1.2- Disubstituted hydrazine hydrochlorides, reaction with

This reaction was first reported by Pellizzari in 1894. It is the preparation of 1,2,4-triazole derivatives by baking the mixture of amide and acyl hydrazide. Therefore, it is generally known as the Pellizzari reaction. This reaction is usually carried out at temperatures > 250°C, but very reactive substrates can proceed at relatively lower temperatures, such as the coupling between diphenylformamidine and formhydrazide at 150°C. This reaction is very useful for the preparation of monosubstituted-, disubstituted-, and 1,3,5-trisubstituted-l,2,4-l/f-triazoles. However, at such a high temperature, transamination may occur between amide and acyl hydrazide, especially for the aliphatic acid hydrazides," resulting in a mixture of triazoles and a lower yield of the expected triazole. It has been found that co-heating the mixture of formamide and hydrazine hydrochloride with two equivalents of pulverized KOH can improve the yield of 1,2,4-triazole to almost 17%. ... 

Reaction of 2,4-dichloro-l,5-naphthyridine with ammonia (170°, 20 hr), hydrazine (100°, 16 hr), or aqueous hydrochloric acid (100°, 3 hr) was shown to yield the 2-amino- (47% yield) and 2-hydroxy-4-chloro derivatives (66% yield), but 2-hydrazino substitution (68% yield) was assumed. Disubstitution with ammonia (190°, 4 hr), hydrazine (100°, 48 hr), and ammonia-phenol (180°, 6 hr) occurred in high yield. Displacement of the 4-oxo group in 2,4-dioxo-l,5-naphthyridine occurs with aniline plus its hydrochloride (180°, 12 hr, 88% yield) to yield 429. Oxo groups in the 2- or 4-positions were... 

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