r u c t u r a l d i r e c t i o n s . The resistance to longitudinal flow i s much less •than the resistance to transverse flow. Hence, penetra-t i o n treatments of wood are much more e f f e c t i v e i n the longi t u d i n a l than the transverse d i r e c t i o n . Hawley ( 8 ) showed that the penetration of the wood should increase as the square root of the v i s c o s i t y . of the treating s*olution,and as the square root of the applied pressure. In practise, the penetration seems to be more nearly proportional to the f i r s t power of the pressure rather than the square root. (b) Technological and Experimental Consideration of The Impregnation Process. • • The f i r s t factor to be investigated was the time pressure r e l a t i o n s h i p i n impregnation. The accompany-ing graphs, giving the tima;,versus percentage increase i n weight rela t i o n s h i p for three pressures, showed that after a time i n t e r v a l of 45 minutes, no further appreciable take-up occurred at any pressure. The pressures of 200 and 300 p . s . i . were much more e f f e c t i v e for impregnation than were pressures of 100 p . s . i . , and that the d i f f e r e n t i a l increase i n take-up i n going from 200 p . s . i . to 300 p . s . i . , was small. P a r a l l e l runs on Cottonwood, showed a marked s i m i l a r i t y i n the graphs. Pressures above 300 p . s . i . did not appreciably increase the solution take-up. Because of t h i s , i t was decided to use pressures of from 200-300 p . s . i . i n a l l impregnations. From experiments on the rate of impregnation, i t became evident that species of balsam, alder and cotton-wood, up to a thickness of one inch, could be completely impregnated i n one hour or l e s s at a pressure of .300 p . s . i . The depth of impregnation into the wood was f a i r l y e a s i l y followed by the use of phlosoglueinol aldehyde reagent,as suggested by Landshoff and Meyer (H ). Upon applying t h i s t e s t , a f a i r l y uniform impregnation appeared to have occurred. . 20. At f i r s t , a major problem i n the impregnation process was the warping of the samples during' impregnation. This d i f f i c u l t y was completely overcome by allowing the wood samples to absorb the solution f i r s t at low pressures (atmospheric or thereabout) for 10 minutes before subjecting them to the higher pressures. The e f f e c t - o f the concentration of the r e s i n i n the impregnating solution, on the r e s i n take-up of the wood, was next t r i e d . In the following table w i l l be found the average values for a number of runs i n which the r e s i n content was varied. Type of Wood No. • of Run D.M.U. Cone. % I n i t i a l M.C. ^ 2% Dry Wt. F i n a l Wt. M.C. on Drying ± 24 Dry Wt. a f t . Imp. % Resin Pickup (on Dry Wt.) Balsam B 1 109& 10% 238 672 6% 273 16.6 tt B 2 20$ 10% 230 689 6% 311 35.4 ti B 4 30$ 10% 236 707 6% 362 53.0 Cotton-wood C 6 1036 10% 193 652 6% 233 40.7 Tt C l l 20$ 10% 183 689 6% 264 44.2 ff 010 30$ 11% 205 693 6% 530 61.0 Alder A14 10$ 10% 264 760 6% 300 13.6 « A13 20$ 10% 261 695 6% 334 27.7 it A15 30% 100 264 724 6% 387 46.8 Each run consisted of 34 samples treated i n two p a r a l l e l impregnations. In a l l cases, the following factors were kept constant: (a) I n i t i a l pH of solu t i o n 8.0 (b) Temperature 65° C (c) Vacuum 30 minutes. (d) Pressure 5 minutes at 15 p . s . i . 5 » " 50 p . s . i . 60 » » 300 p . s . i . From the r e s u l t s of t h i s t a b l e , two things seemed obvious. 21. ( i ) The pick-up i n percent of o r i g i n a l dry weight of the sample seemed somewhat larger than the percent r e s i n of t h e . o r i g i n a l solution. This may have been due to a pr e f e r e n t i a l absorption of D.M.U. i n the i n t e r n a l wood structure,or i t may have been due to the D.M.U. blocking the escape of moisture from the center of the wood ,which fact would pass undetected by the moisture meter. .(.ii) The species tested, impregnated to di f f e r e n t extents-Cottonwood impregnated better than balsanuand a l d e r > and balsam impregnated be t t e r than alder. 