Chemistry:Benzonitrile
Benzonitrile is the chemical compound with the formula C
6H
5(CN), abbreviated PhCN. This aromatic organic compound is a colorless liquid with a cherry or almond like odour. It is mainly used industrially to synthesize the melamine resin precursor benzoguanamine.
Production and reactions
It is prepared by ammoxidation of toluene, that is its reaction with ammonia and oxygen (or air) at 400 to 450 °C (752 to 842 °F).[1]
- C
6H
5CH
3 + 3/2 O
2 + NH
3 → C
6H
5(CN) + 3 H
2O
In the laboratory it can be prepared by the dehydration of benzamide or benzaldehyde oxime[2][3] or by the Rosenmund–von Braun reaction using cuprous cyanide or NaCN/DMSO and bromobenzene.
- Rosenmund-von Braun synthesis
Hydrogenation of benzonitrile in principle gives benzylamine, but owing to transamination, dibenzylamine and tribenzylamine are also produced.
Applications
Laboratory uses
Benzonitrile is a useful solvent and a versatile precursor to many derivatives. It reacts with amines to afford N-substituted benzamides after hydrolysis.[4] It is a precursor to diphenylmethanimine via reaction with phenylmagnesium bromide followed by methanolysis.[5]
Benzonitrile forms coordination complexes with transition metals that are both soluble in organic solvents and conveniently labile. One example is PdCl
2(PhCN)
2. The benzonitrile ligands are readily displaced by stronger ligands, making benzonitrile complexes useful synthetic intermediates.[6]
History
Benzonitrile was reported by Hermann Fehling in 1844. He found the compound as a product from the thermal dehydration of ammonium benzoate. He deduced its structure from the already known analogue reaction of ammonium formate yielding hydrogen cyanide (formonitrile). He also coined the name benzonitrile which gave the name to all the group of nitriles.[7]
In 2018, benzonitrile was reported to be detected in the interstellar medium.[8]
References
- ↑ Maki, Takao; Takeda, Kazuo (June 2000). "Benzoic Acid and Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a03_555. ISBN 3527306730.
- ↑ Loupy, André; Régnier, Serge (August 1999). "Solvent-free microwave-assisted Beckmann rearrangement of benzaldehyde and 2-hydroxyacetophenone oximes". Tetrahedron Letters 40 (34): 6221–6224. doi:10.1016/S0040-4039(99)01159-4. ISSN 0040-4039.
- ↑ One Pot Synthesis of Nitriles from Aldehydes and Hydroxylamine Hydrochloride Using Ferrous Sulphate in DMF Under Reflux Condition† Asian Journal of Chemistry; Vol. 24, No. 3 (2012), 1401-1402.
- ↑ Cooper, F. C.; Partridge, M. W. (1963). "N-Phenylbenzamidine". Organic Syntheses. http://www.orgsyn.org/demo.aspx?prep=cv4p0769.; Collective Volume, 4, pp. 769
- ↑ Pickard, P. L.; Tolbert, T. L. (1973). "Diphenyl Ketimine". Organic Syntheses. http://www.orgsyn.org/demo.aspx?prep=cv5p0520.; Collective Volume, 5, pp. 520
- ↑ Anderson, Gordon K.; Lin, Minren (1990). "Bis(Benzonitrile)Dichloro Complexes of Palladium and Platinum". Reagents for Transition Metal Complex and Organometallic Syntheses. Inorganic Syntheses. 28. John Wiley & Sons. pp. 60–63. doi:10.1002/9780470132593.ch13. ISBN 978-0-470-13259-3.
- ↑ Fehling, Hermann (1844). "Ueber die Zersetzung des benzoësauren Ammoniaks durch die Wärme". Annalen der Chemie und Pharmacie 49 (1): 91–97. doi:10.1002/jlac.18440490106. https://zenodo.org/record/1426978.
- ↑ McGuire, Brett A. et al. (January 2018). "Detection of the aromatic molecule benzonitrile (c\sC6H5CN) in the interstellar medium". Science 359 (6372): 202–205. doi:10.1126/science.aao4890. PMID 29326270. Bibcode: 2018Sci...359..202M.
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