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Verkade base

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(Redirected from Proazaphosphatrane)
Verkade base
Names
Preferred IUPAC name 2,8,9-Trimethyl-2,5,8,9-tetraaza-1-phosphabicycloundecane
Identifiers
CAS Number
3D model (JSmol)
ChemSpider
PubChem CID
UNII
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C9H21N4P/c1-10-4-7-13-8-5-11(2)14(10)12(3)6-9-13/h4-9H2,1-3H3Key: PCYSWBQHCWWSFW-UHFFFAOYSA-N
SMILES
  • CN1CCN2CCN(P1N(CC2)C)C
Properties
Chemical formula C9H21N4P
Molar mass 216.269 g·mol
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 , 100 kPa). Infobox references
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-phosphabicycloundecane is the simplest. Diverse analogues of the Verkade base are known, e.g. with isopropyl groups in place of methyl.

Synthesis 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.

Protonation of Verkade base.

The conjugate acid 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.

Related compounds

Phosphazenes are phosphorus(V) derivatives with the formula RN=P(NR2)3.

References

  1. Verkade, John G.; Urgaonkar, Sameer (2012). "Proazaphosphatrane". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rn00702.pub2. ISBN 978-0471936237.
  2. Schmidt, H.; Lensink, C.; Xi, S. K.; Verkade, J. G. (1989). "New Prophosphatranes: Novel intermediates to five-coordinate phosphatranes". Zeitschrift für Anorganische und Allgemeine Chemie. 578: 75–80. doi:10.1002/zaac.19895780109.
Organophosphorus
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