4. The Drying of the Wood Samples After Impregnation. After impregnation, the excess s o l u t i o n was washed o f f with water, and the wood was placed i n the press to be dried by the high frequency f i e l d . Each charge of wood was so p i l e d i n the condenser arrangement i n the press, so as to have the dimensions equivalent to a previously calculated capacity. The capacity was e a s i l y calculated from the simple equation for a p a r a l l e l plate condenser C -0.225 K A (n-1) t where C i s the capacity i n m.m.f.; K,the d i e l e c t r i c constant; A,the area of the d i e l e c t r i c i n sq. i n . ; t ; t h e thickness of d i e l e c t r i c i n inches; and n,the number of:plates. The high frequency f i e l d , when turned on and tuned to zero resonance, would bring the temperature of the wood p i l e up to 90°C i n about 3 minutes. No s p l i t t i n g or checking occurred under t h i s treatment. The main d i f f i c u l t y here was due to arcing between the plates of the condenser. When the wood was p i l e d i n such a way as to have the re s i n channels of two pieces f a l l one above the other, the po t e n t i a l would b u i l d up around t h i s j o i n t u n t i l a discharge occurred across the condenser. Once th i s discharge occurred, i t was impossible to carry on with the heating, since the charred section through the wood served as a path for further discharges. The great wastage of samples, because of t h i s d i f f i c u l t y , made i t necessary to -feeve--, f i n a l l y , .have the drying af t e r impregnation done i n the experimental k i l n of the Forest Products Laboratory. It must be emphasized that the drying of the wood by the Radio Frequency f i e l d was most p r a c t i c a l . The wood could be dried from above 100$ M.C. to a 10$ M.C. i n about 3 hours. I f the s i z e of the charge was. not l i m i t e d by the size of the press, as was the case here, the thickness of the wood p i l e couid have been so increased as to minimize the e f f e c t of in d i v i d u a l pieces within the p i l e and thus eliminate' the arcing. -• When the wood was p i l e d between the condenser .plates and separated by 1/8" s t r i p s of wood, some decrease i n the arcing tendency was noted. I f the wood could be dried between condenser plates perpendicular to the wood p i l e , an e f f e c t i v e means of minimizing t h i s arcing may be the r e s u l t . . The k i l n drying of the wood after impregnation, was carried out by a standardized k i l n schedule i n an e f f o r t to bring the wood down to 5% M.C. 5. Curing and Pressing. The process of heating and pressing the impregnated woods involved the greatest number of d i f f i c u l t i e s to the whole problem. Since a high frequency f i e l d was to be used for heating, i t was essen t i a l that the material between the plates be a good d i e l e c t r i c . The use of metal molding forms then, was out of the question. The wood, on compression, spread out l a t e r a l l y , as was to be expected,when no such mold was used. Many materials were substituted for the metals i n an e f f o r t to f i n d some suitable d i e l e c t r i c material for the mold. Laminated phenolics, plywood, asbestos board, and s o l i d compressed wood, a l l were tried,but none were s a t i s f a c t o r y . With the accumulation of moisture on the material, arcing invariably resulted,. Once an arc occurred, the mold had to be discarded as useless. When the wood being heated had a M.C. above 10%, arcing also occurred down the ends of the sample. However, with moisture contents below 10%, arcing occurred only occasionally. Attempts to heat and press the wood simultaneously, were notably unsuccessful. The pressure built' up so greatly at the center of the sample with the heating unit i n operation, that the wood sample exploded outwards from the press and shattered. This fact was believed due, i n part, to the very high temperatur'e within the sample, as a r e s u l t of both the R.FI. f i e l d and the exothermic polymerization reaction. It was then decided to heat the wood f i r s t then press i t i n the absence of the R.F. f i e l d . When the wood was heated up to 120°C i n the heater, the temperature, during the subsequent pressing,maintained 23. i t s e l f at about 140°C. This temperature gave the best apparent r e s u l t s for the curing and pressing operation. The pressing schedule used with the temperature of 140°C to give the best sample,from the standpoint of appearance, was: 2 minutes 50 p . s . i . • 2 " .100 " 2 » 200 " 2 " 300 " 2 " 400 " 5 M 1000 *' 5 " maximum pressure- about 1900 p . s . i , On cutting samples which had been cured at temperatures•above 140'C, i t was found that the center portions of the samples were .badly charred. The product was of a very daifcappearance, and was very b r i t t l e . I t was most d i f f i c u l t to read the temperatures of the samples when the R.F. f i e l d was on. The Thermocouples had to be disconnected,and the time necessary to reassemble t h i s unit, was usually,long enough t o i n t e r f e r e with the heating process.IDuring the pressing, however, the thermoscouples were•inserted and the temperature checked. The ef f e c t of conduction of heat from the R.F. platen was appreciable during these runs. The temperature of the wood at the center of the p i l e , next to the