May, 1946
BEHAVIOROF NITROALCOHOLS TOWARD FORMIC ACETICANHYDRIDE
759
Anal. Calcd. for CeH&: N, 26.41. Found: S , slightly loosened so that water was sucked into the flask 26.10, 26.22. without permitting the escape of hydrogen bromide. The Saponification of (B).-A mixture of 5 g. of the solid (B) excess of bromine was then determined by titration with and 35 cc. of concentrated hydrochloric acid was heated on thiosulfate after the addition of potassium iodide solution. a steam-bath for two hours and then evaporated on the The amount of substitution was then ascertained by the steam-bath to dryness. Five t o six extractions of the resi- addition of potassium iodate followed by a second thiodue with ether removed 2.4 g. of an acidic material ( D ) sulfate titration. Table I1 summarizes the results. leaving a residue (E). TABLEI1 The Acidic Product (DL-The crude acid (m. D. 97-116 ”) Solwas recrystallized three or four times from benzene, giving Compound vent % Addition 70Sul~stitution cis-P-methylglutaconic acid of m. p. 150-151”. A mixed I 2 1.2 melting point with a sample of this acid prepared from ClCH=C(CHa)CH2Ch’ CClr 1 2 7 1 4 . 3 CCI, o n 0 0 diethyl a-cyano-p-methyl-gl~taconate~~ gave no depres- C I C H = C ( C H J C H K I CICHzC- CHzCl CClr 2 6 2 9 o n sion. /I A product of m p. 112-115’ was also obtained from the CHz acidic material ( D ) . It is probable that this consisted in CsHrOCHzC(CHa)=CHlarge part of trans-8-methyl-glutaconic acid. CN CClr 8 3 . 4 80.4 80 :18 6 38 8 i i 7 . 2 The Residue (E).-When the chloride salt (E) was ex- Solid dinitrile ( B ) 0 3 O R CHCls 38.6 4 0 . 7 tracted with ammonium hydroxide, the filtered extract Liquid dinitrile (C) CHCla 1 1 . 5 11 .(i 0 3 0 I treated with acetic acid and cooled in a refrigerator, 2.6 g. of crystalline solid separated. Recrystallization of this Summary from absolute alcohol gave 2,6-dihydroxy-4-methylpyridine, m. p. 192-193’. A mixed melting point with a syn1. Eastman Kodak Co. practical “1,3-dichlorothetic sample14 showed no depression. The Liquid Residue (C).-The liquid nitrile remaining isobutane” reacts with cuprous cyanide to give -4-chloro-3-1nethyl-3-butenonitrile, which origiafter the separation of the solid was cooled in an etherDry Ice-bath, but very little solid separated from the sirup. nates from 1,3-dichloro-2-methyl-l-propene, a %@Several distillations led t o the separation of more of the 30’% admixture in the Eastman product, now dissolid ( B ) . Eventually a liquid product b. p. 130-132” a t continued. A method is given for the preparation 12 mm. was obtained; azo41.0498; ~ z ~ O D1.41726; M R D 29.61; db6,0.9799; ~ Z 1.4590; ~ D M R D 29.48. However, of the 1,3-dichlor0-2-methyl-1-propene by the action of quinoline on 1,2,3-trichloro-2-methylthe analytical results were inconclusive. The saponification of the liquid nitrile gave the same propane, whose synthesis from methall yl chloride cis-8-methylglutaconic acid and 2,6-dihydroxy-4-methyl- and sulfuryl chloride is also described. pyridine obtained from the solid ( B ) . 2. The structure of the 4-chloro-3-methyl-3The saponification of the dinitrile with sodium hydroxide butenonitrile, exclusive of stereochemical congave a product of m. p. 208”. Anal. Calcd. for CsHsN20: X, 22.59. Found: K, siderations, has been deduced from a study of the 22.63, 22.69. corresponding acid and amide, whose formation Quantitative Behavior of Unsaturated Compounds with from the nitrile and related imido ester salt is Bromine.-On account of the inconclusive nature of the described. qualitative bromine tests for unsaturation, the quantita3. The action of cuprous cyanide on the Easttive method of McIlhineylO was used on several of our comman “1,3-dichloroisobutane!’ gives a solid and a pounds. In our study of the chloronitrile ( V I ) , a weighed amount of the compound dissolved in carbon tetrachloride liquid dinitrile, both of which on saponification was transferred t o an iodine flask and treated with a known with hydrochloric acid give cis-/3-methylglutaexcess of M/3 bromine solution in the same solvent. The flask was stoppered, shaken and set in a dark place for conic acid and 2,6-dihydroxy-4-methylpyridine. eighteen hours. Water was then poured around the stop- ‘ r R O Y , s.Y . RECEIVEU J A?N ~ U A R3,Y1!:46 per of the flask and the flask was cooled in order to create a decrease in internal pressure, when the stopper vas (2%) Original manuscript received April (i,1 0 4 > , -1
[CONTRIBUTIONFROM
THE
CHEMICAL LABORATORY O F NORTHWESTERN UNIVERSITY]
Behavior of Nitro Alcohols toward Formic Acetic Anhydride BY CHARLES D. HURD,STEVENS S. DRAKEAND OTIS FANCIIER The literature mentions only a few references to esterification of nitro alcohols. These esters are chiefly the acetates, propionates, butyrates and isobutyrates with no mention of formates. Pauwels’ and Shaw2 were the first to report in this field. They prepared 2-nitrobutyl acetate and 2-nitroisopentyl acetate by reaction of the corresponding nitro alcohols with acetic anhydride. Three 1-alkyl-2-nitraethyl acetates were syntbesized, by Schmidt and R ~ t z alkyl , ~ repre(1) Pauwels, Rec. I ~ Q u .c h i m . . 17, 27 (18$18). ( 2 ) Shaw. ibid.. 17, 80 (1898). (3) Schmidt and Rutz. Ber., 61, 2142 (1‘328).
senting methyl, ethyl and n-propyl. A few other acetates were added in 19-40 by Vanderbilt and Hass and by Gl00r.~ The latest work on this subject was by TindalP who reported the preparation of propionates, butyrates, and isobutyrates of twenty-five nitro alcohols. He found that the nitro primary alcohols could be esterified by interaction with the organic acid in the presence of a little sulfuric acid, whereas the nitro secondary alcohols required the use of the acid anhydride. ( 3 ) Vanderhilt and f i a s s . I m i . E118 ( ‘ h e m , 32, 34 ( I ! ) 4 0 ) ; Glswr, U . S. Patent 2,185,2‘37, ( ’ . A , . 34, 2862 (I!l40). ( 3 ) Tindall, i b i d . , 33, 05 (1941).
790
CHARLES D.HURD,STEVENS S. DRAKEAND OTIS FANCHER
He found also that if the crude ester was treated with water or aqueous alkaline solutions t o remove residual acid such a treatment brought about decomposition of the ester into a nitroijlefin a t the time of distillation. The present study concerns itself with the behavior of a few nitro alcohols toward formic acetic anhydride. This reagent was discovered by Bdhal,6who found that i t reacted unidirectionally with simple alcohols t o produce alkyl formates free from acetates. Work in this Laboratory' has shown that formic acetic anhydride is easily prepared by the reaction of anhydrous fonnic acid with ketene and that toward aniline it reacts quantitatively t o give formanilide. 2-Nitro- 1-butanol, 2-nitro-%methyl- 1-propanol and 2-nitro-2-methyl-l,3-propanediolwere investigated with the finding that their formic esters could be prepared smoothly by maintaining a reaction temperature of 50-60' or lower. The use of ether as solvent met this requirement. At higher temperatures, or if sulfuric acid was added as a catalyst, a different reaction ensued giving rise to acetic esters. In other words, conditions which produce a vigorous reaction cause the formation of acetic esters, perhaps by way of preliminary decomposition of the mixed anhydride into acetic anhydride or acetic acid. I t is noteworthy that mixing of formic acetic anhydride and 2-nitro-2-methyl-1-propanol is accompanied by marked cooling. This endothermic effect was not noticed with the other nitro alcohols.
