ESR Study of an Irradiated Crystal of l-Alanine: Two New Proton–Deuteron Exchange Reactions

Two new proton–deuteron exchange reactions in an irradiated crystal of alanine were discovered with the use of α-deutero-l-alanine. It was shown that both exchanges took place between the radical and its adjacent molecule (or molecules): Exchange I took place between the α hydrogen of the radical and a methyl hydrogen of the molecule, and exchange II between a methyl hydrogen of the radical and the α hydrogen of the molecule. Both exchange rates were much higher than the rate of the previously reported one for irradiated alanine (exchange III). Activation energies for exchange I and exchange II were found to be 17.0 ± 1.0 kcal/mole and 21.0 ± 1.5 kcal/mole, respectively.