Improved method for the manufacture of long chain phthalate dialkyl ester compositions

An improved method for producing di-isotridecylphthalate (DTDP) is disclosed by esterification using a tetra-alkyl titanate catalyst made from preferably primary alcohols having at least 4 and preferably up to but not more than 10 carbon atoms. In the esterification process, compared to using tetra-isopropyl titanate catalyst, less of the alcohol from the catalyst contributes to the environmental burden associated with discarding the waste water byproduct, and more is incorporated into the prime DTDP product.