tert-Butyllithium is achemical compound with theformula (CH3)3CLi. As anorganolithium compound, it has applications inorganic synthesis since it is a strongbase, capable ofdeprotonating many carbon molecules, includingbenzene.tert-Butyllithium is available commercially as solutions in hydrocarbons (such as pentane); it is not usually prepared in the laboratory.
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| Names | |
|---|---|
| Preferred IUPAC name tert-Butyllithium[citation needed] | |
| Identifiers | |
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3D model (JSmol) | |
| 3587204 | |
| ChemSpider |
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| ECHA InfoCard | 100.008.939 |
| EC Number |
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| UN number | 3394 |
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| Properties | |
| LiC 4H 9 | |
| Molar mass | 64.055 g mol−1 |
| Appearance | Colorless solid |
| Density | 660 mg cm−3 |
| Boiling point | 36 to 40 °C (97 to 104 °F; 309 to 313 K) |
| Reacts | |
| Acidity (pKa) | 45–53 |
| Hazards | |
| GHS labelling: | |
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| Danger | |
| H225,H250,H260,H300,H304,H310,H314,H330,H336,H411 | |
| P210,P222,P223,P231+P232,P370+P378,P422 | |
| NFPA 704 (fire diamond) | |
| Flash point | −6.6 °C (20.1 °F; 266.5 K) |
| Related compounds | |
Related compounds | n-Butyllithium |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Preparation
edittert-Butyllithium is produced commercially by treatingtert-butyl chloride withlithium metal. Its synthesis was first reported byR. B. Woodward in 1941.[1]
Structure and bonding
editLike other organolithium compounds,tert-butyllithium is acluster compound. Whereasn-butyllithium exists both as a hexamer and a tetramer,tert-butyllithium exists exclusively as a tetramer with acubane structure. Bonding in organolithium clusters involvessigma delocalization and significant Li−Li bonding.[2] Despite its complicated structure,tert-butyllithium is usually depicted in equations as a monomer.
The lithium–carbon bond intert-butyllithium is highly polarized, having about 40 percentionic character. The molecule reacts like acarbanion, as is represented by these tworesonance structures:[3]
Reactions
edittert-Butyllithium is renowned for deprotonation of carbon acids (C-H bonds). One example is the double deprotonation ofallyl alcohol.[4] Other examples are the deprotonation ofvinyl ethers.[5][6][7]
In combination withn-butyllithiium,tert-butylllithium monolithiatesferrocene.[8]tert-Butyllithium deprotonatesdichloromethane:[9]
- H2CCl2 + RLi → HCCl2Li + RH
Similar ton-butyllithium,tert-butyllithium can be used forlithium–halogen exchange reactions.[10][11]
Solvent compatibility
editTo minimize degradation by solvents, reactions involvingtert-butyllithium are often conducted at very low temperatures in special solvents, such as theTrapp solvent mixture.
More so than other alkyllithium compounds,tert-butyllithium reacts withethers.[2] Indiethyl ether, thehalf-life oftert-butyllithium is about 60 minutes at 0 °C. It is even more reactive towardtetrahydrofuran (THF); the half-life in THF solutions is about 40 minutes at −20 °C.[12] Indimethoxyethane, the half-life is about 11 minutes at −70 °C[13]
In this example, the reaction oftert-butyllithium with (THF) is shown:
Safety
edittert-butyllithium is apyrophoric substance, meaning that it spontaneously ignites on exposure to air.Air-free techniques are important so as to prevent this compound from reacting violently with oxygen and moisture:
- t-BuLi + O2 →t-BuOOLi
- t-BuLi + H2O →t-BuH + LiOH
The solvents used in common commercial preparations are themselves flammable. While it is possible to work with this compound usingcannula transfer, traces oftert-butyllithium at the tip of the needle or cannula may ignite and clog the cannula with lithium salts. While some researchers take this "pilot light" effect as a sign that the product is "fresh" and has not degraded due to time or improper storage/handling, others prefer to enclose the needle tip or cannula in a short glass tube, which is flushed with an inert gas and sealed at each end with septa.[14] Serious laboratory accidents involvingtert-butyllithium have occurred. For example, in 2008 a staff research assistant,Sheharbano Sangji, in the lab ofPatrick Harran[15] at theUniversity of California, Los Angeles, died after being severely burned by a fire ignited bytert-butyllithium.[16][17][18]
Large-scale reactions may lead to runaway reactions, fires, and explosions whentert-butyllithium is mixed with ethers such as diethyl ether, and tetrahydrofuran. The use of hydrocarbon solvents may be preferred.
