1658 KISSINGER, MCQUISTION, SCHWARTZ, AND GOODMAN VOL. 22

sulfuric acid. The solution was heated on a steam bath for 15-30 min. In all cases, the cis-diols reacted visibly more rapidly than the trans-diols. A few drops of water were suf- ficient to precipitate the rearrangement product if this had not occurred a t the end of 30 min. The product was filtered, washed with water, and recrystallized. In this manner, the following four rearrangement products were obtained: g,i0-Dihydro-9-phenanthrcrne1 m.p. 147-149" (lit. m.p.,

152O)G from ethanol, was obtained from both cis- and trans-9,10-dihydro-9,10-phenanthrendiol. It is unstable on standing in air or in solution and changes color from pale yellow to pink to red in a relatively short time. After rapid filtration, a single pale yellow crystal was quickly selected for melting point determination. The time interval between commencement of the rearrangement process and the melt- ing point determination approximated 20 min.

10J O-Di(p-tolyl)-9,iO-dihydro-9-phenunthrone (IIIa), m.p. 163-164.5' from absolute ethanol was obtained in 90% yield from cis-IIa and in 80% yield from trans-IIa.

A n d Calcd. for CZ~HZZO: C, 89.80; H, 5.92. Found: C, 89.69; H, 5.88.

13achmann4 DreDared IIIa. m.D. 158-159" bv a similar A I , I

pinacol rearrangement using iodine and glacial acetic acid. iO,i0-Di(i-naphthyl)9,iO-dihydr~9~henunthrone (IIIe),

m.p. 286-287O36 from absolute ethanol was obtained in 90% yield from cis-IIe and in 35% yield from trans-IIe.

(35) F. R. Japp and A. Findlay, J. Chem. SOC., 1121

(36) See Table I, Ref. (e). (1897).

Anal. Calcd. for C&fzzO: C, 91.46; H, 4.97. Found: C, 91.45; H, 5.33.

The infrared spectra of phenanthrones IIIa and IIIe are quite similar and show identical absorption bands, attributed to aromatic ketones at 5.92, 6.27, and 7.90 microns, and to aromatic substituents a t 6.90, 7.18, 12.62, 13.03, 13.26, 13.66, and 14.40 microns."

Reuwangement Product (IIIb), m.p. 104-105" from ethanol was obtained in 95% yield from ck-IIb and in 90% yield from tram-IIb.

Anal. Calcd. for CeoHMOa: C, 87.55; H, 6.61; Mol. wt., 823. Found: C, 87.56; H, 6.71; Mol. wt., 881 i 10% (Signer-Barger).

The infrared spectrum of IIIb showed a weak band at 2 . 9 5 ~ (OH), moderate bands a t 6.23p, 6.92p, 8.13, 9.25, and 10.57~ (aryl substituents), and strong bands a t 6 . 0 1 ~ and 13.65~; A, 253 mp, hnsr 68,200.

Acknowledgment. The authors take pleasure in thanking the Research Corp. for grants initiating and supporting this work. Special thanks are due to William J. Schmitt, S. J., Woodstock College, Woodstock, Md. whose serendipity led us to this investigation.

NEW YORK 58, N. Y.

(37) We are indebted to Mr. Daniel McCarthy for the infrared spectra (KBr) disk for these compounds.

[CONTRIBUTION FROM THE LOS ALAMOS SCIENTIFIC LABORATORY, UNIVEBsITY O F CALIFORNIA]

gem-Dinitro Esters. I. Preparation and Some Reactions of a-Hydroxy-P,fl- dinitropropionic and -butyric Acids

L. W. KISSINGER, W. E. McQUISTION, M. SCHWARTZ, AND LEON GOODMA"

Received April 1, 1067

The preparation of a-hydroxy-B,fl-dinitro-propionic and -butyric acids by the condensation of dinitromethane and 1,l- dinitroethane, respectively, with glyoxylic acid, their esterification and acylation, and some of their physical properties are described.

As part of a study of the chemistry and proper- ties of gem-dinitro esters, . several a-hydroxy-p,p- dinitro acids and esters were prepared by the con- densation of 1, l-dinitroparaffis with glyoxylic acid derivatives.

