UBC Theses and Dissertations

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UBC Theses and Dissertations

A quantitative examination of the nitrate formed by replacement of the N O2 - radical in the presence.. 1926

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A QUITITATIVE EXAMINATION OF THE NITRITE FORMED BY REPLACEMENT OF THE NOf-RADICAL IN THE PRESENCE OF HIGHLY-COLORED RECATION PRODUCTS A QUANTITATIVE INVESTIGATION OF THE REPLACEMENT OF NITRO-GROUPS IH THE BENZINE RING.., BY NEAL MARSHALL CARTER CAT. HO. L£*At-#*ifa.C*Q A^r HP £jt£LL J • QUANTITATIVE BXAMIHATIOH OF THE NITRITE FORMED BT REPLACEMENT OF THE HOg-RADICAL IK THE PBBSEBBB OF HIGHLY-COLORED REACTION PRODUCTS. A QUANTITATIVB INVESTIGATION OF THE REPLACEMENT OF NITRO-GROUPS I I SHE BENZENE RING PREDICTED BT IHB ELECTRONIC CONCEPTION OF POLARITY. - by - MARSHALL HEAL CARTER. A Theeie submitted for the Degree of MASTER OF APPLIED SCIENOE in the Department of CHEMISTRY THE UNIVERSITY OF BRITISH COLUMBIA APRIL, 1986. 0|i^AAa»^ct 1.H.CL, TABUS OF QOHTBKTS IHTBODUOTIOK. A. A statement of the Electronio Conception of Valence as applied to the polarity of various groups substituted in the benzene ring* B. The purpose of the work undertaken, and an explanation of how Part II led to Part I. ggjjgg. A, A review of some studies in replacement of nitro-groups in various benzene der- ivatives by other workers, and a compara- ison of their results With those predicted by the Sleetronio Theory. PAST I. 1. The various methods of estimating the amount of replacement that had oocurred, with facts leading to the abandonment of each; 2. Reasons for the final deoision regarding the use of alcohol as a solvent; Z. The final method of analysis evolved as being most suitable under the conditions* PART II. 1. The various procedures used in effecting the substitution of the nitre-group £. Tables and discussion of the results. THE REPLACEMENT OF HITBO-QROUPS IN THE BENZENE RING. INTRODUCTION A. The latest conception of the atom as consisting of a positively-charged nucleus surrounded by a rotating system of negative eleotrons, not? almost universally accepted, leads to the following conclusion; The neutral atom, by the gain of one electron may baooma negatively oharged; oonversely, by the loss of one electron the atom may beoome positively oharged. This Important statement is the basis of the theory of the Electronic Conception of Valence, as presented by H.S. Fry.1 From it, the following important suppositions are made: (1) The diatomic molecule, Xg, may be considered to under- go a process of "electronic dissociation" represented thus: X2 s X + x. (il) Any other diatomic molecule, undergoing the same pro- cess, would likewise give: Yg r Y + Y. On combin- ation with a molecule of: (Xg =) x + x, the two possible forms Y-^X and Y ^ X may be imagined to result in a oondition of "electronic tautomerism". (ill) In the representations Xg • X 4 X, according to the nature of the element X one or the other of the two + -forma X and X will tend to he the more stable; if the eleotron he designated by the symbol © , the conver- sion of one form to the other may he represented thus; x + e£X; x + e5*i i.e.,i+2e^i This of oourse assumes some substance to be present whioh is capable of supplying the eleotrons. (iv) The above scheme may now he represented as a possible emanation of the tautomerism mentioned under (ii): T ^ X • Y * X • (t. + ©)•£ - Y + X s (Y • e)+X s » Y + X « Y^X. Sow, the actual existence of X and X may be supposed + - +- in the following oases: JaH and HP , where X«H, sinoe Ha and f are- respectively considered to be one our most oharaoteristio positive and negative elements. Again, a similar argument holds for HC1 and H-O-Cl in the oase of 01, and further, in the case of iodine, we have the fact that 101 hydrolyaes thus: + — t-. +' - + + - 101 + H-OH s HOI + I-OH, showing I to be I in 101, whereas • r- + — we are led to suppose it is I in HI, There is no reason to suppose that this effect is limited to univalent atoms, , and therefore we have the following five possibilities for the quadrivalent oarbon atom: +0 + +0+ +0- -0" ~Q~ whioh, when combined in every conceivable manner in the form of a olosed ring of six oarbon atoms, give six and only six It will he noted that the preoeeding six formulae may he converted to conform with the Kekule type hy Joining the oentrio bonds in pairs, thereby obtaining either oontraplex or duplex double bonds as the oase may be* but it is quite immater- ial which type is considered — in either oase the outer bonds have alternate positive and negative values in eaoh of the six possibilities. She underscored statement above is the key to the electronic explanation of substitution in the benzene nucleus, since this fast demands the existence of hydrogen atoms of alternate polarity in the compound benzene Itself: «v- +£* t tL - ±c± A aad ** analogy• any other atom \y& r * — +tt+ or group or atoms substituted *^ -Vr & + -Yr H in the nuoleus for the hydrogen, must have the same polarity that the original hydrogen possessed. Since the full formula of the benzene nuoleus is very awkward to work with, the following abbreviation will be henoeforth used, and applies equally well to either of the six turned +hrot/gh 60' possible formulae mentioned previously: (taking formula JL as *  , " B * 1 ° rSgf 1 ^ ¥*V =* y V Finally, the electronic tautomerism may be extended not only to lntroduoe the existence of positive and negative atoms, but of total polarity of groups of atoms, as in the oase of the CH group recorded by Hef:8 - + + - + - - + C1GN + H-OH s HOI f HO-GH + - +' - + - -fr- ICS + H-OH • BOX t H-OH The tendency of any particular atom or group is to aot with more or less preference for a certain polarity, though 3 in some oases this preferenoe is Tory slight, and leads to the following classification of some of the commoner substituente in the benaene ring: OH, 01, Br, I, HHg, GHg, etc., where the tendency X exceeds ±, +• - OOgH, COH, SO5H, HOg, etc., where the tendency X exceeds 2. That any group may function positively or negatively is at once trident In the consideration of the di-substituted ortho bensene compound In the light of the present theory: + - NO* _ H B. The proceeding brief outline of the logical seqjtenoe of facts that lead to the theory of alternate polarity of the carbon atoms in the benzene ring suffices to introduce the actual subject of this investigation; namely, to gather evidenoe either for or against the above theory by experimental replace- ment of variously-oriented nitro groups in benzene compounds. The replacement was to be ef footed by alkali-metal hydroxides, since the only conceivable reaction: (taking a simple case.) ± + - + + - C6H4(H0g)2 • HaOH * C6H4(H02)(0H) • BaJfO£ would result in a differentiation between positive and negative nitre groups since only H02 can be imagined to partake in the formation of eharaoteristlo HaHOg where the mutually satisfied polarities are aooeptedly distributed as indicated. At this point it may be well to consider the electronic struoture of the Hog-group itself. Nitrous acid, HN02, presents two possibilities of form but only one possibility of polarity with respect to the -HOo group:. . 