Diphosgene decomposition

Two different diphosgene decomposition routes have also been noted in the presence of aluminum(III) chloride, one giving hexachloroethane and carbon dioxide and the second giving trichloroacetyl chloride and phosgene [61]. 

On heating near its boiling point at ordinary pressures, it decomposes to form phosgene and diphosgene, which further decomposes into phosgene. The reaction of decomposition is thus ... 

The reversibility of the decomposition of Diphosgene into carbon tetrachloride and carbon dioxide is still a controversial topic. However, the production of phosgene by reaction of carbon tetrachloride and carbon dioxide over catalysts such as Lewis acids was recently claimed in Russian patents (Ref. 32). The reaction is assumed to proceed through the formation of trichloromethyl chloroformate or bis(trichloromethyl) carbonate. 

The decomposition of diphosgene is catalysed in the presence of various nitrogen-containing derivatives, such as pyridine, quinoline, or tertiary amines, to give complete... 

The catalytic decomposition routes of diphosgene are extremely interesting. The compound is stable at room temperature, but decomposes to phosgene when heated above 300 °C [55-57], or on contact with iron(III) oxide, iron(III) chloride, or aluminum(III) chloride (less active) or activated charcoal (very active) [51]. 

The stability of diphosgene in the presence of various metal (Fe, Al, V) oxides and chlorides has been extensively investigated in order to find practical routes for quantitative decomposition or to establish the compatibility of the reagent with various materials [51]. 

Methyl 2-isocyanato-3-phenylpropenoate 365 is obtained in 68% yield by perrhenate-catalyzed decomposition of methyl 2-azido-3-phenylpropionate 364 in the presence of phosgene [257]. This reaction resulted in a higher yield compared to the same reaction employing diphosgene (instead of phosgene), which afforded the product in just 53% yield [257]. 

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