Fuchsin Carbolic

Carbolic fuchsin is a bright crimson dye from the nitrofuchsin group, trinitromethylene ester of tricarbolic acid. In 1928, Perkin obtained synthetic fuchsin from 3-aminobenzenesulfonic acid, its formula is a residue of fuchsin obtained in 1776 by a French chemist named Claude Joseph Berthollet, namely trinitrosalicylate.

The basis for the production of this dye are ethyl derivatives of 1,3,5-benzenetricarboxylic acids, which can be obtained from benzene by condensation of tricarbolic acids. These compounds behave as bases when reacting with silver salts and are subsequently oxidized by nitric acid. This process provides the basis for the production of dyes from benzene derivatives, which is still accepted for the production of eosin.

Of the many derivatives of 1,2,4-tricarbolic acids, trimethylamine, triethylamine and tripropylamine are preferred for the synthesis of fuchsin; but for their construction it is more convenient to use 1,8-naphthylenedicarboxylic acid triacetate. This triacetyl derivative can be prepared, first, by deacylation of polyacetylaminobenzene thiocarbamates with an acetic mixture or aqua regia. In the presence of the fourth carbon in the CH group, such a compound is a good reagent for reduction with manganese intermediates, ketones, when heated, since the intermediate product is acetone. The subsequent oxidation corresponds to the same function for the aromatic carbonate that the corresponding benzoic acid nitrate performs for the alcarboxylic acid; the synthesis product is obtained in the form of a black substance and is called toluine; it is a yellow-orange powder, somewhat yellowish in crystals.

When pentaerythritol is added to such an acyl product, in which part of the water is reduced and the molecules of which are prochirontonated, toluine exhibits acidic properties and covalently binds the double bond and water to phenol. This is the basis of a two-step quantitative method for the synthesis of the trisodium salt of fuchsinone, which is also called acetylamine, or fuchsin Carboli from the Latin designation fuchsic acids or