The condensation of nitroparafis with carbonyl compounds to form nitro alcohols was first reported by Henry2 in 1895. Subsequent studies of this reac- tion, primarily using mononitroparafhs, were re- viewed by Hass and Riley.3 Chattaway and With- erington4 successfully used the hydrate of a car- bonyl compound in this same condensation to ob- tain nitro alcohols. Shechter and Conrad6 prepared

(1) Present address: Stanford Research Institute, Menlo Park, Calif.

(2) L. Henry, Compt. rend., 120, 1265 (1895). (3) H. €3. Hass and E. F. Riley, Chem. Revs., 32, 406

(1943). 14) F. D. Chattawav and P. Witherington, J. Chem. SOC., - .

1178 (1935).

5612 (1953). (5) H. Shechter and F. Conrad, J. Am. Chem. SOC., 75,

a-hydroxy-p-nitropropionic acid by the condensa- tion of nitromethane with glyoxylic acid in aqueous solution.

In the present investigation a-hydroxy-p,p-di- nitrobutyric acid (I) was prepared by the acid-cata- lyzed condensation of 1, l-dinitroethane with gly- oxylic acid hydrate. It was also obtained, although in lower yield, in the attempted preparation of 2,2,5,5-tetranitro-3,4-hexanediol by the reaction of 1,l-dinitroethane with a commercial grade of gly- oxal.B The a-hydroxy acid was stable in acidic or neutral media but it rapidly reacted with two moles of base to form glyoxylate and dinitroethane an- ions. Esterification with ethanol or methanol in the presence of sulfuric acid was normal in contrast

(6) a-Hydroxy-p,p-dinitrobutyric acid could arise in one of several ways, for instance, by oxidation of an inter- mediate condensation product as a-hydroxy-p,&dinitro- butyraldehyde or by preliminary oxidation of the glyoxal to glyoxylic acid, followed by normal condensation. The mechanism of this reaction, however, waa not investigated.

DECEMBER 1957 GEM-DINITRO ESTERS. I 1659

to that of the propionic analog, giving the corre- sponding ethyl and methyl esters I1 and 111; the former ester was also prepared by the condensa- tion of 1,l-dinitroethane with ethyl glyoxylate hemiacetal. The nitro acid, however, was recovered unchanged after warming with concentrated sul- furic or polyphosphoric acid showing no evidence of lactide or polyester formation. Attempted prep- aration of the a-bromo acid by reaction with phos- phorus tribromide gave instead, a phosphate ester which was free of bromine. Acetylation of the ni- tro acid and esters gave a-acetoxy-p,p-dinitrobu- tyric acid (IV) and the corresponding ethyl and methyl a-acetoxy esters V and VI. a-Trifluoroace- toxy-p,p-dinitrobutyric acid (VIII) was readily prepared by the action of trifluoroacetic anhydride on the acid but it was comparatively unstable.

Ethyl a-hydroxy-p,p-dinitrobutyrate (11) was also rapidly cleaved to the anion of 1,l-dinitroeth- ane by hydrazine hydrate or even dry ammonia. The a-acetoxy derivatives were more stable toward bases than were the free hydroxyl compounds. a- Acetoxy-p,p-dinitrobutyric acid (IV) reacted as a monobasic acid although excess alkali slowly pro- duced the 1,l-dinitroethane anion. Hydrazine hy- drate and dry ammonia each cleaved the a-acetoxy esters from which low yields of 1,l-dinitroethane hydrazinium or ammonium salts were isolated.

H + AcCl FHOCHCOOH + CHaC(N02)2CHCOOH + I I I

OH I

I CHaC(N0z)zCHCOOH I OH

I HZ804 OOCCHI I RoH IV

H + 9 AcCl LROYHCOOR + CH&(N02)2YHCOOR +

I OH 6 H

R = E t I1 R = Et I11 R = Me

CHaC(N02)zCHCOOR I OOCCHI

V R = E t VI R = Me

HaNNHa*HzO I1 ___) HzNNHi"[02N=C(N02)CHa] -

VI1

a-Hydroxy-p,p-dinitropropionic acid (IX) was ob- tained as a dipotassium salt (IXa) by the condensa- tion of potassium glyoxylate hydrate with potas- sium dinitromethane in water. Acidification gave %he free acid IX.

