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Vanadyl ions hydrolysis

Correlation of the observed rates with the concentrations of the substrate species (10) indicates that the metal ion does not catalyze the hydrolysis of the monoanionic form of salicyl phosphate. Combination of the monoanionic form of the substrate with the vanadyl ion would result in an unreactive complex having a neutral carboxyl group. Shift of the proton to the phosphate group could not take place in accordance with the requirements of the general reaction mechanism illustrated in Figure 3. Thus the vanadyl ion would be expected to catalyze the hydrolysis of only the di- and trinegative forms of the substrate. [Pg.174]

Wolterman, G.H., Scott, R.A. and Haight, G.P. (1974) Coupling of adenosine triphosphate hydrolysis to a simple inorganic redox system Vanadyl ion(2+) +hydrogen peroxide. Journal of the American Chemical Society 96, 7569-7570. [Pg.88]

The fact that divalent metal ions, the vanadyl ion, and their chelates, do not catalyze the hydrolysis forms [Ll and [IV] to an appreciable extent is in accord with the proposed mechanism, since coordination of the phosphate group by the metal ion would be prevented or greatly reduced by the presence of two protons. Accordingly metal ion catalysis by Cu and VO ions increases in effectiveness as the number of protons on the substrate is successively reduced. Such behavior would not be expected if transfer of a hydrogen-bonded proton from the carboxyl group to the phenolic ester oxygen were the only pathway for the reaction. Metal ion catalysis of the hydrolysis of [V], [VI],. and [VII] was not measured because of the formation of a solid phase in the presence of Cu and VO ions. [Pg.307]

Complexes of nickel(II), copper(II), cobalt(III), zinc(II), iron(II), palladium(II), plati-num(II) and vanadyl can be obtained. Although the reaction sequence is fairly general for metal ions, it is not easily extendable to substituted 2-aminobenzaldehydes. However, 2-amino-5-me-thylbenzaldehyde has recently been used successfully in the macrocyclization reaction. Although the macrocyclic complexes (67) are very stable to hydrolysis they are susceptible to attack by nucleophiles, as exemplified in equation (25). " The nickel(II) and copper(II) complexes (67) undergo hydrogenation at relatively low pressures. [Pg.173]

The 1 1 dipyridyl-Cu(II) chelate was found to have no catalytic activity toward the hydrolysis of [II] and [III], This result is interpreted as being due to the formation of a mixed ligand chelate compound in which the carboxylate group is bound to the metal ion and is thus prevented from attacking the phosphate group, A similar interpretation is offered for the failure of the 1 1 Cu( II)-N-hydroxyethylethylenediamine chelate to show catalytic activity. However, the 1 1 vanadyl complexes of 3,5-disulfopyrocatechol, 5-sulfo--8-hydroxyquinoline, and 5-sulfosalicylic acid which do not form stable mixed ligand chelates with salicyl phosphate, were found to have considerable catalytic activity. [Pg.307]


See other pages where Vanadyl ions hydrolysis is mentioned: [Pg.245]    [Pg.3313]    [Pg.245]    [Pg.3313]    [Pg.148]    [Pg.173]    [Pg.1103]    [Pg.33]    [Pg.171]    [Pg.1749]    [Pg.511]    [Pg.358]    [Pg.849]    [Pg.1118]    [Pg.259]    [Pg.165]    [Pg.523]    [Pg.379]    [Pg.123]    [Pg.259]    [Pg.1025]    [Pg.2362]    [Pg.6318]    [Pg.517]   
See also in sourсe #XX -- [ Pg.499 ]

See also in sourсe #XX -- [ Pg.3 , Pg.499 ]




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