Kinetics of ionisation of carbon acids in non-aqueous media: detritiation of diethyl malonate by heterocyclic bases

Article abstract of DOI:10.1139/v86-207

To investigate proton transfer processes in non-aqueous media, two procedures have been developed of general applicability for the measurement of detritiation rates of carbon acids.One method is a variation of an existing solvent extraction procedure but with inclusion of a trace of trifluoroacetic acid, while the other involves the simple modification of a gas chromatograph so as to function as a radio-gas chromatograph.They have been established by studying the detritiation of <2-(3)H1>diethyl malonate in six different solvents (dimethylformamide, dimethyl sulfoxide, sulfolane, hexamethylphosphortriamide, tetrahydrofuran, ethanol) as catalyzed by various heterocyclic bases (substituted pyridines, imidazoles, benzimidazoles, pyrrole, pyrazole, purine, adenosine).The results are discussed in terms of solvation effects and catalyst structure.An approximate Broensted correlation is found to exist between log k^T_B for detritiation determined in DMSO and the pK_a of the conjugate base measured in water at 25 deg C.