4^.0 . _ . » i» evident that + ^ p the nitrite formed is derived from form (II).while form (I) is possibly that from which the nitroparaffins are derived. Since, however, the HOg-group is only introduced into the bensene ring dlreotly through the agency of HH02, not HIOo, it will be found that the only possible electronic form- ula of nltrlo acid oontalns a B"02-group +z,0 that is positive instead of negative as ^~0 in the case of nitrous aoid. This faot leads to the important conclusion that only those HOg-groups not whioh haveAbeen dlreotly substituted in the ring should be replaoeable by alkali hydroxides, sinoe the positive, directly- substituted group would not tend towards the formation of Ha-HOg. Any such replacement as might occur in the latter oase may however be explained by the prooess of tautomerlsm mentioned under (iv) on page II. Let us now examine the possibilities of distribut- ion of these positive and negative HOg-groups in the ring. Commencing with bensene itself, suppose it to be mono-substituted by BOg aooording to the reaction: ? ± • - + + • CgH 6—H f HO—H0 2 » CgH5—N02+ H20. Sinoe the N0 2 has been shown to have the tendenoy to raaot as a positive group, it ia logical to asauma the raplaoamant of a positive hydrogen as previously explained; this eliminates three alternate positions in the ring as not being favorable for substitution, leaving only one possibility: "°t for the electronic formula of nitrobenzene + \ ^ + since eaoh of the remaining three positions are equivalent. A similar argument leads to the following |Wz as the only possible di-nitrobenzene sinoe t positions 3 and 6 are equivalent not only - in polarity but from the standpoint of isomer- ism. Finally, the product of the final direct nitration of benzene leads to the symmetrical 1-3-6 trinitrobenzene, and no 4 other direct nitration produots have ever been observed except in minute traces. The aotion of alkali-hydroxides on the above three compounds should theoretically be nil, though any replacement actually occurring might be explained by the aotion of the alkali on the second eleotromer in each case: Spj. Sk &x NO2 f?t m2 X - + - r The curious faot now presents itself that the + — symmetrical 1-3-5 trinitrobenzene whenaoted upon by NaOCH3, instead of giving traces of the compound (i) below as might be expeoted from the eleotromer (vl) above, actually gives6 (11): OCH3 0 C H 3 vlx N«ak r If the indirect nitration of the benzene ring "be now allowed, we find that many combinations of polarity of the XOg-group are now possible. Wo aeeond nitrobenzene should be formed, since the nltro group, having a positive tendency, would always give the one eleotromer where the group is positive. The isomeric demand for three dl-nltro benzenes calls for the three electronic arrangements (A,B,G,) below: Sbi iJo! $CZ VOi /f i r _^ ffdz together with their respective eleotromers, (a,b,o,). It is noticed that the eleotromers (a.b,) should present no differenee in behavior towards ffsOH to their originating forms (A,B,)$ all four having one negative nltro group in oommon, which should be replaceable. If 0, (whioh should not be aoted upon) gives appreciable quantities of o, then both HOg- groups should be replaced equally but not necessarily quanti- tatively. This is a very Important conclusion. If a negative group such as OH Is already in the ring; following the laws of isomerism and the electronic the- ory, a directly-substituted HOg-group has a choice of two pos- itions in whioh to enter, instead of only one as in the case where the group already in position (H02) Is positive. These two possibilities together with the possibilities of further direot nitration are indicated below: 5W ^ JH OH <JH . $» . + not mt + N°z" Experimentally, it is found that the products formed by direct nitration of phenol agree with these five formulae, and that any other isomers must be formed indirectly* The introduction of more than three nitro groups in the benzene ring is exceedingly difficult, the fourth group having to be substituted by very indirect methods, and in all oases, the compounds so formed are most unstable. Such would be expeoted from the considerations presented above* She object of this investigation therefore resol- ves itself into the converse problem ot ascertaining if the replacement of the variously-substituted nitro groups occurs in such a manner as to support the theory whloh has been ad- vanced to interpret their original introduction. This replacement, performed by the agenoy of NaOE, KDH, (possibly HaOCgflg and ZOC2H5), should lead to the form- ation of sodium or potassium nitrite in either oase. It was expected that by Quantitative estimation of this nitrite com- bined with investigation of the product of substitution, no difficulty should be experienced in following the progress of the substitution. Many methods of analysing nitrites have been made standard, and should prove adaptable to this ease, it was thought. When the actual analysis came to be made however, a difficultiesArose whloh hindered the progress of the Investi- gation for over a year. She discussion of these and their final solution will form the topic of PART I. THB REPLACEMENT OF HITRO-GROUPS — — — • » — — — 1 — | — — — I — I II ••••!! !•• • I III llll • • • • • » • » • — ! I • — 1 ^ 1 I—III — • Mil—•» I IH IBS BENZENE RING. A review of some studies in replacement of nitro- groups in various benzene derivatives by other workers, and a oomparaison of their results with those predloted by the Electron!o Theory. Consideration will first be given to purely nitro-dor- lvatives of benzene, then to more complex compounds. Ho evidence in the literature reviewed could be found bearing on the direot replacement of the BOg in nitrobensene by alkali-hydroxides. In abstracts published by the Journal of the Chemical Sooiety, London* of the work done by C.A. Lobry de Bruyn (de B.) much valuable Information was gathered oonoerning the behavior of poly-nltro benzene compounds. Taking these in order of complexity the following facts are noted: (The numerals in parentheses refer to the list of references at the close of this work; the words "favorable" and "unfavorable" refer to the author's conclusion regarding conformation to theory. ) (6) (7) (8) (9) r> ° * r ^ Naoft̂  rSf l NO. OEt r >i Favor- able. "* Favor-(?) Ul)  ' W ****** *° s^**0*- abl#" 6) (10) I | t "aCet > / \ — N ( ) '•»» Favorable Unfavorable, and (18) | ^ *ftOe$ f" moat unusual. lott - 0 - 0 ; a^PvQ, W«i °H both favorable. (5) (IS) + + +- • (is) w t NO2 _ w i . Jit . both favorable. (6) (IS) N ^ 0H« O* "MO*''-* I.+ ~ ^* I Lt f » w j Unfavorable. '"• «D* ̂ r O* • OvO'. unfavorable • Ni4favorable *•* ^ ^ N02 W02 Doubtful. The laat thraa raaulta maka the validity of the original assumption of three positive natro-groups questionable* mt _ ikz «« j^>> Ki!^ Q ™ e Favorable. Lobry do Bruyn finally states' 'that too aotlon of a alooholio ZOH or even of aquooua alkalito on nitro-compounds uaually yielda oomplioatod aso-derivativee although K50g ia ntarly always formed at tho same tint* See also (18). With roapoot to tho influence of wator on tho oouree of thoroaotiona of aodium ethylate, Lobry do Bruyn10 has tho UNmtilf note* ^ y ^ tio.Olt, N01 0 A NftOEtr 0i- ONo. 'N02 + H,© where tho $ of tho (a) oompound inoroaaoa rapidly with tho i» of aloohol preaent. Passing on to tho mora ooraplex nitro-oompounds. Tar* ioua workere have oontributed tho following: ccnc NaOH (ic; cone NaOH COnC. anthranilio sold, asobentoid " eaoxybeneolo " o-nitrosobonsylalooho1 o-asoxytoluol m-aioxy toluol, and on longer heating, m-aiotoluol. HoOH compounds similar to above. This general oomplexity of aotlon is farther borne out by the following reactions , and by the reference (18): (If) HO Me N0Z unfarorablt N-« farorabla he <W) Ha 0Hc IW, NO, Me Me alto ,8gm black ineol.product {probably atilbtna dtr.) and .6g» of a dark rod rt t in- ^.- out product tolublt in M  N 0 2  M a lkal i t t . farorablt Me one N*0Ht (only a vary small yisld) farorablt oomplioatsd brotn «*°» ^ aoorpbous produots "^soluble in alkali and rtprtoipitatad by aold. rTo I TV 4 «i(fNi \J All farorablt • - J^ ^prs u* f N0X " ^ k ^ K02 CI J| •»- N^ r^>ci U r^N o i l l farorablt. r a fnt abort six ooopoundt wtrt lnrtstigattd by Holltman80 by lotting than rtaot with XaOMt. Cht group rtplaotd it marktd by an "x". Rtplaotntat la inooaplttt probably in tbt firat oast. (ii) ' Q ; JUte, -^jc-  + «£* Oontra-dittory. There now follow soma oases that do not fall in any most of which particular grouping, and in wast oases wara raoordad with an entirely different object in view on the part of tha workar. Jackson & Boos (28) NaOMe > no reaotion, both favorable. CI (22) Na««e f M incomplete Mi ml favorahla Ibbotson & Kenner, (28) reagent not mentioned NO, t incomplete cf inoomplete inoomplete We favorable favorable. MO + * o .-o to C l k i d " />.