Phosphazene

Phosphazene

A phosphazene is any of a class of chemical compounds in which a phosphorus atom is covalently linked to a nitrogen atom by a double bond and to three other atoms or radicals by single bonds. Two examples are hexachlorocyclotriphosphazene and bis(triphenylphosphine)iminium chloride.

The corresponding polymers are polyphosphazenes.

Phosphazene bases

Phosphazene bases are strong non-metallic non-ionic and low-nucleophilic bases. They are stronger bases than regular amine or amidine bases such as Hünig's base or DBU. Protonation takes place at a doubly bonded nitrogen atom.

Two commercially available phosphazene bases are BEMP with an acetonitrile pKa of the conjugate acid of 27.6 and the phosphorimidic triamide t-Bu-P4 (pKBH+ = 42.7) also known as Schwesinger base after one of its inventors ["Peralkylated Polyaminophosphazenes - Extremely Strong, Neutral Nitrogen Bases" Angewandte Chemie International Edition in English Volume 26, Issue 11, Date: November 1987, Pages: 1167-1169 Reinhard Schwesinger, Helmut Schlemper DOI|10.1002/anie.198711671] .

In one application t-Bu-P4 is employed in a nucleophilic addition converting the pival aldehyde to the alcohol ["Phosphazene base-promoted functionalization of aryltrimethylsilanes" Koichi Suzawa, Masahiro Ueno, Andrew E. H. Wheatley and Yoshinori Kondo Chem. Commun., 2006, 4850 - 4852, DOI| 10.1039/b611090h] :

The active nucleophile is believed to be a highly reactive phosphazenium species with full negative charge on the arene sp2 carbon.

The related proazaphosphatrane superbases have a saturated P(NR)3 structure and protonation takes place at phosphorus.

External links

* Phosphazene bases [http://www.sigmaaldrich.com/Area_of_Interest/Chemistry/Chemical_Synthesis/Product_Highlights/Phosphazenes.html Link]

References


Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • phosphazène — [fɔsfazɛn] n. m. ÉTYM. 1979, in la Recherche, sept., p. 894; de phosph(ore), az(ote), et suff. ène. ❖ ♦ Chim. Polymère à squelette inorganique formé d atomes de phosphore et d azote liés entre eux par une double liaison. || Phosphazènes cycliques …   Encyclopédie Universelle

  • phosphazene — fosfazenas statusas T sritis chemija formulė R₃P=NR atitikmenys: angl. phosphazene rus. фосфазен …   Chemijos terminų aiškinamasis žodynas

  • phosphazene — noun any of a class of compounds in which a phosphorous atom is covalently linked to a nitrogen atom by a double bond, and to three other atoms or radicals by single bonds …   Wiktionary

  • phosphazene — …   Useful english dictionary

  • Organic base — Acids and Bases Acid dissociation constant Acid base extraction Acid–base reaction Acid–base titration Dissociation constant Acidity function Buffer sol …   Wikipedia

  • Oxazole — IUPAC name 1,3 oxazole Identifiers …   Wikipedia

  • Superbase — In chemistry, a superbase is an extremely strong base. There is no commonly accepted definition for what qualifies as a superbase, but most chemists would accept sodium hydroxide as a benchmark base just as sulfuric acid is a benchmark acid (see… …   Wikipedia

  • Bis(triphenylphosphine)iminium chloride — IUPAC name μ nitrido Bis(triphenylphosphorus) chloride …   Wikipedia

  • Tetraazidomethane — Chembox new Name = Tetraazidomethane ImageFileL1 = tetraazidomethane.png ImageSizeL1 = 120px ImageNameL1 = Tetraazidomethane ImageFileR1 = tetraazidomethane 3D.png ImageSizeR1 = 120px ImageNameR1 = Tetraazidomethane IUPACName = Tetraazidomethane… …   Wikipedia

  • Azide — Azoture Les azotures sont les sels de l acide azothydrique HN3, ainsi que les azotures organiques dans lesquels un des atomes d azotes est lié de façon covalents avec un atome de carbone d un composé organique. Les azotures organiques peuvent par …   Wikipédia en Français

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”