Karl Theophil Fries (1875-1962)

German chemist, born in Kiedrich, near Wiesbaden. He studied at Marburg and Darmstadt and obtained his doctorate in Marburg in 1899 under Theodor Zincke. After a period in the chemical industry (Hoechst) he returned to Marburg as a professor, and there he described in 1908 the rearrangement that bears his name.

He fought in the First World War and from 1918 to 1938 was professor at the Technical University of Brunswick, which he had to leave after a conflict with Nazi habilitation candidates. He returned to Marburg, where he went on teaching until his death in 1962, aged 87.

His research focused on polycyclic compounds and fused heterocycles. Fries' rule also bears his name: the most stable Kekulé structure of a polycyclic aromatic hydrocarbon is the one with the most rings having three double bonds, as in benzene.