June20, 195s
NOVELREDUCTIONS OF N-NITROWDIBENZYLA~IINES
3009
The boiling points of the two dienes follow the obtaining n.m.r. spectra on the dienes and assisting rather empirical rule that similar homologs boil about in the interpretation of this data. They also wish 20" apart; however, the "apparent" low boiling to thank Dr. T. M. Reed, 111, of the University of points of the two compounds are not too '(anoma- Florida, for the use of gas chromatographic equiplous," if the C9FI6and ClaF~8are compared to the ment. Support for this work by the Chemistry fluorocarbons C7F16 (b.p. 82") and CsFle (b.p. 102") Branch of the Office of Naval Research is gratefully and 5" is added for each degree of unsaturation. acknowledged. Acknowledgments.-The authors wish to thank Dr. Max Rogers of Michigan State University for GAINESVILLE, FLA.
[CONTRIBUTION FROM THE
DEPARTMENT OF
CHEMISTRY, POLYTECHNIC INSTITUTE O F BROOKLYN]
Novel Reductions of N-Nitrosodibenzylamines-A
New Reaction1
BY C. G. OVERBERGER, JOSEPH G. LOMBARDINO~ AND RICHARD G. HISKEY RECEIVED hTOVEMBER 29, 1957 N-Nitrosodibenzylamines were reduced by sodium hydrosulfite in basic media or by lithium in liquid ammonia to give an unexpected evolution of nitrogen with formation of hydrocarbon products. For example, reaction of sodiuni hydrosulfite with cis-l-nitroso-2,6-diphenylpiperidinegave cis-1,2-diphenylcyclopentane and 1,5-diphenyl-l-pentene while trans-lriitroso-2,6-diphenylpiperidine gave a mixture of cis- and trans-1,2-diphenylcyclopentane and 1,5-diphenyl-l-pentene. Sodium hydrosulfite reduction of N-nitrosodibenzylamine gave high yields of bibenzyl. The products in almost every case were identical to those isolated from mercuric oxide oxidation of the corresponding r\'-aminodibenzylamine. A mechanism is suggested which has an identical intermediate for these "abnormal" reductions of nitrosamines and for the mercuric oxide oxidation of the corresponding 1,l-disubstituted hydrazines. Other N-nitrosodialkylamines were reduced readily t o dialkylhydrazines by sodium hydrosulfite providing a new, convenient method of reducing nitrosamines.
TABLE I I n the course of a study on the oxidation beCompound reacted Yield, havior of 1,l-disubstituted hydrazines i t was dewith NazSzOp Product % sirable to obtain trans-l-amino-2,6-diphenylpiperi-N-Nitrosodibenzylamine (I) Bibenzyl 77 dinea from trans-l-nitroso-2,6-diphenylpiperidines.cis-l-Nitroso-2,6-diphenyl- cis-1,Z-Diphenylcyclopentane; 5 6 . 8 A wide variety of reducing systems were explored3 piperidine (11) 1,5-diphenyl-l-pentene 21.4 including some methods not previously used for re- Irans-1-Nitroso-2.6-diphenyl- Ivans-1.2-Diphenylcyclopiperidine (111) pentane }60.4 ducing a nitrosamine to a hydrazine. Two of cis-1,2-Diphenylcyclopentane these reducing systems gave especially interesting 1,5-Diphenyl-l-pentene 19 results with trans-l-nitroso-2,6-diphenylpiperidine. N-Nitrosobenzylphenylamine 