Guanidine

Guanidine

Names
IUPAC names Guanidine Iminomethanediamine
Identifiers
CAS Number	113-00-8 Y
3D model (Jmol)	Interactive image Interactive image
Beilstein Reference	506044
ChEBI	CHEBI:42820 Y
ChEMBL	ChEMBL821 Y
ChemSpider	3400 Y
DrugBank	DB00536 Y
ECHA InfoCard	100.003.656
EC Number	204-021-8
Gmelin Reference	100679
IUPHAR/BPS	4783
MeSH	Guanidine
PubChem	3520
UNII	JU58VJ6Y3B Y
InChI InChI=1S/CH5N3/c2-1(3)4/h(H5,2,3,4) Y Key: ZRALSGWEFCBTJO-UHFFFAOYSA-N Y
SMILES [nH]:c(:[nH2]):[nH2] NC(N)=N
Properties
Chemical formula	CH5N3
Molar mass	59.07 g·mol−1
Melting point	50 °C (122 °F; 323 K)
log P	−1.251
Acidity (pKa)	13.6
Thermochemistry
Std enthalpy of formation (ΔfHo298)	−57 – −55 kJ mol−1
Std enthalpy of combustion (ΔcHo298)	−1.0511 – −1.0531 MJ mol−1
Pharmacology
Pharmacokinetics:
Biological half-life	7–8 hours
Hazards
Lethal dose or concentration (LD, LC):
LD50 (median dose)	475 mg/kg (oral, rat)
Related compounds
Related compounds	Urea Biguanide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Guanidine is the compound with the formula HNC(NH
2)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 as a normal product of protein metabolism. Guanidine is the functional group 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. A detailed crystallographic analysis of guanidine was elucidated 148 years after its first synthesis, despite the simplicity of the molecule. In 2013, the positions of the hydrogen atoms and their displacement parameters were accurately determined using single-crystal neutron diffraction.

Guanidine can be obtained from natural sources, being first isolated by Adolph Strecker via the degradation of guanine.

The compound was first synthesized in 1861 by the oxidative degradation of an aromatic natural product, guanine, isolated from Peruvian guano. 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.

With a pK_b of 0.4, guanidine is a strong base. In neutral water, it exists exclusively as guanidinium (C(NH
2)+
3). Most guanidine derivatives are in fact such salts.