Search

The lithium enolate of p-phenylisobutyrophenone in tetrahydrofuran (THF) exists as tetramer contact ion pairs at higher concentrations although there is still a significant level of the monomeric form. Alkylation reaction studies using a variety of alkylating agents reveal that this reaction is first order based on the concentration of the monomer in THF. This suggests that the monomer is the reactive species in alkylation reactions.

The coupled equilibria and alkylation kinetics of the mixed aggregate produced by the lithium enolate (LiSIBP) of p-phenylsulfonylisobutyrophenone (SIBP) and lithium bromide in THF were investigated via experiments. The results, which were obtained via UV-vis spectroscopy, revealed that the ratio of (LiEn) to (Li2EnBr) is between 0.006 and 0.002 while the ratio of reaction proceeding through LiEn to Li2EnBr is between 5.5 and 1.9 when the amounts 0.04-0.22M(LiBr) and ca 0.002M(LiEn) were used.

A study was done on cesium enolate of 1-(4-biphenylyl)-2-methyl-1-propanone. The enolate was chosen because its spectrum allows the double-indicator technique. Results show that the free enolate ion is not the dominant reactive intermediate. It was also shown that the lithium cation diminishes the nucleophilicity of the carbon atom relative to the oxygen.