Derivatives Of Carboxylic Acids - Faculty Personal Homepage- KFUPM

107 Pages·2008·2.67 MB·English

Chapter 15
Derivatives Of Carboxylic
Acids
1
• Derivative Of Carboxylic Acid is a compound
that yields a carboxylic acid upon reaction
with water
2
CCOOMMPPAARRIISSOONN OOFF CCAARRBBOONNYYLL CCOOMMPPOOUUNNDDSS
The typical reaction of an aldehyde or ketone is addition,
or an addition followed by loss of water.
H
C
O O
NuR
enamine
Nu
C C R
-H O NuR
Nu 2 C
R
imine
acetal
Nu
:Nu-R R
hemiacetal
Acid derivatives (acyl compounds) undergo substitution
reactions.
O O
+ :X
C C
R R
X Nu-R a leaving group
3 displacement
:Nu-R
NNuucclleeoopphhiilliicc AAccyyll SSuubbssttiittuuttiioonn
SIMPLIFIED VIEW
1)
.. -
:O: :O:
slow
R C Y R C Y
Nu
addition of
+ Nu:
nucleophile
2)
.. - elimination of
:O: leaving group :O:
-
R C Y R C + Y:
Nu Nu
carbonyl group
forms again
most aren’t this simple, proton
4
transfers are usually required
RREEAACCTTIIVVIITTYY IISS AALLSSOO RREEFFLLEECCTTEEDD IINN (not considering
TTHHEE SSTTAABBIILLIITTYY OOFF TTHHEE LLEEAAVVIINNGG GGRROOUUPP acid catalysis)
MOST
O
REACTIVE
-
R C Cl Cl
O
O O
-
R C O C R O C R
O
-
R C O R'
O-R’
O
-
R C NH NH
2
2
STRONGEST
5
BASE
carboxylic acid
acid halide or
acid anhydride
ketone
ester amide
6
Spectroscopic Properties of Acid derivatives
• IR Spectra
– The carbonyl stretching frequency varies according
to the type of carboxylic acid derivative present
– O-H stretching vibrations of the carboxylic acid give a
broad band at 2500-3100 cm-1
– N-H stretching vibrations of amides appear at 3140-
3500 cm-1
7
1H NMR Spectra
•The α hydrogens of carboxylic acids and their
derivatives appear at δ 2.0-2.5
•The carboxyl group proton appears downfield at δ
10-12
8
Nomenclature Of Acid Chloride
• Acid chlorides are named by dropping the -ic acid from
the name of the carboxylic acid and adding -yl chloride
O
O O
C
CH CH CH C CH C
Cl
3 2 2 3
Cl Cl
butanoyl chloride ethanoyl chloride benzoyl chloride
butyryl chloride acetyl chloride
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PPRREEPPAARRAATTIIOONN OOFF
AACCIIDD CCHHLLOORRIIDDEESS
10