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The solubility of certain inorganic salts in ethyl acetate Boss, Arthur Evan 1923

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1^13-Aar ' 6 6 - S 6 e Solubility of Certain rganic Salts yl Acetate hur Evan Boss THE SOLUBILITY OP CERTAIN INORGANIC SALTS IN ETHYL ACETATE by ARTHUR EVAN BOSS. V A Thesis submitted for the Degree of MASTER OE ARTS in the Department of CHEMISTRY. THE UNIVERSITY OE BRITISH COLUMBIA. A p r i l , 1 9 2 3 . TABLE OE CONTENTS. INTRODUCTION. PREVIOUS WORK. EXPERIMENTAL: Constant Temperature Bath. Plate 1. filtering Device. Standardization of Apparatus. PREPARATION OE THE SOLVENT. PREPARATION OE THE SALTS. PROCEDURE. RESULTS. sum AR^ . Solubility of certain inorganic salts in ethyl acetate. INTRODUCTION The object of the present investigation was to determine the solubility of several salts in ethyl acetate.lt was thought that any data obtained would be useful in working out a theory of solution in general, and would specifically be of importance in analytical chemistry.While the greater number of the separations in quantitative analysis are now carried out in water solutions, the convenience of using organic solvents is becoming more and more evident,but before any systematic procedure can be drawn up a great deal more of reliable data as regards solubilities in the more common organic solvents will have to be deter-mined. Unfortunately the greater number of such deter-minations which have been carried out have been done with solvents the composition of which was not well defined, particularly as to water content.Instead of being anhydrous, such solvents have often contained as m<JChat five percent of water.It was thought that if,in the (2) present investigation, particular attention was paid to having pure liquids and every precaution taken to eliminate water, the data obtained would "be reliable and could "be used for the purposes outlined above. PREVIOUS WORK. Previous work has been done on this subject by A.Naumann (Berichte d.Deutsch. Chera. Gesellschaft, 1904,37,3602) who investigated qualitatively the solubilities of a large number of salts in ethyl acetate.However, as his method of purifying the ester, drying over calcium chloride and then distilling over sodium,is known to be faulty, a great deal of reliance cannot be placed in his results. (The calcium chloride will not completely dry the ester (Wade, Trans. Chern. Soc. London, 1905, I656)and will not remove ethyl aloohol, the most frequent impurity. Treatment with sodium will, if any water is present,cause the formation of sodium hydroxide and hydrolysis of the ester to alcohol and acetic acid, also some acetoacetic ester will be formed, giving an impure product. ) Furthermore he reports potassium permanganate as soluble, and in the present investigation it has been shown that potassium per-manganate is insoluble in absolute ethyl acetate,as it is in absolute ethyl alcohol(Allen's Commercial (3) Organic Analysis,Vol. 1, 110.P.Blakiaton's Son & Co., Philadelphia, publishers)In fact, potassium permanganate can toe used as a test for the absoluteness of the ester,in the same manner as it is commonly used as a test for absolute ethyl aicohol.lt is evident, then, that Haumann did not have water-free ethyl acetate. In a later paper (Berichte etc., 1910, 313)Naumann reports the use of ethyl acetate which distilled at 74. 5*0. at a pressure of 7 50 mm. The boiling point of ethyl acetate has been determined as 77.1° - 77.15* at 7 60mm. pressure. (Beilstein, 1893, p. 407;V/ade, loc. cit.; Wade and Merriman, Trans. Chem. Soc., London, 1912. 101. 2429). In the present investigation it was observed that a fraction of the ester distilled at 72. 5*-74. 