Dimethylchloromethyleneammonium Chloride

Abstract

(1; X = Cl) [3724-43-4] C3H7Cl2N (MW 128.01) InChI = 1S/C3H7ClN.ClH/c1-5(2)3-4;/h3H,1-2H3;1H/q+1;/p-1 InChIKey = QQVDYSUDFZZPSU-UHFFFAOYSA-M (2; X = PO2Cl2) [21382-90-1] C3H7Cl3NO2P (MW 226.43) InChI = 1S/C3H7ClN.Cl2HO2P/c1-5(2)3-4;1-5(2,3)4/h3H,1-2H3;(H,3,4)/q+1;/p-1 InChIKey = DWODIMJPOPDEIC-UHFFFAOYSA-M (formylation of arenes,1-3 heterocycles,1-3 and alkenes;2, 3 conversion of alcohols into chlorides,4 and carboxylic acids into acid chlorides;5 preparation of β-chlorovinyl aldehydes,3, 6 cyclic β-chloro-α,β-unsaturated ketones,7 and the conversion of acyclic precursors into ring systems8) Alternate Names: Vilsmeier reagent; Arnold's reagent. Physical Data: (1) mp 132 °C (dec). Solubility: fairly sol polar solvents. Form Supplied in: the chloride (1) is a white hygroscopic powder and is commercially available. The dichlorophosphate (2) is made in situ. Preparative Methods: Thionyl Chloride,4b Oxalyl Chloride,5 or Phosgene is added slowly to N,N‐Dimethylformamide, with cooling, to give the chloride (1) (eq 1). A solvent (typically dichloromethane,5 chloroform, or 1,1,2-trichloroethylene)9 may be used, and is advisable for large scale preparations. (1) The most commonly used Vilsmeier reagent is that formed by adding Phosphorus Oxychloride to DMF, to give dimethylchloromethyleneammonium dichlorophosphate (2).9 Reagent (2) is more reactive than reagent (1). Recent reports suggest that DMF–Pyrophosphoryl Chloride (P2O3Cl4) gives an even more reactive iminium intermediate (eq 2) than either salt (1) or salt .10 (2) Handling, Storage, and Precautions: the chloride (1) is hygroscopic. DMF is an irritant and is harmful by skin absorption. The halogenating agents (thionyl chloride, phosgene, phosphorus oxychloride, etc.) are all corrosive and lachrymatory. Use in a fume hood.