1,8-Dibromonaphthalene

Chemical Properties

White to yellow powder/crystals.

Application

1,8-Diarylnaphthalene show great potential in highly efficient photoluminescent blue and green OLEDs, chiral ligands and sensors, nonlinear optic chromophores, stereo-dynamic switches and other optoelectronic devices.

Preparation

1,8-dibromonaphthalene was prepared by diazotisation of triazine 1 with sodium nitrite in sulfuric acid, followed by the addition of CuBr/HBr in 44% yield, and cyanation of the dibromide (5) by Weissman’s method gave naphthalene-1,8-dicarbonitrile (4) in 78% yield (Scheme 2).

Reactions

Influence of the conditions on the Pd-catalyzed reaction of 1,8-dibromonaphthalene with 1,2,3,4-tetrafluorobenzene.

Scope of the Pd-catalyzed direct arylation reaction of 2,5-substituted heteroarenes with 1,8-dibromonaphthalene.

Synthesis

The general procedure for the synthesis of 1,8-dibromonaphthalene from 1H-naphtho[1,8-de][1,2,3]triazine was as follows: solid sodium nitrite (NaNO2, 3.5 g, 0.05 mol) was dissolved in 20 mL of water and cooled down to 0 °C. The sodium nitrite solution was added dropwise to a solution of 1H-naphtho[1,8-de][1,2,3]triazine (6.8 g, 0.04 mol) dissolved in 6.9 M sulfuric acid (H2SO4, 100 mL) at -5 °C. The reaction mixture was stirred vigorously with a mechanical stirrer at -5°C for 2 hours, followed by continued stirring at the same temperature for 2 hours. Next, a solution of cuprous bromide (CuBr, 14.6 g, 0.1 mol) dissolved in 47% aqueous hydrobromic acid (HBr, 50 mL) was added dropwise to the above mixture and stirred for 2 hours at -5°C. The reaction mixture was gradually warmed to 85°C and stirring was continued for 1 hour. Upon completion of the reaction, the reaction mixture was extracted with dichloromethane, the organic phases were combined and dried over anhydrous sodium sulfate (Na2SO4). Subsequently, the solvent was removed by vacuum evaporation to give the crude product. The crude product was purified by silica gel column chromatography using petroleum ether as eluent to afford pure 1,8-dibromonaphthalene (2.61 g, 23% yield) as light yellow crystals. The melting point of the product was 104-106 °C. 1H NMR (300 MHz, CDCl3): δ 7.92 (d, J = 7.5 Hz, 2H), 7.79 (d, J = 9.0 Hz, 2H), 7.24 (m, 2H).

Structure and conformation

1,8-Dibromonaphthalene (1,8-DBN) is a symmetrical double bromo-substituted naphthalene with two bromos sitting at the naphthalene ring mirroring each other along the joining carbons.

References

[1] W. NOLAND D. B Venkata Srinivasarao Narina. Synthesis and Crystallography of 8-Halonaphthalene-1-Carbonitriles and Naphthalene-1,8-Dicarbonitrile[J]. Journal of Chemical Research-s, 2011, 383 1: 694-697. DOI:10.3184/174751911X13222107572093.
[2] PROF. DR. ANNA V. GULEVSKAYA Eugeny A E. 1,8‐Diarylnaphthalenes: Synthesis, Properties, and Applications[J]. European Journal of Organic Chemistry, 2022, 2022 48: Pages 53-111. DOI:10.1002/ejoc.202201192.
[3] KETATA N, LIU L, SALEM R B, et al. Mono or double Pd-catalyzed C–H bond functionalization for the annulative π-extension of 1,8-dibromonaphthalene: a one pot access to fluoranthene derivatives[J]. Beilstein Journal of Organic Chemistry, 2024, 16 1. DOI:10.3762/bjoc.20.37.