Carboxybenzyl

Benzyl chloroformate is the benzyl ester of chloroformic acid. Also known as benzyl chlorocarbonate it is an oily colorless liquid although impure samples appear yellow. It is also known for its pungent odor. In contact with water it degrades. Benzyl chloroformate is the benzyl ester of chloroformic acid. Also known as benzyl chlorocarbonate it is an oily colorless liquid although impure samples appear yellow. It is also known for its pungent odor. In contact with water it degrades. It is prepared in the lab by treating benzyl alcohol with phosgene. Phosgene is used in excess to minimise the production of the carbonate. The “carboxybenzyl group” (Cbz, benzyloxycarbonyl) is commonly used in organic synthesis for the introduction of the carboxybenzyl (abbreviated Cbz or Z) protecting group for amines. It is a key protecting group for amines, suppressing its nucleophilic and basic properties. Alternatively, as in the Curtius rearrangement, carboxybenzyl can be generated by the reaction of an isocyanate with benzyl alcohol.