Actually both esters and amides show tautomerism but the thing is their enol percentage is way less that keto percentage. So, usually it is said that these groups dont show tautomerism.
Why their enol form has less percentage?
Well let’s start with our basic ketone group.
Here after removal of alpha hydrogen, the carbanion participates in resonance with the polar pi bond (c=o)
Esters
In esters as you can see after removal of alpha hydrogen it too participates in resonance with the polar pi bond (c=o)
But in this case oxygen lone pair also tries to participate thus there’s a competition for resonance, thus effectiveness of each of them decreases.
Therefore in esters compounds tend to be in their keto form itself
Amides
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