By the entrance of amino or hydroxyl groups into the molecule dyestuffs are formed.
Benzo-orthoxazines, -metoxazines and -paroxazines are known: dibenzoparoxazine or phenoxazine is the parent of a valuable series of dyestuffs; dibenzoparathiazine or thiodiphenylamine is important from the same aspect.
Benzo-ortho-diazines exist in two structural forms, cinnolin and phthalazine; benzo-meta-diazines are known as quinazolines; benzo-para-diazines are termed quinoxalines; the dibenzo-compounds are named phenazines, this last group including many valuable dyestuffs - indulines, safranines, &c. In addition to the types of compounds enumerated above we may also notice purin, tropine and the terpenes.
At the same time, however, all dyestuffs are coloured substances.
The ortho-compounds condense to azimido benzenes, the metacompounds yield azo-dyestuffs, and the para-compounds yield bis-diazo compounds of the type XN2ï¿½C6H4ï¿½N2X.
The azo compounds are intensely coloured, but are not capable of being used as dyestuffs unless they contain salt-forming, acid or basic groups.
Brandy, cigars and dyestuffs are among the manufactures of the place.
TRIPHENYLMETHANE, (C 6 H 5) 3 CH, a hydrocarbon, important as being the parent substance of several series of exceedingly valuable dyestuffs, e.g.
Among such dyestuffs are chrysamine or flavophenine, obtained from salicylic acid and diazotized benzidine, and congo red obtained from sodium naphthionate and diazotized benzidine.
The industries of the place include the manufacture of porcelain, chocolate and dyestuffs, wool-spinning and bell-founding.
Perkin was the first of a series of dyestuffs which are now to be numbered by hundreds.
In addition to dyestuffs, it is a starting-product for the manufacture of many drugs, such as antipyrine, antifebrin, &c. Aniline is manufactured by reducing nitrobenzene with iron and hydrochloric acid and steam-distilling the product.