carboxylic-acids.ppt suitable for tutoring

Carboxylic acid slides suitable for tutoring.

1. Carboxylic Acids
SANTOSH
CHEMISTRY DEPT

2. Carboxylic acids:
R-COOH, R-CO
2
H,
Common names:
HCO
2
H formic acid
CH
3CO
2H acetic acid
CH
3
CH
2
CO
2
H propionic acid
CH
3CH
2CH
2CO
2H butyric acid
CH
3
CH
2
CH
2
CH
2
CO
2
H valeric acid
RC
OH
O

3. 5 4 3 2 1
C—C—C—C—C=O
δ γ β α used in common names
CH
3CH
2CH
2CHCOOH
Br
CH
3CHCH
2COOH
CH
3
bromovaleric acid -methylbutyric acid
isovaleric acid

4. COOH
COOH COOH COOH
CH
3
CH
3
CH
3
benzoic acid
o-toluic acid m-toluic acid p-toluic acid

5. IUPAC nomenclature for carboxylic acids:
parent chain = longest, continuous carbon chain that
contains the carboxyl group  alkane, drop –e, add –oic
acid
HCOOH methanoic acid
CH
3CO
2H ethanoic acid
CH
3
CH
2
CO
2
H propanoic acid
CH
3
CH
3
CHCOOH 2-methylpropanoic acid
Br
CH
3CH
2CHCO
2H 2-bromobutanoic acid

6. Dicarboxylic acids
HOOC-COOH oxalic acid
HO
2
C-CH
2
-CO
2
H malonic acid
HO
2C-CH
2CH
2-CO
2H succinic acid
HO
2C-CH
2CH
2CH
2-CO
2H glutaric acid
HOOC-(CH
2)
4-COOH adipic acid
HOOC-(CH
2)
5-COOH pimelic acid

7. CO
2H
CO
2H
CO
2H
CO
2H
CO
2H
CO
2H
phthalic acid isophthalic acid
terephthalic acid
C
COOHH
C
COOHH
C
COOHH
C
HHOOC
maleic acid
fumaric acid

8. salts of carboxylic acids:
name of cation + name of acid: drop –ic acid, add –ate
CH
3
CO
2
Na sodium acetate or sodium ethanoate
CH
3
CH
2
CH
2
CO
2
NH
4
ammonium butyrate
ammonium butanoate
(CH
3
CH
2
COO)
2
Mg magnesium propionate
magnesium propanoate

9. Physical Properties:
polar + hydrogen bond  relatively high mp/bp
water insoluble
exceptions: four carbons or less
acidic turn blue litmus  red
soluble in 5% NaOH
RCO
2H + NaOH  RCO
2
-
Na
+
+ H
2O
stronger stronger weaker weaker
acid base base acid
•Two molecules of a carboxylic acid can hydrogen bond
together.
CH
3C
O
OH
CH
3
HO
O
C

10. RCO
2H RCO
2
-
covalent ionic
water insoluble water soluble
Carboxylic acids are insoluble in water, but soluble in 5%
NaOH.
1.Identification.
2.Separation of carboxylic acids from basic/neutral organic
compounds.
The carboxylic acid can be extracted with aq. NaOH and
then regenerated by the addition of strong acid.

11. 1.oxidation of 1
o
alcohols:
CH
3CH
2CH
2CH
2-OH + CrO
3  CH
3CH
2CH
2CO
2H
n-butyl alcohol butyric acid
1-butanol butanoic acid
CH
3
CH
3
CH
3
CHCH
2
-OH + KMnO
4
 CH
3
CHCOOH
isobutyl alcohol isobutyric acid
2-methyl-1-propanol` 2-
methylpropanoic acid
General Methods of preparation of Carboxylic Acids:General Methods of preparation of Carboxylic Acids:

12. 2.Oxidation of alkylbenzenes:
CH
3
CH
3
H
3C
CH
2CH
3
KMnO
4, heat
KMnO
4, heat
KMnO
4, heat
COOH
COOH
HOOC
COOH
toluene benzoic acid
p-xylene terephthalic acid
ethylbenzene benzoic acid
+ CO
2
note: aromatic acids
only!

