Hans Thacher Clarke (1887-1972): Chemist and Biochemist

Born in the late Victorian era, Hans Thacher Clarke trained as an organic chemist at University College, London. In 1911, he authored the text A Handbook of Organic Analysis. Qualitative and Quantitative. This book ran to several editions and played an important role in the education of many organic chemists. From 1914 to 1928 he worked for the Eastman Kodak Company, developing methods to synthesize many rare organic chemicals in short supply because of World War I. His interest in the development of these methods led to his association with Roger Adams, James B. Conant, Oliver Kamm, and Carl S. Marvel in producing the first volume of Organic Syntheses in 1922. He was an editor and board member of that publication for many years and he also provided entries and checked preparations.

In 1928 Clarke was appointed Chairman of the Department of Biochemistry, College of Physicians and Surgeons, Columbia University. He upgraded and expanded the facilities, eventually developing a world-class department. The department became home to a significant number of scientists driven from their positions in Germany by the policies of the Third Reich. Many of the 94 graduate students trained there in biochemistry went on to distinguished careers; one of them, Konrad Bloch, became a Nobel laureate. A major contribution of Clarke's department was the development of the isotopic tracer technique for the study of intermediary metabolism. This technique has become indispensable in biochemistry and molecular biology.

An early interest in the chemistry of organic compounds of sulfur led Clarke to demonstrate a thiazole moiety in the structure of vitamin B₁ and to study the formation of thiazolidine carboxylic acid from the reaction of cysteine and formaldehyde. This reaction became important in connection with the determination of the chemical structure of penicillin. Moreover, he had a major administrative role in the USA-UK collaboration (1943-1946) to attempt the chemical synthesis of penicillin.