Sec-Butyllithium

"sec"-Butyllithium is an organometallic compound with the formula CH3CHLiCH2CH3, abbreviated "sec"-BuLi or "s"-BuLi. This chiral organolithium reagent is used as a source of "sec"-butyl carbanion in organic synthesis.
Synthesis.
"sec"-BuLi can be prepared by the reaction of "sec"-butyl halides with lithium metal:
The carbon-lithium bond is highly polar, rendering the carbon basic, as in other organolithium reagents. "Sec"-butyllithium is more basic than the primary organolithium reagent, "n"-butyllithium. It is also more sterically hindered, though it is still useful for syntheses.
Applications.
"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 ether solutions of "n"-BuLi are stable. Many transformations involving "sec"-butyllithium are similar to those involving other organolithium reagents. For example, "sec"-BuLi react with carbonyl compounds and esters to form alcohols. With copper(I) iodide "sec"-BuLi forms lithium di-"sec"-butylcuprates. The first two reactions can also be accomplished by using "sec"-butylmagnesium bromide, a Grignard reagent; in fact, the latter is the typical reagent for this purpose.