Reactions of co-ordinated nitriles. Part II. Nickel(II)- and cobalt(II)-promoted hydrolysis of 2-cyano-8-hydroxyquinoline
- 1 January 1974
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 20,p. 2148-2152
- https://doi.org/10.1039/dt9740002148
Abstract
Base hydrolysis of 2-cyano-8-hydroxyquinoline to the corresponding carboxamide has been studied spectrophotometrically; kOH= 4·85 × 10–3 l mol–1 s–1 at 45 °C and I= 1·0M. The hydrolysis is strongly promoted by nickel(II), cobalt(II), and copper(II). Thus the 1 : 1 complex of nickel(II) and 2-cyano-8-hydroxyquinoline undergoes base hydrolysis 2 × 105 times faster than the uncomplexed substrate at 45 °C. Activation parameters for the uncatalysed base hydrolysis are ΔH‡= 13·4 ± 0·5 kcal mol–1 and ΔS‡=–27 cal K–1 mol–1; corresponding values for the metal-promoted reactions are ΔH‡= 14·2 ± 0·5 kcal mol–1, ΔS‡=–0·8 cal K–1 mol–1[nickel(II)] and ΔH‡= 14·3 ± 0·1 kcal mol–1, ΔS‡=–3 cal K–1 mol–1[cobalt(II)]. The substantial rate acceleration is due to an entropy effect alone and possible mechanisms for the reaction are considered.Keywords
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