Brominations copper bromide

Traces of bromine, carried over with the gas, are removed by the copper turnings as black copper bromide if the level of the blackened copper in tube F rises appreciably, excessive amounts of bromine are being carried over. 

Brom-jod, n. iodine bromide, -kalium, n. potassium bromide, -kalzium, n., kalk, tn. calcium bromide, -kampher, tn. bromo-camphor, Pharm.) monobromated camphor, -kohlenstoff, tn. carbon (tetra)bromide. -korper, tn. Colloids) "bromide body (bromide ion), -kupfer, n. copper bromide, lauge, /. bromine lye (solution of sodium hypobromite and bromide made by passing bromine into sodium hydroxide solution), -lithium, n. lithium bromide. -Idsung, /. bro-nune solution, -magnesium, n. magnesium bromide. -metall, n. metallic bromide. 

Preparation of Copper(II) Bromide. Introduce 1-2 g of a copper powder into a beaker with 50 ml of water and while stirring the reaction mixture, slowly add 3-6 drops of bromine from a dropping funnel. When the reaction terminates, cool the solution, filter it through ordinary cotton wool inserted into a glass funnel, boil it with charcoal (for what purpose ), and evaporate it in a vacuum desiccator. Filter off the formed crystals on a funnel with a filtering bottom. What is the composition of the product Write the equation of the reaction. Test how the copper bromide crystals behave in water and when heated. To do this, put 5-6 small crystals of the salt into each of two test tubes. Carefully add water dropwise to one of the tubes until the solution acquires a light blue colour, and then introduce about 0.2 g of dry potassium bromide, and heat the second tube. What happens Explain the observed phenomena. 

Copper bromide (CuBr2) Copper dibromide Copperfll) bromide Cupric bromide EINECS 232-167-2 HSDB 257. Used in photography (intensifier), organic synthesis (brominating agent), battery electrolyte, wood preservative. Crystals mp = 498° bp = 900° d 9= 4.710. Atomergic Chemetals Cerac Hoechst Celanese Mallinckrodt Inc. Sigma-Aldrich Fine Chem. 

In addition to the metal ion, the halide ion has also got an influence on the kinetic of ATRP by affecting the atom transfer equilibrium. The use of copper bromide instead of copper chloride leads to more rapidly decreasing polydispersities (/ -toluenesulfonyl chloride/copper chloride ( -TsCl/CuCl) conversion = 25%, Mn = 8500, M /Mn = 2 -TsCl/CuBr for the same conversion, Mn = 7800, M /Mn= 1.18 [294,295]). This can be assigned to the better efficiency of bromine in the deactivation step [307,308]. 

For bromination, this chemistry has been developed using copper bromide in acetonitrile [217], Preparation of the iodinated version was trivial and entailed simply stirring the alkyne with elemental iodine [219]. It should be noted that treating an alkynyl bromide with KI and acetie anhydride afforded the Z-l-iodo-2-hromoalkene [220]... 

Copper 1) chloride, bromide and cyanide were used by Sandmeyer to introduce a chlorine, a bromine atom and a cyanide group respectively into a benzene ring by addition to the phenyl diazonium salt. 

Hypobromites, the salts of hypobromous acid, do not keep well because they gradually disproportionate to bromide and bromate. Solutions are best prepared as needed from bromine and alkafl with cooling. Because disproportionation is catalyzed by cobalt, nickel, and copper (70), these impurities should be avoided. SoHd alkaline earth hypobromites, or more properly, bromide hypobromites such as calcium bromide hypobromite [67530-61 CaBr(OBr), have been known for many years, but the pure crystalline hydrates sodium hypobromite pentahydrate [13824-96-9] NaOBr 5H20, and potassium hypobromite tribydrate [13824-97-0], KOBr 3H20, were not described until 1952 (71). Hypobromites are strong bleaching agents, similar to hypochlorites. 

In the dectrolysis of aqueous cupric bromide, CuBr2, 0.500 gram of copper is deposited at one dectrode. How many grams of bromine are formed at the other electrode Write the anode and cathode half-reactions. 

BROMINATION OF AROMATIC COMPOUNDS WITH ALUMINA-SUPPORTED COPPER(II) BROMIDES... 

For instance, bromination of toluene in carbon tetrachloride did not proceed at reflux, even though pentamethylbenzene was brominated at 30°C to give bromopentamethylbenzene quantitatively. Toluene and copper(II) bromide reacted at reflux for 72 h. to give benzyl bromide as the main product. In a similar reaction with alumina-supported copper(II) bromide, bromotoluene (o/p = l) was obtained in good yield and no side-chain-brominated compounds were detected. 

The reaction of alkylbenzenes with copper(II) bromide is critically influenced by the presence of water in small quantities (ref. 10). With toluene, nuclear bromination predominates in a rigorously anhydrous system. When small amounts... 

Alkoxybenzenes were highly regioselectively halogenated by use of copper(II) halides supported on alumina to give 4-halo-alkoxybenzenes in high yield. Bromination of alkoxybenzenes with alumina-supported copper(II) bromide occurred at lower temperature than chlorination with alumina-supported copper(II) chloride (ref. 14). 

The reaction of 1-alkoxynaphtalenes with copper (II) bromide in benzene produced a mixture of 4-bromo-1-alkoxynaphtalenes and 4,4 -dialkoxy-l,l -binaphtyls. For instance, the reaction of 1-methoxynaphtalene 4 with copper(II) bromide in refluxing benzene for 2 h. gave a mixture of 4-bromo-1-methoxy-naphtalene 5 (47 %) and 4,4 -dimethoxy-l,l -binaphtyl 6 (45 %). In contrast, in similar reaction using alumina-supported copper(II) bromide at 30°C, only dimerization occurred and no brominated compounds were obtained. 

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