SYNTHESIS OF ALKYDS INVOLVING REGIOSELECTIVE LIPASE-CATALYZED TRANSESTERIFICATION IN ORGANIC MEDIA

Porcine pancreatic lipase (PPL) is established as an effective biocata lyst for the selective transesterification of triglycerides and diols in organic medium at room temperature yielding primarily 2-monoglyceri de mixtures. Molecular modelling simulations of repeating units of alk yd resin incorporating one- and two-monoglycerides show end-to-end dis tance of 9.76 and 12.82 Angstrom, respectively. The modeling studies o n the trimers of these repeating units also reveal more extended confi guration for the structures based on two-monoglycerides. A comparative study of alcoholysis by conventional base-catalyzed process and this novel biocatalytic process was carried out with coconut oil triglyceri des and a series of diols, followed by polymerization. The rates of tr ansesterification were dependent on the nature of triglyceride, diol, concentration of the enzyme, and temperature. The 1,3 specificity of l ipase produced 2-monoglycerides as determined by periodic acid method, resulting in uniform distribution of fatty acids along the alkyd poly ester backbone. Comparisons are made between those alkyds prepared by base catalysis and biocatalytic method. (C) 1997 John Wiley & Sons, In c.