19136-92-6Relevant articles and documents
Parallel Behavior in Kinetic and NMR Effects: Secondary Deuterium Isotope Effects on the Alkaline Hydrolysis of Esters
Matta, Michael S.,Broadway, Dale E.,Stroot, Michele K.
, p. 4916 - 4918 (2007/10/02)
β-Deuterium secondary kinetic isotope effects (β-D KIEs) on the alkaline hydrolysis of the p-nitrophenyl esters of acetic, propanoic, butanoic, and pentanoic acids in pH 10.70, 0.20 M carbonate buffer at 25 deg C tend to increase with increasing chain length of the esters up to the pentanoate.The β-D KIEs are respectively 0.975 +/- 0.004, 0.960 +/- 0.002, 0.940 +/- 0.001, and 0.948 +/- 0.004.The activation energies of the esterolyses of the isotopically light esters follow a similar pattern, as do the 13C NMR nuclear shieldings in CDCl3 of the isotopically light parent carboxylic acids (20.9, 27.4, 35.9, and 33.8 (ppm)) and 13C NMR one-bond isotope shifts produced by disubstitution of deuterium for hydrogen at the α-carbons of the acids (0.45, 0.55, 0.60, and 0.59 (ppm)).Correlation of nuclear shieldings and isotope shifts is known from previous work.The possibility is considered that all of the kinetics-based and NMR relationships are linked through the operation of a common ground-state feature of the ester and acid alkyl chains.