5*; this was assumed to be a ternary mixture of ethyl acetate, ethyl alcohol, and water(cf*Wade, loc. cit,, and Preparation of Solvent,this paper.)lt is thus apparent that in this case also ITaumann used impure ester. Some work has also been done on the solubility of mercuric chloride in ethyl acetate.The various investigators,however, fail to describe their methods of preparing the ester.Lazczynski(Berichte etc.,1894, 27_, 2286) gives the value at 20* as 29.6 gr.mercuric chloride soluble in 100 gr.ester(interpolated from (4) his results)Linebarg;er (Am. Chem. J.. 1894,16. 214) gives the solubility of mercuric chloride at 20* as 15.93 mol3 of mercuric chloride to 100 mols of ethyl acetate, or 49.11 gr.per 100 gr. Etard(Annales de Chem. et Phys., 1894, (7), 2, 557)gives the value of 40.25^ mercuric chloride in saturated solution at 20°,Herz and Anders (Zeit.anorg. chem., 1907, 52, 17 2) gives the solubility at 25*as 9.7 5 grams of mercuric chloride in 100 grams of ester.It is apparent that there was a wide discrepancy in the purity of the samples of ester used "by these various investigators. EXPERIMENTAL The temperature chosen for the investigation detailed below was 20"C.Eor the purpose of maintaining the solutions at this temperatuee they were immersed in a large water bath,heated by a carbon filament lamp and controlled by a chloroform expansion,mercury column thermostat. The bath was fitted with a rack which served to hold the flasks or test-tubes containing the solutions and which on rotation not only agitated the solutions but also stirred the bath, keeping the temp-erature uniform throughout. The rack was rotated by means of a small electric motor.(Plate 1.) To separate the saturated solution from the /6 (° \o ® "5" • o *-— » -0\ o 0/ R. Section " B R " Constdnf Temperature Bath. *J 11 j ) Lamp. H » — 11 »ovo/fs,A.C Temperature Confroj . "\_ 1X3 Pipette with Rlfen'ncj Device . (5) excess salt it was found necessary to use a filtering device as shown on plate 1.A piece of glass tuMng of suitable length and "bore was slipped over the lower end of the pipette.A tight joint was made at upper end "by slipping a piece of rubber tubing over both, A filter paper was folded over the lower end of the tube and securely wired in place.The solution had to pass through the filter to enter the pipette.The device was at once simple and effective. The thermometer used in determining the temperature at which the ethyl acetate was distilled was a Baird & Tatlock (London) instnoment, graduated to fifths of a degree.It was checked up and found to correspond to a U.S.Bureau of Standards thermometer at 0* 50°, 7 5*, and 100*. The pipettes used for drawing off the samples were 10 cc.and 25 cc. capacity and were standardised by the method of E.G.Mahin, "Quantitative Analysis", p. 17 8. (McGraw-Hill Book Go., Inc., publishers, 1919). The apparent weight of 1 cc. of pure water at 15* C., weighed in air with brass weights is .99805 grams. Weight of water delivered by 10 cc. pipette; (1) 9 .98315 (3) 9.97745 (5) 9 .98745 (2) 9.97985 (4) 9.97 510 (6) 9 .97985 Mean w e i g h t d e l i v e r e d : 9 .98047. (6) Weight of water delivered "by 25 cc. pipette; (1) 24.9526 (3) 24.9410 (5) 24.9520 (2) 24.9640 (4) 24.9580 (6) 24.9482 Mean weight delivered: 24.9626. The weights used were calibrated "by the method of T.W.Richards (j.Am.Chem. Soc., 1900,144.) The following shows th« results obtained: nominal data obt'd prelim, aliquot correction value by substit'n value parts of in mg. (actual) ideal actual-ideal '.01) standard of comparison * .00 .01') .01 .01000 .010005 * .00 .01'') .01 ' .01000 .010005 + .00 '.02) .01-. 01 .02000 .020011 - .01 \05) .02-etc .05000 .05003 - .03 ,1) .05 etc .0001.10010 .10006 * .04 .1") .05.. .0001 .10010 .10006 • .04 .2) .l-.l .20020 .20011 + .09 '.5; .2.. -.0001 .50030 .50029 +-.01 ..5') .2.. -.0001 .50030 .50029 + .01 (1) .5 -.5 1.00060 1.00057 + .03 (2) 1.. .00005 2.00115 2.00115 ±.00 (2') 1.. .00005 2.00115 2.00115 ±.00 (5) 2 2 1 5.00290 5.00290 +.00 (10) 5. ...0001 10.00570 10.0057 5 - .05 110') 5.. .00005 10.00575 ideal (20) 10.. .0002 20.01165 20.01150 + .15 (50) 20.. .0005 50.02890 50.0287 5 • .15 PREPARATION OF THE SOLVEKT. The ethyl acetate used as solvent was purified by the method of Wade and Merriiman (Trans. Qhem. Soc., London. 