** favorable Ml ci inoomplete -*• Me favorable In commenting upon the above six compounds, the word "unfavorable" is not used whan a negavtlve chlorine atom fails to be displaced as expected; *lnoomplete*reaotion probably being the true causa. Quia, (25) + NO favorable favor. favor. Finally, the following interesting oase showing the ease with which a fourth nitro-group is dlsplaoed, is drawn front Cohen: + f favorable HO- HN0Z Many other eases of displacement of nitro-groups may he found in the literature, hut in many oases the object in view was so entirely different, that the author does not feel justified in including any other than those where the reagents used would indicate the formation of nitrites* It will,he seen that the author has based his assump- tions of polarities of the original compound upon the faot that any BOg-group replaoed must have borne a negative sign, henoe giving a starting-point from which to evaluate the remaining groups. This has in a few eases led to somewhat anomalous results, but nevertheless remains the most probable indication of the said polarities* She often-mentioned production of azoxy-compounds as reaction produots indicates a reducing aotlon of the reagent; if this is so, the simultaneous formation of a nitrite does not seem very plausible, as it would be oxidised to nitrate by the liberated oxygen; the reducing power of the reagent not being sufficiently strong to keep the nitrite as such. The reaction may however be mueh more complex, as indicated by the concom- itant formation of still more complicated compounds. In concluding this review, it may be well to mention the comparative pauoity of information regarding the nitro- compounds of naphthalene with respeot to the aotion in question. Fry, following the same argument as for bensene, derives the same abbreviated formula from the only two possible electronic forms that can be constructed from the different H H H H combinations of the aiz types of oarbon atoms previously ment- ioned. It will be seen that the polarities are distributed symmetrically about a vertical oentre line, causing the polar- ity of the hydrogen atoms to be non-alternating. This leads to the probable difference in behavior that may be expected between 1-5 and 1-8 di-substituted naphthalene derivatives (the most common derivatives) due to the fact that in the 1-6 oompounda the substituents should have different polarities while in the 1-8 compounds, the polarities should be the same. She following examples show a diversity of reaction: ^NOK (29), (30) CO V CO""" THS REPLACEMENT Qg HITEO« GROUPS Iff THE BENZENE RING. EZPStmaagAL — PAST I . 1* The various methods of estimating the amount of replacement that had ooourrcd, with faots leading to the Abandonment of eaoh. (A) Titration of excess alkali; (a) by added indicator, (b) by first formation of precipitate, (o) by eleotrlo conductivity measurement (B) By the use of "nitron" to quantitatively precipitate nitrite as nitron nitrate* (0) Reduction of nitrite to NH3 by means of aluminium in the alkaline solution; (D) Measurement of volume of nitric oxide liber- ated by action of mercury and cone. H2SO4 ; (S) Titration of iodine liberated by the action of potassium iodide on the nitrous add. A. The first method of analysis that suggested Itself was due to consideration of the equations: 06H4(H02)g * NaOH s C6H4fOH)(H02) • HaNOg 06H4(HOg)2 + HaOBt s C6H4(GBt)(H0g) • NaHOg It is seen that alkali is used up without being replaced by an equivalent amount of other alkali. Thus, if the titration of the alkali used against a standard acid were known, the amount of alkali used up in the reaction oould he found "by titration of the remaining alkali in the reaction-mixture against the same standard aoid. This differenoe of alkali oould then he oonverted directly to terms of N0 2 replaced hy a simple calculation. HC1 was chosen as the acid most suitable and a formula derived to give the % of replacement direotly from the titrations had the following form: (djff.HOl TlfnHnora.HOl) _ , _ . . __  x m jgggj x (mol.wt.of NOg) s gms. HOg replaoed, (gas. H0 2 replaoed)(mol.wt.of substance) (wv.subst«nce)(no.BOggroupsMmoi.wt.HOgJ * 1 0° * * o f ^ P 1 * 0 ™ * * - To ensure euual conditions regarding CO2-absorption during heating, loss of alkali hy aotion on the glass, etc., a "blank" was run with each set of experiments, consisting of an identical concentration and amount of the reagent alone, whose titration after heating was taken as initial amount of reagent used. Phenolphthalein, unaffected hy HHOg, was first used as an indicator and worked very well for the "blanks". When the reaotio-mixture oame to be titrated however, the first real difficulty arose. They were invariably of a deep red or brown color which so effectually masked the color-ohange of the indic- ator that the end point could not be determined within .6 oc. This error heoomes greatly magnified in the calculation as will be seen. Lessening the concentration of the acid gave a larger titration hut a graater error in determining the end-point. It was observed that when acidity was established, the muddy solution cleared with formation of a curdy hlaokish- brown preolpitate, leaving an amber solution. Back-titration of excess aeid caused the muddiness to reappear, but with no greater success in determining the end point. Methyl red was next tried, but with no greater gain in aocuracy. A few other biological indicators were tried also, with no better result* By observation of the first signs of the above ment- ioned precipitate (a sign of acidity) a consistent titration could be obtained for several compounds, while others gave an obscure, gradually-forming precipitate, and some no preolpitate at all. Hence this method was not sufficiently general. o. The need of a new method of titration not depending on a color-change was now felt , and led to the adoption of an electrical conductivity method whereby the abrupt change in conductivity of a strong base (HaOH) during titration with a strong acid (HOI), due to change from excess OH ions to excess H ions, marks the neutralization point. The reaction mixture was poured into a 400 co beaker and rinsed with distilled water to a volume of 860 oc. The heat of solution was allowed to dissipate before titration. The apparatus was quite standard, being as follows: B - 6-volt storage ha t te ry . H - high-frequenoy al ternat ing current inductance coil (hummer) K - coiled-wire type of variable resistance. T - telephone receiver* Bw- coiled-wire Wheatstone bridge reading to 1/2000 of total fall of potential. B - platinised platinum electrodes. The electrodes "B" were made from two pieces of Pt foil one cm. square, rigidly held one em* apart hy glass supports. The leads were of Pt wire sealed in glass tubes to within jt cm. of the foil. These had to be freshly platinized at the end of about six titrations to maintain a sharp minimum of sound. The readings were taken by immersing the two electrodes into the solution in the beaker, and after running in about 2/3 the calculated amount of acid, "R" was adjusted to give a weak hum in "T*. The contact roller of "B" was now oscillated back and forth about the minimum sound position until the ear "became used to the minimum, which was then fixed with as much accuracy as possible. This requires a quiet room and considerable patience, and the end point is often discon- certing in its eccentricity. The burette reading of the acid and the dial reading on "B" are noted, and the process is repeat' ed after the addition of every 8 oc. for about 8 or 10 oc, then every oc. until the dial readings cease to inorease and begin to decrease, ending with a few more readings 2 cc. apart. The burette readings plotted against the dial readings give a curve with a minimum at the burette reading corresponding to the end-point. (See Plate 1.) PLATE I . It was subsequently found that: (i) The depth to which the Ft foil was immersed (notwithstanding the glass lead tubes) considerably influenced the sound minimum; (ii) the same effect resulted from the aooidental proximity of anything such as the side of the beaker, glass stirring rod, etc.; (iii) the minimum would be different if redetermined after the solution had stood even too short a time for the absorption of GOg to have taken place appreciably; (iv) the minimum tor a "blank" titration was always sharp and oonoave downward whereas the minimum for an actual run was always more or less rounded and convex downward. (Minimum here refers to the shape of the graph.) This faot showed that the complexity of the solution (containing BaOH, HaOEt, BtOH, HaCl, and the organie substance) was influencing the shape of the curve to a degree that allowed as muoh error to oreep into the determination of the end point as was experienced with an indicator. The formation of a precipitate at the end point as mentioned under (b) also doubtlessly influenced the curve. Therefore the method was discarded in favor of a method which would not depend on the determination of the small amount of alkali used up in the presenoe of suoh a large excess. B. "Hitron" (a handy oommeroial abbreviation for 1:4 diphenyl 2:5 endoanllo 4:6 dlhydro 1:2:4 triazole) is a sfiar//7?