In contrast to the behavior of the butyric acid, we were unable to prepare esters of this nitro acid by direct esterification; instead, the a-alkoxy esters were obtained. Thus, methyl a-methoxy-p,p-dini- tropropionate (X) resulted from the reaction of methanol on a-hydroxy-p,@-dinitropropionic acid (IX) in the presence of sulfuric acid. Echyl a-eth- oxy-@,p-dinitropropionate (XII) was pieparsd in a

similar manner from the a-hydroxy ester XI. While the a-hydroxy esters could not be obtained by direct esterification, potassium ethyl a-hy- droxy-p,p-dinitropropionate (XIa) was obtained by the condensation of ethyl glyoxylate hemiacetal and potassium dinitromethane. Upon acidification the free hydroxy ester XI was formed.

This difference in behavior of the butyric and propionic acids suggests the possible intermediate formation of the p,p-dinitroacrylate system in the latter case; however, efforts to prepare this inter- mediate were unsuccessful. Extensive decomposi- tion, with elimination of oxides of nitrogen, was observed when the hydroxy ester XI was treated with dehydrating agents. The alkoxy esters were distilled unchanged from phosphorus pentoxide. Pyrolysis of ethyl a-acetoxy-p,p-dinitropropionate (XIII) resulted in the elimination of acetic acid and oxides of nitrogen, the residue being a mixture of organic compounds from which a pure compo- nent could not be isolated. Treatment of the ace- toxy esters with base or urea again led to a mixture of products resulting from elimination of acetic and nitrous acids. Indeed it was observed in a quali- tative way that nitrous acid was eliminated more readily from these compounds than was acetic acid.

Ethyl a-acetoxy-p,p-dinitropropionate (XIII) was prepared directly by acetylation of the corre- sponding hydroxy ester X I and alternatively by the potassium iodide dehaI~genation'-~ of ethyl a- acetoxy-p-chloro-p,p-dinitropropionate (XV) ; the latter was obtained by acetylation of ethyl a-hy- droxy-p-chloro-p,p-dinitropropionate (XIV) which in turn arose by chlorination of ethyl a-hydroxy- @,p-dinitropropionate potassium salt (XIa).

The potassium dinitromethane used in this work was prepared from 2,2-dinitropropanedio1-ll3 by reaction with aqueous potassium hydroxide and treatment of the resulting potassium salt of 2,2- dinitroethanol with hot alkaline peroxide solution. It is of interest to note that use of strong aqueous alkali alone failed to convert the diol beyond the dinitroethanol stage.

EXPERIMENTAL'^

cu-Hydroxy-~,8-dinitrobufyTic acid (I). A. From glyoxylic acid. A suspension of 20 g. (0.17 mole) of 1,l-dinitroethane in 50 ml. of water containing 2 drops of concentrated sulfuric acid and 0.15 mole of glyoxylic acid" was heated on a steam bath with stirring for 6 hr. On cooling to room temperature the solution remained homogeneous. The crude acid was isolated from the reaction mixture by five ether extractions. After drying, the ether and excess 1,l-dinitroethane were

(7) J. Meisenheimer, Ber., 36, 438 (1903). (8) E. P. Kohler, J. A.m. Chent. SOC., 38, 887 (1916). (9) K, Klager, Anal. Chem., 23, 534 (1951). (10) Microanalyses by M. J. Naranjo and C. A. Esquibel.

All temperatures are uncorrected. (11) The sirupy aqueous solution of glyoxylic acid, pre-

pared by the method of 0. Doebner, Qnn., 311, 129 (1900), was assayed by titration with standard base prior to use.

1660 KISSINGER, MCQUISTION, SCHWARTZ, AND GOODMAN

H + -K + HOCHCOO- + 2K"[OzN=C(NO2)CHCOO] -- + CH(N0z)zCHCOOH

I AH OH

I OH

IX 1 MeOE HzSOi

IXa

CH(N02)2CHCOOMe < 1

OMe X

CH(NOz)2CHCOOEt -, I

OEt

VOL. 22

XI1 LEtOCCOOEt + K+[OzN=C(N02)CHCOOEt] - + H+ CH(NO2)dHCOOEt

I I I OH b H OE

XIa XI 1 Cln

i-ClC(NOz)&HCOOEt - AcCl or (CFsC0)rO 4- H O A

CH(N02)2CHCOOEt I f oocE4 I

AoCl 1 OH XIII -+ KI:

ClC(NOz)&HCOOEt + K +[OzN=C(NOz)CHCOOEtl -- I I

00CCH2 OOCCHs XV

removed under reduced pressure and the residue was crystal- lized from a mixture of 2-nitropropane and chloroform giving 11.5 g. (40% j of a-hydroxy-@,@-dinitrobutyric acid, m.p. 98-100". An analytical sample, m.p. 101-102°, was obtained by recrystallization from chloroform.

