Chloroformates are a class of organic compounds that can be formally described as esters of chloroformic acid. Most are colourless, volatile liquids that degrade in moist air. The most widely used method of preparation is the reaction of phosgene or triphosgene with alcohols and phenols. They are versatile intermediates in the synthesis of organic compounds and often used as reagents to introduce protecting groups (Fmoc, Boc, Cbz etc.).