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12 May 2012 18:11:53 IST

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acidic strength

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why ortho substituted methyl benzoic acid more acidic than benzoic acid

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ROHAN KUMAR

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12 May 2012 19:08:01 IST

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aditya u may heard about intra molecular H-BONDING. IN THIS CASE ALSO H- BONDING IS OCCURRING BETWEEN THE 'O' PRESENT IN THE BENZOIC ACID AND 'H' PRESENT IN METHYL GROUP. WHICH WILL BECOME MORE EFFECTIVE AFTER LOSING 'H' ATOM IN BENZOIC ACID AS "OH" WILL BECOME "O-" WHICH FORMS BETTER H- BOND AS COMPARED TO "OH"

Mayank Sharma

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22 May 2012 09:19:08 IST

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no in my opinion H Bonding doesnt occurs as C-H bond is not sufficiently polar...but is attributed to Ortho effect in Carboxylic acids...

Mayank Sharma

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22 May 2012 09:22:30 IST

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The ortho effect if based on the premise that an ortho-substituted acid (take benzoic acid as an example) is more acidic than the meta or para-substituted form. This effect is not dependent on the nature of the substituent (e- donating or e- withdrawing). The reason for this is that the steric hinderance between the substituent and the neighboring carboxylate forces the carboxylate to bend out of the plane of the aromatic ring. This conformational shift alters the delocalization of the charge into the benzene ring, making it easier for the negative charge to be delocalized throughout the pi-system.

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