R.F. platen, was nearly always about 10°C higher than the rest of the p i l e . This was minimized by placing t r a n s i t e board on either side of the R.F. platen. The use of the Radio Frequency Heater made the p l o t t i n g of accurate, curing curves most d i f f i c u l t . XIV THE PRODUCT ARISING FROM THE IMPREGNATION OF • OF SOFTWOODS BY DDIETHYLOL UREA The f i n a l product after impregnation, heating, and pressing, was not appreciably darker i n colour than the natural wood. The treated wood showed, occasionally, warping to a marked extent. The 3/4" • wood compressed to 3/8" during the treatment. Because of the lack of.an adequate die, the edges of the pieces were usually somewhat s p l i t and spread out, as a r e s u l t of compressing with no l a t e r a l support. 24. The wood product did not respond s a t i s f a c t o r i l y to treatment with ordinary hand t o o l s . Sections cut from the o r i g i n a l treated pieces, showed marked s p l i t t i n g o f f of the fibers,along the l i n e of the cut. Machine handsaws, however, did not leave such a s p l i t cutting l i n e , the cut was neat and clean. The treated wood did not plane e a s i l y . Power planers were necessary to get a clean surface. Upon t r y i n g to drive n a i l s through the product, the treated wood showed marked resistance to the penetration of the n a i l , and usually s p l i t i n the lon g i t u d i n a l d i r e c t i o n soon after the n a i l started to penetrate the sample. The surface of the sample could not be marked by the finger-n a i l and only s l i g h t l y with common f i n i s h i n g n a i l s . In the following table, w i l l be found the average r e s u l t of the tests on some of the fi n i s h e d prpducts. Many of the samples sent for te s t i n g , f a i l e d before maximum tes t conditions were reached. Many other samples i n the runs were rendered unusable by 'the arcing, but the remainder were subjected to the t e s t s , as indicated below: Run No. M.C. fo S.G. Hardness Tension p . s . i . Izod Impact, f t . / l b s . A-201 7.8 0.97 2280 . 8958 -19683 8.9 A-202 7.7 0.97 2470 17861 7.6 A-203 7.7 1.08 2365.. 16804 8.1 B-100 7.5 0.92 3104 26157 8.5 B-101 7.6 1.03 2117 8.43 B-109 8.0 0.98 1725 18450 7.5 B-210 7.3 0.98 1620 14360 6.2 C-16 8.0 0.95 1656 5.3 BU 8.0 0.99 . 2492 29200 16.0 • The A runs were for D.M.U. r e s i n of 10%,20%,30% concentration i n the s o l u t i o n i n that order, the wood being &lder. The B runs were for Balsam. The concentration of the D.M.U., being 10%,20%,30% and 40% ' i n that order. The C runii was Cottonwood, 30% r e s i n content. The BU run was Balsam, 30% r e s i n content. The conditions were the same as for the table on page 20. The tests performed on the completely treated samples showed no c o r r e l a t i o n "between the treatment they had received and the value determined for a d e f i n i t e property. For the most part t h i s was due to f a i l u r e i n the speciman before maximum load was applied. For example, consider the average hardness values determined for a large number of treated alder samples. Hardness of natural alder 1 (arbitrary). " " unimpregnated compressed alder..7 " " alder compressed containing 15$ r e s i n . . . .6.5 " " " " " 28$ » ....5 " " " » » 40$ " • 5.5 This random v a r i a t i o n i n hardness values: was much more evident i n i n d i v i d u a l samples which contained equal r e s i n percentages and were subjected to. the same treatment. A large part of the v a r i a t i o n may be accounted f o r by s p l i t t i n g of the samples while undergoing t e s t s . This lack of c o r r e l a t i o n was also evident i n the other tests performed. These included t e n s i l e strength and impact strength, the values for which,varied i n no reasonable way either with r e s i n percent or with curing temperature. The s p e c i f i c gravity of the treated wood increased i n a regular manner with increase i n percentage r e s i n , but at no time, did i t approach the t h e o r e t i c a l maximum, 1.4, for wood and r e s i n . In general, the strength properties of the impregnated and compressed samples were greater than those of untreated wood but i n many cases this.could have been brought about by compression alone. The water absorption experiments showed a l i t t l e more r e g u l a r i t y i n the values obtained. For large differences i n r e s i n content, there was a marked change i n the amount of water absorbed. The following shows the average increase i n weight of alder after 24 hours of complete immersion. The samples which had a l l been compressed under the same pressure returned to t h e i r o r i g i n a l dimensions. Unimpregnated Compressed .136$ Impregnated & Compressed containing 15$ r e s i n 110$ Impregnated & Compressed containing 28$ r e s i n 80$ Impregnated & Compressed containing 40$ r e s i n 58$ These values although showing a decrease with increase i n r e s i n percent are s t i l l far too high for the product to be of any p r a c t i c a l value. No co r r e l a t i o n was found betwe.en the curing temperature and any of the t e s t s performed. 