Ch. 8: Carboxylic Acids

Question 1

Carboxylic acids

Answer 1

Contain a carbonyl and a hydroxyl group connected to the same carbon– always terminal groups

Question 2

Carboxylic acids nomenclature

Answer 2

Indicated w the suffix -oic acid. Salts are named w the suffix -oate and dicarboxylic acids are -dioic acids

Question 3

Physical properties of Carboxylic acids

Answer 3

Carboxylic acids are polar and hydrogen bond very well, resulting in high boiling points. Often exist as dimers in solution. The acidity of a carboxylic acid is enhanced by the resonance between its oxygen atoms. Acidity can be further enhanced by substituents that are electron withdrawing and decreased by substituents which are electron donating. Beta-dicarboxylic acids, like other 1, 3-dicarbonyl compounds have an alpha hydrogen that is also highly acidic

Question 4

Making Carboxylic acids

Answer 4

The oxidation of primary alcohols or aldehydes using an oxidizing agent like potassium permanganate (KMnO4), dichromate salts (Na2Cr2O7 or K2Cr2O7 ), or chromium trioxide (CrO3)

Question 5

Nucleophilic acyl substitution

Answer 5

Common reaction in carboxylic acids–a nucleophile attacks the electrophilic carbonyl carbon, opening the carbonyl and forming a tetrahedral intermediate. The carbonyl reforms, kicking off the leaving group.

Question 6

Amide formation by nucleophilic acyl substitution

Answer 6

If the nucleophile is ammonia or an amine, an amide is formed. Amides are given the suffix -amide.

Question 7

Lactam

Answer 7

Cyclic amides are called lactams.

Question 8

Ester formation by nucleophilic acyl substitution

Answer 8

If the nucleophile is an alcohol an ester is formed. Esters are given the suffix -oate.

Question 9

Lactones

Answer 9

Cyclic esters are called lactones

Question 10

Anhydride formation by nucleophilic acyl substitution

Answer 10

If the nucleophile is another carboxylic acid, an anhydride is formed. Both linear and cyclic anhydrides are given suffix anhydride

Question 11

Carboxylic acid reduction

Answer 11

Carboxylic acids can be reduced to a primary alcohol w a strong reducing agent like lithium aluminum hydride (LiAlH4). Aldehyde intermediates are formed, but are also reduced to primary alcohols. Sodium borohydride (NaBH4) is a common reducing agent for other organic reaction, but is not strong enough to reduce a carboxylic acid

Question 12

Decarboxylation

Answer 12

Beta dicarboxylic acids and other beta-keto acids can undergo spontaneous decarboxylation when heated, losing a carbon as carbon dioxide. This rxn proceeds via a 6 membered cyclic intermediate

Question 13

Soap

Answer 13

Mixing long chain carboxylic acids (fatty acids) w a strong base results in the formation of a salt we call soap in this process called saponification– soaps contain hydrophilic carboxylate heads and hydrophoboic alkyl chain tails

Question 14

Micelles

Answer 14

Soaps organize in hydrophilic environments to form micelles. A micelle dissolves nonpolar organic molecules in its interior and can be solvated w water due to its exterior shell of hydrophilic groups