What was the role of aprotic polar solvent (e.g. DMF) as catalyst in chlorination using thionyl chloride?
There are two possible answers to this obvious organic lab question: 1. Polar aprotic solvents can help accelerate SN2-type reactions, which chlorinations can be. 2. It is common when doing a chlorination using thionyl chloride to add a drop of DMF; the DMF actually reacts with the thionyl chloride and forms a much more reactive chlorinating reagent. It is this reagent that actually does the chlorination. (This is typically done when forming an acid chloride from a carboxylic acid, for example.
