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[2]
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| Preferred IUPAC name
Propanedinitrile[2] | |||
| Other names
Malonodinitrile, Cyanoacetonitrile, Dicyanomethane, Malonic dinitrile[1]
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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[1] | ||
| Density | 1.049 g cm−3 | ||
| Melting point | 32 °C; 89 °F; 305 K | ||
| Boiling point | 220.1 °C; 428.1 °F; 493.2 K | ||
| 13% (20 °C)[1][clarification needed] | |||
| Thermochemistry | |||
Heat capacity (C)
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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) |
−1,654.0 to −1,654.4 kJ mol−1 | ||
| Hazards | |||
| GHS labelling: | |||
 
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| Danger | |||
| H301, H311, H331, H410 | |||
| P261, P273, P280, P301+P310, P311 | |||
| Flash point | 86 °C (187 °F; 359 K) | ||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose)
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| NIOSH (US health exposure limits): | |||
PEL (Permissible)
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none[1] | ||
REL (Recommended)
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TWA 3 ppm (8 mg/m3)[1] | ||
IDLH (Immediate danger)
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N.D.[1] | ||
| Related compounds | |||
Related alkanenitriles
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Related compounds
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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
editIt can be prepared by dehydration of cyanoacetamide.[3] This method is mainly practiced in China where environmental rules are lax. Most commonly malononitrile is produced by the gas-phase reaction of acetonitrile and cyanogen chloride:[4]
- NCCl + CH3CN → NCCH2CN + HCl
About 20,000,000 kg 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.[4]
Malononitrile is relatively acidic, with a pKa of 11 in water.[5] 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.[6]
References
edit- ^ a b c d e f NIOSH Pocket Guide to Chemical Hazards. "#0378". National Institute for Occupational Safety and Health (NIOSH).
- ^ a b International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. The Royal Society of Chemistry. p. 902. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.
- ^ Surrey, Alexander (1945). "Malononitrile". Organic Syntheses. 25: 63–64. doi:10.15227/orgsyn.025.0063.
- ^ a b Strittmatter, Harald; Hildbrand, Stefan; Pollak, Peter (2007). "Malonic Acid and Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a16_063.pub2. ISBN 978-3527306732.
- ^ Evans pKa table
- ^ Sabnis, R. W.; Rangnekar, D. W.; Sonawane, N. D. (1999). "2-Aminothiophenes By The Gewald Reaction". Journal of Heterocyclic Chemistry. 36 (2): 333–345. doi:10.1002/jhet.5570360203. Retrieved 2007-07-18.