/y yellowish crystalline powder ia,[iavs«ly soluble in water and alcohol, soluble in dilute aoetio aoid. When the aoetio aoid solution is added to any solution acidified with dilute H2S04 and warmed, any HN03 originally present (or set free by the Ho30A) in the second solution is deposited on cooling in ioe 8  * 21 water in the form of a HHOg addition-product of nitron. This addition-produot of nitron nitrate is extra- ordinarily insoluble in water, of the same order as AgCl and Ba30i. HHO£ gives a similar preoipitate less insoluble,33 and other aoids such as HOI, HgS04, HAo, H3PO4, Q6H5C00H, eto., give no preoipitate.24 The nature of the metal originally 35 associated with the aoid radical is immaterial. its use for NOg-determination in organic compounds is oonfirmed, w and BgOg 36 37 may be used to oxidise liberated HMOg to HNO3. Several methods for its use are given, the simplest being as follows: Add 10-12 drops of dilute H2SO4 for eaoh .1 gm. of suspected HO3 per 100 00.of solution. Heat almost to boiling and add 10 00. of a 10$ solution of nitron in 5# aoetie aoid for eaoh suspeoted .1 gm. of HO3. Oool at 0°C. for £-6 hours, filter through a Gooch oruoible containing Swedish filter paper, washing first with a saturated solution of nitron nitrate, then with 3-5 00. water at 0°C. Dry at 110°0. Eaoh gram of dry preoipitate represents .1288 gm. of HOg. This is the procedure followed, with the modificat- ions mentioned below, to suit the circumstances. She reaction-mixture was poured into a beaker and titrated with dilute aoetio aoid until the solution waa just decidedly alkaline as determined by spot-plate trials. In this state it was evaporated almost to dryness to expel any alcohol, (when NaOEt was used as a reagent, the alcohol present would tend to dissolve the nitron nitrate). The distillate was con- densed and extracted with solvents to aid in identification of compounds formed. To oxidize the HaH02 to HaJTOg, 10 oc of a 3$ solut- ion of H20g were now added, and the excess destroyed by boiling again almost to dryness. Water was now added to loo oo and the solution acidified with .1 H aeetio aoid (which does not liberate BHOg from its salts) to cause the usual preoipitate formed on acidification. This curdy mass (if any) was filtered off and the washings added to the filtrate) any preoipitate was later treated for identification. The more or less light-color- ed filtrate was now treated with nitron as described above. In this way, several compounds were analyzed, but as usual, a flaw soon developed. It apparently depends upon the nature of the organic compound whether the nitron nitrate comes down as a true preoipitate, a mass of fine white needles in spangles, or a crystalline oreamy mass so fine that it passes through the pores of the Goooh crucible. In some oases where replacement was known to have taken place, no preoipitate at all oould be induced either by long standing (weeks) or by in- nooulation. All manner of variations of procedure were tried, with no better result; aaad it was finally decided that unless the method would work for all compounds desired, it would have to be discarded, and a still different angle of the problem approached. 0. She next mode of attaok was suggested by the Kjeldahl method of nitrogen determination* namely, reduction of the nitrite to ammonia. Aluminium in solid form was added dirootly to the reaction-mixture in its container, and a small pieoe of paraffin introduced to prevent frothing. On gentle heating, a vigorous exothermic reaction set in between the alkali and the aluminium with evolution of hydrogen and ammonia. frials were made on known amounts of pure AgHOg treated with HaOH to provide a known amount of nitrite. She gases evolved were led through a oondenser and introduced into a definite volume of standard H2S04 by means of an adapter dipping under the surface of the acid. After the action was over, the solution was boiled for a few minutes to drive out all ammonia, and the exoeas H2S04 titrated with HaOH (.1 N.) to determine the amount of ammonia produced. In no case could over 75$ of the calculated value be exceeded, and after a few trials with actual runs of an organic compound which proved no better, the method was dropped. In the presence of mercury, concentrated H2SC>4 has the property of decomposing HNOg and HHOg (or KNOg and KN02) into nitrle oxide at a moderate heat, quantitatively. If this method could be made practicable, it would be very very desircable because of the fact that precautions would not he necessary to prevent the nitrite from oxidizing to nitrate, since both liberate the same equivalent of nitric oxide. Trials were made with known amounts of nitrite (from lg H02) in an apparatus especially adapted for collecting the gas from oontaet with meroury. This will not be described at this stage, since exactly the same apparatus was used for the final successful method of analysis, and this present method proved to be useless; never more than 5-10$ of the expected volume of nitrio oxide could be obtained from the known nitrite* 3. in appeal to H.S. Try for information regarding the method of analysis used by other workers in reporting results on this replacement elioited the statement that no general method was available. She following suggestion however was submitted* When HNOg is liberated from a nitrite in the presence of hydriodio acid by means of the simultaneous action of HC1 or H2so4 on potassium iodide and the nitrite, nitrio oxide and iodine are quantitatively liberated (or produced,) from the HNOg according to the reactions:38 £ HaHOg + E ZI + 4 EC1 : S HaOl + 8 £01 + 2 HgO + 2 NO + lg The iodine may now be titrated in the usual manner: I2 + 2 NagSg03 a 2 Sal + HagS^Og. In the hope that the end point of the titration of the iodine using starch as an indicator would he more def- inite than that of previous titrations attempted, trials were again made with a known nitrite before actual attempts to anal- yze an organic compound were performed. She procedure was as follows: The solution of the nitrite being already neutral, needed no preliminary partial acidification, so twice the cal- culated amount of II was at once dissolved in the solution, in excess of I S . HC1 was run in from a pipette, causing the mixture to turn deep amber from the liberation of the iodine. Standard HftgSgOg (.1000 H.) was run in from a burette until the color had been almost removed, when a few drops of starch sol- ution were added. Addition of further BagSgOg now produced an apparent end point; however, as effervesoenoe of BO was still in progress, it was noticed that the blue color of the starch compound kept reappearing at the surface of the mixture, and required more BagSgOg to remove it. On vigorous stirring, the clear solution could be transformed to a deep blue-black as often as desired apparently. By the time an end point had been obtained which lasted for five minutes, it was found that over four times the required Ba2S203 had been added! Tariations in procedure were now made such as: (1) adding the EC1 and Bag3203 very slowly and oarefully to avoid effervesenee of BO as much as possible; (11)adding almost the calculated amount of BagSgOg before the HCl was added, with the purpose of combining with