Equilibrium Constants and Alkylation Kinetics of Two Lithium Enolates/LiHMDS Mixed Aggregates in THF

Mixed aggregates between lithium enolates and lithium hexamethyldisilazide (LiHMDS) have been studied in THF using UV−vis spectroscopy. The equilibrium constants (K agg) between monomeric LiEn and monomeric LiHMDS are 760 and 560 M-1 when LiEn are LiSIBP and LiBnPAT, respectively. The alkylation kinetics of the reactions with benzyl bromide were studied at 25 °C. The rate constants for the mixed aggregates, k Mixed, are substantially smaller than those of the monomeric enolates.