15-1

Principles and Applications ofInorganic, Organic, and Biological

ChemistryDenniston, Topping, and Caret

4th ed

Chapter 15

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Power Point to Accompany

15-2

Functional Group Formulas

R1 C

O

NR2

R3amideR1, R2, R3 may beH, alkyl, aryl

R1 C

O

OH

R1 may be H,alkyl,or aromatic

Carboxylic acid

15-3

Functional Group Formulas-2

R1 C

O

O R2

R2 may not be H

ester

RC

O

OR C

O anhydrideR may be alkylor aryl

R1 C

O

Cl

R1 may be H,alkyl,or, aromatic

acid chloride

15-4

15.1 Acids: Structure and PropertiesLow molecular weight acids are water

soluble due to hydrogen bonding with water.

CH3

C OH

O

HO

HH

O HH

O H

15-5

Acids: Boiling pointsLow molecular weight acids have

abnormally high boiling points due to dimer formation via H bonding.

CH3 CO H

OCH3C

OH

O

15-6

Acids: Boiling points-2Derivative boiling points vary with

the ability to hydrogen bond.

CH3CH2C OH

O

CH3C O CH3

O

CH3 C

O

NH

H

CH3CH2CH2 OH

bp 117 o

bp 62 o

bp 118 o

bp 222 o

15-7

Acids: Common Namesformic acid

acetic acid

butyric acid

CH OH

O

CH3C OH

O

CH3CH2 CH2 C OH

O

15-8

Acids: IUPAC NamesStart numbering at the COOH carbonReplace the -e of the alkane name with

oic acid. Name the acid:

CH3 CH CH2 CBr

OH

O

IUPAC: 3-bromobutanoic acid

(Common: -bromobutyric acid)

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Examples of Carboxylic Acids

CH3 CH2 CO

OH16

Stearic acid, found in beef fat

COOHCH2

C COOHCH2COOH

OHCitric acid, found in citrus Fruits and part of the central cycle of metabolism

COOHCH OHCH3

Lactic acid, found in soremuscles and yogurt.

15-10

Reactions of Carboxylic AcidsCarboxylic acids are prepared by

oxidation of primary alcohols and aldehydes.

CH3CH2CH2OH

CH3CH2CHO CH3CH2C

OOH

H2CrO4

Warm

15-11

Reactions of Acids-2

1. Carboxylic acids are weak Lowry-Bronsted acids.

2. Acids form acid derivatives.

a) acid chlorides

b) esters (to follow)

c) amides

d) anhydrides

15-12

Reactions of Acids-31. Acids react with water to form

solutions that are weakly acidic.

CH3CO

OH + CH3CO

O +H2O H3O+

15-13

Reactions of Acids-4Acids form salts with bases.

The salts react with strong mineral acids to give the original organic acid.

CH3CO

OH + NaOH

CH3CO

OH + NaHCO3

CH3CO

ONa

CH3CO

ONa

+ H2O

+ H2O + CO2

+ NaClCH3CO

OHCH3CO

ONa + HCl CH3CO

OHCH3CO

ONa

15-14

Acids Form Esters2b. Carboxylic acids react with alcohols

to form esters, an important group in biochemistry. The reaction requires an acid catalyst. The reaction is an equilibrium reaction.

COH

OOH +CH3OH

COH

OO CH3+H2O

H3O+

15-15

15.2 EstersStructure and Physical Properties

Esters are mildly polar

Many have pleasant aromas

E. g. isoamyl acetate=banana oil

ethyl butanoate=pineapple aroma

Boil at approximately the same temperature as carbonyls with comparable molecular weight.

15-16

Esters: IUPAC Names

1. Name the alkyl group attached to the oxygen atom first. (Alcohol part of the ester)

2. Base name for the acid part of the structure from the longest chain ending in the C=O.

Change the oic acid of the acid name to oate and add this to the name in 1 as a second word.

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Esters: IUPAC Names-2A = ethyl propanoate

B = methyl benzoate

acid part alcohol part

C O CH3

O

CH3CH2CO

O CH2CH3

Name

A

B

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Ester Reactions: PreparationCarboxylic acids react with alcohols to

give esters. The reaction is catalyzed by strong mineral acid.

+CH3 OH

H3O+

H3PO4CH2C

OOHCH3 CH3OCH2C

OCH3

+ H2O

15-19

Ester Reactions: HydrolysisThe main reaction of esters is

hydrolysis, reaction with water. However, the uncatalyzed reaction is slow and either mineral acid or base is used as a catalyst. When stoichiometric base is used, the reaction is called saponification (soap making).

