Erik Christian Clemmensen
Erik Christian Clemmensen (August 12, 1876 – May 21, 1941) was a Danish-American chemist. He is most commonly associated with the Clemmensen reduction, a method for converting a carbonyl group into a methylene group.
Erik Christian Clemmensen was born on August 12, 1876 in Odense, Denmark.
He left school at the age of 15. He signed up to join an expedition on a warship, with the aim of becoming a naval officer, but illness prevented them from achieving this goal. Clemmensen studied at the Copenhagen Polytechnic Institute (now the Technical University of Denmark). He emigrated to the United States in 1900 and worked in the pharmaceutical industry. He joined the pharmaceutical company Parke, Davis & Co in Detroit, Michigan. For the invention of the Clemmensen reduction, he received his Ph.D. in 1913 from the University of Copenhagen. 
In 1914, he co-founded the Commonwealth Chemical Corporation in Newark, New York along with H.G. Chapman and Rhea Chittenden, where he developed methods for the manufacture of sodium benzoate, vanillin, and coumarin. After a fire in 1929, the company was acquired by Monsanto Chemical Company and moved to St. Louis, Missouri. While working for Monsanto, Clemmensen helped develop the synthesis of the artificial sweetener saccharin. In 1935, he returned to New York City and founded The Clemmensen Chemical Corp.
He is best known for the reaction that he developed while at Parke, Davis & Co. This reaction involves the reduction of ketones using a zinc amalgam and HCl. It has been employed in the preparation of polycyclic aromatics and aromatics containing linear hydrocarbon side chains, the latter not being obtainable from a Friedel-Crafts alkylation. 
- Alexander R. Surrey (2013) Clemmensen reduction, in Name Reactions in Organic Chemistry (Elsevier, Page 54-56) ISBN 9781483258683
- "100th Anniversary: Clemmensen Reduction". ChemViews. 14 June 2013. Retrieved December 20, 2015.
- Guess the Chemist (ChemistryViews.org)
- Peter Morris. "Erik Christian Clemmensen (1876-1941)". Biographies of Chemists. Retrieved December 20, 2015.
- "Dr. Erik Clemmensen. Head of Chemical Corporation Wrote Scientific Books". New York Times. May 22, 1941.
- "Erik Christian Clemmensen". Den Store Danske. Retrieved December 20, 2015.