Anal. Calcd. for C4HeN207: C, 24.75; H, 3.12; N, 14.43; neut. equiv. 97.05. Found: C: 24.92; H, 3.10; N, 13.97; neut. equiv. 94.

Weak to moderate absorption in the 2.9 to 3.2p (OH) region, and strong absorption a t 5 . 7 4 ~ ( C 4 ) and 6 .34~ (NOz) were observed in the infrared in chloroform and acetonitrile solution. 3. From glyoxal. A suspension of 9 g. (0.075 mole) of 1,1-

dinitroethane and 9 g. (0.05 mole) of 30% aqueous glyoxal in 15 ml. of water was warmed to 70-75' for 8 hr. The reaction mixture was extracted with ether, the ether solu- tion dried with anhydrous magnesium sulfate, and the crude product isolated by evaporation of the ether. One recrystal- lization from a mixture of nitromethane and trichloroeth- ylene gave 3.1 g. (32%) of a-hydroxy-@,@-dinitrobutyric acid (I), m.p. 98-100".

Anal. Calcd. for CdHON207: C, 24.75; H, 3.12; neut. equiv. 97.05. Found: C, 24.85; H, 3.09; neut. equiv. 94.7.

Methyl a-hydroxy-@,@dinitrobutyrate (111). A solution of 17.7 g, (0.09 mole) of a-hydroxy-@,@-dinitrobutyric acid in 100 ml. of methanol containing 1.5 g. of concentrated sul- furic acid was heated under reflux for 7 hr. After removal of the excess methanol under reduced pressure, the residue was dissolved in chloroform, washed free of acid with water, and dried. Removal of the solvent and crystalhation of the residue from an isopropyl ether-hexane mixture gave 15.4 g. (82%) of methyl a-hydroxy-@,@-dinitrobutyrate, m.p. 40-42".

Anal. Calcd. for C&N207: 6, 28.85; H, 3.87; N, 13.46. Found: C, 28.87; H, 3.50; N, 13.13.

Medium absorption at 2 .87~ (OH), and strong absorp- tions a t 5 . 7 0 ~ ( C 4 ) and a t 6 . 3 2 ~ (NOz) were observed in the infrared in chloroform solution.

Ethyl rr-hydroxy-@,@dkitrohut?/rate (11). Ethyl ethoxy- hydroxyacetate'z (5.2 g., 0.035 mole) and 4.5 g. (0.038 mole)

(12) C. Weygand, Organic Preparations, Interscience -I__

Publishers, Inc., New York, 1945, page 456.

of 1,l-dinitroethane suspended in 25 ml. of water containing 1 drop of concentrated sulfuric acid were stirred a t 50" for 3 hr. After ether extraction and drying, removal of the solvent gave a yellow oil which was crystallized from a carbon tetrachloride-hexane mixture. Ethyl a-hydroxy-p,p dinitrobutyrate, m.p. 35-37", was obtained in 61y0 yield. An analytical sample, m.p. 44-45', was obtained by another recrystallization from the same solvent mixture.

Anal. Calcd. for CJXIONZO~: C, 32.44; H, 4.54; N, 12.61. Found: C, 31.79; H, 4.64; N, 12.64.

Medium absorption at 2 .84~ (OH), and strong absorp- tions at 5 .70~ ( C 4 ) and a t 6 . 3 3 ~ (NO4 were observed in the infrared in chloroform solution. The ester was distilled without decomposition a t 90-92' (1 mm.).

a-Acetoxy-p,@-dinitrohtyric acid (IV). A suspension of 2 g. (0.01 mole) of a-hydroxy-@,p-dinitrobutyric acid in 5 ml. of chloroform containing 3 g. (0.04 mole) of acetyl chloride was heated under reflux for 2 hr., the solvent removed by distillation, acd the residue Crystallized from chloroform giving 2.03 g. (96%) of a-acetoxy-p,@-dinitro- butyric acid, m.p. 128-128.5".

Anal. Calcd. for CeHaNlOa: C, 30.52; H, 3.41; N, 11.86; neut. equiv. 236. Found: C, 30.34; H, 3.55; N, 11.52; neut. equiv. 233.

