IIT JEE , AIEEE Forum - Chemistry , Organic Chemistry

AAKRITI

In pinacole pinacolone rearrangement according to migratory aptitude,

is aryl > H or the reverse ?

In SN Sanyal, it is given H > aryl and my friend told that in peter sykes it is aryl > H . I am confused.

AAKRITI

Someone please guide me... please

arun-rashi

i think migratory attitude order is phenyl than H than methyl,because sability fector is responsible so phenyl is more than H but always remember for all reaction is different like bayer villeger,beckmanns etc order control by structure of ractant,stereochemistry,intermediate stbility.

chinmoyrajwanshi

AAKRITI

IF U R GOING FO IIT THEN DONT LEARN ANYTHING UNDERSTAND THINGS

UR QUESTION IS " WHICH BOND WILL SHIFT FIRST "

ANSWER IS " THE BOND WHICH IS WEAKER WILL SHIFT FIRST "

i.e. HYDRIDE SHIFT > PHYNYL SHIFT > METHYL SHIFT

AAKRITI

Hiiiiii Chinmoy Rajwanshi,

I think the one which is more electron rich migrates. Am I wrong?

Arun sir also said this only. But according to you the one whose bond can be easily broken migrates first, right? Therefore there is difference in the opinion.

That is why in some books I found that phenyl shifts first and in some H. So I was confused.

Kindly explain me what made you think I learn things and not understand them.

chinmoyrajwanshi

i have read sanyal , in that it is written that first hydride shift then bigger group to smaller group ( alternate metord to learn )

see rest books can be wrong but sanyal cannot be wrong

thats my opinion

our teachers also gave us the same order

and dont make things standard it can vary from question to question but in most rxns we follow HYDRIDE SHIFT > PHYNYL SHIFT > METHYL SHIFT u can try any question from any book using this , if u not get the answer give me the question i will try it

"phenyl shifts first and in some H" do u read it in arihant

it is written wrong in arihant

AAKRITI

I saw a book today, which says it is difficult to rank H in the migratory aptitude in case of pinacole rearrangement!!

The logic which I've read is it should stabilise the carbocation . This obviously implies aryl > alkyl > H . My sir also taught this only.

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