21 2 BARROW AND GRXFFITHS : CONDENSATION OF

XXV.-Condensation of p-Nitrobenxyl Chloride with A New Mode of F o r m a t i o n Nitroso-compounds.

of N- Oximino-ethers. By FRED BARROW and EVAN DALTON GRIFFITHS.

DURING the course of an investigation on the action of alcoholic potassium hydroxide on p-nitrobenzylidene chloride, it was found by one of us that this substance and p-nitrobenzyl chloride readily undergo condensation with aromatic aldehydes, under the influence of the condensing agent, with the formation of derivatives of stilbene oxide. Thus, for example, p-nitrobenzylidene chloride con- denses with y -nitr obenzaldehy de, yielding a-chlo r o -pp/-d ini t r o - stilbene oxide (I), whilst y-nitrobenzyl chloride gives rise to two stereoisomeric, cis- and trans-, ypl-dinitrostilbene oxides (11).

In view of the remarkable ease with which these condensations take place, a study of the behaviour of the nitro-substituted benzyl- idene and benzyl chlorides towards other classes of compounds con- taining an unsaturated group is being undertaken by the authors, and in the present communication the interaction of p-nitrobenzyl chloride with aromatic nitroso-compounds is described. It has been found that nitrosobenzene, and also the p-nitroso-derivatives of the mono- and di-alkylanilines, readily condense with p-nitro- benzyl chloride in the presence of alcoholic potassium hydroxide, yielding A‘-aryl ethers of p-nitrobenzaldoxime, thus :

N0,°C6H4*CH2CI + NPh:O = HCI + N02*C6H4*CH:NPh:0. The constitution of these condensation products was first estab-

lished by the investigation of the behaviour of the N-phenyl ether prepared from p-nitrobenzyl chloride and nitrosobenzene, towards hydrochloric acid. When heated with concentrated hydrochloric acid, the phenyl ether is rapidly hydrolysed to p-nitrobenz- aldehyde and p-chloroaniliue. The initial products of the hydro- lysis evidently consist of the aldehyde and P-phenylhydroxyl- amine, the latter compound being subsequently converted into p-chloroaniline by the further action of the hydrochloric acid :

N0,-C6H4*CH:NPh:0 + NO,*C,H4*CHO + C,H,*NH*OH -+ C6H4C1*NH,.

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P-NITROBENZYL CHLORIDE WITH NITROSO-COMPOUNDS. 21 3

Further evidence as to the constitution of these condensation products is furnished by the direct synthesis of the N-phenyl ether, by the interaction of 8.phenylhydroxylamine and p-nitrobenz- aldehyde in alcoholic solution :

NO,*C,H,*CHO + NHPh*OH + H,O + NO,*C,H,*CH:NPh:O. It has been shown by Semper and Lichtenstadt (Ber., 1918, 51,

928) that the N-methyl ether of phenyl p-tolyl ketoxime exists in two stereoisomeric forms, corresponding with the syn- and anti- modifications of the oxime. In view of the existence of these isomerides, and also of the

simultaneous formation of cis- and trans-py I-dinitrostilbene oxides by the condensation of p-nitrobenzyl chloride with p-nitrobenz- aldehyde, the crude AT-p-dimethylaminophenyl ether, prepared from p-nitrobenzyl chloride and p-nitrosodimethylaniline, was sub- mitted t o a careful fractional crystallisation from alcohol in order to ascertain whether stereoisomeric ethers are formed in this con- densation, but no evidence of the existence of a second isomeride was obtained.

The interaction of p-nitrobenzyl chloride with nitroso-compounds is analogous to that of the aliphatic diazo-compounds described by Staudinger and Mie-scher (Ilelv. Chim. Acta, 1919, 2, 554), who

have shown that diazo-compounds of the type I l>C<E, readily

react with nitrosobenzene and its derivatives, yielding N-oximino- ethers.