Strong absorptions a t 5 . 6 5 ~ and 5 . 6 8 ~ (64) and 6 . 3 0 ~ (NOz) were observed in the infrared in chloroform solution. A broad band of moderate intensity was observed a t 3.45 to 3.7p (OH) in acetonitrile solution.

a-XriJluoroacetoxy-@,@dinitrobutl/ric acid (VIII). A sus- pension of 2 g. (0.01 mole) of a-hydroxy-@,@-dinitrobutyric acid in 10 ml. of trifluoroacetic anhydride was heated under reflux for 1 hr. Removal of the solvent under reduced pres- swe at 50' gave a quantitative yield of a-trifluoroacetoxy- @,@-dinitrobutyric acid, m.p. 131-131.5'.

Anal. Calcd. for C & F ~ N ~ O B : N, 9.66; neut. equiv. 96.7. Found: N, 9.93; neut. equiv. 97.

Attempts at crystallization from carbon tetrachloride or chloroform led to slow decomposition to the original hydroxy acid. Strong carbonyl absorptions at 5 .50~ and 5.65~, and nitro a t 6.30p, as well as three strong fluorine bands in the 8-9p region, were observed in the infrared on freshly pre- pared samples.

Methyl cracetoxy-pJ8dinitro~t~rate (VI). A solution of

DECEMBER 1957 GEM-DINITRO ESTERS. I 1661

15.5 g. (0.062 mole) of methyl a-hydroxy-@,p-dinitrobutpate and 100 ml. of acetyl chloride waa heated under reflux for 6 hr. The excess acetyl chloride was removed by distillation and the residue fractionated giving methyl a-acetoxy+,& dinitrobutyrate, b.p. 89-91"/0.3 mm., ny 1.4480, in 64% yield.

Anal. Calcd. for C,H1&.O8: C, 33.61; H, 4.03; N, 11.20. Found: C, 33.13; H, 3.93; N, 11.40.

Strong absorptions a t 5 . 6 5 ~ (O), 6.31 and 7 . 6 2 ~ (N01) were observed in the infrared in chloroform solution.

Ethyl aacetoxy-8,~dinitrobutyrate (V). The ethyl ester, b.p. 106-107'/0.05 mm., n y 1.4435, was prepared in 75% yield by the same procedure as described for the methyl ester VI.

A d . Calcd. for C8HlzN~08: C, 36.37; H, 4.58; N, 10.60. Found: C, 36.47; H, 4.54; N, 10.24.

Reaction of arhlldroxy-p,gdinitrobuty.ic acid (I) with p h s - phorus tribromide. To a solution of 0.95 g. (0.005 mole) of the hydroxy acid I in 5 ml. of toluene was added 1.4 g. of phosphorus tribromide with shaking and warming. After cooling the reaction mixture to room temperature a white crystalline product waa collected by filtration and dried in a vacuum desiccator under reduced pressure giving 1.2 g., m.p. 169" (rapid dec.). The compound was free of bromine on fusion with sodium and contained 12.16% N and 10.83% P. It was not further characterized.

Reaction of ethyl: a-hydroxy-p,pdinitrobutyrate (11) with hydrazine and ammonia. Ethyl a-hydroxy-p,@-dinitrobutyr- ate (2.2 g., 0.01 mole) in 15 ml. of 95% ethanol was treated with 0.46 g. (0.01 mole) of hydrazine hydrate a t 10". A yellow salt crystallized in plates almost immediately. After about 1 hr. the suspension was filtered and dried giving 0.98 g. (69%) of 1,l-dinitroethane hydrazine salt (VII), m.p. 135-136" (dec.).

Anal. Calcd. for CZ&NIO~: C, 15.79; H, 5.30; N, 36.84. Found: C, 15.89; H, 5.32; N, 36.68.

An aqueous solution of this salt yas acidified with hydro- chloric acid and extracted with methylene chloride giving, after drying, a solution which had an infrared spectrum identical to that of a solution of 1,l-dinitroethane.

