HSSC Second year Chemistry course slides for Federal Board Pakistan, lectures by Dr. Raja Hashim Ali (also available on Youtube as a series of videos lectures). https://www.youtube.com/playlist?list=PLCfCZszhGHBdVLuL1Mxo58BGDad1EtDtx

1. Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
Chapter 20 - Carboxylic acids and functional
derivatives
Federal Board of Intermediate and Secondary
Education (FBISE)

2. • Describe preparation of carboxylic acids by carbonation of Grignard’s
reagent, hydrolysis of nitriles, and by oxidation of primary alcohols,
aldehydes and alkyl benzenes.
• Discuss reactivity of carboxylic acids.
• Describe the chemistry of carboxlyic acid by conversion to carboxylic acid
derivatives: acyl halides, acid anhydrides, esters, amides and reactions
involving inter-conversion of these.
• Describe the reactions of carboxylic acid derivatives.
• Describe isomerism in carboxylic acids.
After completing this lesson, you will be able to

3. Chapter Overview - Sections
• Carboxylic acids
• Reactions that interconvert carboxylic
acids
• Reactions of acyl halides
• Reactions of acid anhydrides
• Reactions of esters
• Reactions of amides
• Reaction of nitriles
Chapter Overview - Sections

4. Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
20.0 – Introduction to carboxylic acids and functional derivatives
Federal Board of Intermediate and Secondary
Education (FBISE)
Chemistry F.Sc
II

5. S
O
C
X
Hydrogen atom
Carbon atom
Oxygen atom
Sulphur atom
Halogens atom
Single bond
R
Double bond
Triple bond
Hydrocarbon chain
(alkyl chain)
N Nitrogen atom
H
15.7.3 – Color scheme for elements

6. Carboxylic acid
Ether linkage
Ethanoic acid/Acetic acid
CH3COOH C2H4O2
Dimethyl ether/methoxymethane
CH3OCH3  C2H6O
OR R
15.8.5.3 – Functional groups - Common functional groups -
Oxygen containing groups

7. Ester
Ketone Dimethyl ketone/Acetone/Propanone
CH3COCH3  C3H6O
Ethyl acetate/ethyl ethanoate/acetic ester
CH3COOCH2CH3  C4H8O2
C
O
R R
C
O
OR R
15.8.5.4 – Functional groups - Common functional groups -
Carbonyl groups

8. Acid halide
Carboxylic acid anhydride/
Acetate
C
O
O C
O
R R
Acetic anhydride/Ethanoic anhydride/Acetyl
acetate
CH3COOCOCH3 C4H6O3
C O
X
R
Acetyl chloride/Ethanoyl chloride
CH3COCl C2H3OCl
15.8.5.4 – Functional groups - Common functional groups -
Carbonyl groups

9. Amide
Ethylamine/Ethanamine/Acetamine
CH3CH2O  C2H7N
Ethylamide/Ethanamide/Acetamide
CH3CONH2  C2H5ON
N R
H
H
C O
N
H
R
H
Amine
15.8.5.5 – Functional groups - Common functional groups -
Nitrogen containing groups

10. Nitrile
Nitro
C NR
Ethanenitrile/Acetonitrile
CH3CN  C2H3N
Nitroethane
CH3CH2NO2  C2H5NO2
N
O
R
O
-
+
15.8.5.5 – Functional groups - Common functional groups -
Nitrogen containing groups

11. • Carboxylic acids make up a series of fatty acids which are extremely
good for human health.
o The omega-6 and omega-3 are essential fatty acids which are not produced by the
body and help in maintaining the cell membrane and control nutrient use along
with metabolism. If we consume a meal with unsaturated fat, the glucose and
other nutrients will directly rush into the blood stream without being absorbed.
Whereas if there is an intake of saturated fat, digestion will slow down and body
will get more time to absorb the energy and nutrients from the meal.
• Manufacturing of soaps need higher fatty acids. Soaps are generally
sodium or potassium salts of higher fatty acids such as stearic acid.
• Food industry uses many organic acids for the production of soft drinks,
food products etc.
o For example, acetic acid is used in making vinegar.
o Sodium salts of organic acids find application in preservatives.
o Lactic acid, oxalic acid and citric acid are simple carboxylic acids that are quite
prevalent in nature.
• In pharmaceutical industry organic acids are used in many drugs such
as aspirin, phenacetin etc.
• Acetic acids are often used as a coagulant in the manufacturing of
rubber.
• Organic acids find huge application in making dye stuff, perfumes and
rayon.
20.0.1 - Introduction - Carboxylic acid in daily life

