The anomalous hydrolytic behavior of 1-phenylvinyl phosphate

The kinetics of hydrolysis of 1-phenylvinyl phosphate, 1, were studied over a pH range of 1 to 8.3 and over a pD range of 1 to 5.6 at 25 degrees C and mu = 0.5 M with sodium chloride. The hydrolytic behavior of 1 was found to differ, in many respects, from that of alkyl and aryl phosphomonoesters. F...

Full description

Saved in:
Bibliographic Details
Published in:Pharmaceutical research 1992-03, Vol.9 (3), p.378-384
Main Authors: KEARNEY, A. S, STELLA, V. J
Format: Article
Language:English
Subjects:
Algorithms
Biological and medical sciences
Chromatography, High Pressure Liquid
General pharmacology
Hydrogen-Ion Concentration
Hydrolysis
Magnetic Resonance Spectroscopy
Medical sciences
Organophosphorus Compounds - analysis
Organophosphorus Compounds - chemistry
Pharmacology. Drug treatments
Physicochemical properties. Structure-activity relationships
Vinyl Compounds - analysis
Vinyl Compounds - chemistry
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The kinetics of hydrolysis of 1-phenylvinyl phosphate, 1, were studied over a pH range of 1 to 8.3 and over a pD range of 1 to 5.6 at 25 degrees C and mu = 0.5 M with sodium chloride. The hydrolytic behavior of 1 was found to differ, in many respects, from that of alkyl and aryl phosphomonoesters. First, the rates of hydrolysis of 1 were extremely rapid and, in the hydronium ion-catalyzed region, gave a solvent deuterium isotope effect (kH/kD) of 3.20. Also, the 1H-NMR spectrum of acetophenone formed upon complete hydrolysis of 1 in D2O (pD 1.2) revealed that only one deuterium atom was incorporated into the methyl group. Hence, the evidence was consistent with a rate-limiting and nonreversible proton transfer from the solvent to 1. In addition, using an H2 18O labeling study in conjunction with 31P-NMR analysis, the hydrolytic mechanism appeared to involve nucleophilic attack by water at both the alpha-carbon and the phosphorus atom with concurrent C-O and P-O bond fission. Second, in the pH region where the monoanionic species of 1 predominated, buffers had a pronounced catalytic effect on the hydrolysis rate; there appeared to be a normal solvent deuterium isotope effect; and the rate constant, k' o, showed a positive deviation from the established Brønsted relationship. The dissimilarities between 1 and alkyl and aryl phosphomonoesters supported the involvement of an alternate dephosphorylation pathway.
ISSN:0724-8741
1573-904X
DOI:10.1023/A:1015899120700