ABSTRACT
Phosgene is an unusually versatile reagent realizing a wide range of transformations. Despite this, it is very much underused in the laboratory due to its low bp (7.6°C), high latent toxicity, and inadequate odor warning. Two main substitutes have been proposed in the literature to circumvent these dif‘culties: trichloromethyl chloroformate, CCl3CO2Cl [2], which is formally a dimer of phosgene, and bis-trichloromethyl carbonate, CCl3CO3CCl3 [3], which is formally a trimer. Both decompose thermally and catalytically to phosgene by a well-known mechanism [4], and this can be used to generate phosgene in situ. On the other hand, the reaction can proceed directly, with triphosgene in particular showing some speci‘c reactivity [1]. Due to a lower vapor pressure, triphosgene is generally the preferred substitute.
