210 Messrs Ruhemann and Merriman, Contributions to 



which we regard as the parent substance of the compounds 

 C 3 H 7 N 4 I and C 3 H 7 N 4 I 3 . The formation of these iodides, there- 

 fore, is due to a regressive change of tetrazoline. 



This view is supported by the behaviour of aldehydes towards 

 tetrazoline. Under the influence of piperidine as a catalytic 

 agent, a condensation takes place which is to be represented by 

 the equation : 



C 2 H 4 N 4 + R . CHO = H 2 + C 2 H 2 N 4 : CH . R. 



The substances which are thus produced must be represented 

 by the general formula 



/N = Nv 

 R . CH : C\ X'CH, 



and their formation necessitates the isomerisation of tetrazoline. 

 We have applied this reaction to a number of aldehydes. The 

 condensation products readily dissolve in mineral acids, although, 

 thus, partial decomposition takes place, yet these solutions yield 

 with platinic chloride, normal salts having the general formula 



(C 2 H 2 N 4 : CH. R) 2 , H 2 PtCl 6 . 



The hydrolysis of the compounds which are formed by the 

 action of aldehydes on tetrazoline, is completed on boiling their 

 solutions in hydrochloric acid for a short time ; the base, however, 

 which is produced along with the aldehyde, is not the dihydro- 

 tetrazine 



/N : N\ 

 CH 2 ^ JCH, 



but tetrazoline. It, therefore, follows that the hydrolysis is 

 accompanied by the isomerisation of the base to tetrazoline. 



Ruhemann and Stapleton had previously (loc. cit.) stated that 

 tetrazoline forms with platinic chloride the sparingly soluble, 

 canary-yellow compound (C 2 H 4 N 4 ) 2 , PtCl 4 . We now find that 

 the base as well as its hydrochloride, after crystallisation from 

 alcohol, yield a very soluble normal platinichloride 



(G 2 H 4 N 4 ) 2 , H 2 PtCl e , 



but that the insoluble additive product is formed from the 

 hydrochloride before re-crystallisation from alcohol. From this 

 fact it follows that the hydrochloride exists in two tautomeric 

 forms : 



/N = CH X ,N = 0H\ 



NH< )NH, HC1 and NH< >N, HC1. 



X CH = N X X CH,-£T 