1-Phenyl-I-benzylhydrazine 77 Diphenylamine 80 Both sodium hydrosulfite in basic media and lith- N-Nitrosodiphenylamine 40 I-Amino-2 ,&dimethylium in liquid ammonia yielded only hydrocarbon I-~itroso-2,6-dimethylpiperidine piperidine products when applied to the trans-nitrosamine, prompting a more thorough study of the scope of phenylamine; however, the cleavage of the nitrothese novel transformations. gen-nitrogen bond in N-nitrosodiphenylamine has Sodium hydrosulfite in strongly basic media has previously been reported using other reducing been reported previously to reduce C-nitro and C- agents6 It would appear that the sodium hydronitroso functions to primary amine~.~a,bThis sulfite reduction of dialkyl nitrosamines to the powerful reducing agent has now been applied to a corresponding hydrazines is safer and more convenseries of nitrosamines and the results are sum- ient than any previously reported methods. The marized in Table I. products from the nitrosamines I, I1 and I11 were From these results, i t can be seen that nitroso- identical to those isolated from the mercuric oxide dibenzylamines eliminate nitrogen, whereas mixed oxidation of the corresponding 1,l-disubstituted benzylalkyl or dialkyl nitrosoamines are reduced to hydrazines3f6(Table 11)suggesting a common interthe corresponding hydrazines. An exception to mediate for both the mercuric oxide oxidation of this rule is N-nitrosodiphenylamine which gave di- the hydrazines and for sodium hydrosulfite reduc(1) This is t h e 22nd in a series of papers concerned with t h e preparation of nitrosamines (see below). tion and decomposition of azo a n d diazo compounds. For t h e previThe action of lithium in liquid ammonia on a ous paper in this series, see C . G. Overberger and J. G. Lombardino, TFIISJ O U R N A L , 80, 2317 (1958). For a preliminary report of this work see C . G. Overberger, 5. G. Lombardino and R . G . Hiskey, J. Org. Chem., 22, 858 (1957). Presented a t the 132nd Meeting of t h e American Chemical Society, New York, X. Y., Sept., 1957 (Abstracts p. 38-P). ( 2 ) From a portion of the Dissertation submitted by Joseph G . Lombardino in partial fulfillment of the requirements for the degree of Doctor of Philosophy a t t h e Polytechnic Institute of Brooklyn. (3) C . G. Overberger, J. G. Lombardino and R. G. Hiskey, THIS JOURNAL, 79, 6430 (1957). (4) (a) G. T . Redemann and C. E. Redemann, "Organic Syntheses," Coll. Vol. 111, John Wiley and Sons, Inc.. New York, N. Y., 1955, p. 69. fh) J. €3. Conanl and R . 8 . Corson,"Organic Syntheses," Coil. V ( t 1 . T I , John R'ilpy : t n d Srm.;. Inc., K r w York. K. , 1 9 4 3 , I> 33.
TABLE I1 Hydrazine oxidized with mercuric oxide 1, I-Dibenzylhydrazine cis-l-Amino-2,6-diphenylpiperidine
Produrt Bibenzyl cis-1.2-Diphenylcyclopentane 1,5- Diphenyl- I-pentene Irans-l-Amino-2,6-diphenyl-cis- and trans-l,Zpiperidine Liphenylcyclopentane 1.5- Dip henyl-1-pentene
Yield,
%
Ref.
