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Acid catalysed tautomerism and base catalysed Explain the mechanism of attack using reagent D+ in acid catalysed and OD- in base catalysed (donot use bond line diagram) . What are the final ptoducts?? |
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Answer» In the acid-catalyzed reaction, the molecule is first protonated on oxygen and then loses the C-H proton in a second step. When the enol form reverts to the keto – since this is an equilibrium process – it picks up a deuteron instead of a proton since the solution is D2O. Also, the D+ (or H+ if water is the solvent) is regenerated at the end (catalyst). In the base-catalyzed reaction, the C-H proton is removed first by the base (for example hydroxide ion OH-, OD- ) and the proton (or D+ in our case) added to the oxygen atom in a second step. Also, OD- (or OH- if water is the solvent) is regenerated at the end (catalyst). The enolate ion generated from the enol (Fig. I.6) in the base-catalyzed mechanism is nucleophilic due to: Oxygen’s small atomic radius and Formal negative charge. |
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