Attempts to condense p-nitrobenzyl chloride with nitrosoamines, NRR’*NO, were unsuccessful, the nitrosoamine being recovered unchanged, whilst the p-nitrobenzyl chloride was converted by the alcoholic potassium hydroxide into ppl-dinitrostilbene.

The reaction described in the present communication is being extended to other nitroderivatives of benzyl chloride. It has also been found that aromatic chloro-ketones of the types CH,Cl*COR and CHRCl*COR react with nitroso-compounds, yielding LN-oxirnino-ethers .

N N

E X P E R I M E N T A L .

p-Nitrobenzaldoxime-N-phenyl Ether, NO,*C,H,*CH:NPh:O

Equimolecular proportions of p-nitrobenzyl chloride (8.6 grams) and nitrosobenzene (5.4 grams) were dissolved in the minimum amount of alcohol a t the ordinary temperature, and the solution treated with one and a-half times the theoretical amount of potassium hydroxide (4-2 grams) dissolved in methyl alcohol

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214 BAItROW AND GRIP'BI'L'HS : CONDENSATION OF

(30 c.c.). On the addition of the alkali, the colour of the solutioii rapidly changed from green t o light reddish-brown, and the oximino-ether separated in the form of a yellow, crystalline powder. After remaining for one hour a t the ordinary temperature, this was filtered, freed from potassiiim chloride by washing with water, and crystallised from alcohol.

p--Yitro benzaldorcime-N-phPnyl e t he?- crystallises iii small, slender, pale yellow leaflets, which melt a t 1 8 2 O (Foiind : C = 64-46 ; H = 4 * 2 9 ; N=11.50. C,,H,,,O,N, requires C=64.46; PI=4.13; N = l l * 5 7 per cent.). It is very readily soluble in chloroform, moderately so in alcohol and benzene, and almost insoluble in ether and light petroleum.

Hydrolysis.-The AT-phenyl ether (4 grams) was heated for half an hour with concentrated hydrochloric acid (30 c.c.), and, after cooling, the solid which separated was purified by crystallisation from dilute alcohol, and theii from water. It crystallised in almost colourless needles melting a t 1 0 6 O , and was ident,ified as y-nitro- benzaldehyde. The acid solution, from which the p-nitrobenz- aldehyde separated, was extracted with ether, and then rendered alkaline by the addition of sodiuni hydroxide. The base thus liberated gave with acetic anhydride an acetyl derivative melting a t 1 7 5 O , which was identified as 2'-chloroacetanilide.

C'onderzsation of p-i~itrobe?kzaldehycle ccizd P - 1 ~ ~ ~ e i L ~ l l ~ y d ~ o ~ y ~ a n b i n e .

For the purpose of comparison, p-iiitrobenzaldoxinie-N-phenyl ether was prepared by the condensation of p-nitrobenzaldehyde and /3-phenylhyd toxylamine.

Equimolecular proportions of the two components were separately dissolved in alcohol, and, after mixing, the solution was heated for half an hour on the water-bath. The solid which separated crystallised f roni alcohol in pale yellow leaflets meltiiig a t 1 8 2 O , and was identical with the I\'-phenyl ether obtained by the condensation of p-nitrobenzyl chloride and nitrosobenzene.

p-Ni t robenzaldoxime-N-p-~~?~~~thy lurn lnoyhenyl JZl'ther, NO,*C,H,*CH:NO.C,H,*NMe~.

28.6 Grams of p-nitrobenzyl chloride and 25 grams of p-nitroso- dimethylaniline were dissolved in the minimum amount of alcohol a t the ordinary temperature, and to the solution was added the theoretical amount of potassium hydroxide (9.3 grams) dissolved in methyl alcohol (66 c.c.). On the addition of the alkali, the colour of the solution rapidly changed from green t o dark chooo-

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Y- NlTROBENZYL CHLOR CDE WI'I'H NITROSO-COMPOITNDS. 2 15

late-red, and the osimino-ether separated in the form of a brownish-red powder. After one hour, this was filtered, washed with water, and purified by crystallisation from a mixture of equal parts of pyridine and alcohol, the yield being 33.5 grams.

