A method of preparing a dialkyl carbonate includes reacting an alkanol, oxygen, carbon monoxide, and a catalyst to form a mixture that includes a dialkyl carbonate and an alkyl chloroformate. The mixture is separated into a liquid fraction and a gaseous fraction, and alkyl chloroformate is removed from the gaseous fraction. Also described is an apparatus for carrying out the method. The method is particularly useful for preventing corrosion in a cold wash unit that removes further organic impurities from the gaseous fraction.