Vilsmeier reagent

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Vilsmeier reagent
Preferred IUPAC name
1-Chloro-N,N-dimethylmethaniminium chloride
Other names
(chloromethylene)dimethyliminium chloride
3D model (JSmol)
ECHA InfoCard 100.102.443 Edit this at Wikidata
EC Number
  • 425-970-6
  • InChI=1S/C3H7ClN.ClH/c1-5(2)3-4;/h3H,1-2H3;1H/q+1;/p-1
  • C[N+](=CCl)C.[Cl-]
Molar mass 128.00 g·mol−1
Appearance white solid
Melting point 132 °C (270 °F; 405 K)
GHS labelling:
GHS05: CorrosiveGHS07: Exclamation markGHS08: Health hazard
H290, H302, H314, H360
P201, P202, P234, P260, P264, P270, P280, P281, P301+P312, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P308+P313, P310, P321, P330, P363, P390, P404, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

The Vilsmeier reagent is an organic compound with the formula [(CH3)2NCHCl]Cl. It is a salt consisting of the N,N-dimethyliminium cation ([(CH3)2N=CHCl]+) and chloride anion. Depending on the particular reaction, the anion can vary. In typical POCl3-based reactions, the anion is PO2Cl2. The iminium cation [(CH3)2N=CHCl]+ is the reactive component of interest. This iminium species is a derivative of the imidoyl chloride CH3N=CHCl. Analogues of this particular reagent are generated when tertiary amides other than DMF are treated with POCl3.

The salt is a white solid that is soluble in polar organic solvents. Vilsmeier reagent is the active intermediate in the formylation reactions, the Vilsmeier reaction or Vilsmeier-Haack reaction that use mixtures of dimethylformamide and phosphorus oxychloride to generate the Vilsmeier reagent, which in turn attacks a nucleophilic substrate and eventually hydrolyzes to give formyl. It is a source of "O=CH+".[1]

Pathway for formation of Vilsmeier reagent and its mode of action.[2]

See also[edit]


  1. ^ Paul R. Giles, Charles M. Marson (2001). "Dimethylchloromethyleneammonium Chloride". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rd319m. ISBN 0471936235.{{cite journal}}: CS1 maint: uses authors parameter (link)
  2. ^ Jones, G.; Stanforth, S. P. (2000). "The Vilsmeier Reaction of Non-Aromatic Compounds". Org. React. 56 (2): 355–686. doi:10.1002/0471264180.or056.02.