26. XV GENERAL SUMMARY From the work done on t h i s project, i t would seem that no great d i f f i c u l t y i s offered by the impregnation process. The main d i f f i c u l t i e s arose i n the heating and pressing of the impregnated samples so as to form a stable product. The f i b e r s of the wood were not bound i n t h e i r compressed state and so,when immersed i n water, the samples r e a d i l y absorbed water and returned.to t h e i r o r i g i n a l uncompressed state. The increase ./in the mechanical properties of the treated wood could be explained by the compression alone. The physical tests c a r r i e d out on the samples indicated that the treatment was not j u s t i f i e d i n the product. Two possible reasons f o r the i n e f f i c a c y of the Dimethylol Urea would be: (i ) The. concentration of the natural acids of the wood was not s u f f i c i e n t l y high to c a t a l i z e the polymerization of the Dimethylol Urea. ( i i ) On polymerization, the r e s i n did not combine with the c e l l u l a r material and as a consequence had no binding action on the f i b e r s . XVI CONCLUSIONS Dimethylol Urea r e s i n has been found to be rather unsatisfactory for the impregnation of bulk wood. The: dimensional s t a b i l i t y of the product was not appreciably increased. The expense involved i n producing a truly hardened, s a t i s f a c t o r y product, using t h i s r e s i n , would be high. Because of the unsatisfactory r e s u l t s of t h i s work, i t was decided that future work would employ the Phenol Formaldehyde.type r e s i n as the impregnant. This type r e s i n i s known to beimuch more s a t i s f a c t o r y chemical for insuring dimensional s t a b i l i t y i n wood. - o 0 o -27. BIBLIOGRAPHY 1. Berliner, J .F .T . Extracts from an address on '(Chemically Transmuted Wood". C.I .L. Pain. 2. Bernhard, R.K., & Perry, T.D., & Stern, E.G. Mech. Eng. 62 189, (1940). 3. Brajnikoff, B .J . Ind. Chemist-6 502 (1930). 4. Browne, P.L. Ind. & Eng. Chem. 25 835 (1933). 5. Casselman, R. Mech. Eng. 65 737-748 (1943). 6. Esselen, G.J. U.S. Pat. 1,952,664 (1934). 7. Georges,- Irsay de Irsa British Pat. 543,401 Feb. 24, 1942. CA 36 4690. 8. Hawley, L .F . U.S. Dept. of Agric. Tech. Bull £48 - (193177 .9. Huber, R. Ger. Pat. 732,284. Jan. 28, 1943. (C1.38h 2.01). 10. Hunt, G. M. U.S. Dept. of Agric. Cir. 128 (1930). 11. Landshoff & Meyer, Pr. Pat. 800,712. July 17, 1936. CA. 31 238. 12. Nowak, Alf . Uaschau. 43 840 (1939) CA. 36 3925. 13. " " Aust. Pat-. 156108. Oct. 5, 1939. CA. 33 5626. 14. " " Chem. Zent. II 2552 (1942). CA. 38 3105. 15. Nowotny, Z. Angew. Chem; 41 46 (1928) CA. 23 496 (19297. Oesterr. Chem. Ztg. 27 188 (1924) CA. 5 3507. 16. Olsen, A.G. U.S. Pat. 1,981,567. (1934) 17. Russian Pat. 35,141 March 31, 1943. CA.SO 2725. 18. Sanna, Brit . Pat. 311,227. CA. 24 942 (1930) 19. Shishkov, J . App. Chem. (U.S.S.R.)8 1043.(1935) 28. 20. Stamm, A. J . J.A.C.S. 56 1195. (1934). 21. " " Ind. Eng. Chem. 27 401 (1935). . 22. " " U.S. Dept. of Agric. Use . Pub. 240 (1936). 23. " " J . Agric. Res. 38 23 (1929). 24. " " & Hansen, L.A. Ind. Eng. Chem. 27 1480 (1035). 25. " " " " » Ind. Eng. Chem. 29 .831 (1937) 26. " " & SeUa-g, ii.M. U.S. Dept. of Agric. Forest Ser. Pam. Forest Prod. Lao. kadison, wis. Oct., 1936. 27. " 11 & Seborg, R.M. Ind. Eng. Chem. 31 897 (1939). 28. 11 " " " " Ind-. Eng. Chem. 28 .1164 (1936). 29. " " " " Trans. Amer. Inst, of Chem. Eng. 37 (3) 385 (1941).. 30.. " " " Sehorg, R.M. Mech. Eng. 63' 211 Tl94l). 31. " " " "• " U.S. Dept. of Agrie. Forest Ser. Bui. R 1213 Dec.(1938). 32. Walsh, F.L.& Watts, R.L. U.S. Pat. 1,465,383 (1923). 33. "Wood Chemistry" Lewis E . Wise, Editor, Page 493 Aig.S. Monograph #97 Reinhol.d Pub. Co.-34. "Wood Chemistry" Lewis E . w£se , 'Editor , Page 494 A.C.S. Monograph #97 Reinhold Pub. Co# . 35. Wood, Wm. U.S. Pat. 1,738,15a CA. 24 942' (1930). THE PREPARATION OF METHYL TRIMETHYLOL METHANE TABLE OF CONTENTS I PURPOSE Page 1 I I HISTORICAL " 1 I I I THEORETICAL CONSIDERATIONS " 1 17 THE PREPARATION OF METHYL TRIMETHYLOL METHANE » 2 (a) Methods of Preparation Employing Metal Oxides as the Basic Catalyst. " 3 (b) The Use of Buffered Medium and a Solution of Base. " 5 7 CONCLUSION " 8 BIBLIOGRAPHY " 10 ABSTRACT. Attempts to improve the efficiency of the condensation between Formaldehyde and Proprionaldehyde to form Methyl Trimethylol Methane in the presence of a calcium oxide catalyst, proved unsuccessful. An alternate method for the preparation of this compound by carrying out the condensation in a buffered aqueous medium using sodium hydroxide, has been developed. This latter method gave slightly, greater yields. 