12. 20.0.1 - Introduction - Carboxylic acid in daily life

13. • Esters that have fragrant odors are used as a constituent of
perfumes, essential oils, food flavorings, cosmetics, etc.
• Esters are used as an organic solvent.
• Natural esters are found in pheromones.
• Naturally occurring fats and oils are fatty acid esters of glycerol.
• Phosphoesters form the backbone of DNA molecules.
• Nitrate esters, such as nitroglycerin, are known for their
explosive properties.
• Polyesters are used to make plastics.
• Esters are used to make surfactants, e.g., soap and detergents.
• Esters are made by reacting alcohols and carboxylic acids
together in a condensation reaction.
• Different combinations of alcohols and carboxylic acids give rise
to different esters, and each ester has a unique aroma.
• These esters are found naturally in fruits and vegetables and are
also used in perfumes.
• You can now look up an ester in the table and find its aroma by
referring to the picture.
• Ambiguous or “mixed” smells are indicated by the presence of
multiple images in each box.
• Benzyl salicylate is amazing: some people can perceive it while
others can’t. However, people who can’t perceive benzyl
salicylate can tell that it alters the overall aroma of perfume to
which it’s been added! Magic!
• All of these esters are edible in minuscule (microgram) amounts
and are found naturally in all fruits, vegetables, herbs and spices.
20.0.2 - Introduction - Esters in daily life

14. 20.0.2 - Introduction – Esters in daily life

15. • Acetic anhydride is produced on a large scale for many applications.
o Its largest application is for the conversion of cellulose to cellulose acetate, which is a component of
photographic film and other coated materials, and is used in the manufacture of cigarette filters.
o Similarly it is used in the production of aspirin (acetylsalicylic acid), which is prepared by the
acetylation of salicylic acid.
o It is also used as a wood preservative via autoclave impregnation to make a longer-lasting timber.
o In starch industry, acetic anhydride is a common acetylation compound, used for the production of
modified starches (E1414, E1420, E1422)
o It is also used for the synthesis of heroin by the diacetylation of morphine.
• Maleic anhydride is a cyclic anhydride, widely used to make industrial coatings.
o Around 50% of world maleic anhydride output is used in the manufacture of unsaturated polyester
resins (UPR). Chopped glass fibers are added to UPR to produce fibre glass reinforced plastics that
are used in a wide range of applications such as pleasure boats, bathroom fixtures, automobiles,
tanks and pipes.
o The food industry uses maleic anhydride in artificial sweeteners and flavour enhancements.
o Personal care products consuming maleic anhydride include hair sprays, adhesives and floor
polishes.
o Maleic anhydride is also a precursor to compounds used for water treatment detergents, insecticides
and fungicides, pharmaceuticals, and other copolymers.
• Naphthalenetetracarboxylic dianhydride, a building block for complex organic
compounds, is an example of a dianhydride.
20.0.3 - Introduction - Anhydrides in daily life
Acetic anhydride
Maleic anhydride
Naphthalenetetracarboxylic
dianhydride

16. • ATP (Adenosine triphosphate) in its
protonated form is an anhydride derived from
phosphoric acid.
• The "mixed anhydride" 1,3-
bisphosphoglycerate (shown in protonated
form) occurs widely in metabolic pathways.
• 3'-Phosphoadenosine-5'-phosphosulfate
(PAPS) is a mixed anhydride of sulfuric and
phosphoric acids, and is the most common
coenzyme in biological sulfate transfer
reactions.
20.0.3 - Introduction - Anhydrides in daily life
ATP (Adenosine triphosphate)
1,3-bisphosphoglycerate
3’-Phosphoadenosine-5’-
phosphosulfate

