Hofmann, August Wilhelm von (1818–1892)

German chemist who studied the extraction and exploitation of coal-tar derivatives, mainly for dyes.

In 1881 he devised a process for the production of pure primary amines from amides.

Hofmann was born and educated in Giessen, Hesse. He was professor at the Royal College of Chemistry in London 1845–65 and at Berlin from 1865.

In 1858 Hofmann obtained the dye known as fuchsine or magenta by the reaction of carbon tetrachloride (tetrachloromethane) with aniline (phenylamine). Later he isolated from it a compound which he called rosaniline and used this as a starting point for other aniline dyes, including aniline blue (triphenyl rosaniline). With alkyl iodides (iodoalkanes) he obtained a series of violet dyes, which he patented in 1863. These became known as ‘Hofmann's violets’ and were a considerable commercial and financial success.

The term ‘valence’ is a contraction of his notion of ‘quantivalence’ and he devised much of the terminology of the paraffins (alkanes) and their derivatives that was accepted at the 1892 Geneva Conference on nomenclature.