almost all the iodine as liberated, 30 that the solution could be boiled to expel the HO without appreciable loss of iodine from volatilisation due to its low concentration. On titrating the oooled solution for the remaining iodine and adding the total volume, the amount of HagSgOg used was still far too great, as was also the case in (i). (iii) Benzene was added to the solution before acidification to aot as a protecting agent to prevent the liberated HO from combining with the atmospheric oxygen at the immediate surfaoe Of the liquid. It was thought that possibly the formation of NO2 at the surfaoe might be the oause of the continued return of the blue oolor there. The iodine liberated dissolved in the benzene however, and even the titration of that iodine still in the aqueous solution required more HagSgO^ than the calculated amount. (iv) Instead of using tfa^SgOg , the iodine was titrated with KMn04, which loses its oolor and aots as its own indicator. On running in .1 H. KMn04 from a burette into the strongly aoid solution (H2SO4), it was found that the oolor was removed just as promptly after 10 times the calculated amount had been run in, as when the supposed end point was reached! Hence this method had to be discarded, for if it would not yield the true value of a known nitrate, it was much lass likely to do so in a more complicated raaotion-mixture* EXPBRIMBNIAL ~ PiBT I . E. Reasons for tha final deoision against tha usa of alcohol aa a solvent In all tha eases mentioned undar(l) where different methods of analyses vara being tasted, whenever an actual organic compound was used to provide the experimental condit- ions of a typioal run, either ortho or para dinitrobenzene: i ware ohosen because they are the simplest poly-nitro oompounds of benzene which should contain nitro-groups of different pol- arity. How the repeated use of HaOBt, HaCMo, KOEt and XDMe throughout the literature reviewed previously, as a reagent to effect substitution of the nitro-group, is undoubtedly due to the faot that so few of the organic nltro oompounds are soluble in aqueous alkalies, phenols exoepted. Furthermore, It has been shown that in a great many oases the aotlon of the alooholate or alcoholic alkali is more complex than one would be led to suppose, whereas in those instances where the aeneous alkali was used, the reaction usually prooeeded more normally. It was notioed in this investigation that the result of the action of alooholie alkali on those compounds invariably was of a dark ohooolate or muddy brown oolor with a slight sediment. How the expected replacement products, ortho or para nitrophenetole (or possibly sodium nitrophenolate) are all nearly oolorless or of a clear red oolor. Hence here is proof that secondary reactions are going on simultaneously. Three efforts were made to avoid this possibility by testing other possible solvents in plaoe of aloohol. This is rather difficult, sines the requirements eall for a solvent in whioh both the alkali and organic compound shall be mutually soluble. Acetone will dissolve in a weak aqueous alkaline sol- ution, and most organic compounds dissolve readily in acetone, but Its use is at ones prohibited by its proneness to enter into resetions. (i) BBHZEHE — Since organic compounds dissolve fairly readily in benzene, it might be expected that the reaetion at the interfaee with the aqueous solution of the alkali might lead to complete substitution if the two liquids were kept agitated for a sufficient time by refluzing. OBJECTION- The benzene boils off and froths in the condenser. (li) BEHZENB plus CC1. ~ by "weighting" the benzene with the heavier oarbon tetrachloride, the solution of the organic oompound would be forced to boil up through the alkali. 0BJS0TI09- The temperature necessarily must be low, and even so, the benzene tends to boll away. (ill) WATER By increasing the concentration of the alkali, the boiling point may be so rais- ed as to cause many of the organic comp- ounds to melt, forming an emulsion on refluxing, which presents a reacting surface of large extent. OBJECTION-Hone except slowness of action . The results obtained by the use of the aqueous alkali alone aa the reagent were so satisfactory that a further innovation was introduced in the fo rm of an inert atmosphere. Its purpose was meant to he twofold; it would prevent the oxid- ation of any nitrite produced by excluding atmospherio oxygen, and might possibly lessen any tendency still remaining to form complex products. The result was most encouraging, producing, in the case of para dinitrobensene, a clear red solution with no traae of sediment. The oolor almost exaotly matohed that of a synthetic solution of sodium para nitrophenolate of the same concentration, thus giving strong indication that the replace- ment was as expected. The details of the procedure are given later in PART II. This method was finally adopted entirely. KJPBRIMBSTAL gigT I. - » • The final method of analysis evolved. With the apparent replacement taking place satisfact- o r i l y aa described just above, all that remained to perfect the investigation was a certain method of analysis. The author finally evolved such a method by combin- ing the principles of methods "D" and "X" under (1). It will be remembered that by the aotion of HI on HHOg, nitrio oxide was liberated simultaneously with the iodine. Previous experience with the volumetric measurement of HO in method *2>" had not led to much encouragement; however, as a last hope it was deoided to ascertain if the quantitative yield of 10 was more closely approached under these conditions. A trial with a small amount of KHOg gave a much larger volume than had bean obtained before, and more exaot measurements war* than undertaken using exact amounts of HaHOg obtained from pure AgHOg by double decomposition with HaOH. 2 AgHOg + 8 HaOH = AggO * HgO + 2 HaHOg, £ HaHOg • 2 HI + 4 HC1 = £ HaCl • 2 ZC1 • 2 HgO • Ig + 2 HO. lash molecule of HHOg produces a moleoule of HO. The actual replacement obtained was 97*2 % of the theoretloal. all that now remained to ensure success was a trial to be made with an organic compound. Is usual, para dinitrobenxene was ohosen, and the resulting volume of Ho given upon analysis after 44 hours of refluxing was 94*2 %. of the expected volume for total replacement of one nitro-group. The successful method of analysis had at last been obtained. HOTS: Sinoe for every SOg-group displaced from an organic compound, a moleoule of HaHOg appears, which in turn gives rise to one moleoule of HO, the simple relation holds mijuiai'w that for every H0« displaced from a gram-mol of the organic compound, 22,400 oo of HO at H.T.P. are formed. /jf »v-»fv' " I \\ N - i ^ I \\\ J H ^ - 1 '•v l i 1 H £ ! N »*•€»< »do« P* "fT. " > ,-r The exaot procedure of analysis will now be des- cribed with the help of the diagrams opposite. A lj* funnel "P" with a short stem fitted into the short piece of rubber tubing "T" which fits tightly over the outlet "0* from the stopcock "S" serves as a means of intro- ducing the reaotion-mixture from the refluxing flask into the reaction-bulb "B". This is accomplished by raising the reser- voir "R", full of mercury, until it fills «*B»»s"w0"'f3?,t and WP" up to the level " f . *S" is closed, "R" is lowered a few inohes below "B", and about two grams of £1 crystals are placed dry in "P". "P" is now filled from the refluxing flask direct- ly, "S* is opened slightly, allowing the reaction-mixture to be suoked into "Bwt being careful to always keep nP" at least £ full. than all the reaction-mixture and the necessary rinsings of boiled water have been suoked through, "B" will be fobably £ full of tha reaction-mixture plus dissolved £1, and full of mercury. A small bubble of air may be located just below "a". *R* is now lowered three feet below *B" to create a vacuum space in "B" which effectually collects any dissolved air or gas into a larger bubble below "S" when the vacuum is released by raising "Btt. This bubble is expelled by again bringing the level of the liquid to "f", half filling "P" with boiled water and allowing it to run into *B* until "s^O""!" and NP" as far