[21369-64-2] · C6H13Li · n-Hexyllithium · (MW 92.13)
(alkylating agent for various functional groups; metalating agent of aryl and heteroaryl ring systems; slightly less reactive than n-butyllithium)
Physical Data: viscous liquid in pure state; d (2.8 M hexane solution) 0.73 g cm-3 (20 °C).
Solubility: sol at all concentrations in aliphatic and aromatic hydrocarbons; reacts exothermically with water and protic solvents.
Form Supplied in: hexane or toluene solutions are available at concentrations from 2 to 3 M and are nonpyrophoric.
Analysis of Reagent Purity: titration of 0.5 N s-butanol in toluene (10 mL) with hexyllithium via tared syringe at 20 °C using 2,2´-biquinoline as an indicator.
Handling, Storage, and Precautions: should be handled as n-Butyllithium; store in a cool, dry place in a tightly sealed container under an inert atmosphere.
Hexyllithium adds to various carbonyl functionalities, which include both acyclic, i.e. acetophenone,1 and cyclic ketones,2 leading to dihydrojasmone3 and steroid derivatives.4 Carboxylic acid,5,6 lactone,7 bicyclic lactam,8 and ester9 substrates were also useful. Additions to Carbon Dioxide10 and Carbon Monoxide11 were reported. Other functionalities include activated epoxides12 and alkenes.13 Stereoselective addition to chiral N-metalloimines14 and oxazolines15 was achieved.
Unlike n-butyllithium, metalations with n-hexyllithium have not been cited in the literature, but will eventually appear because of its availability. It is already recognized as an alternative to n-butyllithium which generates hexane instead of butane and thus reduces environmental problems when used on an industrial scale. Compared to n-butyllithium, n-hexyllithium, as well as n-octyllithium and 2-ethylhexyllithium, are less reactive.16
Terry L. Rathman
FMC Corporation, Bessemer City, NC, USA