1,2,3,6-Tetrahydrophthalic anhydride

1,2,3,6-Tetrahydrophthalic anhydride (THPA, CAS 85-43-8) is a cyclic organic anhydride derived from the Diels-Alder reaction of butadiene and maleic anhydride. It carries no assigned E-code and is commercially recognised under the abbreviation THPA across polymer and coatings industries.

In epoxy resin formulations, THPA functions as a hardener by reacting with epoxide groups to form ester linkages, producing thermoset networks with controlled crosslink density. It also serves as a reactive intermediate in alkyd and polyester resin synthesis, where it contributes unsaturation that influences flexibility and cure response in coatings and adhesive systems.

THPA is supplied as a solid and is subject to REACH registration requirements within the European Economic Area. Procurement teams should confirm supplier SDS documentation and purity specifications relevant to their formulation standards, as industrial and higher-purity grades may differ in residual monomer content and handling classifications.