1. Carboxylic acids: R-COOH, R-CO2H, Common names:
HCO2H formic acid L. formica ant
CH3CO2H acetic acid L. acetum vinegar
CH3CH2CO2H propionic acid G. “first salt”
CH3CH2CH2CO2H butyric acid L. butyrum butter
CH3CH2CH2CH2CO2H valeric acid L. valerans

2. Carboxylic acids, common names:…
CH3(CH2)4CO2H caproic acid L. caper goat
CH3(CH2)5CO2H ---
CH3(CH2)6CO2H caprylic acid
CH3(CH2)7CO2H ---
CH3(CH2)8CO2H capric acid
CH3(CH2)9CO2H ---
CH3(CH2)10CO2H lauric acid oil of lauryl

3.
C—C—C—C—C=O
δ γ β α used in common names

4. special names

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
CH3CO2H ethanoic acid
CH3CH2CO2H propanoic acid
CH3
CH3CHCOOH 2-methylpropanoic acid Br
CH3CH2CHCO2H 2-bromobutanoic acid

6. dicarboxylic acids:
HOOC-COOH oxalic acid
HO2C-CH2-CO2H malonic acid
HO2C-CH2CH2-CO2H succinic acid
HO2C-CH2CH2CH2-CO2H glutaric acid
HOOC-(CH2)4-COOH adipic acid
HOOC-(CH2)5-COOH pimelic acid
Oh, my! Such good apple pie!

8. salts of carboxylic acids:
name of cation + name of acid: drop –ic acid, add –ate
CH3CO2Na sodium acetate or sodium ethanoate
CH3CH2CH2CO2NH4 ammonium butyrate
ammonium butanoate
(CH3CH2COO)2Mg magnesium propionate
magnesium propanoate

10. polar + hydrogen bond  relatively high mp/bp water insoluble
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
RCO2H NaOH  RCO2-Na H2O
stronger stronger weaker weaker
acid base base acid

11. RCO2H RCO2-
covalent ionic
water insoluble water soluble
Carboxylic acids are insoluble in water, but soluble in 5% NaOH.
Identification.
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.

12. Carboxylic acids, syntheses:
oxidation of primary alcohols
RCH2OH K2Cr2O7  RCOOH
2. oxidation of arenes
ArR KMnO4, heat  ArCOOH
3. carbonation of Grignard reagents
RMgX CO2  RCO2MgX H+  RCOOH
4. hydrolysis of nitriles
RCN H2O, H+, heat  RCOOH

13. oxidation of 1o alcohols:
CH3CH2CH2CH2-OH CrO3  CH3CH2CH2CO2H
n-butyl alcohol butyric acid
1-butanol butanoic acid
CH CH3
CH3CHCH2-OH KMnO4  CH3CHCOOH
isobutyl alcohol isobutyric acid
2-methyl-1-propanol` methylpropanoic acid

14. oxidation of arenes:
note: aromatic acids only!

15. carbonation of Grignard reagent:
R-X RMgX RCO2MgX RCOOH
Increases the carbon chain by one carbon.
Mg CO2 H+
CH3CH2CH2-Br CH3CH2CH2MgBr CH3CH2CH2COOH
n-propyl bromide butyric acid
Mg CO H+

17. Hydrolysis of a nitrile:
H2O, H+
R-CN R-CO2H
heat
H2O, OH-
R-CN R-CO H+  R-CO2H
R-X NaCN  R-CN H+, H2O, heat  RCOOH
1o alkyl halide
Adds one more carbon to the chain.
R-X must be 1o or CH3!

