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
CAS Number	29166-72-1
3D model (JSmol)	Interactive image
ChemSpider	2808676
ECHA InfoCard	100.157.697
PubChem CID	3571581
CompTox Dashboard (EPA)	DTXSID10393758
InChI InChI=1S/C9H21N3/c1-9(2,3)10-8(11(4)5)12(6)7/h1-7H3 Key: YQHJFPFNGVDEDT-UHFFFAOYSA-N
SMILES CC(C)(C)N=C(N(C)C)N(C)C
Properties
Chemical formula	C9H21N3
Molar mass	171.288 g·mol^−1
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H302, H314
Precautionary statements	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). Infobox references

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 (pK_a) of Barton's base is 14.^[1] In acetonitrile its pK_a is 24.31.

Synthesis

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

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

1. 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.