silver tetrafluoroborate 1) lig. SO2/1,2-dichloroethane, -10 deg C, 1 h, 2) 1,2-dichloroethane/H2O, 5 min; Yield given. Multistep reaction. Yields of byproduct given;

silver tetrafluoroborate 1) 1,2-dichloroethane, 0 deg C, 1 h, 2) 1,2-dichloroethane/water, 5 min; Yield given. Multistep reaction. Yields of byproduct given;