187. Primary and Secondary Isotope Effects on Proton Transfers to Diazocarbonyl Compounds

Article abstract of DOI:10.1002/hlca.19800630703

The primary solvent isotope effects on the AS_E-2 type hydrolyses of α-diazocarbonyl compounds p-XC6H4CN2CO2CH3 (X=NO2, H, OCH3 and C6H5CN2CON(CH3)2) are found to be identical despite large differences in their overall hydrolysis rates.The secondary solvent isotope effects diminish considerably with diminishing substrate reactivity, and for two substrates they are smaller than those normally anticipated for a simple proton transfer from the lyonium species.An analysis is presented of these and other abnormal secondary isotope effects found elsewhere, involving consideration of the solvation of the reaction complex.