ON RESEARCH ON NON-AROMATIC DIAZONIUM SALTS. 95 



Researcli on Non-aromatic Diazonium Salts. — Interim Report 

 of the Committee, consisting of Dr. F. D. Chattaway 

 {Chairman), Professor G. Morgan {Secretary), Mr. P. G. 

 W. Bayly, and Dr. N. V. Sidgwick. 



2-Aminothiazole, produced by the condensation of thiocarbamide and 

 chloro-acetaldehyde alcoholate, is a non-aromatic base exhibiting a 

 certain degree of diazotisability. It was formerly known that in con- 

 centrated hydrochloric or hydrobromic acid the base reacted with nitrous 

 acid to yield a very unstable diazo- derivative, not hitherto isolated from 

 solution. This unstable product speedily lost its diazo-nitrogen, giving 

 rise to 2-chlorothiazole or 2-bromothiazole. In feebly acid solution 

 the diazotisation of 2-aminothiazole was known to yield an ill-defined 

 sparingly soluble thiazole-2-diazohydroxide. 



[With G. V. Monow, Ph.D., \E.C.Sc.I.] 

 The foregoing observations on the instability of the diazo- derivatives 

 of 2-aminothiazole in the presence of halogen hydrides were confirmed. 

 It was found that 2-aminothiazole is more readily diazotisable without 

 by-products in the presence of oxy- acids. In 20-per-cent. perchloric 

 acid 2-aminothiazole readily dissolves, and the addition to the solution 

 of ethyl nitrite determines the production of thiazole-2-diazonium 

 perchlorate. This salt was not isolated, as it explodes even in dilute 

 ice-cold solutions. The diazotisation of 2-aminothiazole proceeds less 

 readily in dilute nitric acid owing to the sparing solubility of the nitrate 

 of this base. Diazotisation proceeds smoothly in dilute sulphuric acid, 

 the solution remaining colourless and free from decomposition products. 

 On adding sodium aurichloride the orange-yellow crystalline thiazole-2- 

 diazonium aurichloride was precipitated. 



CH-SU 



II >C • N., 



Au Cli. 



This salt, which is readily hydrolysed to the unstable diazo-hydroxide 

 by water, is stable when dry at the ordinary temperature. 



The foregoing thiazole-2-diazonium salts couple with phenols and 

 reactive aromatic bases, such as y8-naphthylamine. They also condense 

 with the ;8-diketones yielding non-aromatic yellow azo- derivatives. 



Thiazole-2-azo-acetyIacetone 



y\ 

 CH.C H 

 CH-S II : 



II >C-N:N- C O 



CH-N^ \^^ 



CH3 



separates in golden-yellow leaflets decomposed on prolonged boiling in 

 alcoholic solution. 