13. +CO
2
ether
+
RMgX RCO
O
MgX
RCOH
O
+ MgX(OH)
H
3
O+
( R-Li )
3. Carbonation of Grignard Reagents:

14. CH
3
Br
Mg
CH
3
MgBr
CO
2 H
+
CH
3
COOH
p-toluic acid
CH
3
Br
2, hv
CH
2Br
Mg
CH
2MgBr
CO
2
H
+
CH
2COOH
phenylacetic acid

15. RCH
2
Cl RCH
2
CN+
_
: : +CN Cl
RCH
2
COH
O
+NH
4
+
Hydrolysis of NitrilesHydrolysis of Nitriles
DMSO
H
2
SO
4
H
2
O
heat
S
N2

16. CH
3
Br
2, hv
CH
2Br
NaCN
CH
2CN
H
2O, H+, heat
CH
2COOH
CH
3CH
2CH
2CH
2CH
2CH
2-Br
KCN
CH
3CH
2CH
2CH
2CH
2CH
2-CN
H
2O, H+, heat
CH
3CH
2CH
2CH
2CH
2CH
2-COOH
1-bromohexane
heptanoic acid
toluene
phenylacetic acid

17. CO
2H
CH
2OH
CH
3
Br
CN
MgBr
KMnO
4, heat
KMnO
4
Mg
CO
2; then H
+
H
2O, H+, heat

18. RCH
O
RCOH
O
RCN
RCH
2
OH
CCRR
H H
RR
RXRLi
RMgX
RCCl
O
RCOR
O
H H
RR
OHOH
or
CO
2
CrO
3
CrO
3
H
2
SO
4
KMnO
4
H
2SO
4
KMnO
4
NaCN
acetone
DIBAL or
Rosenmund
KMnO
4
Li or
Mg
H
2O
H
2
O
H
2SO
4
H
2
SO
4
H
2
O
or KMnO
4
SYNTHESIS OF CARBOXYLIC ACIDSSYNTHESIS OF CARBOXYLIC ACIDS
R'
KMnO
4
( benzene = R
sidechain = R’ )
ROH
SOCl
2

19. RCH
2
COH
O
RCH
2
CO
O
+NaOH + H
2ONa
+
Carboxylate Ion FormationCarboxylate Ion Formation
pK
a
5
carboxylate ioncarboxylic acid

20. R
C
O
O
H
R
C
O
O
H
H
R
C
O
O
H
H
+
+
..
..
..
..
..
..
..
..
:
:
H
2
SO
4
R
C
O
O
H
H
H
2
SO
4
..
..
:
+
Protonation and Deprotonation Protonation and Deprotonation
of a Carboxylic Acidof a Carboxylic Acid
R
C
O
O
..
..
:
NaOH
..
:
-
equivalent structures
due to resonance

21. •Electron-withdrawing Groups:
–strengthen acids
–weaken bases
•Electron-releasing Groups:
–weaken acids
–strengthen bases
CCO
O
XCCOH
O
X +H
+

22. COH
O
COR
O
CR
O
NO
2
CN
SO
3
H
Substituents with Electron-Withdrawing Substituents with Electron-Withdrawing
Resonance ( - R ) EffectsResonance ( - R ) Effects
-R substituents strengthen acids and weaken bases
carboxyl
alkoxycarbonyl
acyl
nitro
cyano
sulfo
XY

23. OH
SH
CH
3
NH
2
F
Br
OR
OCR
O
..
CR
3
NR
2
Cl
I
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
..
::
: :
+R substituents weaken acids and strengthen bases
Substituents with Electron-ReleasingSubstituents with Electron-Releasing
Resonance ( + R ) EffectsResonance ( + R ) Effects
hydroxy
mercapto
methyl
amino
fluoro
bromo
alkoxy
acyloxy
dialkylamino
alkyl
chloro
iodo
Y
..

24. COH
O
COR
O
CR
O
NO
2
CN
SO
3
H
OR
NH
2
F
Br
OH
SH
NR
2
Cl
I
+
N(CH
3
)
3
Substituents with Electron-WithdrawingSubstituents with Electron-Withdrawing
( - ( - II ) Inductive Effects ) Inductive Effects
-I substituents strengthen acids and weaken bases
carboxyl
alkoxycarbonyl
acyl
hydroxyl
mercapto
amino
chloro
nitro
cyano
sulfonic acid
alkoxy
dialkylamino
trimethylammonium
fluoro
bromo
iodo
X

25. CH
3
CR
3
O
CO
O
Substituents with Electron-ReleasingSubstituents with Electron-Releasing
Inductive ( + Inductive ( + II ) Effects ) Effects
+I substituents weaken acids and strengthen bases
methyl
alkyl
oxide
carboxylate
R

26. CH
3
COH
O
CH
2
COH
O
F
CH
2
COH
O
Cl
CH
2
COH
O
Br
CH
2
COH
O
I
CH
2
COH
O
O
2
N
CH
2
COH
O
NH
2
CH
2
COH
O
OH
pK
a
= 4.75
2.66
2.86
2.86
3.12
1.68
3.83
2.34
increasing
acidity

27. CH
3
COH
O
ClCH
2
COH
O
ClCHCOH
O
Cl
ClCCOH
O
Cl
Cl
COH
O
H
CH
3
COH
O
CH
3
CH
2
COH
O
CH
3
CHCOH
O
CH
3
CH
3
CCOH
OCH
3
CH
3
pK
a = 4.75
2.86
1.29
0.65
3.77
4.75
4.88
4.86
5.05

