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Kinetics of the solvolysis of chloropentacyanocobaltate (III) ions in mixtures of ethane‐1,2‐diol or ethanonitrile with water
Author(s) -
Halawani Kamal H.,
Wells Cecil F.
Publication year - 1992
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550241203
Subject(s) - solvolysis , chemistry , solvation , enthalpy , reaction rate constant , solvent , entropy of activation , kinetics , thermodynamics , inorganic chemistry , organic chemistry , hydrolysis , physics , quantum mechanics
Abstract The kinetics of the solvolysis of [Co(CN) 5 Cl] 3− ions have been investigated in mixtures formed by the addition of ethane‐1,2‐diol or ethanonitrile to water where the physical properties indicate little enhancement of structure in water‐rich conditions. The effect on the kinetics of this solvolysis of this lack of structural change in the solvent shows in the linearity of the variation of log (rate constant) with the reciprocal of the dielectric constant for the addition of ethane‐1,2‐diol to water and the absence of any prominent extrema in the enthalpy or entropy of activation using either co‐solvent. However, the effect of changes in solvation on the solvolysis with these two co‐solvents appears to operate in a similar manner to the effects found when the hydrophobic co‐solvent propan‐2‐ol is added to water. The application of a free energy cycle to the process of the initial state going to the transition state for this dissociative process suggests that, with both co‐solvents, [Co(CN) 5 ] 2− in the transition state is more stable than [Co(CN) 5 Cl] 3− in the initial state. © John Wiley & Sons, Inc.