ENZYMATIC SYNTHESES OF ALKYDS .2. LIPASE-CATALYZED POLYTRANSESTERIFICATION OF DICHLOROETHYL FUMARATE WITH ALIPHATIC AND AROMATIC DIOLS

All-trans alkyds (unsaturated polyesters) were prepared by lipase-catalyzed polytransesterifications of diesters of fumaric acid and 1,4-butane diol. Industrially prepared alkyds, however, contain aromaticity in their backbone, which is introduced by phthalic acid derivatives and/or isomers. Thus, in this study, the specificity of lipases toward aromatic esters, diesters, and diols was investigated in order to find a means of introducing aromaticity in the lipase-catalyzed synthesis of "all-trans" alkyds. It was found that lipases from Pseudomonas and Mucor efficiently catalyzed the polytransesterification of dichloroethyl fumarate with aromatic diols such as benzene dimethanol. Crystallinity was found in the "all-trans" alkyds synthesized in acetonitrile. In order to determine whether this property was due to the nature of diol or the frequency of the double bond in the backbone of the polyester, other alkyds were prepared in which the length of the diol was changed as well as the number of carbons (odd or even) in the diol and the chemical nature of the diol (primary or secondary). In all cases crystallinity was found. It thus seems that the stereochemistry of the double bond is responsible for this property. Molecular weights, which were determined by gel permeation chromatography (GPC) analyses, were comparable with those of the industrially prepared alkyds.