Organic Chemistry · Chapter 8: Carboxylic Acids

Question

In ____, the α-hydrogen is also quite acidic, pKa of around 9.

Answer

In 1,3-dicarbonyls, the α-hydrogen is also quite acidic, pKa of around 9.
In 1,3-dicarbonyls, the α -hydrogen is also quite acidic, pK a of around 9.
Note: This also applies to the α-hydrogens in a β-diketone, β-ketoacids, β-dialdehydes, and other molecules that share the 1,3-dicarbonyl structure
Explanation ↑: As you see above, there is an additional Oxygen atom with the β-ketoester relative to the β-diketone. So that Oxygen-CH3 is going to try to donate some electron density to the molecule thereby decreasing its acidity, and by extension the stability, in turn causing an increase to the pKa.
Why do carboxylic acids dissociate to a greater extent than do alcohols?
The difference is that the hydroxy substituent of a carboxylic acid is attached to a carbonyl group, whose positively polarized and sp2 -hybridized carbonyl carbon exerts a powerful electron-withdrawing inductive effect. In addition, the carboxylate ion is signifi cantly stabilized by resonance, much as is the enolate ion formed by deprotonation of the -carbon in aldehydes and ketones.

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More cards in Chapter 8: Carboxylic Acids

A carboxylic acid contains both a ____ group, bonded to the same carbon.

Carboxylic acids are named by adding the suffix ____ to the parent root when the carboxylic acid is the highest-priority functional group.

The same common-name prefixes are used for both aldehydes and carboxylic acids: ____ for three.

Cyclic carboxylic acids are named by listing the cycloalkane with the suffix ____.

Salts of carboxylic acids are named beginning with the cation, followed by the name of the acid with the ending ____ replacing – oic acid .

____, followed by the name of the acid with the ending – oate replacing – oic acid .

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