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Preparation

tert-Butyllithium is produced commercially by treating tert-butyl chloride with lithium metal. Its synthesis was first reported by R. B. Woodward in 1941.¹

Structure and bonding

Like other organolithium compounds, tert-butyllithium is a cluster compound. Whereas n-butyllithium exists both as a hexamer and a tetramer, tert-butyllithium exists exclusively as a tetramer with a cubane structure. Bonding in organolithium clusters involves sigma 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 in tert-butyllithium is highly polarized, having about 40 percent ionic character. The molecule reacts like a carbanion, as is represented by these two resonance structures:³

Reactions

tert-Butyllithium is renowned for deprotonation of carbon acids (C-H bonds). One example is the double deprotonation of allyl alcohol.⁴ Other examples are the deprotonation of vinyl ethers.⁵⁶⁷

In combination with n-butyllithiium, tert-butylllithium monolithiates ferrocene.⁸ tert-Butyllithium deprotonates dichloromethane:⁹

Similar to n-butyllithium, tert-butyllithium can be used for lithium–halogen exchange reactions.¹⁰¹¹

Solvent compatibility

To minimize degradation by solvents, reactions involving tert-butyllithium are often conducted at very low temperatures in special solvents, such as the Trapp solvent mixture.

More so than other alkyllithium compounds, tert-butyllithium reacts with ethers.¹² In diethyl ether, the half-life of tert-butyllithium is about 60 minutes at 0 °C. It is even more reactive toward tetrahydrofuran (THF); the half-life in THF solutions is about 40 minutes at −20 °C.¹³ In dimethoxyethane, the half-life is about 11 minutes at −70 °C¹⁴

In this example, the reaction of tert-butyllithium with (THF) is shown:

Safety

tert-butyllithium is a pyrophoric 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:

The solvents used in common commercial preparations are themselves flammable. While it is possible to work with this compound using cannula transfer, traces of tert-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.¹⁵ Serious laboratory accidents involving tert-butyllithium have occurred. For example, in 2008 a staff research assistant, Sheharbano Sangji, in the lab of Patrick Harran¹⁶ at the University of California, Los Angeles, died after being severely burned by a fire ignited by tert-butyllithium.¹⁷¹⁸¹⁹

Large-scale reactions may lead to runaway reactions, fires, and explosions when tert-butyllithium is mixed with ethers such as diethyl ether, and tetrahydrofuran. The use of hydrocarbon solvents may be preferred.

See also

• Sheri Sangji case

References

1. 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. /wiki/Bibcode_(identifier) ↩

2. Elschenbroich, C. (2006). Organometallics. Weinheim: Wiley-VCH. ISBN 978-3-527-29390-2. 978-3-527-29390-2 ↩

3. K. P. C. Vollhardt, N. E. Schore (1999). "Organometallic reagents: sources of nucleophilic carbon for alcohol synthesis". Organic Chemistry : Structure And Function, 3rd edition. ↩

4. 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. https://doi.org/10.15227%2Forgsyn.066.0014 ↩

5. Soderquist, John A. (1990). "Acetyltrimethylsilane". Organic Syntheses. 68: 25. doi:10.15227/orgsyn.068.0025. ISSN 2333-3553. https://doi.org/10.15227%2Forgsyn.068.0025 ↩

6. 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. https://doi.org/10.15227%2Forgsyn.073.0215 ↩

7. 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. https://doi.org/10.15227%2Forgsyn.079.0011 ↩

8. 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. https://doi.org/10.15227%2Forgsyn.090.0316 ↩

9. Matteson, Donald S.; Majumdar, Debesh (1983). "Homologation of Boronic Esters to α-Chloro Boronic Esters". Organometallics. 2 (11): 1529–1535. doi:10.1021/om50005a008. /wiki/Doi_(identifier) ↩

10. 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. https://doi.org/10.15227%2Forgsyn.078.0051 ↩

11. 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. https://doi.org/10.15227%2Forgsyn.074.0248 ↩

12. Elschenbroich, C. (2006). Organometallics. Weinheim: Wiley-VCH. ISBN 978-3-527-29390-2. 978-3-527-29390-2 ↩

13. 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. /wiki/Doi_(identifier) ↩

14. 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. /wiki/Journal_of_Organic_Chemistry ↩

15. 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. 978-0-7514-0225-4 ↩

16. "Harran Lab: UCLA". Archived from the original on 2012-10-13. Retrieved 2011-09-21. https://web.archive.org/web/20121013013907/http://faculty.chemistry.ucla.edu/institution/personnel?personnel%5Fid=552980 ↩

17. Jyllian Kemsley (2009-01-22). "Researcher Dies After Lab Fire". Chemical & Engineering News. http://pubs.acs.org/cen/news/87/i04/8704news1.html ↩

18. 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. http://pubs.acs.org/cen/science/87/8731sci1.html ↩

19. Los Angeles Times, 2009-03-01 http://www.latimes.com/news/local/traffic/la-me-uclaburn1-2009mar01,0,5638579.story ↩