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Names | |
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Preferred IUPAC name
2,8,9-Trimethyl-2,5,8,9-tetraza-1-phosphabicyclo[3.3.3]undecane | |
Identifiers | |
3D model (
JSmol)
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ChemSpider | |
PubChem
CID
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UNII | |
CompTox Dashboard (
EPA)
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Properties | |
C9H21N4P | |
Molar mass | 216.269 g·mol−1 |
Appearance | colorless oil |
Boiling point | 263.9 °C (507.0 °F; 537.0 K) |
Except where otherwise noted, data are given for materials in their
standard state (at 25 °C [77 °F], 100 kPa).
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In chemistry, the Verkade base (or Verkade superbase) is a powerful superbase with the formula P(MeNCH2CH2)3N. A colorless oil, it is an aminophosphine although its inventor John Verkade called it proazaphosphatrane. The trimethyl derivative or 2,5,8,9-tetraza-1-phosphabicyclo[3.3.3]undecane is the simplest. [1] Diverse analogues of the Verkade base are known, e.g. with isopropyl groups in place of methyl.
The Verkade base is generated by the reaction of N,N,N-trimethyl tren with tris(dimethylamino)phosphine: [2]
The principal reaction of the Verkade base is protonation. The proton is attacked by the Verkade base at the phosphorus atom within, which induces the formation of a transannular P-N bond. The product exemplifies the structure of an atrane.
The conjugate acid [HP(MeNCH2CH2)3N]+ of the base has a pKa of 32.9 in acetonitrile. For comparison, the conjugate acid of triethylamine has a pKa near 17 in acetonitrile. Owing to its ability to deprotonate weak carbon acids, the Verkade base catalyzes a variety of condensation reactions.
Phosphazenes are phosphorus(V) derivatives with the formula RN=P(NR2)3.