1© 2013 Pearson Education, Inc. Chapter 16, Section 1

General, Organic, and Biological Chemistry

Fourth EditionKaren Timberlake

16.1Carboxylic Acids

Chapter 16Carboxylic Acids and

Ethers

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A carboxylic acid contains a a hydroxyl group (–OH) attached to a carboxyl group, which is a carbonyl group

.

Carboxylic Acids

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IUPAC Names of Carboxylic Acids

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IUPAC Names of Carboxylic Acids

The name of the carboxylic acid of benzene, is benzoic acid. The carbon in the carbonyl group is bonded to . carbon 1 in the benzene ring. The ring is numbered to give the lowest possible . numbers for any substituents. The prefixes ortho, meta, and para may be used to . show the position of one other substituent.

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IUPAC Names of Carboxylic Acids

The prefixes ortho, meta, and para may be used to show the position of one other substituent. Insert diagram of benzoic acid, 4-aminobenzoic acid and 3,4-

dichlorobenzoic acid bottom pg 571 with labels.

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Common Names of Carboxylic Acids Many carboxylic acids are still named by their

common names that include prefixes, form, acet, propion, butyr.

When using the common names, the Greek letters alpha (), beta (), and gamma () are assigned to the carbons adjacent to the carboxyl carbon.

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Formic Acid

A red ant sting contains formic acid that irritates the skin.

H

C

O

OH

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Guide to Naming Carboxylic Acids

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Give the IUPAC and common name for each carboxylic acid.

IUPAC Names for Carboxylic Acids

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Give the IUPAC and common name for each carboxylic acid.

Analyze the Problem.

IUPAC Names for Carboxylic Acids

Functional Group

IUPAC Naming Name

carboxylic acid Change the -e of the alkane name to -oic acid and count from carbon 1 of the carboxyl group for any substituents.

Alkanoic acid

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Give the IUPAC and common name for each carboxylic acid.

Step 1 Identify the longest carbon chain and replace the -e in the corresponding alkane name with -oic acid.

butanoic acid benzoic acid

IUPAC Names for Carboxylic Acids

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Give the IUPAC and common name for each carboxylic acid.

Step 2 Give the location and name of each substituent by counting the carboxyl carbon as 1.

a. 2-methylbutanoic acid b. 3-chlorobenzoic acid

-methylbutyric acid meta-chlorobenzoic acid

IUPAC Names for Carboxylic Acids

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Alpha Hydroxy Acids

Alpha hydroxy acids (AHAs) occur naturally in . fruit, milk, and . sugar cane. are used in skin . care products.

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Give the IUPAC and common names for each of the following.

A.

B.

C.

Learning Check

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Give the IUPAC and common names for each of the following.

A.

B.

C.

Solution

2-Bromobenzoic acid(o-bromobenzoic acid)

2-Methylpropanoic acid(-methylpropionic acid)

ethanoic acid (acetic acid)

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Preparation of Carboxylic Acids

Carboxylic acids are prepared by oxidizing primary alcohols or aldehydes. from the oxidation of ethanol, which produces

ethanoic acid (acetic acid).

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Esters

Esters differ from carboxylic acids by the replacement of H

in the hydroxyl group with an alkyl group. are fragrant components of many fruits, such as

bananas, oranges, and strawberries.

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Esterification is the reaction of a carboxylic acid and alcohol in the presence of an acid catalyst to produce an ester.

Insert esterification reaction pg 580

Esterification

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Acetylsalicylic Acid

Aspirin is used to relieve pain and

reduce inflammation. is an ester of salicylic acid and acetic acid. is derived from the bark of

a willow tree.

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Acetylsalicylic Acid

In 1899, Bayer chemical company in Germany produced an ester of salicylic acid and acetic acid, called acetylsalicylic acid (aspirin) that was less irritating to the stomach than salicylic acid.

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Methyl Salicylate

Oil of wintergreen is used to soothe sore muscles. has a pungent, minty odor. is an ester of salicylic acid and methanol.

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Polyester

Terephthalic acid (an acid with two carboxyl groups) reacts with ethylene glycol to form ester bonds on both ends of the molecules.

This allows them to combine forming long chains of molecules called polyester.

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Esters in Plants

Esters give flowersand fruits their pleasant fragrances and flavors.

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Guide to Naming Esters

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Naming Esters

The name of an ester contains the names of the alkyl group from the alcohol, and the carbon chain from the acid with -ate ending.

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Learning Check

Give the IUPAC and common name of the following ester, responsible for the flavor and odor of pears.

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Give the IUPAC and common name of the following ester, responsible for the flavor and odor of pears.

Step 1 Write the name of the carbon chain from the alcohol as an alkyl group.

propyl from 1-propanol

Solution

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Give the IUPAC and common name of the following ester, responsible for the flavor and odor of pears.

Step 2 Change the -ic acid of the acid name to -ate.

Ethanoate (acetate) Propyl ethanoate (IUPAC name)

Propyl acetate (common name)

Solution

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Boiling Points of Esters

The boiling points of esters are higher than for alkanes of similar mass. are lower than alcohols and carboxylic acids of

similar mass because esters cannot form hydrogen bonds with each other.

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Solubility in Water

Esters are soluble in water when they have 1–5 carbon

atoms. form hydrogen bonds from the partial negatively

charged carbonyl oxygen to the partial positively charged hydrogen atoms in water.

decrease their solubility in water with an increase in the number of carbon atoms.

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In acid hydrolysis, an ester reacts with water to produce a carboxylic

acid and an alcohol. a strong acid catalyst is required.

Acid Hydrolysis of Esters

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Base hydrolysis (also called saponification) is the reaction of an ester with a strong base. produces the salt of the carboxylic acid and an

alcohol.

Base Hydrolysis (Saponification)

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“Soaps”

The base hydrolysis of long-chain fatty acids produces acid salts called “soaps.”

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Cleaning Action of Soap

A soap contains a nonpolar end that dissolves in nonpolar

fats and oils and a polar end that dissolves in water. forms groups of soap molecules called micelles that

dissolve in water and are washed away.