Novel synthetic pathway for the production of phosgene.

Chloride ions are efficient catalysts for the synthesis of phosgene from carbon monoxide and elemental chlorine at room temperature and atmospheric pressure. Control experiments rule out a radical mechanism and highlight the role of triethylmethylammonium trichloride, [NEtMe][Cl], as active species. In the catalytic reaction, commercially available [NEtMe]Cl reacts with Cl to form [NEtMe][Cl], enabling the insertion of CO into an activated Cl─Cl bond with a calculated energy barrier of 56.