Additions to alkenes accompanied by 1,2-hydride shifts
Description: When secondary (or primary) carbocations are formed, adjacent to a more substituted carbon, hydrogen atoms can shift. This leads to formation of a more stable carbocation.
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hey James I think you made a mistake with the description reaction, a third R group was added to the product
Thank you Raj.
Will the predominant product be the hydride shift mechanism? How much more energetically favorable is this product?
Thanks!
Hi James.
For example 3, why is the Cl bonded to C3 and not C2. Is it due to the hydride Shift? If so why?
Is it because although both C2 and C3 and secondary carbons, the R group bonded to C3 is a benzene (bigger and more stable group)?
Thanks.
The benzylic carbocation (carbocation adjacent to benzene ring) is more stable than an ordinary secondary carbocation due to resonance stabilization.
Thank you for this!!! Explaining the mechanism makes so much more sense.
Is it possible to have consecutive hydride shifts?
It certainly is, although for our purposes we generally keep it to one. One fun example of multiple shifts is found in the biosynthesis of lanosterol from squalene. https://en.wikipedia.org/wiki/Lanosterol