83 65
3,6 3
25
3 71 14
3010
C. G . OVERBERGER, J. G. L O ~ A R D AND I N ~It.
nitrosamine has been reported to yield the corresponding h y d r a ~ i n e . ~When applied to cis- and however, to trans-l-nitros0-2,6-diphenylpiperidine, the nitrosamine eliminated all of its nitrogen and yielded only hydrocarbon products. From cis-1nitroso-2,B-diphenylpiperidine (11) was obtained 2670 of 1,5-diphenyl-l-pentene (V) and 45y0 of cis-1,2-diphenylcyclopentane(VI). From trans-lnitroso-2,B-diphenylpiperidine(111) was obtained 91% of a mixture of cis- and trans-1,2-diphenylcyclopentane Again, these products are almost identical to those obtained by mercuric oxide oxidation of the corresponding l-amino-Z,6-diphenylpiperidines (Table 11). Reaction of N-nitrosodibenzylamine with lithium in ammonia gaye a mixture of four products in addition to a small amount of expected bibenzyl (4y0). Among these unexpected products were dibenzylamine (15%) benzylamine (37.5Y0), tribenzylhydrazine (6%) and an as yet unidentified solid containing an azomethine linkage. These products appear anomalous when compared with the very similar cis- and trans-l-nitroso2,B-diphenylpiperidines which eliminate all of their nitrogen in this reaction. No simple explanation for these results is evident; however, it should be noted that the products isolated from the reaction of lithium in ammonia with N-nitrosodibenzylamine are very similar to those isolated from the tbutyl hypochlorite oxidation of 1,I-dibenzylhydrazine.8 In addition to the above-mentioned products, tetrabenzyltetrazene was isolated from the t-butyl hypochlorite oxidation and Overberger and Marks8 have suggested that thermal decomposition of the tetrabenzyltetrazene could yield the observed dibenzylamine and benzylamine. In the present work, however, thermal decomposition of an intermediate tetrazene seems less likely a t the temperature of liquid ammonia. If tetrabenzyltetrazene were formed by combination of two fragments of an intermediate similar to IV (see below), hydrogenolysis of the tetrazene could also yield benzylamine and dibenzylamine. Direct hydrogenolysis of dibenzylhydrazine and dibenzylamine may also occur to account for the reaction products. The following mechanism is proposed for the nitrogen elimination reactions of dibenzyl-type nitrosamines with either sodium hydrosulfite or lithium in liquid ammonia C6H,T$">
C,H,
CSH,
'SH5
N
1-* 9
I
NO
N
I 0 N-OH
HNOH
Nz
VI
:N:
TV
I n this scheme, B- is hydroxyl ion in the sodium hydrosulfite reductions and amide ion in the lith(7) R. C. Cookson and M. E. Trevett. J. Chcm. SOL., 2089 (19%). (8) C . G . Overberger and I3. S. &larks, THISJOTJRNAL, 77, 4101
(19G).
I'(J1. 8u
ium-ammonia reductions. It has been previously pointed out3 that structure I V may be in the equilibrium shown and that this gives rise to the olefin structure V by elimination of nitrogen and a proton. H
/
I
.N IV
:N:B
The stereospecific elimination of nitrogen by a concerted process to give VI with retention of configuration a t the benzyl carbon has also previously been discussed.3 It should be noted that the intermediate IV is identical to that proposed for the mercuric oxide and oxidation of l-amino-2,6-diphenylpiperidines3 the identical products obtained in both cases lend further support to a common intermediate in both reactions.
NHL
N,+VtVI
NO
An intermediate such as I V previously has been discussed in the literature. Kenner and KnightQ have suggested a similar intermediate for the Busch and Weiss6 oxidation of 1,l-dibenzylhydrazine. McBride and Kruse'O have presented evidence for the existence of the conjugate acid of the intermediate VI1 from oxidation of 1,l-dimethylhydrazine. [O] CHI .. .. CH3 e 0CH8)XXHz [,,,,>K-K: e-+ )N=h CHa
CHI
:]
VI1
Carpino" also has suggested an intermediate such as IV for the decomposition of 1,l-dibenzyl-Zarylsulfonhydrazides in basic media. Thus, i t is suggested that all the aforementioned reactions, including sodium hydrosulfite or lithium in ammonia reduction of dibenzylnitrosamines, mercuric oxide oxidation of dibenzylhydrazines and basic decomposition of dibenzyl sulfonhydrazides have a coiiimoii intermediate such as IV.
