advances in organobromine chemistry ii

[...]... phenyl(p-tolyl)methane is the main product, in addition to benzyl bromide In contrast, in a reaction with alumina-supported copper (II) bromide in the presence of water in small quantities, only nuclear bromination occurred and no products resulting from side-chain-bromination were formed It seems that alumina not only activates copper (II) halides but also acts as a dehydrating agent in this system Copper (II) chloride... easy bromine (ref 10) Consequently the bromine adduct was obtained in high yield (83 %) Using NBS and a catalytic amount of the amine, the ratio of the ortho-brominated phenols was remarkably raised 2-Allylphenol and o-cresol were considerably ortho-brominated by NBS even without the amine In NBS-amine system dibromides as by-products were obtained slightly and any para-bromide and bromine adduct in the... 16 BROMINATION OF AROMATIC COMPOUNDS SUPPORTED COPPER (II) BROMIDES WITH ALUMINA- MITSUO KODOMARI, HIROAKI SATOH, KIYOSHI TAKEUCHI Department of Industrial Chemistry, Shibaura Institute of Technology, Minato-ku, Tokyo 108, Japan Copper (II) halides have been used as halogenating agents in homogeneous conditions for compounds containing active hydrogen atoms (refs 1,2), and in heterogeneous in nonpolar... mechanism of electrophilic bromination of olefins Other topics included new selective methods of bromination and oxybromination, brominations in presence of solid supports and catalysts, organobromine compounds as synthons, recent developments in brominated fire retardants and toxicological and environmental aspects of brominated compounds References 1 H Windawi, M Wyatt, Platinum Metals Rev ,37, 186 (1993)... 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 anisole with copper (II) bromide in benzene at 50~ yielded no detectable products after 10 h In contrast, in a similar reaction using... bromine compounds are practiced in numerous applications as intermediates in the pharmaceutical industry (ref 11) Aromatic iodine derivatives are effectual as contrast media for diagnostic imaging by x-ray or magnetic resonance imaging (ref 12) New halogenation methods, such as the homolytic bromination in supercritical carbon dioxide (ref 13) and aromatic chlorinations in liquid HC1 (ref 14) are being... determined by GC Monobromination with bromine leads to exclusive 4-bromophenol, and dibromination with the same reagent gave predominant 2,4-dibromophenol In the case of monobromination with NBS, the main product was 2-bromophenol, but no selectivity appeared in the bromination using two molar amounts of NBS As described above, it was shown that N,N-dibromomethylamine was effective for ortho-dibromination... after 5 h In contrast, in a similar reaction using alumina-supported r bromide, bromomesitylene in 97 % yield from a reaction run at 50~ for 1 h and dibromomesitylene in 99 % yield from the reaction run at 80~ for 5 h were obtained The results of bromination of polymethylbenzenes are summarized in Table 1 Reactivity of the polymethylbenzenes toward copper (II) bromide increased with increasing number... ortho-bromination of phenol However N-bromoamines were very unstable and decomposed explosively in less than a day at room temperature Amines Catalyzed ortho-Bromination (ref 9) We considered N-bromoamines which generated in situ from the reaction of NBS and various amines, should promote the ortho-dibromination of phenol The results of the bromination with NBS in the presence of amines are summarized in. .. with copper (II) chloride in refluxing r produced negligible yields of chlorinated products, similar reaction with alumina-supported copper (II) chloride produced monochlorinated compounds in high yields Copper (II) bromide was more reactive than copper (II) chloride toward the aromatic hydrocarbons Bromination of aromatic hydrocarbons proceeded in carbon tetrachloride to give the corresponding bromo compounds . Pistoia) Industrial Chemicals. Their Characteristics and Development (by G. Agam) Advances in Organobromine Chemistry II (Edited by J R. Desmurs, B. G6rard and M.J. Goldstein) Industrial Chemistry.