1. THE PREPARATION OF METHYL TRI^IETHYLOL METHANE I PURPOSE The purpose of t h i s research on the preparation of the alcohol Methyl Trimethylol Methane (2 hydroxymethyl, 2 n i t r o , 1.3 propandiol), was to develope a more e f f i c i e n t method of production of the alcohol., The n i t r a t i o n of the alcohol, for i t ' s possible use, as a m i l i t a r y explosive, could be accomplished i n good y i e l d s . No attempt was made to increase the e f f i c i e n c y of the n i t r a t i o n . This report confines i t s e l f s o l e l y to the methods of preparation of Methyl Trimethylol Methane. II HISTORICAL The f i r s t preparation of Methyl Trimethylol Methane (M.T.M.M.) was reported i n 1893 i n Justus LUfoig's Annalen d i r Chemie 4. In t h i s procedure the condensation of the Formaldehyde and Proprionaldehyde was car r i e d out i n the presence of Calcium oxide as the basic catalyst and at a temperature of 1Q0 C. This method was found'by Cooper, O'Neill, and Clark to be unsatisfactory for commercial production. Further work was car r i e d "out by Von Herz 3 i n 1927 and l a t e r by Brubaker and Jacobsonl on the synthesis of M.T.M.M. Both these groups of workers used Calcium oxide as the condensation catalyst and varied only the temperature and methods of extraction of the crude product, from the procedure of Lttbig's Annalen. The present method of Clark and Metcalfe 5 i s s t i l l e s s e n t i a l l y the same as the o r i g i n a l with again only the conditions and methods of extraction and r e c r y s t a l l i z a -t i o n a l t e r e d . I I I THEORETICAL CONSIDERATIONS The condensation between the formaldehyde and Proprionaldehyde consists of two reactions, the a l d o l condensation of Formaldehyde and proprionaldehyde to form 2, 2 dimethylol proprionaldehyde 0H20H i CH 3CH 2C*° - H + 2 H-C*° - H CH 3 - C - C*° - H CH20H and the reduction of the carbonyl group to the primary alcohol by the Formaldehyde through the mechanism of the Crossed Cannizzaro Reaction, to form M ethyl Tr-imethylol Methane. CHpOH CH20H GH3-G-C-H + H-CH+HgO -*• CHg-C-CHgOH + H-C-OH CH OH CH OH The a l d o l condensation i s brought about because of the peculiar a c t i v i t y imparted to the hydrogen atoms on a. carbon atom, by the presence of the carbonyl group on an adjacent carbon atom. This a c t i v i t y has been found, however, to be lessened i f an a l k y l group i s linked to the carbon atom to which the active hydrogens are joined, and the a c t i v i t y i s known to decrease as t h i s a l k y l group increases. The hydrogen atoms of proprionaldehyde, because of the small methyl group attached, do not have thei r a c t i v i t y greatly modified, and can undergo f a i r l y r e a d i l y the a l d o l condensation with Formaldehyde. The Cannizzaro Reaction i s possible when the a l d o l • condensation, which i s thought to go at a higher rate, has caused the hydrogen atoms to be replaced with methylol groups. The new aldehyde so formed reacts as a t e r t i a r y aldehyde and undergoes the crossed Cannizzaro Reaction, Certain side reactions may e a s i l y take place which cause appreciable reductions i n the y i e l d s of M.T.M.M., and make the extraction and r e c r y s t a l l i z a t i o n of the crude product most d i f f i c u l t . The chief side reaction i s probably the formation of formaldehyde sugars a r i s i n g from the condensation of formaldehyde molecules i n the presence of an al k a l i n e condensation c a t a l y s t . Linear a l & o l i z a t i o n of proprionaldehyde and formaldehyde may also occur and cause the formation of aldehyde r e s i n s , thus: *0 «0 0^H <*0 JO CH3-CH2-C -H + H-C -H CH3-CHg-CH -C - H + H-C -H Furthermore,the p o s s i b i l i t y of the proprionaldehyde condensing with i t s e l f i n an al k a l i n e medium again with the formation of al d o l r e s i n s , must not be overlooked. The formation of these syrups and resins are very d i f f i c u l t to avoid since the conditions f o r t h e i r formation very cl o s e l y approximate those conditions for the production of M.T.M.M. I t i s the formation of these polymeric side products which has imposed an upper l i m i t to the p r a c t i c a l y i e l d obtainable by the condensation. THE PREPARATION OF METHYL TRBffiTHYLOL METHANE The preparation of Methyl Trimethylol Methane has, for the pnrpose of t h i s report, been divided i n t o two general 3. procedures. F i r s t , i s considered preparations using metal oxides suspended i n an aqueous medium as the condensation catalyst, and as a means of n e u t r a l i z i n g the formic acid a r i s i n g from the Cannizzaro Reaction. Secondly, the procedures involving the use of a buffered aqueous medium, and aqueous solutions of base, are considered, wherein the solution of base i s added to the buffered reaction medium as required to keep the pH constant. A. Methods of Preparation Employing Metal Oxides as the Basic Catalyst. 