34S isotope effect on sulfate ester hydrolysis: mechanistic implications.
In this communication, we report the first determination of 34S kinetic isotope effects (KIEs) for the hydrolysis of sulfate monoesters. The method involves the conversion of the inorganic sulfate, acquired at partial extent of reaction, to SO2, followed by isotope ratio determination by mass spectrometry. The KIEs determined for p-nitrophenyl sulfate and p-acetylphenyl sulfate are 1.0154 (+/-0.0002) and 1.0172 (+/-0.0003), respectively. These results, together with previous peripheral 18O KIE values, are inconsistent with an associative mechanism. The isotope effect method we report should also prove useful for studying the mechanism of other sulfuryl group transfers, including sulfatase and sulfotransferase reactions, as well as sulfate hydrolyses under other conditions.
Department of Chemistry, Indiana University, Bloomington, IN 47405, USA.
Benjamin T
BT
Burlingham
Lisa M
LM
Pratt
Ernest R
ER
Davidson
Vernon J
VJ
Shiner
Jon
J
Fong
Theodore S
TS
Widlanski
D006868:Hydrolysis; D007700:Kinetics; D013455:Sulfur / Q000737:chemistry*; D013460:Sulfur Isotopes; D013463:Sulfuric Acid Esters / Q000737:chemistry*
D013460:Sulfur Isotopes; D013463:Sulfuric Acid Esters; D013455:Sulfur