Tetramethylammonium di-t-butyl phosphate (VI), readily prepared from di-t-butyl phosphite in good yield, was found to be a convenient phosphorylating reagent for organic halides. In boiling dimethoxyethane it reacts easily, especially with bromides and iodides, to form the corresponding alkyl di-t-butyl phosphates (XI). The phosphotriesters (XI) were converted into the corresponding monoalkyl phosphates (XII) by treatment with trifluoroacetic acid in benzene at room temperature. The products were easily isolated and characterized as anilinium salts (XIII).