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EstersAcid hydrolysis: the products are

the acid and an alcohol.

Substitutionhere!

CH3OH

CH3CH2CO

O CH3+H2O

CH3CH2CO

OH +

H3O+

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EstersBase hydrolysis (saponification): the

products are the acid salt and an alcohol.

CH3OH

CH3CH2CO

O CH3+NaOH

CH3CH2CO

ONa+

Substitutionhere!

A salt inbasicsolution.

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Esters: Saponification (Soap making)Saponification (soap making) is

basic hydrolysis of fats

CH2

CH

CH2

O

O

O CO

CO

CO

R

R

R

CH2

CH

CH2

OH

OH

OH

NaO CO

R

3 NaOH

+

a soap, Na or Ksalt of a fatty acid

3R is part of a long chain (fatty) acid (C15 or C17)

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Esters: Condensation PolymersPolyesters are condensation polymers

formed by eliminating a small molecule (e. g. H2O) when combining a diacid and a diol.

Polyethylene terphthalate (PETE) is used to make Mylar, shatterproof plastic bottles, and polyester fabric.

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Polethylene terphthalate

COOHHOOC + OH CH2CH2OHnH+

CHOOCO

O CH2CH2OH+ H2O

Terphthalic acid 1,2-ethanediol

CCO

O CH2CH2OO

* *n

Continued condensationat each end

Repeating unit of the polymer

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15.3 Acid chlorides and Acid AnhydridesAcid chlorides are named:

by replacing the –ic acid ending of the common name with –yl chloride.

by replacing the –oic acid ending of the IUPAC name with –oyl chloride.

CH3CO

Clethanoyl chloride(acetyl chloride)

CO

ClCl4-chlorobenzoyl chloride(p-chlorobenzoyl chloride)

15-26

Acids ChloridesCarboxylic acids form acid

chlorides which are good acyl group transfer reagents.

CH2C

O

OHCH3CH2C

O

ClCH3

PCl3PCl5SOCl2

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Acid chlorides-2Acid chlorides react with water

(hydrolysis) to reform the acid. Substitution of the OH for the Cl occurs at the acyl carbon.

CH3CH2CO

Cl

CH3CH2CO

OH

+

+HCl

H2OSubstitutionhere!

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Acid chlorides-3Acid chlorides react with alcohols to form

esters. Substitution of the OR for the Cl occurs at the acyl carbon.

CH3CH2CO

Cl CH3OH

CH3CH2CO

O CH3

+

+ HCl

Substitutionhere!

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Acid AnhydridesSymmetrical anhydrides are named by

replacing the -acid ending of the acid with –anhydride.

CH3CO

O CO

CH3

ethanoic anhydriceacetic anhydride

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Acid Anhydrides-2Anhydrides are formed using the reactions

below.

CH3CO

O CO

CH3CH3CO

OH OH CO

CH3+

warmH3PO4

CH3CO

O CO

CH3CH3CO

O Cl CO

CH3+

SOCl2

OH CO

CH3

15-31

Acid Anhydrides-3Acetic anhydride reacts with

alcohols to give acetate esters.

CH3CO

O CO

CH3++

OH CH

CH3

CH3

CH3CO

O CH

CH3

CH3

OH CO

CH3

15-32

Anhydrides-4Acetic anhydride reacts with

amines to give amides.

CH3CO

O CO

CH3++

OH CO

CH3

CH3NH2

CH3NHCH3CO

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15.4 Phospho and thioestersPhosphoric acid reacts with alcohols to

give esters.

The ester can then react with a second or third acid to give phosphoric acid anhydrides. ADP and ATP of biochemistry fame are the important examples of phosphoric acid esters.

15-34

Phosphoric acid esters

Ester bond

adenosinetriphosphate, ATP

P

O

O

O O P

O

O

O

N

OHOH

OO CH2

N

NN

NH2

P

O

O

Anhydride bonds

15-35

ThioestersIn biochemistry, acetyl coenzyme A (CoA-SH)

reacts with acyl groups to “activate” them for further biological reaction by forming a thioester.

CH3CO

CoA-SCOO

-

CCH2COO

-

O+ CCH2

COO-

COO-

CH2COO

-

OH

+CoA-SH

Acetyl CoA

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The End

Acids and Derivatives