H/D Kinetic Isotope Effect as a Tool to Elucidate the Reaction Mechanism of Methyl Radicals with Glycine in Aqueous Solutions

Abstract

The H/D kinetic isotope effect (KIE) for the reaction of methyl radicals with glycine in aqueous solutions at pH 10.6 equals 16 ± 3. This result proves that the methyl radical abstracts a hydrogen atom from the methylene group of glycine and not an electron from the unpaired couple on the nitrogen atom. The rate constant of the reaction of methyl radicals with glycine at pH 7.0 is orders of magnitude smaller than that at pH 10.6.

Study of H/D exchange rates to derive the strength of intramolecular hydrogen bonds in halo substituted organic building blocks: An NMR spectroscopic investigation

“…There are number of chemical reactions in which the transfer of one or more protons (viz., hydride ions or hydrogen atoms) takes place in the rate determining step. [30][31][32][33][34] The reaction kinetics depend on several factors, which also include the strength of intramolecular hydrogen bond and the electronic effects caused by the substituents that can be monitored by hydrogen/deuterium (H/D) exchange, a technique which is widely employed for understanding the protein conformation, and dynamics [35][36][37][38][39][40][41] in aqueous media. The inter-and the intramolecular hydrogen bonds can affects the rate of H/D exchange in a particular molecule.…”