In a similar way dry ammonia cleaved the a-hydroxy ester in benzene solution to 1,l-dinitroethane ammonium salt, m.p. 117-119' (dec.), in 63% yield.

a-Hydrozy-8,8dinitropropionic acd (IX). A solution equivalent to 5.3 g. (0.072 mole) of glyoxylic acid11 in 10 ml. of water was neutralized to phenolphthalein with 20% potassium hydroxide solutjon. This waa added dropwise during 15 min. to a stirred suspension of 10.5 g. (0.072 mole) of the potassium salt of dinitromethane in 40 ml. of water a t room temperature. After all of the yellow crystalline potassium salt had disappeared (2 hr.) the solution was acidified with 20% sulfuric acid and extracted seven times with ether. The combined extracts were dried over mag- nesium sulfate. Removal of the solvent under reduced pres- sure yielded a crystalline residue which, upon recrystal- lization from a 2-nitropropane-chlorofom mixture, yielded 8.7 g. of a-hydroxy-&/3-dinitropropionic acid (66%), m.p. 124-127' (dec.). Two more recrystallizations raised the melting point to 131.5-132' (dec.).

Anal. Calcd. for CSI4NzO7: C, 20.01; H, 2.24; N, 15.56; neut. equiv., 90. Found: C, 19.27, 19.35; H, 1.86, 2.03; N, 15.22, 15.27; neut. equiv., 90.

Weak to moderate absorption in the 2.9 to 3.2, region (OH), and strong absorptions a t 5 . 6 8 ~ (C=O), 6.33 and 7.53~ (NOZ) were observed in the infrared in acetonitrile solution.

Methyl a-nzethoxy-8,8dinitropropionate (X). A solution of 5 g. (0.028 mole) of a-hydroxy-&Minitropropionic acid h 50 ml. of methanol containing 5 drops of concentrated sulfuric acid was refluxed 16 hr. After removal of the excess methanol by distillation under reduced pressure, a chloro- form solution of the residue was washed with water, dried, and the chloroform removed, giving a 55% yield of crude methyl a-methoxy-&Sdinitropropionate. On crystallization

from an isopropyl ether-hexane mixture an analytical sample, m.p. 60-61°, was obtained.

Anal. Calcd. for CaNzOl: C, 28.85; H, 3.87: N, 13.46. Found: C, 28.72; H, 3.94; N, 13.20.

Ethyl a-hydroxy-@,fl-dinitropropirnte (XI). Ethyl ethoxy- hydroxyacetatela (5.92 g., 0.04 Ipole) was added dropwise to a stirred suspension of 5.76 g. (0.04 mole) of the potassium salt of dinitromethane in 20 ml. of water. After a few minutes the suspension was warmed on a steam bath until solution was complete, and then allowed to cool to room temperature with stirring. The potassium salt of ethyl a-hydroxy-&& dinitropropionate (8.85 g., 90%) was filtered from the ice- cold reaction mixture'. After washing with methanol and one recrystallization from water, the salt melted with decomposition at 144".

Anal. Calcd. for CarKN20~: C, 24.39; H, 2.87: K, 15.38; N, 11.38. Found: C, 23.00; H, 2.97; K, 15.75; N, 11.36.

Ethyl a-hydroxy-p,pdinitropropionate was freed from its potassium salt by acidification of 28.4 g. (0.12 mole) of the latter in 200 ml. of water with 20% sulfuric acid below 10" and extraction with ether. The combined ether extracts were dried over magnesium sulfate, treated with Norit, and the ether removed under reduced pressure giving 23.6 g. (94%) of ethyl whydroxy-fl,pdinitropropionate, n y 1.4573.

Anal. Calcd. for C&NzO,: C, 28.85; H, 3.87; N, 13.46. Found: C, 29.46; H, 4.11; N, 13.39.

Moderate absorption a t 2.87, (OH), and strong absorp tion at 5 .70~ (M) and 6.33, (NOz) were observed in chloroform solution in the infrared.

Ethyl a-ethozy-p,8dinitropropirnte (XII). A suspension of 9.84 g. (0.04 mole) of the potassium salt of ethyl P- hydroxy-p,&dinitropropionate in 100 ml. of ethanol was cooled to 5" while 2.8 g. (0.028 mole) of concentrated sul- furic acid was added with stirring. The mixture was re- fluxed for 7 hr. and then allowed to cool to room tempersr ture. After removal of the potassium sulfate by filtration, the alcohol was distilled from the filtrate under reduced pressure. The residue was dissolved in 75 ml. of chloroform and treated with Norit and magnesium sulfate. After removal of the chloroform by distillation, the residue yielded 7.0 g. (74%) of product, b.p. 8446.5'/0.3 m. An analytical sample of ethyl a-ethoxy-&Minitropropionate, b.p. 89- 91.5"/0.7 mm., n y 1.4397 was obtained by redistillation from phosphorus pentoxide.

