In a dichlorocarbene addition to cyclohexene using a phase-transfer catalyst, why is it important to vigorously shake the mixture??
Recall that a phase transfer reaction requires two phases, one is polar and the other nonpolar. The catalyst Q+ has a both ionic and a non-polar motif. The Q+ reacts with the nucleophile, N, through a rather weak bond and is transferred to the nonpolar phase in which the Q and N dissociates, leaving raw N to react with the specified reactant within the nonpolar phase. Thus the point is to stir up the reaction by shaking it.
Also, which carbene (:CH2 or :CCl2) would be expected to be more reactive and why?
I would imagine that :CH2 would be more reactive, :CCl2 can donate electrons through delocalization (p-d) and thus stabilize the positive charge.