o-Nitrobenzoyl Chloride

[610-14-0]  · C7H4ClNO3  · o-Nitrobenzoyl Chloride  · (MW 185.57)

(acylating agent in reaction with amines and alcohols; produces crystalline esters from alcohols; building block for the synthesis of several classes of heterocycles)

Physical Data: mp 17-20 °C; bp 148-149 °C/9 mmHg; d 1.404 g cm-3.

Solubility: sol THF, CH2Cl2, CHCl3; reacts with water and alcohols.

Form Supplied in: commercially available; low melting solid.

Purification: distillation under reduced pressure.

Handling, Storage, and Precautions: extremely irritating to skin and eyes. Can cause burns. Use in a fume hood. Reacts with water, liberating HCl. Explosion of distillation residue has been reported.1

Ester Formation.

o-Nitrobenzoyl chloride forms crystalline esters with alcohols (see p-Nitrobenzoyl Chloride) and these esters are readily hydrolyzed under standard conditions for benzoyl removal (eqs 1 and 2). The crystalline nitrobenzoyl esters enable enhancement of enantiomeric excess by recrystallization.2

Synthesis of Heterocycles.

o-Nitrobenzoyl chloride has been used in the synthesis of various heterocycles, particularly quinazolinones (eq 3),3 benzodiazepines (eq 4),4 and xanthones.5 In the quinazolinone synthesis (eq 3), and in many other cases, the nitro group acts as a masked amine. Initial condensation of the acetyl chloride is followed by nitro reduction to the free amine which then participates in further condensation and cyclization. In other cases, o-nitrobenzoyl chloride undergoes initial Friedel-Crafts acylation before cyclization of the amine.5

1. Hazards in the Chemical Laboratory; Bretherick, L., Ed.; Royal Society of Chemistry: London, 1981; p 411.
2. Conte, V.; Di Furia, F.; Licini, G.; Modena, G.; Sbampato, G; Valle, G. TA 1991, 2, 257.
3. (a) Plescia, S.; Daidone, G.; Dattolo, G.; Aiello, E. JHC 1977, 14, 1075. (b) Büchi, G.; DeShong, P. R.; Katsumura, S.; Sugimura, Y. JACS 1979, 101, 5084. (c) Adegoke, E. A.; Alo, B. I.; Familoni, O. B. JHC 1987, 24, 107. (d) Peet, N. P.; Baugh, L. E.; Sunder, S.; Lewis, J. E.; Matthews, E. H.; Olberding, E. L.; Shah, D. N. JMC 1986, 29, 2403.
4. (a) Melani, F.; Cecchi, L.; Filacchioni, G. JHC 1984, 21, 813. (b) Langley, D. R.; Thurston, D. E. JOC 1987, 52, 91. (c) Thurston, D. E.; Jones, G. B.; Davis, M. E. CC 1990, 875.
5. Adams, J. H.; Brown, P. M.; Gupta, P.; Khan, M. S.; Lewis, J. R. T 1981, 37, 209.

Paul Brough

University of Bristol, UK

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