PRODUCTION OF 2-PHENYL-ETHYLENE PHOSPHONIC ACID

摘要

Production of 2-phenyl-ethylene phosphonic acid by reacting styrene with phosphorus pentachloride in a molar ratio of about 1 : 2 in liquid phase and hydrolyzing the resulting complex 2-phenyl-ethylene phosphonic acid tetrachloride with water. The reaction is more particularly started with the use as the liquid phase of the equimolar mixture of 2-phenyl-ethylene phosphonic acid dichloride and phosphorus oxychloride obtained as an intermediary product; styrene and phosphorus pentachloride are introduced thereinto with continuous agitation; resulting complex 2-phenyl-ethylene phosphonic acid tetrachloride is partially hydrolyzed by adding a predetermined quantity of water to an equimolar mixture of 2-phenyl-ethylene phosphonic acid dichloride and phosphorus oxychloride; a portion of the resulting clear solution is continuously used as the liquid phase and phosphorus oxychloride is continuously distilled off under reduced pressure from the balance portion of the solution; remaining 2-phenyl-ethylene phosphonic acid dichloride is hydrolyzed by continuous addition of overstoichiometric proportions of water to an aqueous solution of 2-phenyl-ethylene phosphonic acid; the aqueous solution is cooled and crystalline phosphonic acid is precipitated therefrom.