58502-59-3Relevant academic research and scientific papers
Reactions of carbonyl compounds in basic solutions. Part 24. 1 The mechanism of the base-catalysed ring fission of substituted benzocyclobutene-1,2-diones
Bowden, Keith,Horri, M. Vahid
, p. 989 - 992 (2007/10/03)
The rate coefficients for the base-catalysed ring fission of a series of substituted benzocyclobutenediones to give the corresponding 2-formylbenzoic acids have been determined in water at 25.0 and 60.0°C. The effects of 4-substituents and 4,5-di-substituents on the rates have been correlated using a modified Hammett equation to give a reaction constant, ρ, equal to ca. 3.6 at 25.0°C. The activation parameters have been calculated. The effect of solvent composition on the rates has been studied. The kinetic solvent isotope effect, product composition and enrichment in 18O-enriched water have also been studied. All the evidence indicates a mechanistic pathway which proceeds by rapid reversible addition of hydroxide anion to the dione, followed by intramolecular nucleophilic attack on the second carbonyl group and formation of a carbanionic intermediate.
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.
