2-tert-Butyl-1,1,3,3-tetramethylguanidine

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.

2-tert-Butyl-1,1,3,3-tetramethylguanidine
2-tert-butyl-1,1,3,3-tetramethylguanidine
Names
Preferred IUPAC name
N-tert-Butyl-N,N,N,N-tetramethylguanidine
Other names
BTMG, Barton's base
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.157.697 Edit this at Wikidata
  • InChI=1S/C9H21N3/c1-9(2,3)10-8(11(4)5)12(6)7/h1-7H3
    Key: YQHJFPFNGVDEDT-UHFFFAOYSA-N
  • CC(C)(C)N=C(N(C)C)N(C)C
Properties
C9H21N3
Molar mass 171.288 g·mol−1
Hazards
GHS labelling:
GHS05: CorrosiveGHS07: Exclamation mark
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).

Synthesis

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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

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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

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  1. ^ 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.
  2. ^ Reason and imagination : reflections on research in organic chemistry : selected papers of Derek H.R. Barton. World Scientific/Imperial College Press. 1996. ISBN 9810213611.