ChemicalBook CAS DataBase List 1,8-Dibromonaphthalene

1,8-Dibromonaphthalene synthesis

7synthesis methods

Product Name:1,8-Dibromonaphthalene
CAS Number:17135-74-9
Molecular formula:C10H6Br2
Molecular Weight:285.96

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).
Synthesis of 1,8-dibromonaphthalene

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Yield:17135-74-9 23%

Reaction Conditions:

Stage #1: 1H-naphtho[1,8-de][1,2,3]triazinewith sulfuric acid;sodium nitrite in water at -5; for 4 h;Inert atmosphere;
Stage #2: with hydrogen bromide;copper(I) bromide in water at -5 - 80; for 3 h;Inert atmosphere;

Steps:

1,8-dibromonaphthalene (1a)

Solid NaNO2 (3.5 g, 0.05 mol) was dissolvedin 20 mL H2O and cooled to 0 oC. The sodium nitrite solution was added drop wise into a solution of 1H-naphtho[1,8-de][1,2,3]triazine (6.8 g, 0.04 mol) in 6.9M H2SO4(100 mL) at -5 C over a period of 2 h with vigorous stirring with a mechanical stirrer.The mixture was stirred at -5 C for an additional 2 h. The solution of CuBr (14.6 g,0.1 mol) in aqueous HBr (47%, 50 mL) was dropwised into the resulting mixture and stirred at -5C for 2 h. The reaction mixture was allowed to warm up to 85C and then stirred for 1 h. The reaction mixture was extracted with dichloromethane and the combined extracts were dried with Na2SO4 and evaporated in vacuum to produce crude product.Flash chromatography on silica gel with petroleum ether gave pure 1a(2.61 g, 23%) as a pale yellow crystal. Melting point: 104-106 C. 1H NMR (300 MHz,CDCl3): 7.92 (d, J = 7.5 Hz, 2H), 7.79 (d, J = 9.0 Hz, 2H), 7.24 (m, 2H).

References:

An, Wenbo;Li, Gaoqiang;Ma, Jun;Tian, Youping;Xu, Feng [Synlett,2014,vol. 25,# 11,art. no. ST-2014-W0213-L,p. 1585 - 1590] Location in patent:supporting information

479-27-6 Synthesis