enolate and base is present in excess at all times, the ketone is unable to act as a proton shuttle to catalyze the gradual formation of the thermodynamic product. A weaker base such as an alkoxide, which reversibly deprotonates the substrate, affords the more thermodynamically stable benzylic enolate. An alternative to the weaker base is to use a strong base which is present at a lower concentration than the ketone. For instance, with a slurry of sodium hydride in THF or dimethylformamide (DMF), the base only reacts at the solution-solid interface. A ketone molecule might be deprotonated at the kinetic site. This enolate may then encounter other ketones and the thermodynamic enolate will form through the exchange of protons, even in an aprotic solvent which does not contain hydronium ions. LDA can, however, act as a nucleophile under certain conditions. See also Lithium amide Lithium bis(trimethylsilyl)amide (LiHMDS) Lithium tetramethylpiperidide (LiTMP) References Lithium compounds Diisopropylamino compounds Organolithium compounds Metal amides Non-nucleophilic bases Reagents for organic chemistry Superbases