See also
editReferences
edit- ^Bartlett, Paul D.; C. Gardner Swain; Robert B. Woodward (1941). "t-Butyllithium".J. Am. Chem. Soc.63 (11):3229–3230.Bibcode:1941JAChS..63.3229B.doi:10.1021/ja01856a501.
- ^abElschenbroich, C. (2006).Organometallics. Weinheim: Wiley-VCH.ISBN 978-3-527-29390-2.
- ^K. P. C. Vollhardt, N. E. Schore (1999). "Organometallic reagents: sources of nucleophilic carbon for alcohol synthesis".Organic Chemistry : Structure And Function, 3rd edition.
- ^Danheiser, Rick L.; Fink, David M.; Okano, Kazuo; Tsai, Yeun-Min; Szczepanski, Steven W. (1988)."(1-Oxo-2-Propenyl)Trimethylsilane".Organic Syntheses.66: 14.doi:10.15227/orgsyn.066.0014.ISSN 2333-3553.
- ^Soderquist, John A. (1990)."Acetyltrimethylsilane".Organic Syntheses.68: 25.doi:10.15227/orgsyn.068.0025.ISSN 2333-3553.
- ^Tschantz, M. A.; Burgess, L. E.; Meyers, A. I. (1996)."4-Ketoundecanoic Acid".Organic Syntheses.73: 215.doi:10.15227/orgsyn.073.0215.ISSN 2333-3553.
- ^Jarowicki, Krzysztof; Kocienski, Philip J.; Qun, Liu (2002)."1,2-Metallate Rearrangement: (Z)-4-(2-Propenyl)-3-Octen-1-Ol".Organic Syntheses.79: 11.doi:10.15227/orgsyn.079.0011.ISSN 2333-3553.
- ^Busacca, Carl A.; Eriksson, Magnus C.; Haddad, Nizar; Han, Z. Steve; Lorenz, Jon C.; Qu, Bo; Zeng, Xingzhong; Senanayake, Chris H. (2013)."Practical Synthesis of Di-tert-Butylphosphinoferrocene".Organic Syntheses.90: 316.doi:10.15227/orgsyn.090.0316.ISSN 2333-3553.
- ^Matteson, Donald S.; Majumdar, Debesh (1983). "Homologation of Boronic Esters to α-Chloro Boronic Esters".Organometallics.2 (11):1529–1535.doi:10.1021/om50005a008.
- ^Smith, Adam P.; Savage, Scott A.; Love, J. Christopher; Fraser, Cassandra L. (2002)."Synthesis of 4-, 5-, and 6-Methyl-2,2'-bipyridine by a Negishi Cross-Coupling Strategy: 5-Methyl-2,2'-bipyridine".Organic Syntheses.78: 51.doi:10.15227/orgsyn.078.0051.ISSN 2333-3553.
- ^Amat, Mercedes; Hadida, Sabine; Sathyanarayana, Swargam; Bosch, Joan (1997)."Regioselective Synthesis of 3-Substituted Indoles: 3-Ethylindole".Organic Syntheses.74: 248.doi:10.15227/orgsyn.074.0248.ISSN 2333-3553.
- ^Stanetty, P; Koller, H.; Mihovilovic, M. (1992). "Directed ortho Lithiation of Phenylcarbamic acid 1,1-Dimethylethyl Ester (N-BOC-aniline). Revision and Improvements".Journal of Organic Chemistry.57 (25):6833–6837.doi:10.1021/jo00051a030.
- ^Fitt, J. J.; Gschwend, H. E. (1984). "Reaction of n-, sec-, and tert-butyllithium with dimethoxyethane (DME): a correction".Journal of Organic Chemistry.49:209–210.doi:10.1021/jo00175a056.
- ^Errington, R. M. (1997).Advanced practical inorganic and metalorganic chemistry(Google Books excerpt). London: Blackie Academic & Professional. pp. 47–48.ISBN 978-0-7514-0225-4.
- ^"Harran Lab: UCLA". Archived fromthe original on 2012-10-13. Retrieved2011-09-21.
- ^Jyllian Kemsley (2009-01-22)."Researcher Dies After Lab Fire".Chemical & Engineering News.
- ^Jyllian Kemsley (2009-04-03)."Learning From UCLA: Details of the experiment that led to a researcher's death prompt evaluations of academic safety practices".Chemical & Engineering News.
- ^Los Angeles Times, 2009-03-01