Dialkylphenol phosphorylation

A process of manufacturing triaryl phosphate mixtures which comprises:

• 1. reacting a phosphorylating agent selected from the group consisting of phosphorus oxychloride, phosphorus oxybromide, phosphorus pentoxide, phosphoric acid, phosphorus trichloride and phosphorus pentachloride, with a recycle composition of phenols, the total molar proportion of phenols to atoms of phosphorus in the phosphorylating agent being less than 3:1;
• 2. reacting the product of stage (1) with a feedstock composition of phenols said feedstock composition comprising phenol, at least one monoalkylphenol, and phenol selected from the group consisting of dialkylphenols and trialkylphenols and being the reaction product obtained by alkylating (i) phenol, or (ii) a mixture of phenols comprising a major molar portion of phenols having less than three alkyl carbon atoms, with (iii) a phenol alkylating agent containing from three to sixteen carbon atoms per molecule, the proportion of feedstock composition added at (2) being such that the molar ratio of the total of phenols fed into the process to phosphorus atoms is at least 3:1 to form a mixture of (a) triaryl phosphates and (b) unreacted phenols which is enriched in said phenol selected from the group consisting of dialkylphenols and trialkylphenols when compared to said feedstock composition;
• 3. recovering said unreacted phenols which is enriched in said phenol selected from the group consisting of dialkylphenols and trialkylphenols from the stage (2) product which is then said recycle composition of phenols;
• and
• 4. recycling said recycle composition to stage (1).