1912. 101. 2429). The procedure is as follows: (7) The commercial acetate contains a considerable percentage of alcohol.lt is necessary first to reduce the alcohol content.As alcohol is miscible with water in all proportions and ethyl acetate only partially so, the ester is distilled from anexcess of water.Part of the alcohol remains with the water.This is repeated three times, most of the alcohol being thus removed. The ester is then dried over anhydrous potassium carbonate over night. The ester is poured off the potassium carbonate and two cc. of distilled water added for every 500 cc. of the ester.The later is now fractionated through a good still-head.Binary and ternary mixtures of ethyl alcohol, ethyl acetate and water all distill at a temperature below that at which the pure ester distills. (Wade, Trans. Chem. Soc., 1905, 1656).In this way any alcohol and the exae3S water are removed in the first fractions and the later fractions , are pure dry ester. With fresh supplies of ethyl acetate the later fractions were again distilled off a large volume of water and dried as before,but with recovered solvent it was considered sufficient to go through that process but once.The later fractions, which came over at 77.1*0 (Heading corrected for stem by formula: length of stem exposed(in Degrees) (Vtjx. 000154 ) (8) gave no color: with potassium permanganate (crystals dried over phosphorus pentoxide) and was therefore considered perfectly water-free. PREPARATION OF THE SALTS. The zinc acetate used was Merck, Zn(OH3COO,)2Ht0 This was dehydrated over phosphorus pentoxide, and lost in weight corresponding to two molecules of water of crystallization; Original weight 3.5542 gr. Final weight 2.8032 gr. Lose .5510 gr. Water of crystallization in 3.3542 grams of Zn(CHaC00)i8Hli0 is 36 x 3.3542 = 5501 gr. 219. 5 As z inc a c e t a t e i s given in B e i l s t e i n as occurr ing aa Zn(CH3C00)x 2Hfc0 and as ZnCCHjCOO)^  311,0 an a n a l y s i s was made to make sure t h a t the presen t sample was the former. Weight of zinc a c e t a t e (A) 1.0000 (B) 1.0000 Wt.Gooch f i l t e r 18.4398 18.6725 Wt. " " pyro phosphate 19.1350 19.3682 Wt. z inc pyro phosphate .6952 .6957 Weight of zinc in pyrophosphate (A) .2982 (B) .2984 Weight of zinc in 1 gr. Zn(CH5C60)t2Ht0 .2978 (9) The lead acetate was P"b(CH3C00)z 3HX0, It was dehydrated over phosphorus pentoxide to constant weight.The potassium acetate,sodium acetate,mercuric chloride, potassium permanganate, sodium chloride, sodium "bromide, sodium iodide, potassium chloride, potassium iodide, potassium bromide were dried over phosphorus pentoxide to remove any adsorbed or adventitious moisture. PROCEBURE A portion of the salt whose solubility was to be determined was put in a 150 cc. flask and the anhydrous ethyl acetate added.The flask was corked tightly and. the cork and neck of the flask was then dipped in paraffin wax. The flask was immersed in the bath and about twenty hours allowed for equilibrium to he reached. The flask was then remaved and a 100 cc. sample drawn off with the 25 cc. pipette. The ethyl acetate was distilled off the solution and the residue, if any,determined in the usual way.If no residue was obtained from lOOcc. the salt was considered insoluble. RESULTS OBTAINED. Zinc acetate. The zinc was determined by the phosphate method(E. G.Mahin, "Quantitative Analysis", p. 507, -(10) McGraw-Hill Book Co., I n c . , New Y o r k , - p u b l i s h e r s ) . The zirac was weighed a s p y r o p h o s p h a t e . Weight of z i n c p y r o p h o s p h a t e from 100 c c . s o l u t i o n of z i n c a c e t a t e in e t h y l a c e t a t e : (1) . 0 2 0 3 (4) .0194 (7) .0210 (3) . 0 2 2 1 (5 . 0 1 7 8 8 .0184 (3) .0200 (6) .0207 (9) .0192 Mean; . 