Grandmougin (Berichte, 1891, 24, p. 2546) obtained azoimide from dinitraniline, C 6 H 3 (NO 2) 2 NH 2j by diazotization and conversion of the diazo compound into the perbromide, (NO 2) 2 C 6 H 3 N 2 Br 3.
The constitution of the isomeric diazo hydroxides has given rise to much discussion.
The diazo cyanides, C 6 H 5 N 2 CN, and carboxylic acids, C6H5.
The orthoand parasemidines can be readily distinguished by their behaviour with different reagents; thus with nitrous acid the ortho-semidines give azimido compounds, whilst the para-semidines give complex diazo derivatives; with formic or acetic acids the ortho-semidines give anhydro compounds of a basic character, the para-semidines give acyl products possessing no basic character.
From the primary amines are derived the diazo compounds and azo compounds; closely related are the hydrazines (q.v.).
According to Hantzsch the isomeric diazo hydroxides are structurally identical, and the differences in behaviour are due to stereo-chemica l relations, the isomerism being comparable with that of the oximes.
When warmed with a solution of nitrous acid, they are converted into phenols; if, however, nitrous acid be added to an ice-cold solution of a primary amine in excess of mineral acid, a diazonium salt is formed (see Az o Compounds and DIAzO Compounds), or in absence of excess of acid, a diazoamine is produced.
Constitution of the Diazo Compounds.-P. Griess (Ann., 1866, 137, p. 39) considered that the diazocompounds wereformed by theaddition of complex groupings of the type C 6 H 4 N 2 - to the inorganic acids; whilst A.
The diazo group preferably going into the para-position to the amino group. When the para-position is occupied, the diazo group takes the orthoposition.
Meta-oxyazobenzene, C 6 H 5 N: N(1)C 6 H 4 OH(3), was obtained in 1903 by P. Jacobson (Ber., 1903, 36, p. 4 0 93) by condensing ortho-anisidine with diazo benzene, the resulting compound being then diazotized and reduced by alcohol to benzene-azometa-anisole, from which meta-oxyazobenzene was obtained by hydrolysis with aluminium chloride.