Patent GB-1249073-A (GB)
Title: Preparation of cis-propenylphosphonic acid and derivatives thereof
Inventor: SALCE LUDWIG
IPC: C07F9/38
Filed: 1969-05-12
Abstract: 1,249,073. Preparing cis-propenyl phosphonic acids and derivatives thereof. MERCK & CO. Inc. 12 May, 1969 [15 May, 1968], No. 23986/69. Heading C2C. A cis-olefinic compound of the formula CH 3 CH=CHP(O)(OR) 2  wherein R is H, a univalent substituted or unsubstituted hydrocarbon radical or an equivalent of a cation which may be a metal, NH 4  or amine cation, the two R's being the same or different, is obtained by treating a compound of the formula wherein X is halogen, Y is halogen or OH or an acyloxy, sulphonyloxy or nitrosyl group and R is as defined above with an appropriate reagent selected from a reducing metal (e.g. zinc), a reducing metal salt (e.g. chromous chloride or stannous chloride), sodium sulphite, sodium iodide, diphenyl telluride, a triaryl phosphine, a trialkyl phosphine and a trialkyl phosphite. The halohydrin compound in which Y is OH may be obtained by reacting the (+) isomer of the cis-epoxide of the formula with a hydrogen halide which is preferably bubbled into a solution or suspension of the epoxy compound in an inert organic solvent and the halohydrin product may be directly converted to the olefinic compound by treatment with a reducing metal or reducing metal salt, if desired in the presence of a tertiary amine and POCl 3 , the conversion being generally effected in an inert organic solvent. In an alternative procedure the halohydrin is halogenated to form the corresponding dihalide, i.e. compounds in which Y is a halogen atom, the halogenation being suitably effected with a concentrated halogen acid, a phosphorus halide or oxyhalide, e.g. PBr 3  or POCl 3  or with a thionyl halide, e.g. thionyl chloride. Dehalogenation may suitably be effected by treatment with Zn, chromous-, titanous-, vanadous-, stannous-, or ferrouschloride, sodium sulphite, sodium iodide, diphenyl telluride, a triaryl or trialkyl phosphine or a trialkyl phosphite. The halohydrin may also be acylated with an acid chloride or anhydride, sulphonylated, e.g. with methane-, ptoluene-sulphonyl- or p-bromobenzene-sulphonyl chloride, or nitrosated, e.g. with nitrosyl chloride, to form the corresponding compounds in which Y is acyloxy, sulphonyloxy or nitrosyl which are then treated with a reducing metal or reducing metal salt to form the cis-propenyl phosphonic acid compound. The (+) isomer of (cis-1,2-epoxy-propyl)- phosphonic acid may be obtained by resolving a racemic mixture obtained by selectively reducing an ester of propynylphosphonic acid to the corresponding ester of cis-propenylphosphonic acid, hydrolysing the ester to the corresponding free acid and then epoxidizing the free acid to the () epoxy acid and a detailed example is given for such stepwise process for the production of (+ )(cis-1,2-epoxypropyl)phosphonic acid which is recovered in the form of its diammonium salt. The latter may be converted to the sodium salt which on treatment with silver nitrate yields the silver salt which on reaction with an alkyl, alkenyl, alkynyl or aralkyl halide gives the corresponding esters of ( + ) (cis-1,2-epoxypropyl)phosphonic acid. The aryl esters may be obtained by dissolving propenyl phosphonic acid, thionyl chloride and pyridine in benzene, reacting the acid chloride formed with phenol or a substituted phenol and then epoxidizing the product.