Malononitrile

Malononitrile is an organic compound nitrile with the formula CH₂(CN)₂. It is a colorless or white solid, although aged samples appear yellow or even brown. It is a widely used building block in organic synthesis.

Malononitrile

Skeletal formula of malononitrile
Ball-and-stick model Space-filling model
Names
IUPAC name Malononitrile[1]
Preferred IUPAC name Propanedinitrile[1]
Other names Malonodinitrile Cyanoacetonitrile Dicyanomethane Malonic dinitrile[2]
Identifiers
CAS Number	109-77-3 Y
3D model (JSmol)	Interactive image
Beilstein Reference	773697
ChEBI	CHEBI:33186 Y
ChemSpider	13884495 Y
ECHA InfoCard	100.003.368
EC Number	203-703-2
Gmelin Reference	1303
MeSH	dicyanmethane
PubChem CID	8010
RTECS number	OO3150000
UNII	EBL1KKS93J Y
UN number	2647
CompTox Dashboard (EPA)	DTXSID6021907
InChI InChI=1S/C3H2N2/c4-2-1-3-5/h1H2 Y Key: CUONGYYJJVDODC-UHFFFAOYSA-N Y
SMILES N#CCC#N
Properties
Chemical formula	CH2(CN)2
Molar mass	66.063 g·mol−1
Appearance	Colourless or white solid[2]
Odor	Sweet [3]
Density	1.049 g/cm3
Melting point	30–32 °C (86–90 °F; 303–305 K)[3]
Boiling point	220 °C (428 °F; 493 K)[3]
Solubility in water	133 g/L (20 °C (68 °F; 293 K))[3]
Thermochemistry[citation needed]
Heat capacity (C)	110.29 J⋅K−1⋅mol-1
Std molar entropy (S⦵298)	130.96 J⋅K−1⋅mol-1
Std enthalpy of formation (ΔfH⦵298)	187.7 to 188.1 kJ⋅mol−1
Std enthalpy of combustion (ΔcH⦵298)	−1654.0 to −1654.4 kJ⋅mol−1
Hazards
GHS labelling:[3]
Pictograms
Signal word	Danger
Hazard statements	H300, H311+H331, H317, H319, H410
Precautionary statements	P261, P264, P270, P271, P272, P273, P280, P301+P310+P330, P302+P352+P312, P304+P340+P311, P305+P351+P338, P333+P313, P337+P313, P362, P391, P403+P233, P405, P501
NFPA 704 (fire diamond)	[4] 4 1 1
Flash point	86 °C (187 °F; 359 K)
Autoignition temperature	365 °C (689 °F; 638 K)[3]
Lethal dose or concentration (LD, LC):
LD50 (median dose)	19 mg/kg (oral, mouse) 14 mg/kg (oral, rat)[3] 350 mg/kg (dermal, rat)
LC50 (median concentration)	0.51 mg/L (inhalation, dust/mist, 4h)[3]
NIOSH (US health exposure limits):
PEL (Permissible)	none[2]
REL (Recommended)	TWA 3 ppm (8 mg/m3)[2]
IDLH (Immediate danger)	N.D.[2]
Related compounds
Related alkanenitriles	Acetonitrile Aminoacetonitrile Glycolonitrile Cyanogen Propanenitrile Aminopropionitrile Pivalonitrile Acetone cyanohydrin Butyronitrile Succinonitrile Tetramethylsuccinonitrile
Related compounds	Malonic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation and reactions

It can be prepared by dehydration of cyanoacetamide.^[5] Most commonly malononitrile is produced by the gas-phase reaction of acetonitrile and cyanogen chloride:^[6]

NCCl + CH₃CN → NCCH₂CN + HCl

About 20,000,000 kilograms (20,000 LT) are produced annually (2007). Important outlets include the synthesis of thiamine, the drug triamterene and minoxidil, and the dyes disperse Yellow 90 and disperse Blue 354.^[6]

Malononitrile is relatively acidic, with a pK_a of 11 in water.^[7] This allows it to be used in the Knoevenagel condensation, for example in the preparation of CS gas:

CS-chemical-synthesis

Despite its relative obscurity, Malononitrile is very useful in several reactions, the prime example being a suitable starting reagent for the Gewald reaction, where the nitrile condenses with a ketone or aldehyde in the presence of elemental sulfur and a base to produce a 2-aminothiophene.^[8]

Interstellar occurrence

Due to its permanent dipole moment (i.e., 3.735 ± 0.017 D),^[9] malononitrile was detected in spectral emissions coming from interstellar cloud TMC-1 through the QUIJOTE line survey conducted with the Yebes 40 m radio telescope.^[10][11]