TY - JOUR
T1 - The effect of zinc-bromine interactions on electrophilic bromination in concentrated ZnBr2 solutions
AU - Epstein, Daniel M.
AU - Meyerstein, Dan
N1 - Funding Information:
This study was enabled by a grant from Bromine Compounds Ltd., Beer Sheva, Israel.
PY - 2001
Y1 - 2001
N2 - Facile bromination can be carried out in concentrated solutions of zinc bromide (60-80% w/w ZnBr2 in water) [A. Ewenson, D. Itzhak, M. Freiberg-Bergstein, A. Shushan, B. Croitoru, D. Beneish, N. Faza, WO patent 99/19275, Bromine Compounds Ltd., Israel, 1999]. These brine solutions offer an alternative to expensive and harmful organic solvents. A correlation between the reactivity and the molecular ratio H2O:Zn has been found and quantified using UV-Vis spectroscopy [J.A. Duffy, G.L. Wood, J. Chem. Soc., Dalton Trans. (1987) 1485; E. Eyal, A. Treinin, J. Am. Chem. Soc. 86 (1964) 4287-4290; D. Meyerstein, A. Treinin, Trans. Faraday Soc. 59 (1963) 1114-1120]. Based on spectrophotometric and NMR results, it is proposed that these concentrated aqueous solutions, which behave similarly to anhydrous media, enhance the reactivity of molecular bromine by polarizing the Br-Br bond. Furthermore they affect the electron density distribution in the organic substrates.
AB - Facile bromination can be carried out in concentrated solutions of zinc bromide (60-80% w/w ZnBr2 in water) [A. Ewenson, D. Itzhak, M. Freiberg-Bergstein, A. Shushan, B. Croitoru, D. Beneish, N. Faza, WO patent 99/19275, Bromine Compounds Ltd., Israel, 1999]. These brine solutions offer an alternative to expensive and harmful organic solvents. A correlation between the reactivity and the molecular ratio H2O:Zn has been found and quantified using UV-Vis spectroscopy [J.A. Duffy, G.L. Wood, J. Chem. Soc., Dalton Trans. (1987) 1485; E. Eyal, A. Treinin, J. Am. Chem. Soc. 86 (1964) 4287-4290; D. Meyerstein, A. Treinin, Trans. Faraday Soc. 59 (1963) 1114-1120]. Based on spectrophotometric and NMR results, it is proposed that these concentrated aqueous solutions, which behave similarly to anhydrous media, enhance the reactivity of molecular bromine by polarizing the Br-Br bond. Furthermore they affect the electron density distribution in the organic substrates.
KW - Electrophilic aromatic substitution
KW - Zinc bromide
UR - http://www.scopus.com/inward/record.url?scp=0035204862&partnerID=8YFLogxK
U2 - 10.1016/S1387-7003(01)00313-6
DO - 10.1016/S1387-7003(01)00313-6
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AN - SCOPUS:0035204862
SN - 1387-7003
VL - 4
SP - 705
EP - 707
JO - Inorganic Chemistry Communications
JF - Inorganic Chemistry Communications
IS - 12
ER -