622 REPORT— 1897. 



6. Condensation Products of Aldehydes and Amides. 

 By Charles A. Kohn, Ph.D., B.Sc 



The products obtained originally by Roth by heating together benzaldehyde and 

 acetamide or other aliphalic amides, or benzaldehyde and benzamide, are only 

 formed in comparatively small quantity when the two substances are heated to 

 incipient boiling, very many recrystallisations being necessary in order to get the 

 resulting product pure, owing to the presence of by-products. After trying various 

 condensing agents it was found that by passing dry hydrochloric acid gas into a 

 boiling benzene solution of benzaldehyde and benzamide in the proportion of one 

 molecule of the former to two of the latter, a yield of 75 per cent, of the pure 

 product, which crystallises in long needles melting at 220°, is obtained. Analysis 

 confirms Roth's formula, the condensation taking place according to the equation : 



C,H,.CHO + 2C6H,.CO.NH, = CcH,.CH(NH.CO.C,,H,), + H^O 



Benzylidene dibenzamide. 



The reaction, however, when carried out under similar conditions in the case of 

 acetamide and benzaldehyde, yields the hydrochloride of acetyl-benzylidene-imide 

 or acetyl-benzalimide as a beautifully crystalline compound, which is decomposed 

 by all hydrolytic agents. 



The reaction is best effected in a benzene solution containing equi-molecular 

 proportions of acetamide and benzaldehyde into which the dry hydrochloric acid gas 

 is passed. A yield of 70 per cent, of the hydrochloride is obtained, which begins 

 to melt with decomposition at 130° to 131°. Both analysis and the quantitive 

 decomposition of the substance by water point to the formula CyHgNO.HCl. Its 

 formation is represented as follows : 



ail-.CHO + CIIj.CONH^ + HCl 



= C,H,,.CH : N.CO.CH3.HOI + H,0. 



It is decomposed by water according to the equation : 



aHj.CH : N.C0CH,.H01 + H,.0 



= CJLCHO + CH3.CONH,, + HCl. 



This substance, therefore, appears to be the acetyl derivative of the benzalimide 

 prepared by Busch, and presents similar conditions of instability to the latter. It is 

 not attacked by cold water at once, but if gently warmed, and then allowed to cool 

 immediately after solution has taken place, the analogous product to that obtained 

 with benzaldehyde and benzamide results, a body previously prepared by Roth. It 

 forms acicular needles, and melts at 233°. The change may be represented thus, 

 one molecule of aldehyde being separated : 



CcH-.CH : N.CO.CH3.HCI TT n 

 + CX-CH : N.CO.CH3.HCI '^^^'^ 



= C,IL .CIIO + C,H,,.CII(NII.COCIl3)2 + 2HC1. 

 Benzylidene diacetamide. 



A good yield of this substance is obtained directly by passing dry hydrochloric 

 acid gas into a melted mixture of the two constituents in suitable proportions. 



Analogous decompositions by alcohols are under investigation ; also the con- 

 densation products of other aldehydes, ketones and allied bodies both with amides, 

 nitriles, thioamides and sulphamides. 



By the action of sodium amide on benzaldehyde in benzene solution the sodium 

 salt of benzalimide is obtained as a voluminous white srelatinous precipitate, 

 which when dry forms an amorphous white powder, immediately decomposed by 

 water with evolution of ammonia. 



The equations representing these reactions are : 



C«H5.CH0 + NaNH. =- C,H,.CH : N.Na + H.,0 

 CgHj.CH : N.Na + 2H„0 = Cell- .COH + NHg' + NaOH. 



