Copper monobromide

Copper bromide (CuBr) Copper monobromide Copper(l-i-) bromide Copper(l) bromide Cuprous bromide EINECS 232-131-6 HSDB 270. Used as a catalyst in organic reactions. Solid mp = 504° bp B 1345° d = 4.72 slightly soluble in H2O. Atomergic Chemetals Cerac Hoechst Celanese Sigma-Aldrich Fine Chem. 

CuBr COPPER MONOBROMIDE 606 DyCI3 6H20 DYSPROSIUM CHLORIDE HEXAHYDRATE 647... 

CuBrtg] COPPER MONOBROMIDE (GAS) 607 DyF3 DYSPROSIUM FLUORIDE 648... 

For example, while reaction of 2-butoxynaphtalene with copper(II) bromide in benzene at 50°C for 2 h. produced only 6 % yield of l-bromo-2-butoxynaphtalene, similar reaction with Kieselguhr-supported copper(II) bromide gave 86 % yield of the monobromide. On the other hand, reaction using alumina as a support in benzene proceeded completely even at 10°C in 1 h. to give in addition to the monobromide (77 %), the dibromide (21 %) and the binaphtyl (2 %). 

J. J. van Laar has shown how the form of the vap. press, curves of a liquid mixture can furnish an indication, not a precise computation, of the degree of dissociation of any compound which maybe formed, on the assumption that the different kind of molecules in the liquid—12, Br2, and IBr—possess partial press, each of which is equal to the product of the vap. press, of a given component in the unmixed state and its fractional molecular concentration in the liquid. It is assumed that in the liquid, there is a balanced reaction 2IBr I2-)-Br2, to which the law of mass action applies, where K is the equilibrium constant, and Clt C2, and C respectively denote the concentration of the free iodine, free bromine, and iodine bromide. From this, P. C. E. M. Terwogt infers that at 50 2°, K for the liquid is 7j and that for iodine monobromide about 20 per cent, of the liquid and about 80 per cent, of the vapour is dissociated. That the vapour of iodine monobromide is not quite dissociated into its elements is evident from its absorption spectrum, which shows some fine red orange and yellow lines in addition to those which characterize iodine and bromine. In thin layers, the colour of the vapour is copper red. 0. Ruff29 could uot prove the formation of a compound by the measurements of the light absorption of soln. of iodine and bromine in carbon tetrachloride. 

The monobromide(s) 146 were treated under strong basic conditions at elevated temperature, slowly generating the y-lactone 147 by ring opening, and consecutive Sn2 reaction in 87% yield (Scheme 14). The isopropyl group was introduced in a four-step sequence. Claisen condensation with methyl formate led to a mixture of the enol and the enol ether, which by treatment with diazomethane, yielded in 80% the enol ether, 148. To introduce the methyl groups, the enol ether was converted into the thioenol ether. 1,4-Addition of dimethyl copper lithium afforded the... 

Bromination of coumarins 108 to give bromocoumarins 109 has been carried out by using bromine in acetic acid, Wbromosuccinimide, or copper(II) bromide adsorbed on alumina, but the drawbacks were the low yields of the products and the use of drastic conditions. However, MWI accelerated this bromination with either bromine adsorbed on neutral AI2O3 in a dry medium or iodine monobromide in acetic acid. Bromination took place selectively at the double bond in coumarins to give 109 in 63-92% yields (Scheme 22) (96SC887). 

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