17. • Polymers that are held together by amides are called polyamides.
o Nylon, commonly used in clothes, tyres, carpets and ropes, is a
polyamide.
o Kevlar, used in bulletproof vests and other lightweight sturdy needs,
is a polyamide.
• Diazepam (Valium) is a benzodiazepene tranquilizer.
• N,N-Diethyl-m-toluamide is an active ingredient in the bugs spray.
• Hot n chili amides!
o Capsaicin is found in red and green chilli peppers and is an active
component of paprika.
o Piperine is a component of black and white pepper.
o Zingerone is the pungent hot component in ginger.
• Sulfa drugs
o The first antibiotic, Sulfanilamide
o Folic acid
o Penicillin
• Synthetic dyes
o Mauve (William Henry Perkin)
o Tyrian purple
o Indigo
o Methyl orange
o Butter yellow
o Para red
o Chicago blue
o Some color additives in foods
20.0.4 - Introduction - Amides in daily life

18. • Nitriles occur naturally in a diverse set of plant and animal sources.
• Over 120 naturally occurring nitriles have been isolated from terrestrial and marine sources.
• Nitriles are commonly encountered in fruit pits, especially almonds, and during cooking of
Brassica crops (such as cabbage, brussel sprouts, and cauliflower), which release nitriles
through hydrolysis.
• Mandelonitrile, a cyanohydrin produced by ingesting almonds or some fruit pits, releases
hydrogen cyanide and is responsible for the toxicity of cyanogenic glycosides.
• Over 30 nitrile-containing pharmaceuticals are currently marketed for a diverse variety of
medicinal indications with more than 20 additional nitrile-containing leads in clinical
development.
• The nitrile group is quite robust and, in most cases, is not readily metabolized but passes
through the body unchanged.
• The types of pharmaceuticals containing nitriles are diverse, from vildagliptin, an antidiabetic
drug, to anastrozole, which is the gold standard in treating breast cancer.
o In many instances the nitrile mimics functionality present in substrates for enzymes, whereas in other
cases the nitrile increases water solubility or decreases susceptibility to oxidative metabolism in the liver.
• The nitrile functional group is found in several drugs.
20.0.5 - Introduction - Nitriles in daily life

19. 20.0 - Introduction to carboxylic acid and functional derivatives
Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
Federal Board of Intermediate and Secondary
Education (FBISE)
Chemistry F.Sc
II

20. Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
20.1 – Carboxylic acids
Federal Board of Intermediate and Secondary
Education (FBISE)
Chemistry F.Sc
II

21. • Many carboxylic acids are known by their common names, which was given to them before the systematic names were
evolved.
• The positions of other groups attached with the chain containing the carboxyl group are indicated by the Greek letters
α, β, γ etc.
o The carbon atom adjacent to the carboxylic group is called α (alpha) carbon and the carbon atom in the carboxyl group is not the α
carbon.
20.1.1.1 – Carboxylic acid - Nomenclature - Common system
rules
Valeric acidFormic acid
Acetic acid
Propionic acid
Butyric acid Caproic acid
Benzoic acid

22. • From the name of alkane, which contains the same number of carbon atoms
as the longest continuous chain the carboxyl group, the ending -e is dropped
and -oic acid is added in its place.
20.1.1.2 – Carboxylic acid - Nomenclature - IUPAC System
Pentanoic acidMethanoic acid
Ethanoic acid
Propanoic acid
Butanoic acid Hexanoic acid
Benzene carboxylic acid

23. • The carbon atoms of the chain containing the carboxyl group are numbered
to indicate the positions of other groups attached with it.
• The carbon atom of the carboxyl group is given the number 1.
20.1.1.2 – Carboxylic acid - Nomenclature - IUPAC System

