250 REPORTS ON THE STATE OF SCIENCE, ETC. 
Triazole Series. 
When 5-aminotriazoles are diazotised in hydrochloric acid solution the resulting 
salt decomposes fairly quickly at 0° C. into nitrogen and the corresponding chloro- 
triazole.! If, however, oxy-acids are used instead of hydrochloric acid, more stable 
diazonium salts are obtained, although these are too unstable to be isolated? The 
sparingly soluble diazonium aurichloride has been isolated and is stable in the dry 
state. When a solution of the diazonium nitrate is evaporated to dryness in vacuo 
over potassium hydroxide a colourless isodiazo hydroxide is obtained, which is quite 
stable at 100° C. and couples only after being acidified. The diazonium complex is 
replaced by hydrogen on reduction with alcohol, and with stannous chloride the 
hydrazine is obtained.’ 
1 Thiele & Manchot, A. 1898, 308, 33. ” Morgan & Reilly, 7. 1916, 109, 155. 
Thiazole Series. 
2-Aminothiazole reacts in the same way as aminotriazole with nitrous acid. In 
hydrochloric acid solution an unstable diazonium chloride is produced. This de- 
composes rapidly at 0° C. into nitrogen and chlorothiazole. Oxy-acids give more 
stable salts, especially sulphuric acid. The perchlorate is explosive even at 0° C. 
The yellow diazonium aurichloride is sparingly soluble and is stable in the dry state 
but becomes brown on washing with water. In feebly acid solution aqueous sodium 
nitrite gives an unstable orange-red powder, probably an isodiazo compound. 
Reduction of the diazonium sulphate with alcohol causes the replacement of the 
diazonium complex by hydrogen.” 
1 Morgan & Morrow, 7. 1915, 107, 1291. 2 Hantzsch & Popp, A. 1889, 250, 274. 
Pyridine and Quinoline Series. 
Nitrous acid acts on the amines derived from these bodies in the same way. The 
a and y amines when treated in hydrochloric acid solution yield forthwith the corre- 
sponding chloro derivatives. This reaction suggests a rapid decomposition of a probable 
intermediate diazonium chloride.' Oxy-acids have not been used and these would 
probably give better results. The S-amines form diazonium chlorides, which do not 
appear to have been isolated but have been coupled with phenols.? The corresponding 
B8-diazoaminopyridine is a yellow, crystalline, stable compound.* 
1 Marckwald, B. 1898, 31, 2496; B. 1894, 27, 1325; H. Meyer, Monatsch. 1894, 
15, 173; Claus & Howitz, J. Pr. Chem. 1894, (ii) 50, 23. * Mohr, B. 1898, 31, 
2495; Watson & Mills, 7. 1910, 97, 743. 3 Mohr, loc. cit. 
