Ch. 14: Carboxylic Acids, Esters, Amines and Amides

Chem 20 El Camino College 1

H 3 C O Carboxylic Acids, Esters, Amines O H CH 3 O H 3 C O H 3 C H 3 C N amine CH 3 carboxylic acid ester O C OH carboxyl group 2

Naming Carboxylic Acids  Name the longest carbon chain containing the carboxyl group.

 Use the suffix “oic acid”  # the chain to give the carboxyl gp the lowest #  Give the location and name of other substituents in alphabetical order, using numbers, hyphens, and commas between numbers 3

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Name These O O C H OH H 3 C methanoic acid (formic acid) C OH ethanoic acid (acetic acid) O C H 3 CH 2 C OH propanoic acid O OH 3-methylpentanoic acid 5

Benzoic Acid  Benzoic acid is an important carboxylic acid O O O H C C OH HC C OH OH HC CH C H 6

Carboxylic Acid Properties  Carboxylic acids are extremely polar  They have higher boiling pts than alcohols, ketones, and aldehydes of similar mass  propanal, bp = 49 o C  1-propanol, bp = 97 o C  acetic acid, bp = 118 o C  Carboxylic acids with 4 C or less are water soluble 7

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Esterification  Carboxylic acids react with alcohols in the presence of heat and acid (H + ) to form esters and water  The OH comes off the carboxylic acid, and the H comes off the alcohol  A new bond forms to make the ester O O O H + CH 2 CH 3 H 3 C O H CH 2 CH 3 H 3 C O + H 2 O 10

H O OH Draw the Ester Product O H + , heat + H O CH 3 H O O O CH 3 OH + H O CH 2 CH 3 H + , heat O CH 2 CH 3 O O H + , heat OH + H O CH 3 CH 3 O 11

Naming Esters  Name the the part that came from an alcohol (directly connected to an oxygen) first, use “yl”  Then name the part that came from a carboxylic acid, use the “oate” suffix O O O C H 3 C O methyl ethanoate CH 3 H 3 CH 2 C C O methyl propanoate CH 3 C H 3 CH 2 C O ethyl propanoate CH 2 CH 3 12

Properties of Esters  The scents of many flowers and fruits are esters 13

Types of Amines  Amines are classified as primary (1 o ), secondary (2 o ), or tertiary (3 o )  In 1 o amines, the N is attached to 1 carbon  In 2 o amines, the N is attached to 2 carbons  In 3 o amines, the N is attached to 3 carbons N H H ammonia H N H 3 C H 1 o amine H N H 3 C H 3 C 2 o amine H N H 3 C H 3 C 3 o amine CH 2 CH 3 14

Naming of Amines  Name the carbon attachments in alphabetical order, use the word “amine”  Use di- and tri- for identical substituents H 3 C H N H methylamine H 3 C H 3 C N H dimethylamine H 3 C H 3 C N CH 2 CH 3 ethyldimethylamine 15

Properties of Amines  Amines tend to be bad-smelling compounds  Amines are polar, they have relatively high boiling points  Small amines are water soluble.

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Amide  Amides are derivative of carboxylic acids, in which a nitrogen group replaces the hydroxyl group. Amide is formed when a salt of carboxylic with ammonia or amine is heated; a molecule of water is eliminated.

 Amide can be hydrolyzed back to carboxylic acid and ammonium salt in acidic solution, or to a salt of carboxylic acid and ammonia or amine in basic solution.

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