An unexpected highly exothermic decomposition was observed during routine safety analysis of the magnesium-iodine exchange reaction of 2-iodo-4-fluorotoluene (3) with commercially available i-PrMgCl (2.0 M solution in THF). When the reaction mixture was scanned in an adiabatic calorimeter with the use of a 2° C/min temperature ramp, a rapid exothermic decomposition with an onset temperature of approximately 80° C was ...
