Transcript Carboxylic Acids and Their Derivatives

Power Point to Accompany
Principles and Applications of
Inorganic, Organic, and Biological
Chemistry
Denniston, Topping, and Caret
4th ed
Chapter 15
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
15-1
Functional Group Formulas
O
R1 C OH
O
R2
R1 C N
Carboxylic acid amide R3
R1 may be H,
R1, R2, R3 may be
alkyl,or aromatic H, alkyl, aryl
15-2
Functional Group Formulas-2
O
R1 C O R2
ester
R2 may not
be H
O O
R C O CR
O
R1 C Cl
acid chloride
R1 may be H,
alkyl,or, aromatic
anhydride
R may be alkyl
or aryl
15-3
15.1 Acids: Structure and Properties
Low molecular weight acids are water
soluble due to hydrogen bonding with
water.
O H
H
O
O H
C O
H
H
CH3
H
O
H
15-4
Acids: Boiling points
Low molecular weight acids have
abnormally high boiling points due to
dimer formation via H bonding.
O
H O
CH3 C
C CH3
O H
O
15-5
Acids: Boiling points-2
Derivative boiling points vary with
the ability to hydrogen bond.
O
CH3CH2CH2 OH
bp 117
o
O
bp 118
O
CH3C O CH3
bp 62
CH3CH2C OH
o
o
H
CH3 C N
bp 222
o H
15-6
Acids: Common Names
O
formic acid
HC OH
acetic acid
O
CH3C OH
O
butyric acid
CH3CH2 CH2 C OH
15-7
Acids: IUPAC Names
Start numbering at the COOH carbon
Replace the -e of the alkane name with
oic acid. Name the acid:
O
Br
CH3 CH CH2 C OH
IUPAC: 3-bromobutanoic acid
(Common: g-bromobutyric acid)
15-8
Examples of Carboxylic Acids
O
CH3 CH2 16C OH
Stearic acid,
found in beef fat
COOH
CH2
Citric acid, found in citrus
HO C COOH Fruits and part of the central
cycle of metabolism
CH2
COOH
COOH
H C OH
CH3
Lactic acid, found in sore
muscles and yogurt.
15-9
Reactions of Carboxylic Acids
Carboxylic acids are prepared by
oxidation of primary alcohols and
aldehydes.
CH3CH2CH2OH
O
H2CrO4
O
CH3CH2C OH
Warm
CH3CH2CH
15-10
Reactions of Acids-2
1. Carboxylic acids are weak LowryBronsted acids.
2. Acids form acid derivatives.
a) acid chlorides
b) esters (to follow)
c) amides
d) anhydrides
15-11
Reactions of Acids-3
1. Acids react with water to form
solutions that are weakly acidic.
O
CH3C OH + H2O
O
CH3C O + H3O+
15-12
Reactions of Acids-4
Acids form salts with bases.
The salts react with strong mineral
acids to give the original organic
acid.
O
O
CH3C OH + NaOH CH3C ONa + H2O
O
O
CH3C OH + NaHCO3 CH3C ONa + H2O + CO2
O
CH3C ONa + HCl
O
CH3C OH+ NaCl
15-13
Acids Form Esters
2b. 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.
O
O
C OH
C O CH3+H O
+
CH
OH
2
3
OH
OH
H3O+
15-14
15.2 Esters
Structure 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.
15-15
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.
15-16
Esters: IUPAC Names-2
A = ethyl propanoate
B = methyl benzoate
O
N
CH3 CH2 C O CH2 CH3 A
a acid part alcohol part
m
O
C O CH3 B
e
15-17
Ester Reactions: Preparation
Carboxylic acids react with alcohols to
give esters. The reaction is catalyzed
by strong mineral acid.
O
O
+
H3O
CH3CH2C O CH3
CH3CH2C OH
H3PO4
+ CH3 OH
+ H2O
15-18
Ester Reactions: Hydrolysis
The 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).