as "f* are full of water only, and "B" contains no traoe of air consequently. The remainder of N?" if now filled with moderately strong HC1 which is allowed to run into "B" by lowering "Rnand opening "S". When the level of the acid has reached "a", BS" is tightly shut and the flask "B" well shaken. If any replace- ment has occurred, "B" rapidly becomes half-filled with the liberated HO, forcing mercury into R. "0" and "T" are now filled with boiled water by means of a capillary pipette (not shown). "H" and "0" art the two bulbs of an ordinary gas absorption apparatus which is filled with conoentrated NaOH. A short piece of tubing oonneots "S", the capillary, with another piece of capillary tubing "C" about three inohes long. By using compressed air in nH", the alkali in "G" is forced through "C" until a drop hangs from "d". This drop is placed in contact with the top of the liquid in "T" and the free end of "0" quickly forced into "T". By now raising "Rn above "C" and opening n S B , the HO is allowed to pass into "G" until the liquid in "B" reaches "8". "3" is then closed tightly, "R" lowered away below *B"; when raised again, as much as 10 oo more gas will be found in "B" that had previously not been given off. This is passed into "G", and the prooess repeated as often as gas is found to collect in "B" (usually about six times; vigorous shaking of "B" while under reduoed pressure assists greatly.) HOTS: The action of oono.HaOH on HO is very slow.39 When the final bubble of gas has been passed over, instead of causing the liquid in nB" to stop at wS w t it is allowed to flow to "«" thus forcing every last trace of HO from "B" into "G", where the C0« liberated by the acid from the carbonate always found in the BaOH used for the reagent is absorbed* While the CO© is being absorbed in "Gn, "C" is disconnected from the shorx piece of rubber tubing "F(". (A seal of liquid between "a'"and "ew keeps the gas in "G") A long piece of capillary glass tubing bent as shown at nD" Is fitted into "?,", and when the CO© has been removed, oompressed air is foroed into "H" to drive the liquid seal through the capillary. When the liquid which was at "e" has almost reaohed the tip "H* of "D", a pinohoock on the compressed air tube is closed, keeping a small liquid seal in place at "H* while "5" is being being introduced under the mouth of "V*. "7" is a gas-measuring tube graduated to 50 oc filled with mercury and Inverted in a beaker full of mercury as shown. When "H* is safely under the mouth of "Y", the pinch- cook is released and the HO completely transferred into "V". *D" is now removed and "V" (still inverted in tbs mercury) set aside to assume room temperature if necessary. "B" is emptied and completely rinsed by successive washings of hot water to be ready for the next run. The llguld emptied from "B" may now be examined for recognition of the product formed. It is now seen that this technique provides a method of accurately measuring the volume of HO liberated without allowing access of atmospheric oxygen at any stage. When "7* has assumed room temperature, this is read on a therm- ometer close by, the reading of the level wLn of the meroury is taken, and the differense nh" between the two meroury levels is measured by a small celluloid scale. The gas in "V is assumed to be saturated with water vapor at the temperature nt" if the tube "V" was wetted before filling with mercury. If "wwr vapor pressure of water at "t", *W • vol.of gas, "p"= atmospheric pressure, then: V .» w » h (in mm.) _ 870 _ - _ _,o„_- „j» „-. ̂  ,T _ « —TSo" gylft x ** •©lass of HO at H.T.P. THE REPLACEMEHT OF NITRO-GROUPS Hi THE BgjjZggB BIHG. BZPBRIMBHTAL - PART I I . 1 . The various procedures used in effecting the actual replacement of the nitro-group. During the earlier part of this work, as has heen above explained, practically all runs made were used up in trials of different methods of analyses. Sot only did these trials prove fruitless, hut in many oases the technique of the actual replacement-action was at fault. In PABI I, (£), reasons were given why the use of alcohol as a solvent should he abandoned, and in (3) the use of an inert atmosphere was proven desirable. Consequently, little will be mentioned regarding the early procedures, and more attention devoted to the final technique adopted. Duplicate samples of the compound in question were introduced in amounts of .5 gm. each into thiok-walled 5/8"- bore soft-glass tubes some 30 om. in length, having a round seal at the bottom* If the substance was solid it was pulver- ized before weighing; if liquid, it was weighed in a very thin- walled glass weighing bulb which would break when dropped into the tube. The neck of the tube was then constricted, leaving a small funnel-shaped end, through which half the desired vol- ume of double-strength reagent was first introduced, followed by an equal volume of absolute alcohol (when HaOBt was being used) or of water (when HaOH was being used) • Shis gave the desired volume of proper concentration, and provided a means of Incidentally rinsing out the oonstrlotion so that adhering alkali would not prevent a perfect seal. After sealingt the tubes were placed in a horizon- tal bomb furnace heated by gas to 110-120°C. ejpsgss. Consider- able difficulty was experienced in keeping the temperature constant. When removed after cooling, the contents were in all cases a deep chocolate muddy brown color, with a resinous sediment along that side of the tube that was bottom-most. faking the usual precautions regarding opening the tubeB, no pressure was ever experienced on opening any tube containing nltro compounds. Exactly similar tubes were later heated in a circular rack suspended in a boiling water bath. The temper- ature could thus be kept constant, but admitted of only one regulation. By first heating the tubes to about 90°C, oooling to 70° and vigorously shaking before final raising of the temperature to 100°, the solution of the compound in the reagent was assured. Since the heating oould not he continued over- night, a similar opportunity was taken for shaking each morn- ing, as in some oases the tubes were heated for a total of 48 hours. Despite the faot that the tubes were shaken, evid- ence was sometimes found of undissolved produot, and as the method of analysis being tried at the time did not allow the mat of a larger volume of reagent, a second procedure was tried. fo allow greater agitation during heating, the principle of refluxing was tried. She weighed samples were introduced Into 160-oc Florence flasks and the reagent added in two portions as before to faoilitate rinsing, amall upright water condensers were attached, fitted with CaClg-tubes at the upper extremity to exclude C02 which would change the concen- tration of the alkali during the long period of refluxing. The flasks were heated to the boiling point of the reagent (80-86°C. depending on the concentration of the KaOEt) on an electric hotplate. Ho trouble was experienced with bumping. This method led to the final one adopted of re- fluxing with water solutions of SaOH, and very little change In the mode of heating was made until the inert atmosphere idea was Introduced, which will next be described. As an inert atmosphere, hydrogen was first used but soon discarded as being too dangerous, nitrogen then was — T . ' —- -i ZZ -rr- W02 l°A •HP —EL '- ' J21AJ0Q uasung m i±uid adopted, beingAfirst manufactured by passing ammonia from a tank of liquid ammonia over heated copper oxide in a long pyrex glass tube: 2 NH3 + 3 CuO = 3 Cu + 3 HgO. Later, a tank of compressed nitrogen free from oxygen became available. She actual mode of operation may be followed from references to Plate III opposite. The substance and reagent are introduced in the 160*co Brlenmeyer flask "£" which is connected to a small watts condenser *C" by means of a tight rubber oork. A flex- ible rubber tube "T" about two feet long and of £"-bore is connected to the upper end of the condenser tube. She free end of *£" is now connected to the tank of nitrogen, the oork "R" loosened, and "Tw,,Onand,,Bn are thor- oughly swept cut with nitrogen. With the nitrogen