2-tert-Butyl-1,1,3,3-tetramethylguanidine
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Names | |
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Preferred IUPAC name
N′′-tert-Butyl-N,N,N′,N′-tetramethylguanidine | |
Other names
BTMG, Barton's base
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Identifiers | |
3D model (JSmol)
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ChemSpider | |
ECHA InfoCard | 100.157.697 |
PubChem CID
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CompTox Dashboard (EPA)
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Properties | |
C9H21N3 | |
Molar mass | 171.288 g·mol−1 |
Hazards | |
GHS labelling: | |
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Danger | |
H302, H314 | |
P260, P264, P270, P280, P301+P312, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P330, P363, P405, P501 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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2-tert-Butyl-1,1,3,3-tetramethylguanidine is an organic base, also known as Barton's base. It is named after Nobel Prize-winning British chemist Derek Barton. Barton and his assistants prepared a series of guanidines with steric hindrance in 1982; in this case five alkyl groups: four methyl groups and one tert-butyl group.[1][2] In 50% water ethanol mixture, the acidity constant (pKa) of Barton's base is 14.[1] In acetonitrile its pKa is 24.31.
Synthesis
[edit]The base is prepared by the reaction of tert-butylamine with a Vilsmeier salt. The latter is the reaction product of phosgene with tetramethylurea.
Applications
[edit]Barton's base can be used in many organic reactions, including in alkylations and in the formation of aziridines. It is often a milder alternative to traditional, strong inorganic bases.
References
[edit]- ^ a b Barton, Derek H. R.; Elliott, John D.; Géro, Stephen D. (1982). "Synthesis and properties of a series of sterically hindered guanidine bases". J. Chem. Soc., Perkin Trans. 1: 2085–2090. doi:10.1039/P19820002085.
- ^ Reason and imagination : reflections on research in organic chemistry : selected papers of Derek H.R. Barton. World Scientific/Imperial College Press. 1996. ISBN 9810213611.