Guanidine
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| Guanidine | |
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| IUPAC name | Guanidine |
| Identifiers | |
| CAS number | [113-00-8] |
| SMILES | C(=N)(N)N |
| Properties | |
| Molecular formula | CH5N3 |
| Molar mass | 59.0706 g mol−1 |
| Density | x.xxx g cm−3 |
| Melting point |
50 °C |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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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.
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[edit] Guanidinium cation
With a pKa of 12.5, guanidine is protonated in physiological conditions, with a charge of +1. This conjugate acid of guanidine is called the guanidinium cation, [CH6N3]+.
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Notable guanidinium salts include guanidine hydrochloride, which 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. Another such salt is guanidinium thiocyanate.
[edit] Guanidine derivatives
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. Examples of guanidines are triazabicyclodecene and saxitoxin. other derivatives could include guanidine hydroxide, the active ingredient in some non-lye relaxers. Guanidinium salts are well known for their denaturing action on proteins. Guanidinium chloride is one of the most effective denaturants. In 6 M GndHCl all proteins with an ordered structure do lose it, and most of them become randomly coiled, that is, they do not contain any residual structure.
[edit] Use as an alternative fuel
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.
[edit] See also
[edit] References
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