Names | |||
---|---|---|---|
Preferred IUPAC name Guanidine [1] | |||
Other names Iminomethanediamine | |||
Identifiers | |||
3D model (JSmol) | |||
506044 | |||
ChEBI | |||
ChEMBL | |||
ChemSpider | |||
DrugBank | |||
ECHA InfoCard | 100.003.656 | ||
EC Number |
| ||
100679 | |||
MeSH | Guanidine | ||
PubChem CID | |||
UNII | |||
CompTox Dashboard (EPA) | |||
| |||
| |||
Properties | |||
CH5N3 | |||
Molar mass | 59.072 g·mol−1 | ||
Melting point | 50 °C (122 °F; 323 K) | ||
log P | −1.251 | ||
Conjugate acid | Guanidinium | ||
Thermochemistry | |||
Std enthalpy of formation (ΔfH⦵298) | −57 – −55 kJ mol−1 | ||
Std enthalpy of combustion (ΔcH⦵298) | −1.0511 – −1.0531 MJ mol−1 | ||
Pharmacology | |||
Pharmacokinetics: | |||
7–8 hours | |||
Hazards | |||
Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) | 475 mg/kg (oral, rat) [2] | ||
Related compounds | |||
Related compounds | |||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Guanidine is the compound with the formula HNC(NH2)2. It is a colourless solid that dissolves in polar solvents. It is a strong base that is used in the production of plastics and explosives. It is found in urine predominantly in patients experiencing renal failure. [3] A guanidine moiety also appears in larger organic molecules, including on the side chain of arginine.
Guanidine can be thought of as a nitrogenous analogue of carbonic acid. That is, the C=O group in carbonic acid is replaced by a C=NH group, and each OH is replaced by a NH
2 group. [4] Isobutene can be seen as the carbon analogue in much the same way. A detailed crystallographic analysis of guanidine was elucidated 148 years after its first synthesis, despite the simplicity of the molecule. [5] In 2013, the positions of the hydrogen atoms and their displacement parameters were accurately determined using single-crystal neutron diffraction. [6]
Guanidine can be obtained from natural sources, being first isolated in 1861 by Adolph Strecker via the oxidative degradation of an aromatic natural product, guanine, isolated from Peruvian guano. [7] [8]
A laboratory method of producing guanidine is gentle (180-190 °C) thermal decomposition of dry ammonium thiocyanate in anhydrous conditions:
The commercial route involves a two step process starting with the reaction of dicyandiamide with ammonium salts. Via the intermediacy of biguanidine, this ammonolysis step affords salts of the guanidinium cation (see below). In the second step, the salt is treated with base, such as sodium methoxide. [7]
The conjugate acid is called the guanidinium cation, (C(NH
2)+
3). This planar, symmetric ion consists of three amino groups each bonded to the central carbon atom with a covalent bond of order 4/3. It is a highly stable +1 cation in aqueous solution due to the efficient resonance stabilization of the charge and efficient solvation by water molecules. As a result, its pKaH is 13.6 [9] (pKb of 0.4) meaning that guanidine is a very strong base in water; in neutral water, it exists almost exclusively as guanidinium. Due to this, most guanidine derivatives are salts containing the conjugate acid.
Guanidine can be selectively detected using sodium 1,2-naphthoquinone-4-sulfonic acid (Folin's reagent) and acidified urea. [10]
The main salt of commercial interest is the nitrate [C(NH
2)3]NO
3. It is used as a propellant, for example in air bags.
Since the Middle Ages in Europe, guanidine has been used to treat diabetes as the active antihyperglycemic ingredient in French lilac. Due to its long-term hepatotoxicity, further research for blood sugar control was suspended at first after the discovery of insulin. Later development of nontoxic, safe biguanides led to the long-used first-line diabetes control medicine metformin, introduced to Europe in the 1950s & United States in 1995 and now prescribed to over 17 million patients per year in the US. [11] [12]
Guanidinium chloride [11] is a now-controversial adjuant in treatment of botulism. Recent studies have shown some significant subsets of patients who see no improvement after the administration of this drug. [13]
Guanidine exists protonated, as guanidinium, in solution at physiological pH.
