Guanidine is a colorless crystalline substance that dissolves in air due to absorption of moisture. Strong single acid base pK a = 12.5. With HCl , HNO 3 forms stable salts.
| Guanidine | |
|---|---|
 | |
 | |
| General | |
| Traditional names | guanidine |
| Chem. formula | CH₅N₃ |
| Rat formula | CH 5 N 3 |
| Physical properties | |
| condition | solid in |
| Molar mass | 59.07 g / mol |
| Thermal properties | |
| T. melt. | 50 ° C |
| Enthalpy of Education | -56.01 kJ / mol |
| Classification | |
| Reg. CAS number | 113-00-8 |
| PubChem | |
| Reg. EINECS number | |
| Smiles | |
| Inchi | |
| Chebi | and |
| ChemSpider | |
Content
- 1 History
- 2 Properties
- 3 Getting
- 4 Protonation and basicity
- 5 Derivatives of guanidine
- 6 Application
- 7 Security
- 8 Notes
History
It is found in urine as a product of normal protein metabolism . The substance was first synthesized by the oxidative degradation of natural aromatic products, guanine isolated from Peruvian guano [1] . Despite the simplicity of the structure of the molecule, the crystal structure was first described 148 years after the discovery. [2] .
Properties
Easily alkylated . It has fungicidal and bactericidal activity.
Getting
- In industry, guanidines are obtained by fusion of ammonium salts with urea or cyanguanidine,
- NH 4 NO 3 + 2 (NH 2 ) 2 CO → (NH 2 ) 2 C = NH * HNO 3 + CO 2 + 2NH 3
- as well as hydrogenolysis of cyanguanidine on Raney nickel :
- NH 2 -C (= NH) -NH-CN → [H 2 , Ni] NH 2 -C (NH) -NH 2
- It is recovered by means of ion exchange resins from urea production wastes.
- Carbonate recovered from melamine waste
- Other salts are obtained by reaction with a guanidine base
- Alcohol solutions in the reaction of guanidinium chloride with the corresponding alcoholates
Protonation and basicity
Due to the resonant charge delocalization in the symmetric guanidinium cation formed upon protonation of guanidine, guanidine is a strong base comparable in strength (pKa = 13.5) with sodium hydroxide .
High basicity is also characteristic of substituted guanidines: for example, the guanidine group of the amino acid arginine (pKa 12.48) is protonated under physiological conditions (at pH <10).
resonance structure canonical forms
Guanidine chloride is used to denature proteins. Moreover, the concentration and free energy of the opening are linearly dependent. Guanidinium thiocyanate is also used for the same purpose.
Guanidine derivatives
Guanidines are a group of organic compounds with the general structure (R 1 R 2 N) (R 3 R 4 N) C = NR 5 . The central bond within this structure is the imine; another recognizable substructure is the aminal . Examples of guanidines are arginine , triazobicyclodecene and saxitoxin . Other derivatives may include guanidine hydroxide. Guanidine salts are well known for their denaturing effect on proteins. Guanidine chloride is the most famous denaturant. In its 6 M solution, almost all proteins with an ordered structure lose their order.
Biguanides are hypoglycemic drugs used in diabetes. Biguanide molecules consist of a polymethylene chain and a guanidine group at both ends.
Application
- Guanidine salts are used in industry:
- - dinitrate - as an explosive ,
- - phosphate - in the textile industry to impart refractory properties to fabrics,
- - carbonate - in the synthesis of surfactants and cosmetics for hair straightening
- - phosphate - in the textile industry to impart refractory properties to fabrics,
- The condensation product of guanidine with formaldehyde is used as an ion exchange resin .
- It is also used in the manufacture of plastics.
- As a promising alternative fuel [3]
- Nitroguanidine, guanidinium nitrate, guanidinium perchlorate are used as rocket fuel.
- Chromate - Corrosion Inhibitor
Security
Toxic, causes alkaline burns on skin.
Notes
- ↑ A. Strecker, Liebigs Ann. Chem. 1861 , 118 , 151.
- ↑ T. Yamada, X. Liu, U. Englert, H. Yamane, R. Dronskowski, Chem. Eur. J. 2009 , 15 , 5651.
- ↑ European Patent Office application EP20050746871 (link not available)