Guanidine is a crystalline compound of strong alkalinity formed by the oxidation of guanine. It is used in the manufacture of plastics and explosives. It is found in urine as a normal product of protein metabolism. With a pKa of 12.5, guanidine is protonated, with a charge of +1 in physiological conditions.

Guanidine Hydrochloride has chaotropic properties and is used to denature proteins. Empirically, guanidine hydrochloride is known to denature proteins with a linear relationship between concentration and free energy of unfolding.

Guanidines are a group of organic compounds sharing a common functional group with the general structure (R¹R²N)(R³R⁴N)C=N-R⁵. The central bond within this group is that of an imine; the other recognizable motif within this group is an aminal. An example of a guanidine is triazabicyclodecene.

Guanidine is currently being considered as an alternative fuel. In the presence of a catalyst, a mole of free-base guanidine combines with 2 moles of water to form 3 moles of ammonia and 1 mole of carbon dioxide. The ammonia can be used directly as a fuel for internal combustion engines, or decomposed into nitrogen and hydrogen gas for use in fuel cells. The guanidine could be supplied as a fuel in solid form as pure guanidine (melting point ~ 50 C) or as a lower melting point eutectic mixture with urea. Guanidine could also be supplied as solutions in ethanol, as a replacement for the gasoline component in E85 fuel.

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amines | functional groups

Guanidin | Guanidina | グアニジン | Guanidyna | Гуанидин