Kekulé von Stradonitz, Friedrich August (1829–1896)

German chemist whose theory in 1858 of molecular structure revolutionized organic chemistry. He proposed two resonant forms of the benzene ring.

In 1865 Kekulé announced his theory of the structure of benzene, which he envisaged as a hexagonal ring of six carbon atoms connected by alternate single and double bonds. In 1867 he proposed the tetrahedral carbon atom, which was to become the cornerstone of modern structural organic chemistry.

Kekulé was born in Darmstadt and studied at Giessen and Paris. After working in Switzerland, he went in 1854 to London, where he met many leading chemists of the day. When he returned to Germany 1855, he opened a small private laboratory in Heidelberg. In 1858 he became professor at Ghent; in 1865 at Bonn.

In 1858, Kekulé published a paper in which, after giving reasons why carbon should be regarded as a four-valent element, he set out the essential features of his theory of the linking of atoms.