Overview
2,6-Di-tert-butylpyridine is a weak base used in the preparation of 2, 6-di-tert-butylpyridine hydrotriflate. It is used as a proton scavenger to check the progress of the living polymerization of isobutylene. It is associated with cerric ammonium nitrate and used in the alfa-enolation of aldehydes. It is involved in the preparation of vinyl triflate using polymer-bound 2,6-di-tert-butylpyridine. Since it was first synthesized by Brown and Kanner[1], 2,6-di-tert-butylpyridine has attracted the interest of many researchers because of its unusually low basicity: with its two-alkyl substituents, DTBP is nevertheless a weaker base than unsubstituted pyridine in aqueous solution. Brown and Kanner[1] and others[2] proposed that the abnormally low basicity of DTBP was caused by steric hindrance to hydration of DTBPH+. Recent determinations of gas-phase proton affinities of DTBP and other alkyl-substituted pyridines showed that the basicity of DTBP in the gas phase was normal[2, 3], which confirmed that its weak basicity in water was due to solvent effects on DTBP and (or) DTBPH+. A complete analysis of the thermodynamic cycles linking the protonation processes of DTBP and other pyridines in the gas phase and in aqueous solution led Arnett and Chawla[2] to conclude that there was indeed some hindrance to the hydration of DTBPH+ as reflected in its abnormally low enthalpy of hydration. However, more recently Hopkins et al.[3], after investigating the protonation of additional tertbutylpyridines and repeating the thermodynamic determinations of Amett and Chawla[2] of DTBP, concluded from their new data that the hydration enthalpy of DTBPH+ was normal but that the corresponding entropy was abnormal; they suggested that the rotation of the water molecule attached to DTBPH+ and of -CMe3 was restricted. These results and conclusions were in agreement with the gas phase studies of Moet-Ner and Sieck[4] on the attachment of one water molecule to a series of pyridinium cations including DTBPH+.
Reference
- H. C. BROWN and B. KANNERJ. Am. Chem. Soc. 75, 3865 (1953).
- E. M. ARNETT and B. CHAWLAJ. Am. Chem. Soc. 101, 7141 (1979).
- H.P.HOPKINSD,.V.JAHAGIRDAP.RS,.MOULIKD,.H.AUE, H. M. WEBB,W. R. DAVIDSON and M. D. PEDLEY. J.. Am. Chem. Soc. 106,4341 (1984).
- M. MEOT-NEaRnd L. W. SIECK J. Am. Chem. Soc. 105, 2956 (1983)
Chemical Properties
dark brown liquid
Uses
2,6-Di-
tert-butylpyridine was used as proton trapping agent to investigate the living polymerization of isobutylene. It was also used with cerric ammonium nitrate in the α-enolation of aldehydes leading to 1,4-dicarbonyl systems.
Uses
2,6-Di-tert-butylpyridine is used in the preparation of 2, 6-di-tert-butylpyridine hydrotriflate. It is used as a proton scavenger to check the progress of the living polymerization of isobutylene. It is associated with cerric ammonium nitrate and used in the alfa-enolation of aldehydes. It is involved in the preparation of vinyl triflate using polymer-bound 2,6-di-tert-butylpyridine.
Definition
ChEBI: 2,6-di-tert-butylpyridine is a member of pyridines.
General Description
Reactivity of 2,6-di-
tert-butylpyridine with iron(III) tetraphenylporphyrin pi-cation radical has been examined by proton NMR spectroscopy. Reaction of 2,6-di-
tert-butylpyridine with methyl iodide and methyl fluorosulfonate under high pressure has been reported.
Purification Methods
Redistil it from KOH pellets. [Beilstein 20 III/IV 2868.]
