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 $\alpha$ hydrogen of the radical and a methyl hydrogen of the molecule, and exchange II between a methyl hydrogen of the radical and the $\alpha$ 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.