Intramolecular General Base Catalysis in the Hydrolysis of a Phosphate Diester. Calculational Guidance to a Choice of Mechanism
作者:Anthony J. Kirby、Michelle Medeiros、José R. Mora、Pedro S. M. Oliveira、Almahdi Amer、Nicholas H. Williams、Faruk Nome
DOI:10.1021/jo302498g
日期:2013.2.15
assisted by intramolecularcatalysis by a (weakly basic) pyridine nitrogen acting as a general base. Catalysis is relatively efficient for this mechanism, with an estimated effective molarity (EM) of the general base of >15 M, consistent with the absence of catalysis by typical buffers. Further new results confirm that varying the nonleaving group has minimal effect on the rate of spontaneous diester hydrolysis
The spontaneous hydrolysis of 2-pyridyl phosphate is a good model for the special mechanism for the hydrolysis of phosphate monoester monoanions
作者:Michelle Medeiros、Alex M. Manfredi、Anthony J. Kirby、Faruk Nome
DOI:10.1002/poc.3165
日期:2013.12
The microscopic pKa of the pyridine N of the phosphate monoester 2‐pyridyl phosphate (MPP) is 2.76, significantly higher than that expected for the leaving group (RO) oxygen of a typical monoester ROPO3=. This favours the prototropic equilibrium considered to be the key step in the rapid hydrolysis of a typical monoester, and the observed rate of hydrolysis of the monoanion MPP− is shown to be close