Isotope effects in the hydrogen abstraction from aliphatic compounds by radiolytically produced hydrogen atoms in aqueous solutions

The isotope effect on the abstraction of the α-hydrogen of 2-propanol by hydrogen atoms has been determined. An identical isotope effect k_Hα/k_Dα = 7.5 ± 1 was found both in neutral and acid solutions, indicating the identity of the "residual hydrogen" with hydrogen atoms. The reactivity of the α-hydrogen in 2-propanol toward hydrogen atoms was found to be 110 times higher than that of the β-hydrogens. The isotope effects on hydrogen abstraction by hydrogen atoms from formate, methanol, and acetate were determined and found to be 6.5 ± 0.5, 20 ± 1, and 22 ± 4, respectively. The high values for the H-D isotope effect were obtained for hydrogen abstraction reactions of a relatively low rate, where a tunneling effect may be involved.