Triplet state of orotic acid and orotic acid methyl ester in solution

Flash photolysis of orotic acid and orotic acid methyl ester in aqueous solution was studied. The transients were identified as triplet excited states on the basis of their lifetimes, sensitization, quenching, and self-quenching experiments. The rate constants for self-quenching and for decay of the triplet were measured and discussed in terms of dimerization and competing unimolecular and pseudo-unimolecular processes. A triplet energy of 60 kcal mole−1 was deduced for both orotic acid and orotic acid methyl ester from triplet energy transfer measurements.