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Glycine exists as a zwitterion but o- and p- aminobenzonic acids do not. Explain. |
Answer» Solution :In o- or p -aminobenzoic acids , the lone PAIR of ELECTRONS on the `NH_2` group is dontateed towards the benzene ring. As a result , acidic character of `-COOH` group and BASIC character of `-NH_(2)` group DECREASES. Therefore the weakly acidic `-COOH`group cannot transfer a `H^(+)` ion to the weakly basic `-NH_2` group. Thus, o-or p-aminobenoic acids do not exist as zwitterions.  However , in glycine , no such electron -WITHDRAWING benzene ring is present . As a result , `-NH_2` group is sufficiently basic and hence accepts a proton form `-COOH` group to form a zwitterion. `underset("Glycine")(H_2N-CH_2-COOH) hArrH_(3)overset(+)N-CH_2-COO^(-)` . |
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