20. carboxylic acids, reactions:
as acids
conversion into functional derivatives
a)  acid chlorides
b)  esters
c)  amides
reduction
alpha-halogenation
EAS

21. as acids:
with active metals
RCO2H Na  RCO2-Na H2(g)
with bases
RCO2H NaOH  RCO2-Na H2O
relative acid strength?
CH4 < NH3 < HCCH < ROH < HOH < H2CO3 < RCO2H < HF
quantitative
HA H2O  H3O A ionization in water
Ka = [H3O+] [A-] / [HA]

22. Ka for carboxylic acids  10-5
Why are carboxylic acids more acidic than alcohols?
ROH H2O  H3O RO-
RCOOH H2O  H3O RCOO-
ΔGo = R T log Keq
The position of the equilibrium is determined by the free energy change, ΔGo.
ΔGo = ΔH - TΔS
ΔGo  ΔH Ka is inversely related to ΔH, the potential energy difference between the acid and its conjugate base. The smaller the ΔH, the larger the Ka and the stronger the acid.

23. ΔH
The smaller the ΔH, the more the equilibrium lies to the right, giving a larger Ka ( a stronger acid ).

24. Resonance stabilization of the carboxylate ion decreases the ΔH, shifts the ionization in water to the right, increases the Ka, and results in carboxylic acids being stronger acids.

25. Effect of substituent groups on acid strength?
CH3COOH x 10-5
ClCH2COOH x 10-5
Cl2CHCOOH 5,530 x 10-5
Cl3CCOOH 23,200 x 10-5
-Cl is electron withdrawing and delocalizes the negative charge on the carboxylate ion, lowering the PE, decreasing the ΔH, shifting the ionization to the right and increasing acid strength.

26. Effect of substituent groups on acid strength of benzoic acids?
Electron withdrawing groups will stabilize the anion, decrease the ΔH, shift the ionization to the right, increasing the Ka, increasing acid strength.
Electron donating groups will destabilize the anion, increase the ΔH, shift the ionization in water to the left, decreasing the Ka, decreasing acid strength.

27. -NH2, -NHR, -NR2
-OH
-OR electron donating
-NHCOCH3
-C6H5 -R -H -X
-CHO, -COR
-SO3H
-COOH, -COOR electron withdrawing
-CN
-NR3+
-NO2

28. Relative acid strength?Ka
p-aminobenzoic acid 1.4 x 10-5
p-hydroxybenzoic acid 2.6 x 10-5
p-methoxybenzoic acid 3.3 x 10-5
p-toluic acid x 10-5
benzoic acid x 10-5
p-chlorobenzoic acid x 10-5
p-nitrobenzoic acid x 10-5

29. Conversion into functional derivatives:
 acid chlorides

30.  esters
“direct” esterification: H+
RCOOH R´OH  RCO2R´ H2O
-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 PCl3  RCOCl R´OH  RCO2R´
-convert the acid into the acid chloride first; not reversible

32.  amides
“indirect” only!
RCOOH SOCl2  RCOCl NH3  RCONH2
amide
Directly reacting ammonia with a carboxylic acid results in an ammonium salt:
RCOOH NH3  RCOO-NH4+
acid base

34. Reduction:
RCO2H LiAlH4; then H+  RCH2OH
1o alcohol
Carboxylic acids resist catalytic reduction under normal conditions.
RCOOH H2, Ni  NR

36. Alpha-halogenation: (Hell-Volhard-Zelinsky reaction)
RCH2COOH X2, P  RCHCOOH HX X
α-haloacid
X2 = Cl2, Br2

38. 5. EAS: (-COOH is deactivating and meta- directing)

39. spectroscopy:
IR: -COOH O—H stretch – 3000 cm-1 (b)
C=O stretch – 1725 (s)
nmr: -COOH – 12 ppm

40. p-toluic acid
-COO—H stretch
C=O

41. c b a

42. Carboxylic acids, syntheses:
oxidation of primary alcohols
RCH2OH K2Cr2O7  RCOOH
2. oxidation of arenes
ArR KMnO4, heat  ArCOOH
3. carbonation of Grignard reagents
RMgX CO2  RCO2MgX H+  RCOOH
4. hydrolysis of nitriles
RCN H2O, H+, heat  RCOOH

43. carboxylic acids, reactions:
as acids
conversion into functional derivatives
a)  acid chlorides
b)  esters
c)  amides
reduction
alpha-halogenation
EAS