sec-Butyllithium

sec-Butyllithium

Names
IUPAC name sec-Butyllithium
Systematic IUPAC name Butan-2-yllithium
Identifiers
CAS Number	598-30-1
3D model (Jmol)	Interactive image Interactive image
Beilstein Reference	3587206
ChemSpider	10254345
ECHA InfoCard	100.009.026
EC Number	209-927-7
PubChem	102446
InChI InChI=1S/C4H9.Li/c1-3-4-2;/h3H,4H2,1-2H3; Key: VATDYQWILMGLEW-UHFFFAOYSA-N InChI=1/C4H9.Li/c1-3-4-2;/h3H,4H2,1-2H3;/rC4H9Li/c1-3-4(2)5/h4H,3H2,1-2H3 Key: VATDYQWILMGLEW-MHILWDCKAX
SMILES [Li]C(C)CC CC([Li])CC
Properties
Chemical formula	C4H9Li
Molar mass	64.06 g·mol^−1
Acidity (pKa)	51
Hazards
Safety data sheet	Fisher MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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.^[1]

sec-BuLi can be prepared by the reaction of sec-butyl halides with lithium metal:^[2]

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.

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.^[1] 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.

References

1. Ovaska, T. V. "s-Butyllithium" in Encyclopedia of Reagents for Organic Synthesis, 2001 John Wiley & Sons: New York. doi:10.1002/047084289X.rb397.
2. Hay, D. R.; Song, Z.; Smith, S. G.; Beak, P. (1988). "Complex-induced proximity effects and dipole-stabilized carbanions: kinetic evidence for the role of complexes in the α-lithiations of carboxamides". J. Am. Chem. Soc. 110 (24): 8145–8153. doi:10.1021/ja00232a029.