9-Bromoanthracene

9-bromoanthracene is a kind of bromine-derived anthracene. It is known to be able to reversibly photodimerize in a head-to tail fashion upon irradiation by long-wavelength ultraviolet light. The photodimers of 9-bromoanthracene are suitable to be used as alkyl halide initiators in the atom transfer radical polymerization (ATRP) reactions. It is also used as the intermediate for the preparation of the 9-substitued form of the polycyclic aromatic hydrocarbon (PAH) anthracene.

white to light yellow crystal powder. boiling point 190°C (0.16kPa, sublimation), relative density 1.409. soluble in acetic acid; carbon disulfide.

9-Bromoanthracene acts as an intermediate in the preparation of 9-substituted derivative of the polycyclic aromatic hydrocarbon (PAH) anthracene.

Anthracene (5 g, 28.05 mmol) was dissolved in CHCl3. Then N-bromosuccinimide (NBS，4.99 g, 28.05 mmol) was added in batches away from light, and the reaction solution was continuously stirred for 12 h. The resulting mixture was stirred for another 30 min with appropriate water, and extracted with CH2Cl2. The CH2Cl2 solution was dried over anhydrous MgSO4. After removing CH2Cl2 solvent, the residue was recrystallized from anhydrous ethanol to give 4.78 g (66.3 %) of a green-yellow needle solid 9-Bromoanthracene. 1H NMR (500 MHz, CDCl3) δ 8.55 (d, J = 8.9 Hz, 2H), 8.48 (s, 1H), 8.03 (d, J = 8.4 Hz, 2H), 7.67 – 7.60 (m, 2H), 7.56 – 7.51 (m, 2H). EI-MS (m/z): Calculated for C14H9Br: 257.13. Found [M+ ]: 255.96.
Synthesis of 9-bromoanthracene

The Sonogashira reaction of 9-Bromoanthracene and ethynyltrimethylsilane gave not only the expected anticipated 9-(trimethylsilylethynyl)anthracene and 2-(trimethylsilyl)aceanthrylene and (E)-4-(9-anthracenyl)-1,3-bis(trimethylsilyl)-but-3-en-1-yne were also obtained in moderate yields. The mechanistic principle may be that the coupling of bromo(anthracenyl)bis(triphenylphosphine)palladium(II) can occur either directly or after coordination and migratory insertion of the free alkyne.

The Journal of Organic Chemistry, 57, p. 2740, 1992 DOI: 10.1021/jo00035a038

Crystallise 9-bromoanthracene from MeOH or EtOH followed by sublimation in vacuo. [Masnori et al. J Am Chem Soc 108 126 1986, Beilstein 5 IV 2295.]

9-Bromoanthracene could be used to synthesise 6-bromoaceanthrylene-1,2-dione by Friedel-Crafts acylation reaction with oxalyl chloride. The pure 9-Bromoanthracene’s energy level is -5.710 eV. A 1:1 co-crystal of Picric acid and 9-Bromoanthracene was prepared by a solvent evaporation method. The PIC: BRA co-crystal shows significantly reduced impact sensitivity relative to pure Picric acid. The primary non-covalent interaction occurs between the electron-poor π-system of Picric acid and the electron-rich π-system of 9-Bromoanthracene. The distance between the Picric acid centroid and the 9-Bromoanthracene centroid was measured to be 3.492 Å, a typical value in materials which exhibit aromatic face-to-face πinteractions (<4.00 Å). An interaction is also indicated between aromatic hydrogen on the 9-Bromoanthracene ring and nitro group oxygen on a parallel Picric acid ring (C3-H3…O6). The donor-acceptor π ... π interactions dominate the formation of the Picric Acid co-crystal. The π electron cloud of the 9-Bromoanthracene ring is concentrated towards the electron-poor region at the centre of the Picric acid moiety, and the two rings combine. The π system of picric acid is known to deform due to the electron-withdrawing effect of nitro groups and an electron vacancy formed at the centre of the ring. This is partially filled by π electrons of the 9-Bromoanthracene ring. In other words, a charge transformation complex is formed[4].

[1]Cohen, Nicole A., et al. Macromolecular Chemistry and Physics 210.3 ‐4 (2009): 263-268.
[2]Xu, Xiaoming, Wenzhe Lu, and Richard B. Cole. Analytical chemistry 68.23 (1996): 4244-4253.
[3]Dang, Hung, and Miguel A. Garcia-Garibay. Journal of the American Chemical Society 123.2 (2001): 355-356.
[4] Se Hun Kim. “Highly efficient deep-blue emitting organic light emitting diode based on the multifunctional fluorescent molecule comprising covalently bonded carbazole and anthracene moieties.” Journal of Materials Chemistry B 13 1 (2011): 9139–9148.