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phase transfer catalytic reactions

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qwerty:
In a dichlorocarbene addition to cyclohexene using a phase-transfer catalyst, why is it important to vigorously shake the mixture??

Also, which carbene (:CH2 or :CCl2) would be expected to be more reactive and why?

Thanks

Mitch:
:CH2 is more reactive because the chlorines help stabalize the carbene.

GCT:

--- Quote ---In a dichlorocarbene addition to cyclohexene using a phase-transfer catalyst, why is it important to vigorously shake the mixture??
--- End quote ---

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.



--- Quote ---Also, which carbene (:CH2 or :CCl2) would be expected to be more reactive and why?
--- End quote ---

I would imagine that :CH2 would be more reactive, :CCl2 can donate electrons through delocalization (p-d) and thus stabilize the positive charge.



--- Quote ---Thanks
--- End quote ---


qwerty:
Thanks, but can you clarify what N and Q are?

GCT:
N is the nucleophile and Q is the transfer catalyst.  You might want to review what phase transfer catalysts are all about as I'm a bit rusty on this topic.

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