Benzyloxycarbonyl, a most important amino protecting group in peptide synthesis as well as in organic chemistry, is usually abbreviated Z or Cbz. A standard temporary amino protecting group in solution synthesis. Z is cleaved by hydrogenolysis or strong acids as neat HF or HBr/acetic acid. Halogenation of the aromatic nucleus generates more acid-stabile protective groups as 2-chloro-Z, whereas p- and o-methoxy groups render it more acid-labile.