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Organic Chemistry

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26 Jun 2012 12:52:26 IST

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ortho effect in benzoic acid

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Sagar Saxena

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26 Jun 2012 20:02:58 IST

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whenever an group is present at ortho positon then it increases the acidity of the benzoic acidic doesnt matter what effect it gives

this is because due to the ortho group the acidic group i.e. COOH will rotate from the plane of the ring structure therefore

the COOH group will stop taking part in resonance thereby increasing the acidity of the ortho substituted benzoic acid

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Yash Pandit

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2 Jul 2012 11:45:16 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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