15-19
Esters
Acid hydrolysis: the products are
the acid and an alcohol.
O
CH3CH2C O CH3 + H2O
Substitution
here!
H3
+
O
O
CH3CH2C OH +CH3OH
15-20
Esters
Base hydrolysis (saponification): the
products are the acid salt and an
alcohol.
O
CH3CH2C O CH3 + NaOH
Substitution
here!
A salt in
basic
solution.
O
CH3CH2C ONa +CH3OH
15-21
Esters: Saponification (Soap making)
Saponification (soap making) is
basic hydrolysis of fats
CH2OH
O
CH2O C R
CH OH
O
3 NaOH
CH
OH
2
CH O C R
+
O
O
CH2O C R
3 NaO C R
R is part of a
long chain (fatty)
acid (C15 or C17)
a soap, Na or K
salt of a fatty acid
15-22
Esters: Condensation Polymers
Polyesters 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.
15-23
Polethylene terphthalate
HOOC
COOH + n HO CH2CH2OH
Terphthalic acid
HOOC
O
* C
H+ 1,2-ethanediol
O
C O CH2CH2OH
+ H2O
Continued condensation
at each end
O
C O CH2CH2O
n*
Repeating unit of the polymer
15-24
15.3 Acid chlorides and Acid Anhydrides
Acid 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.
O
ethanoyl chloride
CH3C Cl (acetyl chloride)
Cl
O
4-chlorobenzoyl chloride
C Cl (p-chlorobenzoyl chloride)
15-25
Acids Chlorides
Carboxylic acids form acid
chlorides which are good acyl
group transfer reagents.
PCl3
O
PCl
5
CH3CH2 C Cl
CH3 CH2C OH
SOCl2
O
15-26
Acid chlorides-2
Acid chlorides react with water
(hydrolysis) to reform the acid.
Substitution of the OH for the Cl occurs
at the acyl carbon.
O
CH3CH2C Cl + H2O
Substitution
here!
O
CH3CH2C OH +HCl
15-27
Acid chlorides-3
Acid chlorides react with alcohols to form
esters. Substitution of the OR for the Cl
occurs at the acyl carbon.
O
CH3CH2C Cl + CH3OH
Substitution
here!
O
CH3CH2C O CH3 + HCl
15-28
Acid Anhydrides
Symmetrical anhydrides are named by
replacing the -acid ending of the acid with
–anhydride.
O O
ethanoic anhydrice
CH3C O C CH3 acetic anhydride
15-29
Acid Anhydrides-2
Anhydrides are formed using the reactions
below.
O O
O
O
warm
+
CH3C OH HO C CH3 H3PO4 CH3C O C CH3
O
CH3C O
+
O
Cl C CH3
O O
CH3C O C CH3
SOCl2
O
HO C CH3
15-30
Acid Anhydrides-3
Acetic anhydride reacts with
alcohols to give acetate esters.
O O
CH3C O C CH3
+ CH3
HO CH
CH3
CH3
O
CH3C O CH
+
CH3
O
HO C CH3
15-31
Anhydrides-4
Acetic anhydride reacts with
amines to give amides.
O O
CH3C O C CH3
+
CH3NH2
O
CH3C NH CH3
+
O
HO C CH3
15-32
15.4 Phospho and thioesters
Phosphoric 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.
15-33
Phosphoric acid esters
NH2
Ester bond
Anhydride bonds
O
O
N
N
O
O P O P O P O CH2
O O O
adenosine
triphosphate, ATP
N
N
OH
O
15-34
OH
Thioesters
In biochemistry, acetyl coenzyme A (CoA-SH)
reacts with acyl groups to “activate” them
for further biological reaction by forming a
thioester.
-
O
COO
CoA-S C CH3 + C O
Acetyl CoA CH2 COO
COO
CH2
HO C COO
CH2
COO
+ CoA-SH
15-35
The End
Acids and Derivatives
15-36