DCCHOBt

DCCHOBt is a term used in organic synthesis to denote a two-reagent system composed of dicyclohexylcarbodiimide (DCC) and 1-hydroxybenzotriazole (HOBt) that is employed together to promote amide bond formation. It is not a single, well-defined chemical compound but rather a formulation or mixture that appears in various protocols for peptide synthesis and other carboxyl activation reactions. The exact composition and ratio can vary by supplier and procedure.

In typical reactions, DCC activates a carboxyl group to form a reactive O-acylisourea intermediate, which can react with amines to form amide bonds. The addition of HOBt (and sometimes HOAt) facilitates formation of a more stable active ester and suppresses racemization of chiral centers. The reaction is usually carried out in dry organic solvents such as dichloromethane or DMF, at room temperature or slightly cooler.

DCCHOBt reactions produce insoluble dicyclohexylurea (DCU) as a byproduct, which can be filtered off. The combination generally increases coupling efficiency and reduces side reactions compared to DCC alone, but it may be sensitive to moisture and heat. Alternative activators and additives exist for different substrates and synthetic needs.

Safety: DCC and HOBt derivatives are irritants and can pose hazards; ensure proper ventilation, avoid inhalation or skin contact, and store away from heat or shocks when dry. Waste should be disposed of according to institutional hazardous waste guidelines.