The N-p-rlimeth?/Znminophe?~yl ether crystallises in chocolate-red needles melting a t 20lo, and forms a yellow hydrochloride and sulphate (Found : C = 63.09 ; H = 5.20; N = 14.58. C15H1503N3 requires C=63*15; H=5.26; N=14*74 per cent.). It is readily soluble in chloroform and pyridine, sparingly so in benzene and alcohol, and practically insoluble in light petroleum and ether. When heated with concentrated hydrochloric acid, i t readily under- goes hydrolysis, with the formation of 2'-nitrobenzaldehyde.

p -A- i t 1-0 Z, e 11 xuldo xi m e-N - p -die t h y lami no p h e n y 1 E t her, NO,* C,H CH :NO.C,H,*NE t, .

This was prepared from p-nitrosodiethylaniline and p-nitro- benzyl chloride in a similar manner t o that described above, and purified by crystallisation from a mixture of equal parts of pyridine and alcohol. It crystallises in large, lustrous, bright crimson leaflets, which melt a t 167O, is readily soluble in pyridine and chloroform, but only sparingly so in alcohol and benzene (Found: C = 64-99 ; €1 = 6-01 ; N = 13.34. C,,H,,O,N, requires C = 65.17 ; H = 6.07 ; N = 13.42 per cent.).

p-.Sitro b enznlcloxime-N-p-d i-n-propylaminoph en,y7 Ether, NO,*C,€I,*CH:NO*C,H,.NPr.,.

This compound is obtained in a similar manner from p-nitrosodi- wpropylaniline, and separates from alcohol in felted, slender, dark crimson needles melting a t 135-138O with previous softening a t 130° (Found : N = 12.31. C1,,H,,0,N3 requires N = 12-32 per cent.). It is much more readily soluble in the common solvents than the dirnethylarninopheiiyl ether.

p-n'itro berizaldoxi,ne-N-p-ethylami?~ophenyl Ether , N0,*CGH,.CH:NO*C,H4*NHEt.

The condensation of p-nitrosoethylaniline, prepared by Fischer and Hepp's method ( B e y . , 1886, 19, 2993), with p-nitrobenzyl chloride was carried out a t 4 5 O , the reaction proceeding only slowly at the ordinary temperature.

The p-ethylamin.ophen y l ether crystallises from benzene in deep crimson needles melting at 1 6 8 O (Found : C = 63.08 ; H = 5-25 ; N=14*53. C,,H,,O,N, requires C=63*15; 13=5-26; N=14.74

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216 PERKIN AND TUCKER: THE OXIDATION O F CARBAZOLIC.

per cent.). It is readily soluble in alcohol an’d chloroform, less so in benzene, and only very sparingly so in ether and light petroleum.

p-Nitro benzaldoxime-N-p-nitrophenyl Ether, NO,*C,H,*CH:NO* C,H,-NO,.

The p-nitronitrosobenzene required for the preparation of this compound was obtained by the addition of the calculated amount of Caro’s acid to a well-cooled solution of p-nitroaniline in con- centrated sulphuric acid, and was separated from the accompany- ing p-dinitrobenzene by fractional distillation in steam (compare Bamberger, Rer., 1903, 36, 3808). The product resulting from the condensation of the nitroso-compound with p-nitrobenzyl chloride consisted of a mixture of the oximino-ether and pp’-dinitrostilbene, which was readily separated by taking advantage of the sparing solubility of the latter compound in alcohol.

The p-nitrophenyl ether separates from alcohol in the form of a pale yellow, crystalline powder, which melts a t 1 8 6 O (Found: N=14.54. CI3H9O5N3 requires 14.63 per cent.). It is readily soluble in chloroform, moderately so in alcohol and benzene, and insoluble in ether and light petroleum.

CHEMISTRY DEPARTMENT, BIRKBECK COLLEUE. [Receiwd, J a w a r y 27th, 1921.1

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