24. • Carboxylic acids may be classified as mono-, di-, or poly- carboxylic acids as they
contin one, two or many carboxylic groups respectively in their molecules.
20.1.1.2 – Carboxylic acid - Nomenclature - IUPAC System
1,2-benzene dioic acid
or phtalic acid
Ethanedioic acid
(oxalic acid)
propanedioic acid
(malonic acid)
butanedioic acid
(succinic acid)
pentanedioic acid
(Glutaric acid)
hexanedioic acid
(Adipic acid)

25. 20.1.1.3 – Carboxylic acid - Nomenclature - Metal salts of
carboxylate anions
Sodium acetate Potassium propanoate

26. • Carboxylic acids are compounds containing a carboxyl group (COOH).
• The CO2H unit is planar and consistent with sp2 hybridization and a
resonance interaction of the lone pairs of the hydroxyl oxygen with the π
system of the carbonyl.
• The C=O double bond is shorter than the C–O single bond.
• The C–O single bond of a carboxylic acid is shorter than the C–O bond of an
alcohol.
20.1.3 – Carboxylic acids - Structure

27. • The polar nature of both the C=O and
O–H bonds (due to the
electronegativity difference of the
atoms) results in the formation of
strong hydrogen bonds with other
carboxylic acid molecules or other H-
bonding systems (e.g., water).
• The implications are
o Higher melting and boiling points as
compared to analogous alcohols.
o High solubility in aqueous media.
o Hydrogen bonded dimers in gas phase
and dimers or aggregates in pure liquid.
20.1.4 – Carboxylic acids - Physical properties

28. • Carboxylic acids are soluble in organic
solvents regardless of size.
• Like alcohols, carboxylic acids having ≤ 5
C’s are water soluble because they can
form hydrogen bonds with H2O.
• Like alcohols, carboxylic acids having > 5
C’s are insoluble in water because the non-
polar alkyl portion is too large to dissolve
in the polar H2O solvent.
• These fatty acids dissolve in a non-polar
fat like environment but do not dissolve in
water.
• Carboxylic acids have a very characteristic
NMR and IR absorptions.
20.1.4 – Carboxylic acids - Physical properties

29. • Carboxylic acids are the most acidic
simple organic compounds (pKa ~ 5).
• But they are only weak acids
compared to acids like HCl (pKa ~ -3)
or H2SO4 (pKa ~ -7). (lower the pKa,
the stronger the acid).
• Resonance stabilization of the
carboxylate ion allows the negative
charge to be delocalized between the
two electronegative oxygen atoms
(compared with alcohols pKa ~16).
• Adjacent electron withdrawing
substituents increase the acidity by
further stabilizing the carboxylate.
20.1.5 – Carboxylic acids - Acidity
Carboxylic acid Structure pKa
Ethanoic acid CH3COOH 4.7
Propanoic acid CH3CH2COOH 4.9
Fluoroethanoic acid CH2FCOOH 2.6
Chloroethanoic acid CH2ClCOOH 2.9
Dichloroethanoic acid CHCl2COOH 1.3
Trichloroethanoic acid CCl3COOH 0.9
Nitroethanoic acid O2NCH2COOH -1.7

30. • Carboxylic acids are weaker acids than mineral acids.
20.1.5 – Carboxylic acid - Acidity

31. • Carboxylic acid can be prepared by
the following methods.
o Ozonolysis of alkynes.
o Carbonation of Grignard’s reagent by
CO2.
o Hydrolysis of nitriles
o Oxidation of primary alcohols
o Oxidation of aldehydes
o Oxidation of alkyl benzenes
20.1.6 – Carboxylic acids - Preparation

32. • When ozone reacts with alkyne
followed by aqueous work up,
we get 2RCO2H.R C C R + O3
R C
O
RC
O
O
alkyne Acid anhydride
+H2O R C
OH
O
+ RC
OH
O
R C
O
RC
O
O
Carboxylic acidAcid anhydride
20.1.6.1 – Carboxylic acids - Preparation - Ozonolysis of alkynes

