skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Solvent isotope effect on the rate of methoxyl exchange between methyl borate and methanol

Journal Article · · J. Am. Chem. Soc.; (United States)
DOI:https://doi.org/10.1021/ja00490a021· OSTI ID:6374608

NMR studies of methyl borate in methanol solution indicate fast methoxyl exchange with a large deuterium solvent isotope effect: k/sub CH/sub 3/OH//k/sub CH/sub 3/OD/ = 11.0 at 25/sup 0/C. The temperature dependence of the first-order rate constants (s/sup -1/) is given by k/sub CH/sub 3/OH/ = 5.7 x 10/sup 3/ e/sup -2360/RT/ and k/sub CH/sub 3/OD/ = 9.1 x 10/sup 3/ e/sup -4060/RT/. These constants refer to a pH-independent phase of the exchange. Catalysis by lyonium and lyate ions occurs with approximate rate constants (M/sup -1/ s/sup -1/) k/sub CH/sub 3/OH/sub 2//sup +// = 1.4 x 10/sup 5/, k/sub CH/sub 3/OD/sub 2//sup +// = 1.0 x 10/sup 5/, and k/sub CH/sub 3/O/sup -// = 7 x 10/sup 10/. 4 figs.

Research Organization:
Univ. of Virginia, Charlottesville
OSTI ID:
6374608
Journal Information:
J. Am. Chem. Soc.; (United States), Vol. 100:22
Country of Publication:
United States
Language:
English