Process for the preparation of dialkyl phosphoric acids

A process to produce dialkyl phosphoric acid that comprises:

• (a) reacting PCl.sub.3 with C.sub.1 -C.sub.12 alkanol in a molar ratio of said alkanol:PCl.sub.3 of 3 at 10.degree.-15.degree. C., under an inert gas atmosphere, to produce a mixture of bis-(alkyl) hydrogen phosphite, alkyl chloride, and HCl;
• (b) chlorinating said mixture with a stoichiometric amount of chlorine gas at about 20.degree. C., until the reaction mixture attains a yellow-green color and a stable Platinum-Calomel electrode reading is obtained in the range of about 880-910 m.v.;
• optionally sparging with inert gas at about 50.degree. C. until the HCl content is below about one weight percent, thus producing a solution of dialkyl phosphorochloridate in alkyl chloride;
• (c) hydrolyzing said solution with water at 80.degree.-100.degree. C. for about 4-6 hours, using sufficient water to effect a final HCl content below about 11 weight percent, to produce dialkyl phosphoric acid product;
• and
• (d) separating said product.