Kekulé von Stradonitz, Friedrich August (frē'drikh ou'goost kā'kOOlā fun shträ'dōnits) [key], 1829–96, German organic chemist. He was professor at Ghent (1858–65) and at Bonn from 1865. He made studies of various carbon compounds, especially benzene, for the molecular structure of which he developed the ring theory. This theory is of fundamental importance to modern chemistry.