Transmission of polar effects. Part XI. Polar and steric effects in the reactions of arylaliphatic carboxylic acids

Abstract

The rate coefficients for the reaction with diazodiphenylmethane in ethanol at 30" and the acidcatalyzed esterification with methanol at 60' of a number of arylaliphatic carboxylic acids and their pK, values in 80% Zmethoxyethanol-water have been measured. Rate coefficients havealso been measured for the alkaline hydrolysis in 70% dioxan-water of their 2-diethylaminoethyl esters at 45". The pK, values and diazodiphenylmethane esterification rate coefficients were also measured for a series of 2-substituted fluorene-9-carboxylic acids. The latter results have been correlated by Hammett equations and the transmission of polar effects in fluorene is discussed. Polar and steric substituent constants are evaluated for the arylaliphatic systems. These values are used to successfully correlate the hydrolysis and ionization reactions using the Taft-Ingold equation.

The Fe(III) and Ga(III) coordination chemistry of 3-(1-hydroxymethylidene) and 3-(1-hydroxydecylidene)-5-(2-hydroxyethyl)pyrrolidine-2,4-dione: Novel tetramic acid degradation products of homoserine lactone bacterial quorum sensing molecules

“…For one, the addition of weakly electron-donating methylene groups serves to destabilize the anionic species and increase the pK a of 2 . A more significant contribution likely arises from the hydrophobic nature of 2 , which contributes to the increased pK a through the decreased solvation of the deprotonated species [43,44]. A final reasoning for this observation may be the result of aggregation and molecular association of the C12-TA in solution.…”