Vol. 68
for thirty minutes, then set aside overnight. Vacuum distillation gave a forerun of 1.2 g. of unreacted nitro alcohol (m. p. 85-86') and a main fraction which, on redistillation, yielded 7.8 g. (44% yield) of 2-nitroisobutyl formate, b. p. 65' (5 mm.). Hydrolysis of this ester by refluxing with dilute sodium hydroxide solution yielded sodium formate, characterized by Duclaux constants, and by conversion t o p-bromophenacyl formate. Two modifications of the esterification without solvent were performed, both of which yielded the acetate rather than the formate. In one, the same equimolar reaction mixture was heated t o boiling immediately after mixing. In the other, a drop of concentrated sulfuric acid was added to the cool endothermic mixture. After one minute a vigorous reaction took place with sufficient heat evolution to cause rapid solution of the solid alcohol. The reaction was largely completed at this stage, but the mixture was refluxed for an hour. After cooling, ether was added and the solutiov was extracted with sodium bicarbonate solution, dried over sodium sulfate, and distilled. Both runs yielded 75-80y0 of 2-nitroisobutyl acetate, b. p. 92-94' (I0 mm.). Hydrolysis of both and derivatization yielded p-bromophenacyl acetate; m. p. and mixed m. p. 85-86 O 2-Nitrobutyl Formate.-Mixing of 15.6 g. of 2-nitro-lbutanof and 10 ml. of formic acetic anhydride was not arcompanied by any appreciable temperature change. With general details as in the previous run, 17 g. (887 yield) of 2-nitrobutyl formate was collected at 72-76 8 (5 mm.), chiefly a t 75-76". Hydrolysis and conversion to the p-bromopheiiacyl derivative showed it t o be the formate. I t was also prepared differently by refluxing for eight hours a mixture of 6.7 g. of formic acetic anhydride, 8.5 g. of 2-nitro-1-butanol and 75 ml. of dry ether. Five grams (48% yield) of product, b. p. 65-66' (2 mm.), was redistilled t o give a pure sample which was collected at 98-98.5' (10 mm.); nmJD 1.4345. Anal. Calcd. for ChHoOJJ: N, 9.52. Found: N, 9.85. 2-Nitro-2-methyl-l,3-propanediol Diformate.-With ether (75 ml.) as solvent as in the preparation of Z-nitroExperimental isobutyl formate, 3.7 g. (53%) of product, b. p. 101-103' The nitro alcohols used in this investigation were gener- (3 mm.), was obtained from 5 g. of 2-nitro-2-niethyl-l,3ously supplied by Commercial Solvents Corporation. One propanediol and 7.2 g. of formic acetic anhydride. This was a liquid and the rest were cream-colored, waxy solids: fraction possessed these constants: nn.6D 1.4520, dmse 2-nitro-1-butanol, b. p. 127-130" (25 mm.) ; 2-nitro-2- 1.297. methyl-1-propanol, m. p. 85-86' ; 2-nitro-2-methyl-I ,3Anal. Calcd. for CsHgOeN: N, 7.33. Found: N, 8.05. prbpanediol, 111. p. 144-145' ; tris-(hydroxymethy1)-nitro- Without the ether as diluent a vigorous exothermic remethane, m. p. 149-150". action was observed. The quantities of reagents taken Formic acetic anhydride' was prepared from ketene. were 10 ml. of anhydride and 8.3 g. of the diol. Reaction I t distilled a t 36-38' (28 mm.) and its purity was checked was complete even before the contents of the flask could be by reaction with aniline to produce formanilide quantita- cooled by an ice-bath. The resulting product was a pale tively: b. p. 135" (6 mm.); m. p. 47'. Kept in a glass yellow, viscous solution. Distillation a t 2 mm. yielded stoppered bottle it still yielded formanilide quantitatively 12 g. (89qo) a t 109-112"; @D 1.4493; dm, 1.2379. This after a two-week period. was chiefly 2-nitro-2-methyl-l,3-propanediol diacetate as 2-Nitroisobutyl Formate.-Six and four-tenths grams of judged by hydrolysis and conversion t o p-bromophenacyl formic acetic anhydride was added into an ice-cold mixture acetate, m. p. 85-86". When mixed with an authentic of 8.5 g. of 2-nitro-2-methyl-1-propanol and 75 ml. of ah- specimen the m. p. was 86.5-87.5'. solute ether. The solution was refluxed for eight hours Tris-(hydroxymethy1)-nitromethane.-Twenty ml. of and distilled. The fraction, h. p. 59-60' (3 mni.), weighed formic acetic anhydride gradually brought 1.32 g. of tris7.2 g. (Sly0 yield). On redistillation through a 10-cm. (hydroxymethy1)-nitromethane into solution with no \.igreux column a little unused nitro alcohol was sepa- temperature effect. No doubt, the formic ester was obrated in the first fraction (94-96" (13 mm.)). This fraction tained but it could not be distilled without decomposition partially solidified. The pure formate was collected a t a t 0.001 mm. and a bath temperature of 140". 97.5-99'' (16 mm.) or 86-87' (10 mm.); n s J ~ 1.4327, Acknowledgment.-Microanalyses were perdm20 1.145. Anal. Calcd. for C L H ~ O ~ NN, : 9.52. Found: N, formed by W. Brandt and R. Pivan. Assistance 9.