0199 . .0199 grams of zinc pyrophosphate corresponds to .02396 grams of zinc acetate per 100 cc. of solution. This corresponds to ,02592 grams per 100 grams of solution. Mercuric chloride. As mercuric chloride is quite soluble in ethyl acetate it was determined from 10 cc. samples by evaporating the ester off the saturated solution in weighing bottles in a water oven. Weight of mercuric chloride from 10 cc. solution: (1) 2 .4356 (4) 2 .4250 (2) 2.4257 (5) 2 .4305 (5) 2 .4359 (6) 2.4B85 Mean: 2 .4362 Weight of 10 cc. of saturated solution: (1) 11.6302 (4) 11.9628 (2) 11.0861 5) 11.0742 (3J 11.0552 (6) 11.0428 Mean: 11.0585. (11) Lead acetate. Some runs were made with the crystalline Pb (CH COO) 3H 0. The crystals were broken down to a fine powder by the dehydrating power of the ester,and a colloidal suspension of the particles was formed. As this could not be filtered it was treated with Fullers Earth which completely cleared the solution. However, when the ester was distilled off no residue was left. Runs made with the dehydrated salt also gave no residue.lt was therefore decided that lead acetate is insoluble in ethyl acetate. Potassium acetate. It was expected that potassium acetate would be soluble,following the general rule that most deliquescent salts are soluble in ethyl alcohol.lt was found, however,that no residue could be distinguished even from 200 cc.of the ester.Potassium acetate,then, is insoluble in ethyl acetate. Sodium acetate. No residue was left from the evaporation of ethyl acetate which had had an opportunity to dissolve sodium acetate. (12) Potassium carbonate. Dry potassium carbonate was used to dry the ester after it had been distilled off water.Enough carbonate was added so that after standing over night some of the carbonate was still in the dry state,that is, on shaking it would be seen that soma of the dry carbonate was stirred up.If the acetate was carefully decanted off the carbonate, taking care that none of the salt was carried over, no residue was left on distilling off 500 cc.Potassium carbonate,then,is insoluble in ethyl acetate. Potassium permanganate. As mentioned above(previous work ) potassium permanganate was found to be insoluble in ethyl acetate.No coloration was shown even on standing for twenty-four hours. Sodium chloride. No residue was left from ester which had been over sodium chloride for twenty-four hours. Sodium bromide. No residue was left from ester which had been over sodium bromide for twenty-four hours. (13) Sodium iodide. No residue was left on distillation of ethyl acetate which had "been in contact with sodium iodide for twenty-four hours. Potassium chloride. No residue was left on distillation of ethyl acetate v/hich had been in contact with potassium chloride for twenty-four hours. Potassium "bromide. No residue was left on distillation of ethyl acetate which had been in contact with potassium bromide for twenty-four hours. Potassium iodide. No residue was left on distillation of ethyl acetate which had been in contact with potassium iodide for twenty-four hours. (14) SUMMARY Ethyl acetate has been purified, by the method of Wade and Merriman.Solubilities in it have been determined as follows: Zinc acetate - .02396 gr.per 100 cc. solution. .02592 gr.per 100 gr. solution. Mercuric chloride -24.502 gr.per 100 cc.solution. 21.97 5 gr.per 100 gr. solution. Lead acetate - insoluble. Potassium acetate - insoluble. Sodium acetate - insoluble. Potassium carbonate - insoluble. Potassium permanganate - insoluble. Sodium chloride - insoluble. Sodium bromide - insoluble. Sodium iodide - insoluble. Potassium chloride - insoluble. Potassium bromide - insoluble. Potassium iodide - insoluble. In conclusion, I wish to thank Dr. E. H.Archibald for his advice a.nd assistance and for the keen interest he has taken in the progress of the work. Chemical Laboratories, University of British Columbia. 


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