Guanidinium chloride (also known as guanidine hydrochloride) has chaotropic properties and is used to denature proteins. Guanidinium chloride is known to denature proteins with a linear relationship between concentration and free energy of unfolding. In aqueous solutions containing 6 M guanidinium chloride, almost all proteins lose their entire secondary structure and become randomly coiled peptide chains. Guanidinium thiocyanate is also used for its denaturing effect on various biological samples.
Recent studies suggest that guanidinium is produced by bacteria as a toxic byproduct. To alleviate the toxicity of guanidinium, bacteria have developed a class of transporters known as guanidinium exporters or Gdx proteins to expel the extra amounts of this ion to the outside of the cell. [14] Gdx proteins, are highly selective for guanidinium and mono-substituted guanidinyl compounds and share an overlapping set of non-canonical substrates with drug exporter EmrE. [15]
Guanidinium hydroxide is the active ingredient in some non-lye hair relaxers.
Guanidines are a group of organic compounds sharing a common functional group with the general structure (R
1R
2N)(R
3R
4N)C=N−R
5. The central bond within this group is that of an imine, and the group is related structurally to amidines and ureas. Examples of guanidines are arginine, triazabicyclodecene, saxitoxin, and creatine.
Galegine is an isoamylene guanidine. [16]
An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen ion, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid.
In chemistry, amines are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines, trimethylamine, and aniline. Inorganic derivatives of ammonia are also called amines, such as monochloramine.
In biochemistry, denaturation is a process in which proteins or nucleic acids lose the quaternary structure, tertiary structure, and secondary structure which is present in their native state, by application of some external stress or compound such as a strong acid or base, a concentrated inorganic salt, an organic solvent, agitation and radiation or heat. If proteins in a living cell are denatured, this results in disruption of cell activity and possibly cell death. Protein denaturation is also a consequence of cell death. Denatured proteins can exhibit a wide range of characteristics, from conformational change and loss of solubility to aggregation due to the exposure of hydrophobic groups. The loss of solubility as a result of denaturation is called coagulation. Denatured proteins lose their 3D structure and therefore cannot function.
The term chloride refers either to a chloride ion, which is a negatively charged chlorine atom, or a non-charged chlorine atom covalently bonded to the rest of the molecule by a single bond. Many inorganic chlorides are salts. Many organic compounds are chlorides. The pronunciation of the word "chloride" is.
In organic chemistry, isothiocyanate is the functional group −N=C=S, formed by substituting the oxygen in the isocyanate group with a sulfur. Many natural isothiocyanates from plants are produced by enzymatic conversion of metabolites called glucosinolates. These natural isothiocyanates, such as allyl isothiocyanate, are also known as mustard oils. An artificial isothiocyanate, phenyl isothiocyanate, is used for amino acid sequencing in the Edman degradation.
In organic chemistry, a carbamate is a category of organic compounds with the general formula R2NC(O)OR and structure >N−C(=O)−O−, which are formally derived from carbamic acid. The term includes organic compounds, formally obtained by replacing one or more of the hydrogen atoms by other organic functional groups; as well as salts with the carbamate anion H2NCOO−.
A chaotropic agent is a molecule in water solution that can disrupt the hydrogen bonding network between water molecules. This has an effect on the stability of the native state of other molecules in the solution, mainly macromolecules by weakening the hydrophobic effect. For example, a chaotropic agent reduces the amount of order in the structure of a protein formed by water molecules, both in the bulk and the hydration shells around hydrophobic amino acids, and may cause its denaturation.
In chemistry, a trimer is a molecule or polyatomic anion formed by combination or association of three molecules or ions of the same substance. In technical jargon, a trimer is a kind of oligomer derived from three identical precursors often in competition with polymerization.
