guanidin

Guanidine (systematic name 2-imino-1,3-diaminopropane) is an organic compound with the formula HNC(NH2)2. It is a colorless, highly polar solid that is highly soluble in water.

As a base, guanidine is one of the strongest amidines: its conjugate acid, guanidinium, has a pKa around 13.6 in aqueous solution. The molecule features a central carbon double-bonded to an imine nitrogen and single-bonded to two amino groups; resonance among the three nitrogens stabilizes the cation after protonation.

In biology, the guanidino group is a functional moiety found in the amino acid arginine and in creatine; derivatives of guanidine are used in pharmaceuticals and as reagents.

In chemistry, guanidine and its salts are employed as strong bases for deprotonation, and as reagents to install guanidino groups in substrates.

Industrial preparation often proceeds from dicyandiamide via ammoniation and hydrolysis to yield guanidine or its salts, such as guanidine hydrochloride or guanidine carbonate, which can be neutralized to the free base.

Guanidine is a corrosive, irritant substance. It should be handled with protective equipment, in a well‑ventilated area, and disposed of according to regulations.