Anal. Calcd. for C7HlzNz0~: C, 35.60; H, 5.12; N, 11.86. Found: C, 35.46; H, 5.09; N, 11.46.

Strong absorptions at 5.72~ (M) and 6 .32~ (NO2) were observed in the infrared in chloroform solution; no absorp tion in the OH stretching region was observed.

Ethyl a-acetoxy-&j%linitropropionate (XIII). A. By met- ylation of ethyl cu-hydroxy-fi,fidinitropropionate (XI). To a solution of 5.1 g. (0.024 mole) of ethyl cw-hydroxy-p,fl- dinitropropionate in 1.7 g. (0.028 mole) of acetic acid cooled in an ice bath was added 15 ml. of trifluoroacetic anhydride.18 The solution was allowed to warm to room temperature with stirring during 1 hr. After removal of the volatile components by distillation under reduced pressure the residue crystallized giving, after recrystallization from a benzene-hexane mixture, 5.3 g. (89%) of ethyl a-acetoxy- P,B-dinitropropionate, m.p. 54-54.5". Strong absorptions a t 5.65 and 5 . 7 2 ~ ( C 4 ) and 6 .32~ (NOz) were observed in the infrared in chloroform solution.

Anal. Calcd. for C,H10N208: C, 33.61; H, 4.03; N, 11.20. Found: C, 34.55; H, 4.22; N, 11.38.

Acetylation with acetyl chloride gave the same com- pound in lower yields. B. From ethyl u-acetoq,+chloro-&@dinitropropionate

(XV). A solution of 1.4 g. (0.005 mole) of ethyl a-acetoxy- 8-chloro-8,&dinitropropionate in 3 ml. of methanol was treated with 1.7 g. (0.01 mole) of potassium iodide in 6 ml. of 50% methanol a t 0 to 5'. After about 10 min. 1.0 g.

(13) E. J. Bourne, M. Stacey, J. C. Tatlow, and J. M. Tedder, J . Chem. Soc., 2976 (1949).

VOL. 22 1662 UNGNADE AND TCfSSmGER

(70%) of the potassium salt of ethyl a-acetoxy-fl,@-dinitro- propionate precipitated. The crude salt was suspended in water, acidified with 20% sulfuric acid, chilled, and the solid removed by filtration. Extraction of the solid with benzene, evaporation of the benzene, and recrystallization of the residue from hexryle yielded ethyl a-acetoxy-fl,p- dinitropropionate, m.p. 54-55'.

Anal. Calcd. for C T H ~ ~ N ~ O ~ : C, 33.61; H, 4.03; N, 11.20. Found: C, 32.98; H, 3.87; N, 11.16.

A sample of the purified potassium salt melted at 122" with decomposition.

Anal. Calcd. for C7H8KN208: K! 13.56. Found: K, 13.58.

Ethyl a-acetoxy-fl-chloro-P,Bdinitropropionate (XV). A solution of crude ethyl a-hydroxy-@-chloro-P,P-dinitro- propionate (XIV) in excess acetyl chloride was heated under reflux for 4 hr. After removal of the excess acetyl chloride, the residue was fractionated giving ethyl a-acetoxy-p- chloro-fl,fl-dinitropropionate, b.p. 67-69"/0.01 mm., ny 1.4484 in about 30% yield.

Anal. Calcd. for C,H9C1N208: C, 29.54: H, 3.19; N, 9.84. Found: C, 29.78; H, 3.29; N, 9.53.

Strong absorptions a t 5.64, 5 . 7 1 ~ ( C 4 ) and 6 . 2 2 ~ (NOa) were observed in the infrared in chloroform solution.

Ethyl a-hydroxy-p-chloro-fl,p-dinitropropimate (XIV). A suspension of 12.3 g. (0.05 mole) of the potassium salt of ethyl a-hydroxy-&Minitropropionate in 50 ml. of methylene chloride was cooled in an ice bath while 5 g. (0.07 mole) of chlorine in 50 ml. of cold methylene chloride was added with stirring. After 15 min. the yellow salt had been re- placed by potassium chloride which was removed by filtra-

tion. Crude ethyl a-hydroxy-fl-chloro-fl,@-dinitropropionate suitable for conversion to the a-acetoxy ester XV was obtained in 94% yield by removing the solvent under reduced pressure. An analytical sample, b.p. 70"/0.2 mm., n;' 1.4419, was obtained by fractional distillation under reduced pressure. Weak to moderate absorption at 2 . 8 4 (OH), and strong absorption at 5 .71~ ( C 4 ) and 6 . 3 0 ~ (NO2) were observed in the infrared in chloroform solution.

