The triplet energies of butenedioic acid derivatives

Abstract The oxygen perturbation spectra of butenedioic acid derivatives were measured and the vertical triplet energies were determined to be 62 kcal mol −1 for fumaronitrile, about 66 kcal mol −1 for dimethyl fumarate, 71 kcal mol −1 or more for dimethyl and 72 kcal mol −1 for maleic anhydride.