Production of high viscosity phosphoric and phosphonic acid aryl esters

Abstract

A process for the production of a relatively high molecular weight phosphoric or phosphonic acid aryl ester, comprising reacting a phosphoric or phosphonic acid aryl ester with formaldehyde in the presence of sulphuric acid at a temperature from about 10.degree. to 120.degree. C. Advantageously, the aryl ester is of the formula ##STR1## in which R is a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms, a halogen atom, an aryloxy group, or an aryl group; R.sub.1 is a group OC.sub.6 H.sub.m R.sub.n in which m+n=5, an alkyl group, a haloalkyl group or an optionally substituted aryl group; R.sub.2 is a group OC.sub.6 H.sub.m R.sub.n, in which m+n=5; and n is from 1 to 3, about 0.5 mole of formaldehyde in the form of paraformaldehyde or trioxane is employed per mole of aryl ester, about 1.5 to 2 moles of sulphuric acid are used per mole of aryl ester, the sulphuric acid is employed as a solution of at least about 95% concentration, and the reaction is effected at a temperature of about 40.degree. to 80.degree. C. in the presence of an inert solvent. The products are new and useful as flame-proofing agents in the production of laminated papers and polyesters, as fire-retarding plasticizers in plastics such as PVC, as additives to plastics such as polyphenylene oxides and also as low-flammability hydraulic oils.

Dependencies are inferred from the claim text.