1. Procedure of Clark & Metcalfe 5 The method of Clark and Metcalfe was taken as the most promising preparation. Into a 3 l i t e r f l a s k were placed 1.5 moles of propionaldehyde and 4.5 moles of formaldehyde (40$ so l u t i o n ) . Ice was then added to produce a volume of 3 l i t e r s when 42 grams CaO were added slowly with shaking. The mixture was' allowed to stand at least 16 hours and then heated for about 1 hour at 50°C i n a water bath u n t i l the reaction was completed, as shown by the appearance of a pale yellow color i n the. reaction mixture. Upon completion of the reaction, the calcium was pr e c i p i t a t e d by the dropwise addition of'hot oxalic acid. The calcium oxalate was removed by f i l t r a t i o n and the f i l t r a t e evaporated at a temperature of 50°C and a pressure of 10 mm. u n t i l the water was removed. The syrup was allowed to s o l i d i f y - and the r e s u l t i n g mass was c r y s t a l l i z e d from 1.4 dioxane. Repeated c r y s t a l l i z a t i o n , i f necessary, y i e l d s a product melting at 199°C. Using t h i s method, the control runs, two samples of which are outlined i n Table I,were made before any modifications to the procedure were.introduced. TABLE I Propanal. Formaldehyde CaO ?/ater Time Y i e l d M.P. Gms. Mol. ' Gms.. Moles Gms. L i t e r s Hrs. 1o C 87. 1.5 135 4.5 42 3 17 60.5 198.1 87 1.5 135 4.5 42 3 20 61.0 198.7 In an attempt to r a i s e the melting point of the product, as suggested by Metcalfe, Mann, and C l a r k 5 , the c r y s t a l s were refluxed with 1$ H pS0 4. No appreciable increment i n the melting point wis observed. This condensation procedure of Clark and Metcalfe was then subjected to numerous modifications as outlined. 2. Modifications of the Procedure of Clark and Metcalfe (a) Temperature. The procedure of Clark was followed i m p l i c i t l y with the exception that d i f f e r e n t reactions were allowed to proceed at constant temperatures near 0°C, 20*C, 35-40°C and 50* C. At temperatures near 0*C,free formaldehyde was e a s i l y detected i n the aqueous d i s t i l l a t e , a f t e r the concentration of the product from the aqueous reaction medium. A white product formed on the walls of the condensor consisting apparently of paraformaldehyde. The y i e l d of M.T.M.M. was very poor. Lengthening the period of condensation did not appreciably increase the y i e l d . At room temperature, approximately 20*C, the y i e l d s were quite i n keeping with the r e s u l t s of Clark and Metcalfe. Temperatures i n the range 35-40°C gave approx-imately the same re s u l t s as f o r 20*C. No increase i n a syrup formation was noted. When temperatures of 50°- 55°C were t r i e d the formation of syrups was most pronounced. The reaction medium became a dark golden brown colour, which increased i n i n t e n s i t y as the d i s t i l l a t i o n of the water was carr i e d out. The f i n a l product was a brown syrup from which only a small y i e l d of poor quality brown coloured c r y s t a l s was secured. R e c r y s t a l l i z a t i o n from 1.4 dioxane, did not greatly improve the q u a l i t y of the product because of the high contamination by the syrup. The following table shows the r e s u l t s of t y p i c a l runs. 1.5 moles of proprionaldehyde, 4.5 moles of formaldehyde, 42 gms. of CaO i n 3000 ces. of water were the concentrations used, and the reactions were allowed to proceed for 18 hours. . TABLE II Temperature Y i e l d • M.P. 0"C 20° C 35"- 40" C 50° C 18$ 61$ 60.3$ less than 8$ 191° C 198* C 198° C (b). Catalyst. The calcium oxide was replaced by magnesium and 5 barium oxides i n the procedure of Clark and Metcalfe, but neither of these two were successful as condensation cat-a l y s t s . Magnesium oxide gave only sweet smelling syrups .and no c r y s t a l s of M.T.M.M. Barium oxide gave high y i e l d s of syrups,from which a small y i e l d of crys t a l s of very low pu r i t y could be i s o l a t e d . The melting point of these cr y s t a l s was 1 7 0 °C. (c) Removal of Calcium Salts before Concentration. Since considerable formation of syrup occurs during the concentration of the M.T.M.M. from the aqueous medium, i t was thought that some method could