33. • This is a nucleophilic addition of RMgX to carbon dioxide
and takes place in two steps.
• Step1:
o The nucleophilic C in the Grignard’s reagent adds to the
electrophilic C in the polar carbonyl group.
o Electrons from the C=O move to the electronegative O
creating an intermediate magnesium carboxylate complex.
• Step2:
o This is the work-up step, a simple acid/base reaction.
o Protonation of the carboxylate oxygen creates the carboxylic
acid product from the intermediate complex.
20.1.6.2 – Carboxylic acids - Preparation - Carbonation of
Grignard’s reagent

34. • 1° and 2° alkyl halides (X = Cl, Br, I) or tosylates undergo SN2 substitution
with cyanide salts to give nitriles.
• Nitriles can be hydrolyzed to carboxylic acids without the isolation of the
amide intermediate.
• Note that the carbon skeleton is extended by 1 C atom during this reaction
sequence.
• Although aromatic nitriles cannot be prepared via the SN2 reaction, they too
can be converted to the aromatic carboxylic acid by hydrolysis.
20.1.6.3 – Carboxylic acids - Preparation - Hydrolysis of nitriles
Alkyl halide Carboxylic acidNitriles

35. • Alcohols are easily oxidized by alkaline KMnO4 or K2Cr2O7 + H2SO4
solutions to give different products.
• A primary alcohol is first oxidized to an aldehyde, which is further oxidized
to a carboxylic acid.
20.1.6.4 – Carboxylic acid - Preparation - Oxidation of primary
alcohol
CH3COH CH3COOH
K2Cr2O7 + H2SO4
50°C
Acetic acid
CH3–CH2–OH CH3COH + H2O
K2Cr2O7 + H2SO4
50°C
acetaldehydeEthyl alcohol

36. • An aldehyde is oxidized to a carboxylic acid.
20.1.6.5 – Carboxylic acid - Preparation - Oxidation of aldehydes
CH3COH CH3COOH
K2Cr2O7 + H2SO4
50°C
Acetic acidacetaldehyde
aldehyde Carboxylic acid

37. • When treated under strong oxidizing conditions, benzylic-H are oxidized all
the way to the carboxylic acid.
• Common reagents : Hot, acidic KMnO4
20.1.6.6 – Carboxylic acid - Preparation - Oxidation of alkyl
benzenes
Toluene Benzoic acid

38. • The carboxyl group shows the chemistry of both the carbonyl
and the hydroxyl groups.
• In most reactions, the carboxyl group is retained.
• However, the reactivity of the molecules is due to the presence
of the carbonyl group.
• The image shows the electrostatic potential for acetic acid
(ethanoic acid).
• The more red an area is, the higher the electron density and
the more blue an area is, the lower the electron density.
• There is low electron density (blue) on H atom of the COOH
group alcohol, i.e., H+ character.
• The H atom of the R–COOH is acidic (pKa ~ 5).
• The most important reactions of carboxylic acids converts
them into carboxylic acid derivatives such as acyl halides,
esters and amides via nucleophilic acyl substitution reactions.
20.1.7 – Carboxylic acid - Reactivity

39. • Carboxylic acids undergo the following types of reactions.
o The reactions in which hydrogen atom of the carboxyl group is involved (salt
formation).
o The reaction in which OH group is replaced by another group.
o The reactions involving carboxyl group as a whole.
20.1.7 – Carboxylic acid - Reactions

40. • They furnish H when dissolved in water.
• In the presence of water (H2O), the proton breaks away as H3O+ ion.
20.1.7.1.1 – Carboxylic acid - Reactions - Involving H atom of the
carboxyl group - With water
Acetic acid Water
Acetate
(Carboxylate) ion
Hydronium
ion

41. • Carboxylic acids react with bases (NaOH, KOH) to form salts.
20.1.7.1.2 – Carboxylic acid - Reactions - Involving H atom of the
carboxyl group - With bases
CH3–COOH + NaOH CH3COONa + H2O
Sodium
hydroxide
Acetic acid
Sodium
acetate
Water