Experimental
CSH,
N I
G.HISKEY
Preparation of Nitrosamines.-S-T-Nitrosodiber~zyla~ni~~c was prepared according to the procedure of Overberger, et al.,le by the nitrosation of dibenzylamine, m.p. 60-61" (m.p. 61°).1a The preparation of cis- and trans-l-nitroso-2,6-diphenylpiperidine has been described previously.s N-Nitrosobenzylphenylamine and K-nitrosodiphenylamine were Eastman Kodak Co. organic chemicals. A sample of l-nitros0-2,6-dimethylpiperidine~~ was kindly furnished by Dr. B. Marks. Reaction of N-Nitrosodibenzylamine with Sodium Hydrosulfite.--A solution of 3.4 g. (0.015 mole) of N-nitrosodi(9) J. Renner and E. C. Knight, Der., 69, 341 (1936). (10) W. R. McBride and H. W. Kruse, THISJOURNAL, 79, 572 (lS57). (11) L. A. Carpino, ibid., 79, 4427 (1957). (12) C. G. Overberger, 13. S. Marks, L. Palmer and N. Byrd, ibid.. 77, 4100 (1955).
June 20, 1958
NOVELREDUCTIONS O F N-NITROSODIBENZYLAMINES
3011
the olefin and gave 1.58 g. (63%) of a white solid, m.p. 50benzylamine and 100 ml. of a 1: 1mixture of ethanol and 20% aqueous sodium hydroxide solution was prepared a t 58". 60". Attempts to fractionate this mixture of 1,2-diphenylA tube was attached t o the condenser so as t o lead evolved cyclopentanes by crystallization, failed. Reaction of N-Nitrosobenzylphenylaminewith Sodium gases into a 1-liter graduate filled with water and inverted in a beaker of water. The solution was stirred under a Hydrosulfite.-As previously described for the reaction of stream of nitrogen for 0.5 hour and then 5.25 g. (0.030 mole) N-nitrosodibenzylamine, a solution of 5.0 g. (0.0235 mole) of sodium hydrosulfite was placed in a solids addition tube of N-nitrosobenzylphenylamines, m.p. 57-58', was preand the system sealed. The solid was added in one portion pared in 50 ml. of 20% aqueous sodium hydroxide and 75 and after 10 minutes nitrogen began to evolve. After ap- ml. of ethanol. After stirring the solution under a nitrogen proximately 4 hours, the theoretical volume of nitrogen, 367 atmosphere a t 58" for 30 minutes, 8.2 g.,(O.O47 mole) of tnl., had been evolved. The reaction mixture was added sodium hydrosulfite was added in one portion to the closed to an equal volume of salt solution, extracted three times system. No significant gas evolution was noted over 12 with ether and the ether layers dried over magnesium sulfate. hours after which the reaction was poured into water,.exOn removal of solvent and recrystallization of the residual tracted with ether and the extracts dried over magnesium sulfate. Evaporation of the solvent yielded 3.6 g. (77%) of solid, there was obtained 2.10 g. (77%) of bibenzyl, m.p. 1-phenyl-1-benzylhydrazine. A hydrochloric acid salt was 53-54'. A mixture melting point with a sample of authenprepared in ether, m.p. 170-173' (167O).l6 tic bibenzyl, m.p. 51.5-52.5', melted a t 53.0-54.5'. Reaction of N-Nitrosodiphenylamine with Sodium HyIn another experiment, 25 g. of N-nitrosodibenzylamine drosulfite.-Into 5.0 g. (0.025 mole) of K-nitrosodiphenylwas reduced and the products distilled in an attempt t o detect amine (m.p. 66-67') dissolved in 50 nil. of ethanol and 50 ml; side products, but only bibenzyl could be identified. Reaction of cis-l-Nitroso-2,6-diphenylpiperidine with of 20% aqueous sodium hydroxide solution, heated to 60 Sodium Hydrosulfite.