Benzamidine

Benzamidine is an organic compound with the formula C6H5C(NH)NH2. It is the simplest aryl amidine. The compound is a white solid that is slightly soluble in water. It is usually handled as the hydrochloride salt, a white, water-soluble solid.

Structure
Benzamidine has one short C=NH bond and one longer C-NH2 bond, which are respectively 129 and 135 pm in length, respectively.

The triangular diamine group gives it a distinctive shape which shows up in difference density maps.

Applications
Benzamidine is a reversible competitive inhibitor of trypsin, trypsin-like enzymes, and serine proteases.

It is often used as a ligand in protein crystallography to prevent proteases from degrading a protein of interest. The benzamidine moiety is also found in some pharmaceuticals, such as dabigatran.

Condensation with various haloketones provides a synthetic route to 2,4-disubstituted imidazoles.
 * Disubstituted-imidazole-synthesis OrgSyn.png