be found of pr e c i p i t a t i n g the calcium which would give a minimum of syrup formation i n the subsequent heating. Hot saturated o x a l i c acid, d i l u t e , (6 W.), sulphuric acid, and carbon dioxide gas were compared i n p a r a l l e l runs i n which the concentration of the reagents was the same as i n Table I I . -It was found that hot oxalic acid was the most e f f e c t i v e method of removing the calcium s a l t s . Sulphuric acid was almost as good. Carbon dioxide was comparatively poor since much syrup formed during the d i s t i l l a t i o n , w h i c h contaminated the c r y s t a l s of M.T.M.M. very badly. TABLE II I P r e c i p i t a t i o n Agent Y i e l d M.P. H 2 S 0 A 6- N -Oxalic (hot sat.) co 2 5 8 $ 6 1 $ Heavy syrup 1 9 8 : 4 ° C 1 9 8 . 8 ° C B. The Use of Buffered Medium and a Solution of Base. Both sodium acetate and sodium oxalate were employed as buffers. 1 . Sodium Acetate as Buffer The f i r s t runs using a buffered medium and a solution of base, employed sodium acetate as the buffering agent and calcium hydroxide as the base. The y i e l d s , though sometimes good, were very inconsistent and the formation of syrups resulted i n poorer quality products. Sodium acetate was therefore, abandoned fo r sodium oxalate as the buffering agent. 6. 2. Sodium Oxalate as Buffer. Oxalate has been shown to have the a f f e c t of i n h i b i t i n g the formation of syrups i n the condensation of formaldehyde and nitroalkanes°. Sodium oxalate was chosen as a buffering agent i n the M.T.M.M. condensation,in the hope that i t would act as an i n h i b i t o r of syrup formation i n t h i s reaction. (a) Apparatus The apparatus consisted of a f i v e l i t e r round bottomed f l a s k f i t t e d with a rubber stopper, and set i n a water bath heated by a conical heater. A mercury seal with a small glass propeller attached was mounted on the stopper and connected to a variable speed motor. A 500 cc. separating funnel, on a glass connection, was also mounted i n t h i s stopper. A small hole was l e f t i n the rubber stopper to provide an a i r outlet,as the volume of l i q u i d i n the fl a s k was increased. A circulating* system, to an outside reservoir, had to be devised for the purpose of taking the pH, since the electrodes could not be introduced conveniently, d i r e c t l y into the reaction medium. This system consisted of two 8 mm.glass tubes passed through the stopper. The f i r s t l e d to the bottom of the reaction flask,and served to draw the reaction medium from the f l a s k to the small glass res e r v o i r . The second terminated just below the rubber stopper and served to return the l i q u i d from the reservoir, by means of a small monelmetal c i r c u l a t i n g pump,to the reaction vessel. The two electrodes of a Beckmann Model M pH Meter were mounted i n the rubber stopper of the rese r v o i r . (b) Procedure 116 grams (2 moles) of proprionaldehyde and 180 grams (6 moles) of formaldehyde (40$ formalin solution) were placed i n the fi v e l i t e r f l a s k . The volume of l i q u i d was then made up to two l i t e r s with water. S u f f i c i e n t sodium oxalate was then added to make the f i n a l concentration of th i s s a l t . 7.5 gms per liter,when a l l the solution of base was added. A trace of CaO was then added. The c i r c u l a t i n g system and the s t i r r e r were started and the temperature of the reaction mix brought to 35°C. The pH was brought to pH 9.3 with NaOH. 2 moles of NaOH i n solution of the desired concentration were added dropwise to keep the pH constant. This addition was usually complete after 60 hours. After a l l the NaOH was added, the water bath was rai s e d to 50° C for two hours. The solution was then made aci d to approximately pH 3- with oxalic a c i d . The water was d i s t i l l e d o f f at 34* C and 12 mm-pressure. The M.T.M.M. was extracted from the dry sa l t s by re f l u x i n g with 1.4 dioxane 7. present i n excess. The excess 1.4 dioxane was then d i s t i l l e d o f f i n vacue. The M.T.M.M. was allowed to c r y s t a l l i z e out, and the crys t a l s were secured i n a sintered glass f i l t e r . Further d i s t i l l a t i o n , i n vacuo,of the dioxane solution yielded more c r y s t a l s . These crystals.together with those a r i s i n g from again extract-ing the sodium formate residue with dioxane and reconcen-t r a t i n g , were then washed by suspension i n ether. .This crude product was then r e c r y s t a l l i z e d from dioxane.,re-washed i n ether,and dried. (c) Observations By t h i s procedure, a.product p r a c t i c a l l y free from a l l syrup could be prepared. The solution was colourless, or only s l i g h t l y yellow,before concentration, and,provided the mixture was acid before d i s t i l l a t i o n , i t would remain colourless, y i e l d i n g only a white s o l i d when dry. I f , however, the d i s t i l l a t i o n was carried out frem a neutral or basic medium the formation of syrups was soon noticeable and a dark brown s o l i d would be l e f t . The trace of CaO noticeably improved the y i e l d over runs i n which no CaO was added. The concentration of the NaOH had an a f f e c t upon the y i e l d . The use of 6 N NaOH made the c o n t r o l l i n g of the pH most d i f f i c u l t and the s o l u t i o n often became too basic. When too much base was present, syrup formation was again noticeable. 