Figure: 21_03-02T2.jpg Title: Esters, Amides, and Nitriles Commonly Used as Solvents for Organic Reactions Caption: Table 21-2 Esters, amides, and nitriles commonly used as solvents for organic reactions. Notes:
Figure: 21_05.jpg Title: IR Frequencies of Lactones and Lactams Caption: Ring strain in a lactam increases the carbonyl stretching frequency. Notes: High strained systems have higher C=O frequencies.
21.1 - Part 1 Structure and Properties of Carboxylic Acid Derivatives - Wade 7th
Chapter 21 2
All the derivatives can be converted to the
carboxylic acid by acidic or basic hydrolysis.
Esters and amides are commonly found in
Chapter 21 3
Esters from Carboxylic Acids
Esters can be made from the carboxylic acid
through the Fischer esterification.
Excess alcohol is used to drive the equilibrium
toward the ester.
Chapter 21 4
Nomenclature of Esters
Esters are named as alkyl carboxylates.
The first word is derived from the alkyl group
of the alcohol, and the second word from the
carboxylate group of the carboxylic acid.
Chapter 21 5
Reaction of —OH and —COOH on same molecule
produces a cyclic ester called lactone.
To name, add the word lactone to the IUPAC acid
name or replace the -ic acid of common name with
Chapter 21 6
Amides are the product of the reaction of a carboxylic
acid with ammonia or an amine.
Not basic because the lone pair on nitrogen is
delocalized by resonance.
The C—N bond has double-bond character.
Chapter 21 7
Protonation of Amides
Under acidic conditions, the double-bonded
oxygen will get protonated.
Chapter 21 8
Classes of Amides
1° amide has one C—N bond (two N—H).
2° amide or N-substituted amide has two C—N bonds
3° amide or N,N-disubstituted amide has three C—N
bonds (no N—H).
3º amide 2º amide 1º amide
Chapter 21 9
Nomenclature of Amides
For 1° amide, drop -ic or -oic acid from the
carboxylic acid name, add -amide.
Alkyl groups bonded to nitrogen are named
with N-alkyl to indicate their attachment to the
Chapter 21 10
Cyclic amides are called lactams.
To name, add the word lactam to the IUPAC
acid name or replace the -ic acid of common
name with -olactam.
Chapter 21 11
Nitriles contain the cyano group (—C≡N).
They can be hydrolyzed to carboxylic acids.
Chapter 21 12
Structures of Acetonitrile and
In both compounds, the atoms at the ends of the triple bonds
are sp hybridized, and the bond angles are 180°.
In place of the acetylenic hydrogen atom, the nitrile has a lone
pair of electrons in the sp orbital of nitrogen.
The nonbonding electrons on the nitrogen are not basic.
Chapter 21 13
For IUPAC names, add -nitrile to the alkane name.
The Ethyl Octanoate group can also be named as a
substituent, the cyano group.
Common names come from the carboxylic acid.
Replace -ic acid with -onitrile.
CH3 C N
acetonitrile 3-cyanopentanoic acid
CH3 CH2 CH CH2 COOH
Chapter 21 14
R C Cl
R C Br
Also called acyl halides.
These are more reactive than carboxylic acids, so
they are used to synthesize other acid derivatives
such as esters and amides.
Used in the Friedel–Crafts acylation to make
Chapter 21 15
Acid Halide Nomenclature
CH3CH2 C Cl
CH3CHCH2 C Br
propanoyl chloride 3-bromobutanoyl bromide
Named by replacing -ic acid with -yl halide.
Acyl chlorides are more common.
Chapter 21 16
Two molecules of acid combine with the loss of water
to form the anhydride.
Anhydrides are more reactive than acids, but less
reactive than acid chlorides.
A carboxylate ion is the leaving group in nucleophilic
acyl substitution reactions.
Chapter 21 17
CH3 C O
CH3 CF3 C O
CF3 CH3 C O
ethanoic methanoic anhydride
(acetic formic anhydride)
The word acid is replaced with anhydride.
For a mixed anhydride, name both acids.
Chapter 21 18
The functional group with the highest priority
determines the parent name.
CH C NCH2CH3
acid > ester > amide > nitrile > aldehyde > ketone >
alcohol > amine > alkene > alkyne
Chapter 21 19
Boiling Points of Carboxylic Acid Derivatives
Chapter 21 21
Amides have very high boiling points and melting
points compared to other compounds of similar
Melting points increase with increasing number of
Tertiary amides cannot hydrogen bond, but still have
high boiling points.
Chapter 21 22
Acid chlorides and anhydrides are too
reactive to be used with water or alcohol.
Esters, 3° amides, and nitriles are good
polar aprotic solvents.
Solvents commonly used in organic
Chapter 21 30
The carbonyl carbons of acid derivatives appear at
shifts around 170 to 180 ppm, slightly more shielded
than the carbonyl carbons of ketones and aldehydes.
The α-carbon atoms absorb around 30 to 40 ppm.