GC-MS DETERMINATION OF IMPURITIES IN 2-ETHYL-HEXANOL RECOVERED FROM DI-2-ETHYLHEXYL ORTHOPHTHALATE PLASTICIZER PRODUCTION

The basic industrial method for large scale synthesis of di-2-ethylhex yl orthophthalate (dioctyl phthalate, DOP) is the direct esterificatio n of phthalic anhydride with 2-ethylhexanol (2-EH) catalyzed by tetrab utoxytitanium (TBT). A serious shortcoming of the DOP so produced is t he presence of color and unpleasant odor. It is assumed that this is c aused by impurities in the starting raw material and by secondary reac tion products which accumulate in the recycled 2-EH and pass into the plasticizer during processing [1]. Gas chromatographic (GC) studies [2 -4] identified a total of 25 impurities present in various amounts in 2-EH obtained by various methods. Fourteen of these were detected by G C in recycled 2-EH. However, in both the starting and recovered alcoho l the structures of most of the impurities was not established. It is necessary to obtain information on the impurities which accumulate in the recycled 2-EH during production in order to optimize the process p arameters for continuous DOP synthesis and improve the economics of th e process. The goal of this work was selection of optimal conditions f or chromatographic separation and identification of impurities in recy cled 2-EH.