Amidines are organic compounds with the functional group RC(NR)NR2, where the R groups can be the same or different. They are the imine derivatives of amides (RC(O)NR2). The simplest amidine is formamidine, HC(=NH)NH2.
A superbase is a compound that has a particularly high affinity for protons. Superbases are of theoretical interest and potentially valuable in organic synthesis. Superbases have been described and used since the 1850s.
Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group [R−N+≡N]X− where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide.
Guanidinium thiocyanate(GTC) or guanidinium isothiocyanate (GITC) is a chemical compound used as a general protein denaturant, being a chaotropic agent, although it is most commonly used as a nucleic acid protector in the extraction of DNA and RNA from cells.
Cyanogen bromide is the inorganic compound with the formula (CN)Br or BrCN. It is a colorless solid that is widely used to modify biopolymers, fragment proteins and peptides, and synthesize other compounds. The compound is classified as a pseudohalogen.
Iodine compounds are compounds containing the element iodine. Iodine can form compounds using multiple oxidation states. Iodine is quite reactive, but it is much less reactive than the other halogens. For example, while chlorine gas will halogenate carbon monoxide, nitric oxide, and sulfur dioxide, iodine will not do so. Furthermore, iodination of metals tends to result in lower oxidation states than chlorination or bromination; for example, rhenium metal reacts with chlorine to form rhenium hexachloride, but with bromine it forms only rhenium pentabromide and iodine can achieve only rhenium tetraiodide. By the same token, however, since iodine has the lowest ionisation energy among the halogens and is the most easily oxidised of them, it has a more significant cationic chemistry and its higher oxidation states are rather more stable than those of bromine and chlorine, for example in iodine heptafluoride.
Acid guanidinium thiocyanate-phenol-chloroform extraction is a liquid–liquid extraction technique in biochemistry. It is widely used in molecular biology for isolating RNA. This method may take longer than a column-based system such as the silica-based purification, but has higher purity and the advantage of high recovery of RNA: an RNA column is typically unsuitable for purification of short RNA species, such as siRNA, miRNA, gRNA and tRNA.
Phosphazenes refer to classes of organophosphorus compounds featuring phosphorus(V) with a double bond between P and N. One class of phosphazenes have the formula R−N=P(−NR2)3. These phosphazenes are also known as iminophosphoranes and phosphine imides. They are superbases. Another class of compounds called phosphazenes are represented with the formula (−N=P 2−)n, where X = halogen, alkoxy group, amide and other organyl groups. One example is hexachlorocyclotriphosphazene (−N=P 2−)3. Bis(triphenylphosphine)iminium chloride [Ph3P=N=PPh3]+Cl−is also referred to as a phosphazene, where Ph = phenyl group. This article focuses on those phosphazenes with the formula R−N=P(−NR2)3.
In molecular biology, Proteinase K is a broad-spectrum serine protease. The enzyme was discovered in 1974 in extracts of the fungus Parengyodontium album. Proteinase K is able to digest hair (keratin), hence, the name "Proteinase K". The predominant site of cleavage is the peptide bond adjacent to the carboxyl group of aliphatic and aromatic amino acids with blocked alpha amino groups. It is commonly used for its broad specificity. This enzyme belongs to Peptidase family S8 (subtilisin). The molecular weight of Proteinase K is 28,900 daltons.
Guanidinium chloride or guanidine hydrochloride, usually abbreviated GdmCl and sometimes GdnHCl or GuHCl, is the hydrochloride salt of guanidine.
Ammonium thiocyanate is an inorganic compound with the formula [NH4]+[SCN]−. It is an ammonium salt of thiocyanic acid. It consists of ammonium cations [NH4]+ and thiocyanate anions [SCN]−.
Phenol–chloroform extraction is a liquid-liquid extraction technique in molecular biology used to separate nucleic acids from proteins and lipids.