28. COOH
Cl
COOH
Cl
COOH
Cl
COOH
NO
2
COOH
NO
2
COOH
O
2
N
Benzoic Acid: pK
a
= 4.19
pK
a = 2.92
3.82
3.98
2.16
3.47
3.41
ortho
meta
para
ortho
meta
para

29. Benzoic Acid: pK
a
= 4.19
COOH
OCH
3
COOH
OCH
3
COOH
OH
COOH
OH
COOH
OH
2.97
4.06
4.48
4.08
4.46

30. 1.as acids
2.conversion into functional derivatives
a)  acid chlorides
b)  esters
c)  amides
3.reduction
4.alpha-halogenation
5.EAS
Chemical Properties of Carboxylic Acids:Chemical Properties of Carboxylic Acids:

31. a)with active metals
RCO
2H + Na  RCO
2
-
Na
+
+ H
2(g)
b)with bases
RCO
2
H + NaOH  RCO
2
-
Na
+
+ H
2
O
c)relative acid strength?
CH
4
< NH
3
< HCCH < ROH < HOH < H
2
CO
3
< RCO
2
H < HF
d)quantitative
HA + H
2
O  H
3
O
+
+ A
-
ionization in water
Ka = [H
3
O
+
] [A
-
] / [HA]
1) 1) Salt formation:Salt formation:

32. RC
OH
O
SOCl
2
or PCl
3
orPCl5
RC
Cl
O
CO
2H + SOCl
2 COCl
CH
3CH
2CH
2C
O
OH
PCl
3
CH
3CH
2CH
2C
O
Cl
2) 2) Formation of acid chlorides:Formation of acid chlorides:

33. “direct” esterification: H
+
RCOOH + R´OH  RCO
2R´ + H
2O
-reversible and often does not favor the ester
-use an excess of the alcohol or acid to shift equilibrium
-or remove the products to shift equilibrium to completion
“indirect” esterification:
RCOOH + PCl
3
 RCOCl + R´OH  RCO
2
R´
-convert the acid into the acid chloride first; not reversible
3) 3) Formation of esters:Formation of esters:

34. C C
O
O
CH
3
+ H
2O
SOCl
2
C
CH
3OH
O
OH
+CH
3OH
O
Cl
H
+

35. “indirect” only.
RCOOH + SOCl
2  RCOCl + NH
3  RCONH
2
amide
Directly reacting ammonia with a carboxylic acid results in an
ammonium salt:
RCOOH + NH
3  RCOO
-
NH
4
+
acid base
OH
O
3-Methylbutanoic acid
PCl
3
Cl
O
NH
3
NH
2
O
4) 4) Formation of amides:Formation of amides:

36. C
O
OH
PCl
3
C
O
Cl
C
O
NH
2
NH
3
NH
3
amide
C
O
ONH
4
ammonium salt

37. RCO
2
H + LiAlH
4
; then H
+
 RCH
2
OH
1
o
alcohol
Carboxylic acids resist catalytic reduction under normal
conditions.
RCOOH + H
2
, Ni  No Reaction (NR)
CH
3CH
2CH
2CH
2CH
2CH
2CH
2COOH
Octanoic acid
(Caprylic acid)
LiAlH
4 H
+
CH
3CH
2CH
2CH
2CH
2CH
2CH
2CH
2OH
1-Octanol
5) 5) Reduction:Reduction:

38. CH
2C
O
OH
H
2, Pt
NR
LiAlH
4
H
+
CH
2CH
2OH

39. RCH
2
COOH + X
2
, P  RCHCOOH + HX
X
α-haloacid
X
2
= Cl
2
, Br
2
COOH
Br
2,P
NR (no alpha H)
CH
3CH
2CH
2CH
2COOH + Br
2,P CH
3CH
2CH
2CHCOOH
Brpentanoic acid
2-bromopentanoic acid
6) 6) Halogenation of alkyl groupsHalogenation of alkyl groups (Hell-Volhard-Zelinsky (Hell-Volhard-Zelinsky
reaction):reaction):

40. RCH
2COOH + Br
2,P RCHCOOH + HBr
Br
NH
2
OH
RCHCOOH
RCHCOOH
RCH=CHCOOHRCH
2CHCOOH
Br
aminoacid
N
aO
H
;then H
+
NH
3
KOH(alc)
then H
+

41. (-COOH is deactivating and meta- directing)
CO
2H
CO
2H
NO
2
CO
2H
SO
3H
CO
2H
Br
NR
HNO
3,H
2SO
4
H
2SO
4,SO
3
Br
2,Fe
CH
3Cl,AlCl
3
benzoic acid
5) 5) Aromatic Substitution:Aromatic Substitution: