14605-20-0Relevant academic research and scientific papers
Base-catalysed hydrolysis of γ-lactones: Reactivity-structure correlations for 3-(aryl- and alkylmethylene)-(z)-1(3h)-isobenzofuranones
Bowden, Keith,Agnihotri, Kanwaljit,Ranson, Richard J.,Perjessy, Alexander,Hrnciar, Pavol,Prokes, Ivan,Fabian, Walter M. F.
, p. 841 - 848 (2007/10/03)
Rate coefficients were measured for the base-catalysed hydrolysis of a series of γ-lactones, i.e. 39 substituted 3-(aryl- and alkylmethylene)-(Z)-1(3H)-isobenzofuranones (3-aryl- and alkylmethylenephthalides) in 70% (v/v) aqueous dioxane at 30·0 °C. A Hammett reaction constant for the 3- or 4-substituted phenyl series is ca 1·5, whereas those for the 2-substituted phenyl and 4-substituted 1-naphthyl series, using para-σ values, are ca 1·0 and 1·9. These results are related to an electrostatic field effect model. A very successful correlation between the rates of alkaline hydrolysis of all 39 phthalides and the carbonyl stretching frequencies in chloroform was found. Substituent effects in widely different environments give linearly related effects on both reactivity and physical properties. Computational studies using the semi-empirical AM1 method correctly modelled both the details of the mechanistic pathway and the substituent effects.
Reactions of Carbonyl Compounds in Basic Solutions. Part 13. The Mechanism of the Alkaline Hydrolysis of 3-(3-Substituted Phenoxy)phthalides, -3-methylphthalides, -3-phenylphthalides, naphthalides, -3-phenylnaphthalides, and Phenanthralides, and of 3-Substituted 3-Methoxyphthalides
Anvia, Fredrick,Bowden, Keith,Kaissi, Faiq A. El,Saez, Victoria
, p. 1809 - 1814 (2007/10/02)
Rate coefficients have been measured for the alkaline hydrolysis of 3-(3-substituted phenoxy)phthalides, -3-methylphthalides, -3-phenylphthalides, naphthalides, -3-phenylnaphthalides, and phenanthralides at 30.0 and 50.0 deg C and for a series of methyl pseudo-2-acylbenzoates at several temperatures in 70percent (v/v) dioxane-water.The enthalpies and entropies of activation have been evaluated.The effects of substitution on the phenoxy esters have been assessed by means of the Hammett equation.The results for the methyl esters are related to the steric effect of substituentsusing the Taft equation.All the pseudo-esters are hydrolysed with rate-determining attack by hydroxide anion at the carbonyl group, followed by rapid ring fission to form the carboxylate anion of the corresponding acid as the product.Reactivity-selectivity is not shown over the whole range of the six series of the phenyl pseudo-esters.These results are discussed in terms of the structure of the transition state and the steric, stereochemical and polar factors influencing reactivity.
Reactions of Carbonyl Compounds in Basic Solutions. Part 12. The Mechanism of the Alkaline Hydrolysis of 3-Substituted Phenyl 2-Acetyl- and 2-Benzoylbenzoates
Anvia, Fredrick,Bowden, Keith
, p. 1805 - 1807 (2007/10/02)
Rate coefficients have been measured for the alkaline hydrolysis of 3-substituted phenyl 2-acetyl- and 2-benzoyl-benzoates in 70percent (v/v) dioxane-water at several temperatures.The enthalpies and entropies of activation have been evaluated.The effects of substitution have been assessed by means of the Hammett equation.Comparison of the reaction constants with those for model systems, as well as the relative rates and activation parameters, indicate that the rate-determining step for the 2-acetyl esters is attack by hydroxide anion at the keto-carbonyl group and for the2-benzoyl esters it is the intramolecular attack on the ester-carbonyl group, which follows equilibrium addition of the hydroxide anion at the keto-carbonyl group.
