2-Bromo-3-nitrotoluene

Chemical Properties

Pale yellow low melting solid

Uses

2-Bromo-3-nitrotoluene may be used in the preparation of unsymmetrical dimethyl dinitro biphenyl, via Ullmann reaction. It may be used as starting material in the synthesis of 10-methylfluoranthene.

General Description

Crystal structure of 2-bromo-3-nitrotoluene has been studied and the dihedral angle between the nitro group and the phenyl ring is reported to be 54.1(4)°.

Synthesis

The general procedure for the preparation of 2-bromo-3-nitrotoluene by diazotization reaction using 2-methyl-6-nitroaniline as starting material was as follows: first, 2-methyl-6-nitroaniline (30.4 g, 0.2 mol) was suspended in water (250 mL) and 40% aqueous hydrobromic acid (100 mL), refluxed for 10 min and then cooled to 0 °C. A solution of sodium nitrite (13.8 g, 0.2 mol) in water (80 mL) was added slowly and dropwise at a temperature below 5 °C. The resulting diazonium salt solution was continued to be stirred at 0-5 °C for 30 min, followed by the slow addition of a stirring mixed solution of cuprous bromide (28.7 g, 0.2 mol) in hydrobromic acid (80 mL) and water (150 mL) at room temperature. The reaction mixture was stirred at room temperature for 30 minutes and then heated and stirred on a steam bath for 1 hour. Upon completion of the reaction, it was washed with saturated sodium bicarbonate solution and brine, dried over magnesium sulfate and concentrated. The residue was purified by column chromatography using petroleum ether as eluent to give 2-bromo-3-nitrotoluene as a light yellow solid (25.9 g, 60% yield).

References

[1] European Journal of Organic Chemistry, 2005, # 16, p. 3536 - 3541
[2] Angewandte Chemie - International Edition, 2012, vol. 51, # 12, p. 2925 - 2929
[3] Angewandte Chemie - International Edition, 2010, vol. 49, # 40, p. 7257 - 7260
[4] Bioorganic and Medicinal Chemistry Letters, 2011, vol. 21, # 2, p. 644 - 651
[5] Patent: WO2011/22337, 2011, A1. Location in patent: Page/Page column 97