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Organic Chemistry

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5 Mar 2010 16:01:18 IST

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is CH3 -R or +R group

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is CH3 -R or +R group

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shahrukh khan

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5 Mar 2010 16:08:25 IST

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it is +R effect my frnd

sandeep

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5 Mar 2010 16:16:07 IST

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remember ................... methyl groups have ''electron pushing'' tendency . so CH3 is a +R group

AIR 538 Asish

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5 Mar 2010 18:07:30 IST

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above answers are wrong.... Methyl groups dont have R effect at all (they cant undergo resonance) but they have donating inductive and hyperconjugative effects. which is +I and +H (or M)

HIMANSHU JAIN

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5 Mar 2010 18:14:21 IST

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ya!! i totally agree with the last answer.

As much no. of hydrogen atoms are attached with carbon atoms, more is hyperconjugation.

It shows +I effect.

Since, it doesn't have any lone pair, so no resonance effect.

charanjit ghai

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5 Mar 2010 19:54:13 IST

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frnds -CH3 group can also show +R effect through hyperconjugation effect.in Ph-CH3,CH3 is attached to a C which is directly attached to CH3 has vaccant p orbital n 3 alpha CH bonds.so through hyperconjugation C in CH3 takes electrons from H, which result in bond fission on double bond. as a reut ressonating structures can be formed.

Madhusudan Chavan

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11 Mar 2010 17:32:34 IST

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resonance or mesomerism involves delocalisation of pi and n-electrons in a conjugate system. The generation of centres of high and low electron density in conjugated systems as a result of the phenomenon of resonance ( or mesomerism) is called resonance effect ( R-effect) or mesomeric effect ( M-effect).

Electron withdrawing groups such as C=O, COOR,CN, NO2, etc. when placed adjacent ot a double bond withdraw electrons of the double bond toward themselves, such groups are said to possess -R ( or -M) effect.

Groups such as OH,OR,NH2, X,etc. with one or more lone pair of electrons when present adjacent to double bond, donate or release electrons to the double bond, are said to possess +R ( or +M) effect.

Thus in the strickt sence we cannot classify alkyl group as +R or -R.

However, alkyl group attached to C=C can show hyperconjugation, electron donating effect, so we can consider it to be +R effect.

SUNIL KHORWAL

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13 Mar 2010 12:02:10 IST

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CH3, only show R effect not +R or -R

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