Author Topic: phenylcyclopropane rearrangment rxns  (Read 2443 times)

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stratosphere

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phenylcyclopropane rearrangment rxns
« on: March 09, 2004, 09:59:00 PM »
after finding this convenient synthesis of phenylcyclopropane from cinnamdehyde and hydrazine:

http://www.orgsyn.org/orgsyn/prep.asp?prep=cv5p0929



i was looking for articles dealing with rearrangement reactions of this molecule to 1-phenyl-2-propene.

stratosphere

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the only info ive been able to find on this is
« Reply #1 on: March 11, 2004, 09:39:00 PM »
the only info ive been able to find on this is from my chem text, and basically states that cyclopropane undergoes isomerization to propene at 500C with a contact time of ~0.5s, it goes on to state that substituted cyclopropanes can undergo at sometimes much lower temps.
it does not state what solid phase catalysts aid in the isomerization.
(presumably this would carried out by running the vapor through a heated tube, which may or may not contain a catalyst)

due to the stabilizing influence of the phenyl group on a alpha-carbon radical, i would assume the predominate product would be 1-phenyl-1-propene especially if the temperature is kept as low as possible while still getting a resonable rate of isomerization,
the stabilizing influence of the phenyl group on isomerization intermediates (a-carbon radical) would also presumably lower the temp needed as compared to a alkyl substituted cyclopropane, however i cannot find good data for even simple alkylcyclopropanes.
the (newer) literature on cyclopropane isomerizations seems to focus on arcane aspects of photocatalyzed pericyclic reactions with YAG lasers etc, raman scattering, etc.