Organic Chemistry · Chapter 8: Carboxylic Acids

Question

Rank order of stability, and by extension acidity from least to most: Dicarboxylic acids, monocarboxylic acids, and carboxylate anion of dicarboxylic acid.
Order: ____.

Answer

Rank order of stability, and by extension acidity from least to most: Dicarboxylic acids, monocarboxylic acids, and carboxylate anion of dicarboxylic acid.
Order: Dicarboxylate Acid with Carboxylate Anion → Monocarboxylic Acid → Dicarboxylic Acid.
Rank order of stability, and by extension acidity from least to most: Dicarboxylic acids, monocarboxylic acids, and car…
Reasoning: In dicarboxylic acids, each –COOH group influences the other –COOH group. Carboxylic acids are electron-withdrawing due to the electronegative oxygen atoms they contain. The net result is that dicarboxylic acids are more acidic than the analogous monocarboxylic acids. However, when one proton is removed from the molecule, the carboxylate anion is formed, resulting in an immediate decrease in the acidity of the remaining carboxylic acid. This makes sense because if the second group were deprotonated, it would create a doubly charged species with two negative charges repelling each other. Due to this instability, the second proton is actually less acidic (harder to remove) than the analogous proton of a monocarboxylic acid.
↓↓↓↓↓↓↓↓
↓↓↓↓↓↓↓↓
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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