-A solution of 3.0 g. (0.0113 mole) of and stirred magnetically, was passed a stream of nitrogen cis-l-nitroso-2,6-diphenylpiperidine(m.p. 67-69°)3 and gas. Then, 8.78 g. (0.051 mole) of sodium hydrosulfite 100 ml. of a 1: 1 mixture of ethanol and 20% aqueous so- was added in one portion and heating and stirring continued dium hydroxide was prepared. The solution was main- for five hours. The reaction was then poured into 300 ml. of water, extracted twice with ether and the extracts dried tained a t rjSOin a water-bath and stirred under a stream of over magnesium sulfate. On complete evaporation of solnitrogen for 30 minutes. Then 4.35 g. (0.025 mole) of sodium hydrosulfite was placed in the solids addition tube vent under high vacuum, 3.4 g. (80%) of diphenylamine as and the system sealed. The solid was added in one portion white plates was obtained which on recrystallization from an ethanol-water mixture melted a t 53.2-54.4' (m.p. 53.9").17 and after approximately 7 minutes, the evolution of nitrogen A sulfuric acid salt of the product was prepared in ether, gas was observed. After 4.5 hours the theoretical amount of nitrogen, 276 ml., had been evolved. The reaction was m.p. 124.5-126' (m.p. 123-125").17 Reaction of cis-l-Nitroso-2,6-dimethylpiperidine with poured into an equal volume of salt water, extracted with Sodium Hydrosulfite.-Under conditions identical to those two 100-ml. portions of Skellysolve B, b.p. 60-70", and the extracts dried over magnesium sulfate. The solvent was used for the reaction of iY-nitrosodiphenylaruine with soreduced to approximately 50 ml., the residual solution dium hydrosulfite, 2.24 g. (0.0157 mole) of cis-l-nitroso-2,6passed through 100 g. of neutral alumina (Woelm, activity dimethylpiperidine12and 6.0 g. (0.036 mole) of sodium hyone) using dry Skellysolve B as eluent and eight 100-ml. drosulfite yielded, after drying an ether solution of the prodfractions collected. All fractions were combined and evapo- uct and treatment with picric acid in ether, 2.2 g. (39.8%) rated to dryness under vacuum to yield a clear liquid, a mix- of the picric acid salt of l-amino-Z,B-dimethylpiperidine, A mixture melting point with the picric ture of isomeric material weighing 1.97 g. (790/0). A com- m.p. 167.5-169'. parison of the quantitative infrared spectrum of this liquid acid salt of authentic l-amin0-2,6-dimethylpiperidine,~* m.p. 167-168', melted a t 167-169'. with that of an authentic13 mixture of cis-l,2-diphenylcycloReduction of cis-l-Nitroso-2,6-diphenylpiperidine with pentane, m.p. 46-4i0,i4 and 1,5-diphenyl-l-pentene1s showed identical absorption peaks. The intensity of the Lithium in Ammonia.-To 0.26 g. (0.03T5 g. atom) of lithpeak a t 10.37 ,u indicated3 that 21.4% of the liquid was 1,5- ium ribbon dissolved in 100 ml. of liquid ammonia was diphenyl-1-pentene. added dropwise with stirring a solution of 2.0 g. (0.0075 The sample used for infrared analysis was combined with mole) of cis-l-nitroso-2,6-diphenylpiperidinedissolved in 50 the main portion of liquid and the combined material dis- ml. of dry ether and 10 ml. of dry dioxane. After complete solved in 10 xnl. of acetic acid. To this was added a solu- addition, color changes from blue to white and then from violet to red were evident. The red solution was stirred tion of 0.68 g. (0.0029 mole) of 2,4-dinitrobenzenesulfenyl chloride in 