Malononitrile
Organic compound with formula CH2(CN)2
From Wikipedia, the free encyclopedia
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.
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| Names | |||
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| IUPAC name
Malononitrile[1] | |||
| Preferred IUPAC name
Propanedinitrile[1] | |||
Other names
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| Identifiers | |||
3D model (JSmol) |
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| 773697 | |||
| ChEBI | |||
| ChemSpider | |||
| ECHA InfoCard | 100.003.368 | ||
| EC Number |
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| 1303 | |||
| MeSH | dicyanmethane | ||
PubChem CID |
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| RTECS number |
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| UNII | |||
| UN number | 2647 | ||
CompTox Dashboard (EPA) |
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| Properties | |||
| 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] | ||
| 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] | |||
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| Danger | |||
| H300, H311+H331, H317, H319, H410 | |||
| 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) | |||
| Flash point | 86 °C (187 °F; 359 K) | ||
| 365 °C (689 °F; 638 K)[3] | |||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) |
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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 |
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Related compounds |
Malonic acid | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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 pKa of 11 in water.[7] This allows it to be used in the Knoevenagel condensation, for example in the preparation of CS gas:
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] It can also be used as a Michael donor.[9]
Interstellar occurrence
Due to its permanent dipole moment (i.e., 3.735 ± 0.017 D),[10] 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.[11][12]