Why ketone more acidic than ester

While the pK a values for alkyl C-H bonds is typically on the order of , pK a values for these alpha hydrogens is more on the order of This can most easily be explained by resonance stabilization of the product carbanion, as illustrated in the diagram below.

In the presence of a proton source, the product can either revert back into the starting ketone or aldehyde or can form a new product, the enol. The equilibrium reaction between the ketone or aldehyde and the enol form is commonly referred to as "keto-enol tautomerism". Do ketones have resonance?

This gives an empty p-orbital in carbon and a p-orbital in oxygen with two electrons, leading to a positive charge on carbon, and a negative charge on oxygen. Is carbon a nucleophile? A nucleophile is Lewis base, i. As a Group IV element, a neutral carbon does not have any lone pairs. It is not nucleophilic. Which carbonyl is more reactive?

Factors that place more positive charge on the carbonyl electron withdrawing groups nearby make the carbonyl more positive and more reactive. Factors that place additional electron density on the carbonyl electron donors nearby make the carbonyl less reactive. Are esters ketones? An ester is a ketone where one of the carbons is bonded to an oxygen that is bonded to something else. A carboxylic acid is where an ester's oxygen is bonded with a hydrogen. Aldehyde is a ketone where one of the bonds on the carbon is a hydrogen.

Alcohols are simply an OH group bonded to a carbon. Which aldehyde is most reactive? Is aldehyde more acidic than alcohol? The stronger the acid, the weaker the conjugate base.

So, while aldehydes, alcohols, and water all have pKa values of about the same, on average, water is the most acidic. Ketones are the least acidic. Steven Farmer Sonoma State University. Acidity of Alpha Hydrogens Alkyl hydrogen atoms bonded to a carbon atom in a a alpha position relative to a carbonyl group display unusual acidity. Relative Acidity of Alpha Hydrogens The acidity of alpha hydrogens varies by carbonyl functional group as shown in the table below.

Exercise 1. Answer 1. Contributors and Attributions.