4 ml. of warm acetic acid. On standing, the an additional 1.5 hours and then hydrolyzed with 25 ml. of ethanol followed by 100 ml. of water. The white reaction yellow solution deposited a yellow solid, m.p. 112.5-114.5'. A mixture melting point with the 2,4-dinitrobenzenesul- mixture was poured into water and extracted twice with ether and dried. Removal of the solvent followed by fenyl chloride derivative of authentic 1,5-diphenyl-l-penchromatography of the residue on alumina gave 1.17 g. tene, m.p. 113-115°,3 was not depressed, m.p. 113-115'. The filtrate was evaporated to dryness, then placed under (710/c) of a liquid mixture of isomeric materials. An infrahigh vacuum in a desiccator over potassium hydroxide pel- red spectrum of the mixture showed it to be ideutical to a mixlets for 12 hours. The residual red oil was extracted several ture of authentic ~is-l,2-diphenylcyclopentane~~ and 1,5times with dry Skellysolve B and the extracts chromato- diphenyl-l-pentene.16 The intensity of the absorption a t graphed through neutral alumina (Woelm, activity one). 10.37 p indicated that 26% of the mixture was 1,5-diphenylThe first six 50-1111. fractions yielded 1.42 g. (56.8%) of cis- 1-pentene. Reduction of trans-l-Nitroso-2,6-diphenylpiperidinewith 1,2-diphenylcyclopentane,m.p. 43-45' (46').13J4 A mixture melting point with authentic18 cis-1 ,Zdiphenylcyclo- Lithium in Ammonia.-Reduction was carried out as depentane, m.p. 46-47', was not depressed, m.p. 43.5-46'. scribed above for the cis isomer except that the white soluReaction of trans-l-Nitroso-2,6-diphenylpiperidine with tion obtained after complete addition was allowed to stand Sodium Hydrosulfite.-The reaction of trans-l-nitroso-2,6- overnight a t room temperature. Hydrolysis and extraction diphenylpiperidine3 with sodium hydrosulfite was carried followed by removal of the solvent yielded 1.52 g. (91.5%) out as described above for the cis isomer. Chromatograph- of a liquid whose infrared spectrum was identical with that ing the reaction products in Skellysolve B yielded 83% of of a mixture of authentic cis- and trans-l,2-diphenylcyclothe theoretical amount of isomeric products. A quantita- ~ e n t a n e . ~ Attempts J~ to fractionate this mixture chrotive infrared spectra was identical with that of an authentic matographically were unsuccessful. mixture of cis- and trans-1,2-diphenylcy~lopentane~~~~ Reaction of N-Nitrosobenzylphenylamine with Lithium and 1,5-diphenyl-l-pentene.15 From the intensity of the in Ammonia.-In a similar manner, reduction of 3.0 g. absorption a t 10.37 p3 it was estimated that 19% of the mixture was 1,5-diphenyl-l-pentene. Treatment of the mix- (0.014 mole) of N-nitrosobenzylphenylamine with 0.49 g. ture with 2,4-dinitrobenzenesulfenyl chloride in acetic acid (0.07 g. atom) of lithium afforded an oil which on treatment followed by chromatography using Skellysolve B removed with dry hydrochloric acid in ether solution yielded 2.52 g. (76%) of benzylphenylamine hydrochloride, m.p. 213.5(13) F. Japp and G. Lander, J . Chcm. SOL.,71, 131 (1897). (14) H. A. Weidlich, Ber., 71, 1601 (1938). (15) C. G. Overberger and J. I. bfonagle, TRISJOURNAL, 78, 4470 (195fi).
(16) A. Michaelis a n d B. Phillips, Ann., 262, 287 (1889). (17) I. Heilbron, "Dictionary of Organic Compounds," Univ. Press, N e w York, N. Y., 1953, p. 402.
