Post on 27-Dec-2015
R H
O
R R
O
R OH
O
R X
O
R
O
R
O
R
O
X
O
Chapter 16 Chapter 17 Chapters 18 and 19
17. CARBOXYLIC ACIDS AND DERIVATIVES. (approx. lecture time: 4 lectures)Topics covered: 17.1-17.2A-I,17.3-17.8,17.13.
Some important carboxylic acids
CH3CO2HOH
O
O
CH3O
CH3
OH
O
OH
O
O
O
Na+_
HO
O
OH
OH3C
OH
OH
OOHO
HO
O
OH
Carboxylic Acids are Weak Acids
pKa = 4.7
(vineger)
OH
OF
OH
OClor
which acid is stronger?
OH
O
or OH
O
F3C
Nomenclature
CN
CH3CN CN
CN
NC
acetonitrile acrylonitrile benzonitrile 1,4-dicyanobenzene
NaCN
sodium cyanide
Synthesis of Carboxylic Acids
Synthesis of Carboxylic Acids via Carboxylation
using Grignard
reagent
Addition-Elimination at the Acyl Carbon (explains > 95% of the chemistry)
ORDER OF REACTIVITY:
> R-CN
Nitrileand acid
“Acyl transfer”
Interconversion of Carboxylic Acid Derivatives
In principle, any carboxylic acid derivative can be converted to another. In practice, acid chlorides (RCOCl), being the most reactive, are best for making them all (except nitriles)
interconversion between amide and nitrile:
This reaction is also an “acyl transfer”
All acyl transfers
Acid anhydrides are next in reactivity, and these can be converted to esters and amides:
All acyl transfers
Esterification of Carboxylic Acids
Forward reaction: EsterificationReverse reaction:Hydrolysis
(Acids and esters have an intimate relationship)
Esterification and Hydroylsis Mechanisms
Acid-catalyzed esterification and hydrolysis:
Base-catalyzed hydrolysis:
Hydrolysis of Amides(Basis of peptide hydrolysis and protein digestion)
Acid-catalyzed:
Base-catalyzed:
R Cl
O
R O
O
OR'
R OR'
O
R OH
O
R NH2
OR C N> > > >
??
?
?
?
?
?
?
?
?
R-X
NaCN (SN2)
1. Mg/ether2. CO2
???
?
Ask yourself what interconversions are possible, indicating the reagent required and then a reaction mechanism.
You should know the ones in red !
Interconversion of Carboxylic Acid Derivatives
Some Important Amides
Kevlar(Nomex is the meta isomer)
TylenolPenicillin
Imodium (an opiod)
LSDCapsaicin
N
N(CH3)2O OH
ClHO
CH3O
HN
O
HO
HN CH3
O N
S
O
HN
R
O
H
CO2H
CH3
CH3
HN
N
Et2N O
CH3
H
H
N
NO
O
H
H
n
“bullet proof” vests