Azo- and diazo- derivatives

AVlien it is remembered that each one of these compounds is capable of forming a large number of derivatives by further substitution, and a series of salts, it is plain that the chemistry of 

The hydrazins are theoretically derivable from the group BaN—NHa, diamidogen, by the substitution of acid, alcoholic, or phenylic radicals for one or more of the hydrogen atoms. They may be primary, secondary, tertiary, or quaternary, as the sub-.stitution removes are two, three, or four of the H atoms. The secondary hydrazins may be symmetrical or unsymmetrical, according to the formula RHN—NHR and RaN—NHa. They also form compounds resembling the ammonium salts, known as azonium -compounds. In short, they play the part of compound ammonias. The substituted groups may be acyclic as in ethyl-hydrazin, CaHsHN —NHa, but in the inajority it is a cyclic derivative as in phenyl hydrazin. 

These compounds are valuable reagents in synthetic chemistry. With the chlorids of the acid radicals they form amids they may produce compound ammonias they form carbazic and sulfocarbazic acids with COa and CSa by limited oxidation they form tetrazones, substances having the formula RjN—N=N— NRi, as the azo-compounds (see below) are produced from the amins, etc. They also combine with ketones to form products of condensation. 

Phenyl hydrazin—CeHs—HN—NH,—is obtained by the action of zinc-dust and acetic acid on diazo-ainidobenzene. It is a yellow oil, sparingly soluble in water, soluble in alcohol and in ether, possessed of strong reducing power, and acting as a jnonacid base to form crystallized salts. 

Phenyl-acetyl-hydrazin—Hydracetin— CeHs,HN—NH—C3H3O —is produced by the action of acetyl chlorid, or of acetic anhy- drid, upon phenyl hydrazin. It is a white, tasteless, odorless, crystalline powder, sparingly soluble in HjO, readily soluble in alcohol. It acts as a reducing agent.- It is the active ingi edient in the antipyretic known as pyrodin. 

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