at about 10 lbs. pressure, the oork "R" is tightly fitted into **B" and the pinchcock *?" closed before removing "S" from the nitrogen supply. "T* is now slipped over one of the arms of a five- armed glass joining-tube "J". The rubber connections of three similar condensers are connected to the remaining three free arms of *J" while the fifth arm is connected to a tube "3? "S" is a reservoir of nitrogen from which the gas can be forced by opening the valve "W* allowing water to flow in and the gas to escape through the valve "V". When all four condensers with their appended Brlenmeyers are in readiness, the four pinohoooks (P| are open- ed one after the other.allowing the nitrogen under 10 lbs. pressure in the four systems to escape and sweep out all the air In "3" which is immediately connected to the valve "V" which is then left open. A small non-luminous flame about -fr" in height Is now lit under the lowest portion of the Brlenmeyer flasks, an ordinary Bunsen burner being quite suitable. She capillary glass tube *G" open at bothends, serves admirably to prevent "bumping" She four condensers are damped at a slight angle in stands, and the water may be run from one to the other in series. It is important that *S" does not collapse at the point "S", otherwise a sudden bump of the liquid will Slow the flask off the oondenaer instead of being dissipated in the reservoir "B" which is only needed for such an emergency. EXPERIMENTAL — PART II. 8. Sables and discussion of results. The faot has already been often mentioned that the early part of this work was taken up in a searoh for a suitable method, and until this was discovered, the results obtained were of little use. However, in a few oases, one mode of analysis was need long enough to make a few oomparaisons of the influence of varying such factors as time, temperature, normal- ity of reagent, etc. A few of these will be included. In all, over 75 separate runs were made and used in the search for the proper analysis; another £5 were made in perfecting the final method and in making larger quantities of the compounds for identification, and finally, 47 runs have been made to date using the final method, with plans laid out for several more to be subsequently done. The chemicals used were purchased from the Eastman Kodak Chemical works of Rochester, H.Y., U.S.A. She M.P. of those compounds common enough commercially to have consistently uniform M.P .data recorded, was in eaoh case found to be suff- iciently close to the recorded value to warrant the assumption of probable sufficient purity for those oompounds which have inconsistently reoorded melting points. TABLE 1. Samples of dinitrobensene, refluxcd with alcoholic HaOH, and analysed (?) by titration with indicator. 1 2 3 4 5 6 7 8 9 10 XI I S 13 iso- mer 0 0 0 0 • p p p p p p p we igh t in gms. .6000 m m m a a a a a « 1.0000 .3000 1.0000 reagent CO. 50 a a a a a a it * it M It M norm. .500 « it • 910 .188 • 300 • 500 w tt a • 185 . 871 .910 temp. (°C.) 84 a a 88 79 8 1 84 a a a 80 180 88 time (hrs) 6 11 24 6 24 15 5 8 18 24 £5 6 6 replacement oalo. 50£ a a a 0 0 50 a a a a a a o b s . 38.0jf 4 1 . 8 4 2 . 4 76 .4 36.0 4 3 . 0 44 .9 3 3 . 3 41 .8 4 3 . 0 23.8 47 .8 6 8 . 5 favorable to theory unfavorable favorable Sons 1,2,3, show an increasing replacement with increase of time, other circumstances being equal. Buns 8,9,10, show a like relation, indicating that the progress of the reaction slows up at the end of about 15 hrs. 1,4, show increased replacement with increase of con- centration, but 4 exoeeds the theory. Like relations could be drawn from the following two tables, but the accuracy of the results do not warrant it. In commenting on the favorabillty, only the general trend of the figures is taken into account, no attention being paid to suoh exceptions as 4 and 13. In the following oases, the signs attributed to the groups are distributed in suoh a way as to satisfy the polar- ity of the greatest number of groups aooording to the scheme given on page IV of the INTRODUCTION. TABLE 8. Samples of various compounds, refluxed with alcoholic HaOH, and analysed (?) by the eleotrioal conductivity titration method. 180 mer weight In gms. reagent oo. norm |S time (hrs) replacement oalo. obs. 14 16 •8800 1.0000 50 60 BI3B0BEHZEHB 16 If lit e * P .9990 1.0000 1.0080 80 80 50 .111 .185 79 80 84 85 1.8$ 0.5 Favorable MHRlHILBra .800 .800 .800 81 81 81 44 44 44 0 100 0 7 .6 4 6 . 0 0 . 9 favorable n 19 80 3:4 4:2 .9990 1.0000 IlfHO J1UH0 TOLUKHE 80 50 .600 • 500 81 81 44 44 0 0 0.0 14.6 Favorable Unfavorable Hh y ml In 14,16,18, there should be no question about the indicated polarities; in 17 it is evident one group must have a polarity oontrary to its tendenoy, and In view of the ob- served replacement, the 50g group naturally Is chosen. In 19 and 80, no arrangement will give all groups their normal polarity; In eaoh case two have been satisfied with the result that the replacement in 80 should not be expected. In all oases, there is a sufficiently large exeess of reagent always added to combine with all the H02 in the com- pound plus a generous excess to displace any possible equilib- rium. TABLS 3. Samples of various compounds, sealed in tubes with alooholio UaOH and heated in a water hath. Analyzed (?) partly hf eleotrio titration (designated by #) and the remainder by titration with an Indicator. 81 88 88 84 86 85 £6 87 88 89 30 31 32 33 34 35 36 37 38 39 40 41 42 43 i s o - mer 0 0 a m m a P P P P 0 0 0 m P P 1; l ! 1 1< 1 1 1 1< ,6 6 :5 6 :8 .8 (8 :8 weight in g a s . 1.0000 1.0000 1.0010 1.0000 1.0000 •9940 1.0000 1.0000 1.0010 .9990 1.0000 1.0000 1.0010 .9940 l . oo lO •9990 .7010 .6980 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 reagent 0 0 . ] 80 ££ ££ 84 £0 88 £4 £0 ££ ££ £4 £2 2£ £2 £8 £2 D] 26 £5 £4 18 £4 £4 18 18 norm. f IZBAS 1.668 •476 .476 .531 • 568 .476 .631 .568 •476 .476 HIIRO . 5 8 1 .476 .476 .476 .476 .476 BUBO • 486 • 486 .562 .374 .668 .562 • 374 .374 temp. (°o.) ILIHB 100 100 100 100 100 100 100 100 100 . 100 TOIUSI 100 100 100 100 100 100 HAPHTI PLOO 100 100 100 100 100 100 100 time !hra) 31 52 70 4 30 64 4 31 52 70 IB 4 62 70 64 52 70 UIiBB] £ 2 30 32 31 30 33 31 replacement c a l c . 0 * 0 0 100 100 100 0 0 0 0 0 0 0 100 0 0 1 60 60 60 50 0 0 0 0 ob 8. 11.40 1 5 . 4 19 .9 £3 .4 38 .2 3 1 . 0 1 2 . 3 9 . 0 7 . 4 2 6 . 5 1 2 . 3 16 .4 19 .9 31 .0 7 .4 £6 .6 32.7 4 1 . 5 26 .8 26 .4 25.9 £ 0 . 2 £5 .0 £6 .9 # t * | Doubtful Favorable Favorable Doubtful Favorable Doubtful Favorable Unfavorable Runs £1 to 36 show the influence of time upon the result very well, since temperature is oonstant and concentrations nearly so. fhe results are discussed on the next page with the formulae. ~^i NO? Referring to the formulae for nltraniline given on page 31, the unexpected replacement In runs 21,22,23 may he due to aotlon on the eleotromer, sinoe it is seen that the rate of substitution is very slowly increased with time. This would indicate the slow conversion of the stable eleotromer to the unstable one. The same explanation may hold for oases 30,31,32, for here the groups have their proper sign and no replacement should be expected. For 35, as in the ease of 17, the polar- ities must be chosen. Since replacement has occurred, the U0 2 has been given the negative. The results for 36 are exactly as predicted; for 40 they are not. In 1:8 dinitronaphthalene, as was shown on page 7, there are two positive positions in the 1-8 carbon atoms, or if the formula be turned up side down, there are two negat- ive positions. Since H0g tends to act positively, it is logio- al to assume the two nitro groups would oooupy the two positive positions, and would have very, little tendenoe to revery to the eleotromer. The facts in runs 41 to 43 do not bear this out. The melting points of the various compounds separated from the reaction-mixtures as lndioated previously, are here appended, and do not favor the theory of straightforward substitution. 