Carboxylic Acids and Derivatives

Milbank High School

Learning Objectives/Study Questions 1.What is the general structure for a carboxylic

acid? An ester? An amide? What is the functional group for each of these classes of organic molecules?

2.How are the common names of carboxylic acids, esters, and amides determined? How are these compounds named using IUPAC nomenclature?

3.Why are the boiling points of carboxylic acids higher than those of alcohols of similar molar mass? How do the boiling points of esters and amides compare with alcohols of similar molar mass?

Learning Objectives/Study Questions 4.How do the solubilities of carboxylic acids,

esters, and amides of five carbons or less compare to the solubilities of comparable alkanes and alcohols in water?

5.How are carboxylic acids, esters, and amides prepared?

6.What typical reactions take place with carboxylic acids, esters, and amides?

7.What are some common carboxylic acids and esters and their uses?

8.What are phosphate esters? Why are they important?

Carboxylic Acids: The Functional Groups Carboxyl group

Combo of the carbonyl and hydroxyl groups

                                                                                                   

                                                                                                   

                                                                                                   

Amides/Esters:Derivatives of carboxylic acids

AmidesFunctional group has a nitrogen instead of an

oxygen attached to the carbonyl group

EstersLike an ether and carboxylic acid

                                                                                                   

                                                                                                   

                                                                                                   

                                                                                                   

                                                                                                   

Common Carboxylic Acids: Structures and Names Formic acid (methanoic acid)

Ants Acetic acid (ethanoic acid)

Vinegar Weak acid

Propionic acid Butyric Acid (butanoic acid)

Rancid butter Found in body odor

                     

                         

                                

        

                                      

Benzoic Acid/Dicarboxylic acids

Benzoic Acid

Dicarboxylic acidsTable 16.3Two carboxylic groups

                              

Preparation of Carboxylic Acids

Final oxidation products of aldehydes and/or primary alcohols

Our body oxidize alcohols to acids Liver converts ethanol to acetic acid

                                                        

                                                 

Physical Properties of Carboxylic Acids Colorless liquids with disagreeable odors

Caproic acid Produced by skin bacteria Body odor, locker room smell

High melting points Boiling points increase with the number of

carbons 1-4 carbons: soluble in water

Physical Properties of Carboxylic Acids Sometimes carboxylic acids produce dimers

Changes physical propertiesLower freezing points and other properties

                                         

Neutralization

All carboxylic acids react with NaOH, KOH and other strong bases to form water-soluble salts

RCOOH + NaOH(aq) RCOO-Na+(aq) + H2O

RCOOH + NaHCO3 (aq)  RCOO-Na(aq) + H2O + CO2(g)

Esters

Derivatives of carboxylic acids Widely found in nature Pleasant odors

Fruits and flowers -ic ending replaced by -ate

Physical Properties

Boiling point: about same as those of ketones

3-5 carbons borderline for solubility (again) Uses:

Solvents (nail-polish remover)

Preparation of Esters:Esterification Prepared by treating carboxylic acids with

an alcohol in the presence of HCl or H2SO4

                                                                                          

Hydrolysis

Alkoxy group (-OR’) replaced by another group

Basically the reverse of esterification

                                                                                        

                                                                                        

                                                                                                             

                                                                                                             

Saponification

Base is used to hydrolyze an ester

                                                   

                                                                  

Amides

Nitrogen atom attached to a carbonyl atom Naming:

-ic or –oic replaced by –amide

Amides

Naming Con’tName substituent attached to nitrogen Indicate with N

                                                                                                                                        

Physical Properties of Amides

Most are solids Colorless, odorless Soluble to about 5-6 carbons Very high boiling points

Polar nature of amide groupFormation of hydrogen bonds

Synthesis of Amides

Addition of ammonia to a carboxylic acid

                                                                                                                                      

Hydrolysis of Amides

Amide + water = carboxylic acid Can be basic or acidic