IIT JEE 2009 P2 Q3

In the following carbocation, H/CH3 that is most likely to migrate to the positively charged carbon is

A) CH3 at C-4

B) H at C-4

C) CH3 at C2
D) H at C2

21 Answers

1
shubh_452 ·

thr is no conjugation....so o of oh shows -i effevt and increase charge on the carbocation formed causing decrease in stability

1
gordo ·

migratory aptitude is directly proportional to nucleophilicity.....1)

a carbocation that is near an atom having a lone pair of e- like o or N is more stable than a 3° carbocation (reason there forms a c=0+ where there is a + charge on O..in this case the octet of all the atoms is complete)......2)
using these two statements, we can say that the answer shud be D)

11
Anirudh Narayanan ·

arey....i know that CH3 and OH groups have opposite effects........and that CH3 releases electrons......so OH's gotta withdraw them ....... so how'll it help the stability of the carbocation??

1
~AjInKyA~ ·

final answer
d

11
Anirudh Narayanan ·

i thought that -OH group withdraws electrons??

1
AARTHI ·

ans is surely d....due to stabilisation offered by oxygen.....

1
kamalendu ghosh ·

yes!! answer is d

1
Ghosty ·

answer is D
because + charge on carbon bearing -OH is most stable as O as lone pair of electrons... Think of pinacol pinacolone rearrangement

1
~AjInKyA~ ·

C4
Is rite
just q of h or ch3
but i think ch3 is more common
n seeeing situations , h i s stable , n so ch3 is too
but ch3 can make it more stable , i donno y but i can feel it
A

11
Anirudh Narayanan ·

If H at C4 goes as H- to the carbocation (hydride shift) then, the positive charge will move to a tertiary position and will become more stable....so i think answer is b

1
~AjInKyA~ ·

A

62
Lokesh Verma ·

[url=http://iitjee2009solutions.targetiit.com]Solution Key with Question Paper of 2009 IIT JEE[/url]

1
shubh_452 ·

ans.- b
3degree carbocation

1
greatvishal swami ·

yeah ajln
and u r rite tooo

1
~AjInKyA~ ·

U R RITE VISHAL

1
~AjInKyA~ ·

but how com yaaaar?
in C2
ders OH
n it will pull elektron
then y will methy or go fm C2?
then definately
C4 naaaaaaaaaa ?

then only
H OR METHYL
naaaaaa
but methyl is more efficient
then
A

1
greatvishal swami ·

a

1
voldy ·

D is right

1
~AjInKyA~ ·

i m sry
i think
A
SURE a

1
~AjInKyA~ ·

yes
D is rite !

1
kamalendu ghosh ·

I did d

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