Verkade base
Chemical compound
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-tetraaza-1-phosphabicyclo[3.3.3]undecane is the simplest. Diverse analogues of the Verkade base are known, e.g. with isopropyl groups in place of methyl.
01Synthesis and reactions
The Verkade base is generated by the reaction of N,N,N-trimethyltren with tris(dimethylamino)phosphine:
- P(NMe2)3 + (MeNHCH2CH2)3N → P(MeNCH2CH2)3N + 3 Me2NH
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.
Sources and credits
This article is adapted from the Wikipedia article “Verkade base”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- P(MeNC2H4)3N.svg by Smokefoot, Public domain
- VerkadeProtn.svg by Smokefoot, Public domain
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