This invention relates to a novel process for preparing citraconic anhydride. More specifically it relates to a continuous vapor phase oxidation process. Citraconic anhydride is useful as a curing agent for epoxy resins, and can be isomerized into itaconic acid, a valuable raw material for synthetic resins.
U.S. Pat. No. 3,701,805 discloses the vapor phase catalytic conversion of citric acid, isocitric acid, isocitric lactone, aconitic acid or their anhydrides to citraconic anhydride by heating the starting materials in admixture with an inert gas at about 215.degree.-400.degree. C.
it is also known in the art that citraconic anhydride can be prepared by the pyrolysis of citric acid.