Summary: 1-hydroxybenzotriazole derivatives are used with carbodiimide as additives to generate active esters during peptide bond formation. They are also used as additives during the peptide bond formation. Dissociation constants of the 1-hdroxybenzotriazole (HOBt) and its derivatives, 1-hydroxy-6-chlorobenzotriazole, 1-hydroxy-6- trifluoromethylbenzotriazole, 1-hydroxy-6-nitrobenzotriazole were determined ...