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Copper(II) bromide (Cu Br 2) is a chemical compound that forms an unstable tetrahydrate CuBr 2 ·4H 2 O. It is used in photographic processing as an intensifier and as a brominating agent in organic synthesis .
Frequently, however, C–Cl bonds are too inert, and bromide or iodide leaving groups are required for acceptable rates. The main group metal in the organometallic partner usually is an electropositive element such as tin , zinc , silicon, or boron .
In the original paper describing this reaction, methylmagnesium bromide is reacted with isophorone with and without 1 mole percent of added copper(I) chloride (see figure). [10] Without added salt the main products are alcohol B (42%) from nucleophilic addition to the carbonyl group and diene C (48%) as its dehydration reaction product.
In addition the four copper atoms form a planar Cu 4 ring based on three-center two-electron bonds. The copper to copper bond length is 242 pm compared to 256 pm in bulk copper. In pentamesitylpentacopper a 5-membered copper ring is formed, similar to (2,4,6-trimethylphenyl)gold, and pentafluorophenylcopper is a tetramer. [9]
The copper(I) ion also oxidizes easily in air. It is commonly prepared by the reduction of cupric salts with sulfite in the presence of bromide. [4] For example, the reduction of copper(II) bromide with sulfite yields copper(I) bromide and hydrogen bromide: 2 CuBr 2 + H 2 O + SO 2− 3 → 2 CuBr + SO 2− 4 + 2 HBr
The classic example of a dehydration reaction is the Fischer esterification, which involves treating a carboxylic acid with an alcohol to give an ester RCO 2 H + R′OH ⇌ RCO 2 R′ + H 2 O Often such reactions require the presence of a dehydrating agent, i.e. a substance that reacts with water.
A sample of copper(I) oxide. Copper forms a rich variety of compounds, usually with oxidation states +1 and +2, which are often called cuprous and cupric, respectively. [1] Copper compounds, whether organic complexes or organometallics, promote or catalyse numerous chemical and biological processes. [2]
Copper bromide can refer to: Copper(I) bromide, CuBr; Copper(II) bromide, CuBr 2 This page was last edited on 31 December 2019, at 11:21 (UTC). Text is ...