Question

How would you convert chloroform to diethyl carbonate?

Answer 1

This two-step process uses the principle that chloroform is unstable and can oxidize to the highly toxic phosgene, which then readily reacts with ethanol to form the relatively harmless diethyl carbonate.

1. Oxidation of Chloroform to Phosgene: When exposed to sunlight and air, chloroform undergoes oxidation to produce phosgene (COCl₂), a highly toxic gas, and hydrochloric acid.
   \[\ce{CHCl3 + O2 -> 2COCl2 + HCl}\]
2. Reaction of Phosgene with Ethanol: The phosgene generated then reacts with ethanol in the presence of a catalyst or under controlled conditions. In this reaction, the two chlorine atoms in phosgene are replaced by two ethoxy (C₂H₅O−) groups from the ethanol.
   \[\ce{COCl2 + 2C2H5OH -> (C2H5O)2CO + 2HCl}\]