Louis Henry: The Henry reaction and other organic syntheses

Louis Henry (1834-1913) was a Belgian chemist having a sharp deductive reasoning in organic chemistry, which led him to synthesize hundreds of new compounds in a wide range of functionalities. He isolated pure berberine from the roots of Berberis vulgaris, determined its composition, and prepared many of its derivatives. He proved the analogy between the sulfocyanides and thiocyanates of the monatomic alcoholic radicals and synthesized a variety of new organic thiocyanates. He demonstrated that monatomic nitriles should be considered to be primary amines where a positive triatomic radical had replaced the three hydrogen atoms of the ammonia, and presented a new general method for preparing nitriles based on the fact that phosphorus pentasulfide exchanged its sulfur for oxygen. Henry studied the reaction of iodine chloride with a variety of compounds and prepared the corresponding halohydrins. He proved the identity of the four valences of the carbon atom, the isomerism of many glyceric compounds, carried on the total synthesis of glycerin and discovered dipropargyl (a linear isomer of benzene) and diallylene. He described the preparation of many derivatives allyl, diallyl, and dipropargyl and their physical and chemical properties, in particular, the reaction with hypochlorous and hypobromous acids. He proved that nitromethane was able to combine with aldehydes and ketones to form nitro alcohols conforming the general system of the alcohols; this led him to develop the nitro-aldol reaction (Henry's reaction). Henry determined that lactide was a dilactic substance represented by two molecules of lactic acid minus two molecules of water and synthesized methylene lactate by reacting 1,3,5 trioxane with lactic acid.