Patent GB-1249072-A (GB)
Title: Halogen-containing phosphonic acid derivatives, their preparation and their conversion to (bis-1,2-epoxypropyl)phosphonic acid compounds
Inventor: FIRESTONE RAYMOND ARMOND
IPC: C07F9/14
Filed: 1969-05-12
Abstract: 1,249,072. (Cis 1,2-epoxypropyl)phosphonic acid, (1-haloethoxy) methyl phosphonic acids. MERCK & CO. Inc. 12 May, 1969 [15 May, 1968], No. 23969/69. Heading C2C. (Cis 1,2-epoxypropyl)phosphonic acid or a salt or ester thereof is obtained by treating a (1-haloethoxy) methyl phosphonic acid or a salt or ester thereof with a metal hydride (e.g. Na, K or Li hydride) or with an alkali metal amide or an organo-metallic reagent. The (1-haloethoxy) methyl phosphonic acid or derivative may be a compound of the formula CH 3 .CHX.OCH 2 P(O)(OR<SP>1</SP>) 2  in which X is halogen, e.g. Cl, Br, F or I and R<SP>1</SP> is H, C 1 -C 5  alkyl, C 2 -C 5  alkenyl or C 2 -C 5  alkynyl, aryl, aralkyl, or the cation derived from an alkali or alkaline earth metal or magnesium, and the invention includes such compounds per se. The organo metallic reagent may be an organolithium, -rubidium, or -caesium wherein the organo group is hydrocarbyl. When the product is a salt of (cis-1,2-epoxypropyl) phosphonic acid it may be converted to the free acid by use of a cation exchange column on the hydrogen cycle and when the product is an ester it may be converted to the free acid by hydrogenolysis, by treatment with aqueous mineral acid, e.g. HC1 or H 2 SO 4 , under buffered conditions, or by treatment with trimethylchlorosilane followed by aqueous hydrolysis. The free acid or ester thereof may be converted to a salt by treatment with a suitable base. The main process may be carried out in a solvent, e.g. an ether or hydrocarbon. The epoxy product may be obtained as a racemic mixture or as one or more of four optically active isomers and (-)(cis-1,2-epoxypropyl)- phosphonic acid can be obtained by using the corresponding 2S(1-haloethoxy) methyl phosphonic acid precursor, e.g. 25(1-chloroethoxy)- methyl phosphonic acid which is obtainable by treating (1 - chloroethoxy)methyl phosphonic acid with one equivalent of strychnine in tetrahydrofuran, separating the two diastereomeric strychnine salts by crystallization and regenerating the free acid from the 2,5 strychnine salt of [(1-chloroethoxy)methyl]phosphonic acid. (1-Haloethoxy)methyl phosphonic acids and their salts and esters are obtained by treating hydroxymethyl phosphonic acid or salt or ester thereof with acetaldehyde in the presence of a gaseous hydrogen halide and the preparation of dimethyl (1-chloroethoxy) methyl phosphonate, (1-bromoethoxy) methyl phosphonic acid, and diethyl (1-iodoethoxy) methyl phosphonate is described. Hydroxymethylphosphonic acid esters are obtained by treating an alcohol or phenol with a phosphorus trihalide in the presence of a strong base followed by the reaction of the phosphite triester obtained with additional phosphorus trihalide to yield a halophosphite diester which is then treated with a base to form the corresponding phosphite diester followed by treatment of the latter with an excess of formaldehyde. The dimethyl ester may also be obtained by treating hydroxymethyl phosphonic acid with diazomethane. The () and (-)(cis-1,2-epoxy propyl) phosphonic acid and salts thereof have microbial properties and may be used as active ingredients in therapeutic or antiseptic compositions which may contain a diluent, granulating agent, preservative, binder, sterile excipient or flavouring or coating agent and may be in the form of a capsule, tablet or liquid solution or suspension.