Monoalkyl phosphonic acid ester production process

A process for the production of monoalkyl phosphoric acid ester compositions comprising the steps of:

• a) preparing a slurry or paste reagent composition by intimately blending and exclusively reacting, at from about room temperature to about 80.degree. C. or the ultimate phosphation reaction temperature, an effective amount of phosphoric anhydride with from about 75 weight percent to about 117 weight percent phosphoric acid, said reagent composition having an effective equivalent polyphosphoric acid weight percent of from about 118 to about 125;
• and
• b) reacting said reagent composition with at least one alcohol of the formula RO{C.sub.n H.sub.2n O}.sub.x H wherein R is selected from the group consisting of a saturated or unsaturated aliphatic C.sub.1 -C.sub.30 straight or branched carbon chain, a phenyl, a mono-, di-, or tri-substituted phenyl, a phenyl C.sub.1 -C.sub.6 alkyl and a mono-, di-, or tri-substituted phenyl C.sub.1 -C.sub.6 alkyl, wherein the phenyl substituent group(s) each have a total of 1 to 30 carbon atoms, and wherein each substitution may be a saturated or unsaturated straight or branched carbon chain, a phenyl, an alkyl phenyl, a phenyl alkyl, or an alkyl phenyl alkyl group;
• wherein n is from 2 to 4 and may be the same or different for each alkylene oxide unit;
• and wherein x is from 0 to 100, for a reaction time of from about 4 to about 12 hours;
• wherein in the ester compositions, the monoalkyl to dialkyl phosphate weight ratio is greater than 80:20 and the weight percent of the residual alcohol and phosphoric acid are individually each less than 6%.