Chemistry Pinacol Rearrangement of asymmetrical diol

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The discussion centers on the pinacol rearrangement of 1,1-diphenylethane-1,2-diol and the protonation of hydroxyl groups at carbon 1 or carbon 2. The initial hypothesis suggests that protonation occurs at carbon 1 to form a stable tertiary carbocation. However, it is clarified that for the rearrangement to proceed, the hydroxyl group on carbon 2 must be the one that leaves. This indicates a need to consider the stability and reactivity of both hydroxyl groups in the mechanism. Understanding the correct protonation site is crucial for predicting the rearrangement pathway.
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Homework Statement
write down the mechanism of pinacol arrangement of the following diols
Relevant Equations
none
I have a question for the first part a), pinacol rearrangement of 1,1-diphenylethane-1,2-diol (did I name that right..?).
How would you know if protonation takes place on the hydroxyl molecule attached to carbon 1 or carbon 2?
My guess is that the hydroxyl group at carbon 1 would be protonated, since leaving of the hydroxyl group (as water) will yield tertiary carbocation, which is stable.
Is this approach correct?
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Thank you for your help!
 
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qkfqkekr said:
Homework Statement:: write down the mechanism of pinacol arrangement of the following diols
Relevant Equations:: none

I have a question for the first part a), pinacol rearrangement of 1,1-diphenylethane-1,2-diol (did I name that right..?).
How would you know if protonation takes place on the hydroxyl molecule attached to carbon 1 or carbon 2?
My guess is that the hydroxyl group at carbon 1 would be protonated, since leaving of the hydroxyl group (as water) will yield tertiary carbocation, which is stable.
Is this approach correct?
View attachment 287170


Thank you for your help!
If the hydroxyl group at carbon 1 was protonated, then which group would undergo rearrangement for the piñacolada to become piñacologne? I believe it needs to be the hydroxyl group on carbon 2.
 
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