Leaving Group Dependence of the Rates of Halogen–Magnesium Exchange Reactions

published on 09.05.2012
Relative reactivities and absolute rate constants of the reactions of haloarenes with i-PrMgCl·LiCl were investigated in THF at 0 °C. The rate of the halogen–magnesium exchange decreases in the series ArI > ArBr > ArCl (relative reactivities: 1011:106:1). Preliminary experiments show that the p-tolylsulfinyl group is exchanged slightly faster than iodide, while a tosyl group is exchanged at least 104 times more slowly than a bromide.
TU München