Anal. Calcd. for Cd37ClN207: C, 24.75; H, 2.91; N, 3 1.55. Found: 6, 24.90; H, 3.04; N, 11.80.

Potassium dinitromthane. An aqueous solution of 2,2- dinitropropanediol-1,3 was treated with excess cold 35% potassium hydroxide solution and, after chilling, the result- ing potassium salt of 2,2-dinitroethanol was filtered and air dried. This salt (15.1 g., 0.087 mole) was suspended in 80 ml. of water containing 6.6 g. (0.1 mole) of 85% potassium hydroxide. During a 5-min. period, 20 g. (0.18 mole) of 30% hydrogen peroxide was added with stirring. The tempera- ture of the reaction mixture rose to 45' during the addition. After warming on a steam bath for 40 min., a second portion of hydrogen peroxide equal to the first was added during 15 min. and heating was continued for another 15 min. The reaction mixture was allowed to cool to room temperature, chilled, and the potassium salt filtered, washed with meth- anol, and air dried (11.3 g., 900/o).

Anal. Calcd. for CHKN20d: K, 27.13. Found: K, 26.91. As a safety precaution, all potassium salts were stored

only for short periods of time and were handled while moist with water or alcohol.

Los ALAMOS, N. M.

[CONTRIBUTION FROM THE LOS ALAMOS SCIENTIFIC LABORATORY]

Derivatives of Nitromethylamines. I. Nitromethyl Isocyanates

HERBERT E. UNGNADE AND L. W. KISSINGER

Received March 8, 1967

Nitromethyl isocyanate, a-nitroethyl isocyanate, and a-nitroisopropyl isocyanate have been prepared by thermal re- arrangement of the corresponding acid azides. The compounds are unstable and only a-nitroethyl isocyanate could be dis- tilled. Infrared absorption spectra and other properties of these isocyanates are described.

While nitromethylamine is apparently unknown, two types of related compounds have been de- scribed. The nitromethy lurethan I was believed to be obtained when the azide of nitrocyanoacetic acid (11) was refluxed with ethanol. The urethan I has not been isolated and its structure is based on the products of hydrolysis of crude material which

CH(NOz)( CN)NHCOOEt I

CH( NO2)( CN)CONa I1

include one mole of carbon dioxide, one mole of hy- drogen cyanide, ethanol, and ammonium chloride. The stable crystalline compounds IIIa have been prepared by coupling aryl diazonium salts with ac- tive methylene compounds and IIIb result from the analogous coupling reaction with secondary nitro-

( 1 ) A. Darapsky and D. Hillers, J . pralct. Chem., 92, 305 (1925).

paraffins or their methylol derivatives.2*2a'COOMe, CN, CONK2, SO&, SOAr, NOz. R = H or alkyl.

ArNHN=CX IIIa

X = H, COOMe, CN, CONH,, SOnAr, SOAr, NOS ArN=NC(N02)Rz

IIIb

NOz

R = H or alkyl -___

(2) S. Hunig and 0. Boes, Ann., 579,28 (1953); E. Bam- berger, 0. Schmidt, and H. Levenstein, Ber., 33, 2059 (1900); H. E. Baumgarten and M. R. DeBrunner, J . Am. Chem. SOC., 76, 3489 (1954); C. F. Feasly and E. F. Deger- ing, J . Org. Chem., 8, 13 (1943); Z. Eckstein and T. Urban- ski, Bull. acad. polon. Sei., Classe I l l , 3,433 (1955).

(2a) Other analogs of nitromethylamine which are re- ported in the literature, probably owe their stability to special structural features, as for instance, the a-nitro- pyrroles [H. Fischer and W. Zerweck, Ber., 55, 1949 (1922)j and the 3-nitrocinnolines [H. E. Baumgarten and M. R. DeBrunner, J . Am. Chem. Soc., 76, 3490 (1954)l.