Abstract: Disclosed are an epoxidized polyester which comprises, per molecule, at least three bifunctional groups each having the general formula ##STR1## wherein R.sup.1 and R.sup.2 are the same or different and each is a hydrogen atom or an alkyl group containing 1 to 5 carbon atoms, or R.sup.1 and R.sup.2 taken together represent an endomethylene group, and which has a number average molecular weight of about 1,000 to about 10,000, as well as processes for preparing the epoxidized polyester.

Abstract: This invention provides a process for producing methyltetrahydrophthalic anhydride characterized in that maleic anhydride and a C.sub.5 fraction are subjected to Diels-Alder reaction in the presence of a radical polymerization inhibitor and oxygen. According to the process of this invention, formation of gels as byproduct is substantially completely inhibited.

Abstract: Disclosed is a process for preparing 3,4,5,6-tetrahydrophthalimide comprising the steps of:(i) reacting a crude 3,4,5,6-tetrahydrophthalic anhydride containing as impurities at least one carboxylic anhydride (A) selected from the group consisting of phthalic anhydride, hexahydrophthalic anhydride and structural isomers of 3,4,5,6-tetrahydrophtalic anhydride with an alcohol for conversion of substantially all the carboxylic anhydride (A) into the monoester thereof to obtain a reaction mixture containing the monoester, 3,4,5,6-tetrahydrophthalic anhydride, and if any, a monoester of 3,4,5,6-tetrahydrophthalic anhydride, and(ii) adding ammonia to the reaction mixture to subject the 3,4,5,6-tetrahydrophthalic anhydride, and if any, the monoester thereof to a reaction for conversion into 3,4,5,6-tetrahydrophthalimide.

Abstract: Disclosed is a curing agent composition for epoxy resin, prepared by mixing together the following components (i), (ii) and (iii) and heating the mixture for modification:(i) at least one organic carboxylic acid zinc salt,(ii) at least one acid anhydride, and(iii) either (a) at least one phenol compound or (b) at least one glycidyl ester or glycidyl ether compound.

Abstract: .DELTA..sup.1 -THPA or a derivative thereof is prepared by isomerizing .DELTA..sup.4 -THPA or a derivative thereof in the presence of (a) a palladium catalyst, and (b) an inorganic salt and/or a sulfur compound.