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ChemicalBook CAS DataBase List Cuprous bromide
7787-70-4

Cuprous bromide synthesis

3synthesis methods
It is prepared pyrometallurgically with copper metal and elemental bromine in a process similar to that for copper(I) chloride. It can also be produced by the reduction of copper(II) sulfate solutions in the presence of sodium bromide using metallic copper or sulfite as the reducing agent. Copper(I) bromide is used as a polymerization catalyst in organic reactions.
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Yield:-

Reaction Conditions:

Stage #1: copper(II) sulfate;sodium bromide in water;
Stage #2: with sodium sulfite in water;
Stage #3: with hydrogen bromide in hexane;

Steps:

28

Example 2828.1 28.2[0329] Methyl 4-bromo-3-(trifluoromethoxy)benzoate (28.2). To a solution of 4-amino-3-(trifluoromethoxy)benzoic acid (2.00 g, 9.10 mmol) in MeOH (25.0 mL), was slowly added HCl (1.0 mL, 1.0 M in ether) at room temperature. The resulting reaction mixture was stirred at room temperature overnight. Benzene (20 mL) was added, and the reaction was heated at reflux with a Dean-Stark trap to remove the half volume of the solvent. The rest of the solvent was then evaporated to give the product. MS (ESI) m/e = 235.9 [M+l]+, Calc'd for CgHeF3NOs, 235.1. The crude product was used in the next step without further purification. To an ice-cooled suspension of methyl 4-amino-3- (trifluoromethoxy)benzoate hydrogen chloride salt (8.60 g, 31.70 mmol) in 17.1 mL of water and concentrated HBr (48 %, 17.1 mL), was slowly added a prepared 2.5 M solution of sodium nitrite (2.20 g in 12.7 mL) at 00C. The reaction mixture was stirred at 0 0C for 10 minutes. Meanwhile, a solution OfCuSO4 (6.68 g) in 35 mL of water was heated and sodium bromide (6.52 g) was added. The solution became a green color, and a solution OfNa2SOs (2.80 g) in water (10 mL) was then added to it. The solution was cooled at 0 0C and washed with water (25 x 3 mL). The water was then decanted off. Concentrated HBr (16.7 mL) was added, and the solution became a purple color. The solution of CuBr was slowly added to the diazonium salt (prepared above) at 00C. After addition, the ice-bath was removed, and an oil-bath was placed under the reaction vessel. The reaction mixture was then heated to 600C for 15 minutes, at 80 0C for 15 minutes, and then at 1000C for 20 minutes. The reaction mixture was next cooled to room temperature and made basic with Na2CO3 to a pH 8. The aqueous solution was extracted with EtOAc (100 x 2 mL). The organic layer was washed with brine (25 mL) and dried with MgSO4. The solvent was removed to give the crude product 28.2. 1H NMR (CDCl3) δ 3.96 (s, 3H), 7.75 (d, J= 8.4 Hz5 1 H), 7.86 (d, J= 8.4 Hz, 1 H), 7.98 (s, IH).

References:

WO2008/30520,2008,A1 Location in patent:Page/Page column 136

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