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Catalytic effect of MO4 2- (M=Cr, Mo and W) on hydrolyses of carbon and phosphorus esters

Title
Catalytic effect of MO4 2- (M=Cr, Mo and W) on hydrolyses of carbon and phosphorus esters
Authors
Ahn B.-T.Park H.-S.Lee E.-J.Um I.-H.
Ewha Authors
안병태엄익환
SCOPUS Author ID
안병태scopusscopus; 엄익환scopusscopus
Issue Date
2000
Journal Title
Bulletin of the Korean Chemical Society
ISSN
0253-2964JCR Link
Citation
Bulletin of the Korean Chemical Society vol. 21, no. 9, pp. 905 - 908
Indexed
SCI; SCIE; SCOPUS; KCI WOS scopus
Document Type
Article
Abstract
Second-order rate constants have been measured spectrophotometrically for the hydrolysis of p-nitrophenyl acetate (PNPA) and p-nitrophenyl diphenylphosphinate (PNPDPP) with MO4 2- (M = Cr, Mo and W) in phosphate buffer (pH = 8.00) at 35.0 °C. These MO4 2- species exhibit large catalytic effect in the hydrolysis of PNPA and PNPDPP except WO4 2- in the reaction with PNPA. The catalytic effect of these MO4 2- species has been observed to be much more significant in the hydrolysis of PNPDPP than in the hydrolysis of PNPA. Since the smallest CrO4 2- would be most highly solvated by H2O molecules, CrO4 2- is expected to exhibit the least catalytic effect, if solvation effect is the most important factor. However, in fact, CrO4 2- shows the highest catalytic effect toward PNPA, indicating that solvation effect is not solely responsible for the catalytic effect. The most basic CrO4 2- shows the highest catalytic effect, while the least basic WO4 2- is least reactive toward PNPA, indicating that the basicity of MO4 2- might be an important factor. However, in the hydrolysis of PNPDPP, no correlation is observed between the basicity and catalytic effect, suggesting that basicity alone can not be responsible for the catalytic effect shown by the MO4 2- species. Formation of a chelate is suggested to be responsible for the high catalytic effect of MO4 2- in the hydrolysis reaction of PNPA and PNPDPP. The formation of chelate is considered to be more suitable for the reaction with PNPDPP than with PNPA based on the larger catalytic effect observed in the reaction with PNPDPP than with PNPA.
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자연과학대학 > 화학·나노과학전공 > Journal papers
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