Oxford
3018
J. H.UOYEK .ZND L. li. MORGAN, Jri.
815' (214-216°).1s 11 iiii.\lure iiielting point with an authentic sample of the hydrochloric acid salt of beiizylphenylxinine, m.p. 214.&216', melted at 213-215'. Reaction of N-Nitrosodibenzylamine with Lithium in Liquid Ammonia.-To a stirred solution of 1.54 g. (0.22 g . atom) of lithiuni dissolved in 250 nil. of liquid ammonia was added dropwise a solution of 10.0 g . (0.044 mole) of N-nitrosodibeiizylamine in 125 ml. of dry ether and 25 ml. o f dry dioxane. External cooling was removed and after 10 minutes color change from blue to white tlicn from orange to bright red was observed. The red reaction wa5 stirred for 1.5 hours and then hydrolyzed with 50 nil. of ethanol followed by 50 ml. of water. The reaction mixture nas poured into 500 nil. of water, extracted with ethcr arid the extracts dried over magnesium sulfate. Removal of solvciit yielded 2.0 g. of rcsidue. At this point, in another exlmimeiit, 6y6 of tribeiizylhytlraziue, m.p. 82.5-84" (n1.p. 86")8was isolated by crystalli. . zation from the residue. A picrate salt was prepared in ether, n1.p. 138-140.5 (m.p. 140-141°).8 The mixture was extracted with dry Skellysolve l3 several times and the extracts chromatographed through neutral alumina ( Woelrn, activity one). -4 Skellysolvc B-illsoluble material was recrystallized froin ethanol, 0.50 g., 1ii.p. 205207". This solid contains iiitrogeii and an infrared spectrum exhibited a strong absorption a t 6.0s b , probably C=K.Ig The solid reacts slowly with a rnethamolic hydrochloric acid solution of 2,4-diriitroplieriylii)-tlrazineto give (18) W ,S. Emerson and 1'. A I . Waltcrs, 'TJIIS J U U I < N . U . , 60, 2023 (I'J38): K. Brand, Her., 42, 3400 (IOOS). (I!)) 1.. J. Bellamy, "The Infrared SlJectra uf ~ ~ ~ I l I ~ hlulccules." J l e x J u l i n \Vile? a n d Sons, Inc., S e w Yijrk, X . Y . , 1951, 11. 221;.
VOI.
so
an orange derivative, ri1.p. 118-131". The sulid was 1101 further characterized. The first 25-ml. fraction obtaiiietl from the columii, usiiig dry Skellysolve B as eluent, yielded 0.32 g. ( 4 % ) of hibenzyl, m.p. 50-51.5'; a mixture melting point with iiuthentic bibenzyl melted a t 60-52". The iiext three fractions yielded 1.75 g . (37.5%) of benzylainine, whosc picrate salt prepared in ethcr, melted at 197-200" ( 195-199°).2t' '1 mixture ineltirig point with the picrate salt of authetitic benzylarnine melted a t 197.5-200'. A yellow band was removed from the column, using dry methanol its cluellt, yielding 1.3 g . (15%) of dibenzylamiric, whose picrate sult prepared in ether melted at 139-141". 1 1 mixture iiieltiiig point with the picrate salt of authentic dibciizylarniiie prcpared in ether mclted a t 138.5-140°. The picrate salt of authentic dibenzylaniiiic was prepared b y adding excess saturated picric acid in ethcr t o an ethcr solution of the amine. Three separate preparations of this salt using various samples of dibenzylamine all yielded t: >-ellow solid, m.p. 140'. The previously rcported8 picratc of dibenzylamine could iiot be duplicated. .In analytical sample was prepared by recrystallization from cthanol to yield yellow needles, i n p . 140-141' (93-94").* Calcd. for C2oHlsSaO7: C, 5G.34; 1-1, ,L.25; S . 10.14. Foutid: C, 56.48; H, 4.61; N, 13.19.
Acknowledgment.-We wish to gratefully ac' knowledge the support of this work by the National Science Foundation, Grant NSF-1433. (20) G. J e r u s a l e m , .I. C/ic,m. Suc., 95, 1283 (1009). 121) S n u l y s e s I)? Schivarzkopf 1 , a b ~ r r a t o r i r hS. c w E'ork,
N. 1'
UIWOKLYN 1, S.Y .
O l C CIiEMISIIIY, 'YULANE U N I
Pyrolysis of Pyruvic Acid Hydrazonesl I3Y
5. 13. I3OYEIi A N D L. 1