0 117 58 46. £ 46 71 m 90 96 114 (all liquids) 170 56 45.2 63 -10.5 123 96 137 16 (all liquids) 38,51 47, 52 126 P 171 58 114 58 146 184d. 114 139 52 ,138 M.P. of dinitro benzenes (a) M.P• of nitro phenetoles M.P. of nitro phenols M.P. of compounds found from (a) M.P. of nitranilines (b) M.P. of amino phenetoles M.P. of amino phenols M.P. of nitro phenetoles M.P. of nitro phenols M.P. of compounds found from (b) M.P. of nitrotoluenes (o) M.P. of methyl phenetoles M.P. of methyl phenols M.P. of compounds found from (e) Here all the possibilities of substitution are taken into account, and only in the oase of the dlnitrobenzenes are the products of the reaction positively identified. Since any method depending on titration would not necessarily show from the analysis whether it was the nitro group being replaced or not, melting point data is essential for ascertaining the course of the reaction. In the final analysis adopted, the replacement of the nitro group is positively identified, since HO oan only be formed from the nitrite liberated. TABLE 4. Various compounds refluzed in an atmosphere of nitrogen with aqueous HaOH, and analysed by the author's own method. Before giving the table, it may be mentioned that the products of reaction from ortho and para dinitrobenzene were positively recognized as ortho and para nltrophenol. In the oase of the meta compound, it was recovered practically quantitatively unchanged, agreeing very well with the analysis result. TABLE 4 . (1 ) - (2) • (3) - 4gN02 IgNOp lgN0| Height .2997 .2998 .2997 V o l . o f HO at H.T.P. 43 .6 o a l o . 43 .6 " 43 .6 " 4 0 . 2 obs . 4 1 . 5 4 8 . 3 ' n If i> Beplaoement 100 o a l o . 100 » 100 » 9 2 . 3 obs, 95 ,1 " 97 .1 " 44 • 6 46 47 48 49 60 61 62 59 64 65 66 57 56 59 60 61 62 63 64 64 65 66 67 68 69 i s o - mer 0 ft m m P P P 0 0 » ft n P P n a 2:4 2:4 2 : 4 ^ •9ft sym sym sym sym sym sym sym weight i n gB8 .7007 .7010 .3516 .5018 .3482 •3502 .3494 .2995 •3025 • 2995 .3015 .3060 .2995 • 3004 .3052 •4230 .4250 • 5985 • 5002 .5036 .4980 .4980 .4038 .3990 .5002 .5027 « . mm reagent vol 50 50 50 50 50 50 50 50 26 50 26 25 50 25 25 25 norm time (hrs) $ 1 'eplaoement oaloul . DINITROBEHZSHB 1.0 1.0 1 .0 0 .5 1 .0 1 .0 1 .0 15 4 15 44 0 . 6 1 .5 44 H3R4NI1IHE 1 .0 2 .0 1 .0 2 .0 5 .0 1 .0 2 . 0 3 17 5 16 17 3 17 100 100 100 NIUBOPHEHOI 2 .0 | 17 | NITROTOLU] 2 .0 I 17 SHE 100 DIHITROTOLUEHB 26 25 26 1 .0 2 .0 4 .0 2 . 3 6 20 fEIS IZROTO£OBHS 25 25 1 .0 0 . 5 3 24 (KOH) 2KIHITR0BENZME 25 26 25 25 0 . 5 4 .0 2 .0 2 . 0 ntnix 30 30 0 . 6 0 . 5 4 (EOH) 2 40 50 R0PHEH01 4 (KOH) 8 (EOH) 60 0 0 0 50 50 50 0 0 or 0 or 0 or 0 0 0 100 or 0 0 0 0 0 0 0 0 0 0 0 0 obs, 32.6 3 . 3 3 .6 6 .4 4 5 , 8 4 4 . 7 4 7 . 1 0 . 0 0 . 0 0 . 0 0 . 0 2 .5 0 . 0 0 .0 0 , 0 0 .0 2 1 . 1 29.8 20. 32 . 31 .2 27 .5 1 .3 30 .6 28 .9 1 2 . 3 2 4 . 1 favorable favorable favorable favorable doubtful favorable unfavorable N 0 2 \A unf N O * 4- N*O^VJNO2 unf, I — , £ . .. 1 TABLE 4. (oont.) 70 71 72 73 7* 76 76 77 78 7* 80 81 82 83 84 i s o - mer 1:5 1:5 1:6 1:6 l ;5 1:8 1:8 1:8 136 138 188 138 138 weight in grm .4987 .4989 • 5000 .4996 .5000 •4967 • 4984 • 5010 • 8953 • 3990 reagent vol norm time (hra) £ Replacement oaloul. DmXBOBAPHSHALSHB 50 60 25 25 26 50 50 25 1 .0 2 .0 4 . 0 6.0 10.0 1.0 £ .0 4.0 8 43 20 18 16 8 43 20 60 60 50 50 60 0 0 0 ALPBA-H ITROH APHTHAEKNB 25 85 2 .0 10.0 15 15 0 0 TBI NKHQIAPHTHALBMB • 5012 •5068 .6078 .5022 • 5085 25 25 25 26 26 2 .0 2 .0 5*0 5.0 5 . 0 0 . 2 18 8 12 24 0 0 0 0 0 0 D 8 . 0 . 0 0.0 0 . 0 7*6 9 .7 8 . 6 11*8 4 . 3 0 . 0 0.0 11*7 52.4 17.0 20,0 16.2 i CO - * f e KIO; N O * frS w + o3 •*• -t- ax, Discussing this table in fall would he a lengthy prooees; the figures apeak for themselves. Buna 44 to 60 need no comment; nitranillne was discussed on page 31, hut runs 53,64,56 would tend to ahow that the tendency for the nitro group to he positive is greater than the tendenoy for the amino group to he negative in the meta form, where one must show its superiority. This oontradieta the conclusions in table 2. Bun 66 ia deoidedly contradict- ory. Buna 69,60,61,62 are doubtful because of the possibility of tautomeric change to the eleotromer being very great. Buna 63 to 69 are,however,unfavorable; the groups all have their proper aign, and espeoially in the ease of 68 and 69, there should be no tendenoy whatever towards eleotromeriam. Buna 78,79, are entirely as expected, whereas runs 70 to 77 are almost contradictory. By referring to the formulae, the 1:5 isomer has certainly one replaceable group, while the 1:8 could only show replacement by most unlikely eleotromeriam. The replaoement noted must, however, be due to this change. This brings us to the final case where in 1:3:8 trinitronaphthalene, the three positive NOg groups should show the least tendency of all towards electromerism. The results deny this. In practically all of Table 4 the time faotor is used in arranging the results — this may not be the best arrangement, for the speed of reaction is dependant on two factors: (i) the rate of action of the reagent on replaceable groups, (ii)the rate of tautomeric change in an effort to produce replaceable groups. Unless many experiments are carried out with a determination of these rates in view, no satisfactory results or conclusions can be made. Attempts to identify products in most oases tend to show that possibly more complex reactions have been taking plaoe than has been suspected, exactly the result that many other workers have found. In conclusion, the author wishes to make clear the fact that he believes either (1) the Electronic theory of alternate polarity does not hold, or (11) that the tautomeric ohanges predicted by the theory so predominate as to render any speoulatlon on the oourse of an untried replaoement futile. The author takes this opportunity to express his sincere indebtedness to: Br. B.H. 0L4BK and Dr. B.H. ARCHIBALD for their helpful suggestions and kindly criticism. REFERENCES. 1 . FRY.H.S. 2. 3. "The E l e c t r o n i c Conception of Valence and the Const i tu t ion of Benzene" London, 1921. Page 1 1 . Annalen, 287, (1895) pp. 315-6 . "The E l e c t r o n i c Conception of Valence and the Const i tu t ion of Benzene" London, 1921 Page 84. HOLLEMAN & WALKER "Textbook of Organic Chemistry" F i f t h e d i t i o n , Hew York. Pages460, 461 . Chemical Abstracts , 15, p . 1708. Abstracts of the Journal of the Chemical S o c i e t y , London, 1885 ( i ) p . 657. i b i d . 1891 p . 428. i b i d . 1894 ( i ) p . 573. HOLLEMAN & WALKER "Textbook of Organic Chemistry" F i f t h e d i t i o n , New York. Page 460. Abstr. J. Chem. S o c , 1889 ( i ) p .745 Chemical Abs trac t s , 15 , p . 1708. "Organic Chemistry" 1902 Amer. E d i t . Vol .11 Page 67 . Abstr. J. Chem. S o c , 1891 i b i d . 1894 i b i d . 1895 Vol . V, p .320 . Jour. Chem. S o c , London, pp. 656-59 . "T.N.T. and other Hitroto luenes" p . 99 . Abstr. J. Chem. S o c , 1899 ( i ) p . 745. i b i d . 1916 ( i ) p . 2 3 . i b i d . 1921 ( i ) p . 167. JACKSON & BOOS Jour. Amer .Chem.Soc , 20 , p .1898. LBBOTSON & KENNER, Trans. Jour.Chem.Soc,1923 (1) p .1260 . NEF, FRY,H.S. HOLLEMAN.A.F. de BRUYN,C.L. de BRUYN,C.L, de BRUYN,CL. STBGER.A, HOLLEMAN.A.F RICHTER, de BRUYN de BRUYN de BRUYN 5, 6. 7, 8, 9, 10, 11. 12. 13. 14. 15. 16, 17, 18. 19, 20. 21, 22. 23, 24. 25. 26. 27 . RICHTER C.L ,C.L , C L BEILSTEJ, KENNER & PARKIN, Trans. 1920 ( i i ) a.c. SMITH, de BRUYN,C.L. HOLLEMAN.A.F. HOLLEMAN.A.F. ( i ) p ( i ) p 428. , 574. 653. COHEN, GUIA.M. ,E . S i •Organic Chemistry" 1907, V o l . I I , p . 9 0 . La Gazetta, I t a l y , 19f5 ( I ) p . 362. iws) "The E lec t ron ic Conception of Valence and the Const i tut ion of the Benzene Ring" London, 1921, p . 224. "Organic Chemistry" 1902 Amer. E d i t . Vol .11 Page 397. 28 . 29 . 30. 31 . 32 . 33 . 34. 35. 36 . 37. 38. 39 . BEILSTEH? MELLOR, MELLOR, A b s t r . Jour . Chem. i b i d . Vol . V, p . 565. Chemical Abstracts , i b i d . i b i d . i b i d . i b i d . i b i d . i b i d . S o c , 1 9 0 8 ( i i ) p . 79. 1904 ( i ) p . 175. , 1907 ( i ) 260, ( I i ) 907, 1906 ( i i ) 4 1 8 , ( i ) 307. 1906 ( i i ) p . 282. 1904 ( i i ) p . 394. 1910 ( i i ) p .1109 . 1922 ( i i ) p . 524. 1908 ( i i ) p . 130, 1909 ( i i ) p . 517. "Modern Inorganic Chemistry" 1925, p . 631 . i b i d . p . 638.


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