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Acid catalysed dehydration of alcohol with a bicyclo group
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Mojo Jojo
Acid catalysed dehydration of alcohol with a bicyclo group
Pathway 2 is unlikely. The tert-butyl group stays put, i.e., it remains attached to the same carbon throughout the reaction. It is the rest of the molecule that rearranges. The mechanism of this reaction was demonstrated 70 years ago. Compare this reaction with Possible nonclassical ion from a bicyclic system on ChemSE. There is information at the link on labeling to elaborate the mechanism.
Pathway 2 is unlikely. The tert-butyl group stays put, i.e., it remains attached to the same carbon throughout the reaction. It is the rest of the molecule that rearranges. The mechanism of this reaction was demonstrated 70 years ago. Compare this reaction with Possible nonclassical ion from a bicyclic system on ChemSE. There is information at the link on labeling to elaborate the mechanism.
There is not much difference (strain) between a 5- ans 6-membered ring. The delocalized cation is the same.in 2, 3 and 4. Aromatization drives the reaction.More
(a) I have gone through your linked answer (but could not access the references mentioned therein) and what I understood is that isotope labeling can decide the correct mechanism between the two discussed above. So, is it determined in the cited paper? (b) In your mechanism, is there any driving force between (1) and (2)? Or this is not important and final stable product decides it?More
(a) In 1950 they didnt use isotopic labeling which is one way of testing the mechanism. They expected 4 but got 6 in the link. That result led to the spiro mechanism. (b) The cation 2 is resonance stabilized. The migratory aptitude of methyl is less than RCH2-. More
Pathway 2 is unlikely. The tert-butyl group stays put, i.e., it remains attached to the same carbon throughout the reaction. It is the rest of the molecule that rearranges. The mechanism of this reaction was demonstrated 70 years ago. Compare this reaction with Possible nonclassical ion from a bicyclic system on ChemSE. There is information at the link on labeling to elaborate the mechanism.
Pathway 2 is unlikely. The tert-butyl group stays put, i.e., it remains attached to the same carbon throughout the reaction. It is the rest of the molecule that rearranges. The mechanism of this reaction was demonstrated 70 years ago. Compare this reaction with Possible nonclassical ion from a bicyclic system on ChemSE. There is information at the link on labeling to elaborate the mechanism.
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