-OH weakens C=C bond of enol by electronegativity: but isn't OH e- donating?

[TheRelevant]

Hey guys,

EK mentions that the enol is less stable because C=C is weakened by the electronegativity of oxygen. However, isnt the -OH group electron donating? Why would an electron donating group then weaken the C=C bond?

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[chemtopper]

electron density of lone pairs on the oxygen atom repels the pi electron density of the C=C bond which results in the unstability of C=C bond. A pi bond is electron rich bond and becomes unstable in the presence of electron donating groups.

 

[TheRelevant]

Thanks so much chemtopper! That was very helpful

 

[chemtopper]

Thanks so much chemtopper! That was very helpful

you are welcome!