3 N. NaOH gave s l i g h t l y smaller y i e l d s than when 1 N NaOH wan used. This may i n part be due to the d i l u t i o n factor but one run i n which 3 N NaOH was used was diluted before the complete addition of the NaOH so that the f i n a l volume of the reaction was f i v e l i t e r s . This run showed no increase i n the y i e l d of M.T.M.M. but rather a s l i g h t decrease, probably due to the increased time of d i s t i l l a t i o n . The condensation takes place without any appreciable v a r i a t i o n i n y i e l d from a pH of 8.7 to one of 12.5. Below t h i s range the presence of much free formaldehyde after three days, and the r e l a t i v e l y poor y i e l d , i n d i c a t e d that the reaction had not gone to completion. Above pH 12.5 the formation of syrups increased and a poorer product resulted with a lowered y i e l d . (d) Exp er iment a l The r e s u l t s of some t y p i c a l runs car r i e d out using t h i s method are tabulated i n Table IV. 8. TABLE IV Propanal. Formald. F i n a l Volume L i t e r s Cone. NaOH Time Yield M.P. 1. 116 gms(2moles) 180 gms (6m) 2.4 6 N 48 hrs 50$ 194° C g n « ft 11 ti it 2.8 3 N 60 tt 54$ 196° C 3. n " n ft it 11 5.0 3 N 60 48$ 197" C A_ i i rt it it M 11 4.0 1- N 48 rt 55$ 198° C 5. n n n t i 11 it 4.0 1 N 60 n 60$ 198° C 6. "' " " tt it n ' 4.0 1 N 60 it 66$ 198°. 8 C 17 ft ft tt n it 4.0 1 N 60 ft 65$ 198° C In runs #6 and #7 a trace of CaO had been added. In a l l others.no CaO was present. (e) Alternate Procedure for the Preparation of Methyl Trimethylol Methane. 2 moles of proprionaldehyde, and 6 moles of formaldehyde are added to s u f f i c i e n t water to make a f i n a l volume of two l i t e r s . 30 gms. of sodium oxalate are then added. The solution i s warmed to 35°C. The pH i s brought to pH 9.3 with 6 N NaOH. 80 gms of NaOH are then dissolved i n 2 l i t e r s - o f water (1 N solution) and t h i s solution i s added dropwise to the constantly agitated mixture,so that the pH can be kept constant. This addition takes approximately 60 hours. When a l l the NaOH i s added the solution i s warmed for 2 hours at 50° C. Then warm oxalic a c i d (saturated) i s added to the reaction medium to bring the pH to pH 3. A l l the water i s then removed by vacuum d i s t i l l a t i o n . The alcohol i s then extracted from the s o l i d residue by r e f l u x i n g with excess 1.4 dioxane, the excess then removed by vacuum d i s t i l l i n g , and the c r y s t a l l i z a t i o n i s then allowed to take place. More cry s t a l s may be obtained by further extraction of the s o l i d residue with dioxane, and by further evaporation of the f i r s t dioxane f r a c t i o n . The crys t a l s are thenwashed with ether, r e c r y s t a l l i z e d from dioxane, rewashed with ether,and dried. V CONCLUSION The procedure of Clark and Metcalfe, when subjected 9. to varying conditions of time and temperature, to di f f e r e n t types of catalysts, and to d i f f e r e n t catalyst p r e c i p i t a t i n g agents, f a i l e d to give a higher y i e l d of Methyl Trimethylol Methane. Methyl Trimethylol Methane could be,prepared by the condensation of proprionaldehyde and formaldehyde i n a sodium oxalate buffered,aqueous medium. S u f f i c i e n t NaOH to complete the Cannizzaro Reaction.when made up as a one normal solution and added dropwise to keep a constant pH value,and further, a trace of CaO,served to give the best r e s u l t s i n y i e l d . Yields s l i g h t l y i n excess of Clark and Metcalfe, were obtained by t h i s method. - o 0 o -10. BIBLIOGRAPHY 1. Brubaker M.M. and Jacobson R.A., C A. 37_, P.890 U.S. pat. 2,292, 926, Aug. 11 . 2. Clark, R.A., Cooper W.C., and O'Neill, A.N., War Research Problem XR-35, A p r i l 1943. 3. Von Herz, Edmund, CA. 23, P. 3346, Ger. 474, 173 Oct.6, 1927. 4. Liebigs Annalen d i r Chemie 276. 1893 5. Metcalf, S.W. Mann, J.H., and Clark, R.H., War Research Report XR-35 A p r i l 1944. 6. Wyler, J.A. U.S. Pat. 2,231, 403, Feb. 11, 1941. 

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