- Sec-Butyllithium
"sec"-Butyllithium is the
chemical compound with the formula CH3CHLiCH2CH3, abbreviated "sec"-BuLi or "s"-BuLi Thisorganolithium reagent is used as a source of "sec"-butylcarbanion inorganic synthesis .Ovaska, T. V. "s-Butyllithium" in Encyclopedia of Reagents for Organic Synthesis, 2001 John Wiley & Sons: New York. doi|10.1002/047084289X.rb397]Sec-BuLi can be prepared by the reaction of "sec"-butyl
halides with lithium metal: [cite journal | author = Hay, D. R.; Song, Z.; Smith, S. G.; Beak, P. | title = Complex-induced proximity effects and dipole-stabilized carbanions: kinetic evidence for the role of complexes in the α-lithiations of carboxamides | journal =J. Am. Chem. Soc. | year = 1988 | volume = 110 | pages = 8145–8153 | doi = 10.1021/ja00232a029] :CH3CHClCH2CH3 + 2 Li → CH3CHLiCH2CH3 + LiClThe carbon-lithium bond is highly polar, rendering the carbon verynucleophilic and basic, as in otherorganolithium reagents. "Sec"-butyllithium is more basic than primaryorganolithium reagents such asn-butyl lithium . It is also more sterically hindered, though it is still useful for syntheses."sec"-BuLi is employed for deprotonations of particularly weak carbon acids where the more conventional reagent "n"-BuLi is unsatisfactory. It is, however, so basic that its use requires greater care than for "n"-BuLi. For example
diethyl ether is attacked by "sec"-BuLi at room temperature in minutes, whereas its solutions of "n"-BuLi are stable. Many transformatins involving "sec"-butyllithium are similar to those involving other organolithium reagents. For example, "sec"-BuLi react with carbonyl compounds andester s to formalcohol s. Withcopper(I) iodide "sec"-BuLi forms lithium di-"sec"-butylcuprates. The first two reactions can also be accomplished by using "sec"-butylmagnesium bromide, aGrignard reagent ; in fact, the latter is the typical reagent for this purpose.References
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