Kinetic and mechanistic studies of the reaction of a range of bases and metal-hydroxo complexes with the phosphonate ester 2,4-dinitrophenyl ethyl methylphosphonate in aqueous solution

The base hydrolysis and spontaneous water hydrolysis of the phosphonate ester 2,4-dinitrophenyl ethyl methylphosphonate (DNPEMP) has been studied in detail and the activation parameters for these processes determined. The catalytic effect of a series of 19 oxygen and nitrogen bases and metal hydroxo...

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Bibliographic Details
Published in:Transition metal chemistry (Weinheim) 1998-04, Vol.23 (2), p.133
Main Authors: Hay, Robert W, Govan, Norman, Norman, Paul R
Format: Article
Language:English
Subjects:
Aqueous solutions
Catalysis
Online Access:Get full text
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Summary:The base hydrolysis and spontaneous water hydrolysis of the phosphonate ester 2,4-dinitrophenyl ethyl methylphosphonate (DNPEMP) has been studied in detail and the activation parameters for these processes determined. The catalytic effect of a series of 19 oxygen and nitrogen bases and metal hydroxo complexes has been studied. The Brønsted plot of pK versus logkN has a slope (β) of 0.47, which is fairly typical for phosphate and phosphonate esters. alpha-Effect nucleophiles such as 2-iodosobenzoate, hypochlorite and the hydroperoxide ion (HO-2) exhibit enhanced reactivity, as does fluoride ion and the bifunctional metal complex [Cu(tmen) (OH2)(OH)]+ (tmen = N,N,N',N',-tetramethylethylenediamine). Reactions involving these species appear to take place by a nucleophilic pathway, while the other oxygen and nitrogen bases act as general base catalysts. The solvent deuterium isotope effect for Et3N catalysis, kH2O/kD2O=1.3, is consistent with general base catalysis. The mechanisms of these reactions are discussed in detail.[PUBLICATION ABSTRACT]
ISSN:0340-4285
1572-901X
DOI:10.1023/A:1006938908480