Carbodiimides are a class of organic compounds characterized by the presence of the functional group -N=C=N-. They are commonly used as coupling agents in the synthesis of peptides and proteins, facilitating the formation of amide bonds between carboxylic acids and amines. One of the most widely used carbodiimides is 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), which is favored for its efficiency and mild reaction conditions. Carbodiimides can also react with water, so they are often used in anhydrous conditions to prevent hydrolysis and ensure successful coupling reactions.