ION PAIRING AND REACTIVITY OF ENOLATE ANIONS. 6. KINETICS AND THERMODYNAMICS FOR REACTION OF ALKALI ACETOACETONATES WITH ALKYL HALIDES IN DIMETHYL SULFOXIDE

Article abstract of DOI:10.1021/ja00293a045

Rates and heats of reaction are reported for the C-alkylation of alkali salts of various symmetrical β-diketones with methyl and ethyl iodide in dimethyl sulfoxide (Me2SO).Product analysis by FT-NMR established that the reactions were clean over the concentration range of the kinetic and thermodinamical study and, with only one exception, gave 100 percent carbon alkylation within the limits of detection.The effects of ion pairing, temperature, and alkylating agent were probed to yield an extensive comparison of the effects of structural change on the kinetics of alkylation with methyl or ethyl iodide.The formation of 3-methyl-3-ethylacetylacetonate by alternative routes (methylation of potassium 3-ethylacetoacetonate and ethylation of potassium 3-methylacetylacetone allows an unprecedented comparison of the energetics of each step along the reaction profile from isomeric reactants in the gas phase, through isomeric transition states, to a common product in Me2SO solution.