42. • Carboxylic acids decompose carbonate and bicarbonates evolving carbon
dioxide gas with effervescence.
20.1.7.1.3 – Carboxylic acid - Reactions - Involving H atom of the
carboxyl group - With carbonates and bicarbonates
2CH3–COOH + Na2CO3 2CH3COONa + CO2+ H2O
Sodium
hydroxide
Acetic acid
Sodium
acetate
Water
Carbon
dioxid
e
CH3–COOH + NaHCO3 CH3COONa + CO2+ H2O
Sodium
hydroxide
Acetic acid
Sodium
acetate
Water
Carbon
dioxid
e

43. • Carboxylic acids react with active metals such as NA, K, Ca, Mg etc. to form
their salts with the formation of hydrogen gas.
20.1.7.1.4 – Carboxylic acid - Reactions - Involving H atom of the
carboxyl group - With metals
2CH3–COOH + 2Na 2CH3COONa + H2
SodiumAcetic acid
Sodium
acetate
Hydrogen

44. • The addition of a nucleophile to the carboxyl group is always followed by the
displacement of the –OH group by some group producing a carboxylic acid
derivative.
• The –OH group can be replaced by X, OR and NH2 to form acid halides,
esters and amide respectively.
20.1.7.2 – Carboxylic acid - Reactions - Involving OH group of
the carboxylic acid

45. • Acyl chlorides/acid halides are prepared by treating the carboxylic acid with
thionyl chloride, SOCl2, in the presence of a base.
20.1.7.2.1 – Carboxylic acid - Reactions - Involving OH group of
the carboxylic acid - Preparation of acyl chlorides
Thionyl
chloride
Carboxylic
acid
Acyl
chlorides
Sulphur
dioxide
Hydrochloric
acid
+ HCl

46. 20.1.7.2.2 – Carboxylic acid - Reactions - Involving OH group of
the carboxylic acid - Preparation of acid anhydrides
• Symmetrical anhydrides can be are prepared by heating the carboxylic acid.
• Symmetrical anhydrides are by far the most commonly encountered, e.g.,
acetic anhydride.
Carboxylic
acid
Acid
anhydrides
Water

47. • The reaction of an alcohol and a carboxylic acid yields an ester and water, and is known as
Fischer esterification.
• Esters are obtained by refluxing the parent carboxylic acid with the appropriate alcohol with an
acid catalyst.
• The equilibrium can be driven to completion by using an excess of either the alcohol or the
carboxylic acid or by removing the water as it forms.
• Alcohol reactivity order : CH3OH > 1° > 2° > 3° (steric effects).
20.1.7.2.3 – Carboxylic acid - Reactions - Involving OH group of
the carboxylic acid - Preparation of esters

48. 20.1.7.2.3 – Carboxylic acid - Reactions - Involving OH group of
the carboxylic acid - Preparation of esters
• Esters can also be made from other carboxylic acid derivatives especially
from acyl halides and anhydrides, by reacting them with the appropriate
alcohol in the presence of a weak base.
• Study Tip:
o The carboxylic acid and alcohol combination used to prepare an ester are reflected
by the name of the ester, e.g., ethyl acetate (or ethyl ethanoate) (CH3CO2CH2CH3)
can be made from acetic acid (or ethanoic acid) (CH3COOH) and ethanol
(CH2CH3OH).

49. 20.1.7.2.3.1 – Carboxylic acid - Reactions - Involving OH group of
the carboxylic acid - Preparation of esters - Mechanism
• Step 1:
o An acid base reaction
o Protonation of the carbonyl makes it more electrophilic.
• Step 2:
o The alcohol O functions as the nucleophile attacking the
electrophilic C in the C=O, with the electrons moving towards the
oxonium ion, creating the tetrahedral intermediate.
• Step 3:
o An acid base reaction.
o Deprotonate the alcoholic oxygen.
• Step 4:
o An acid base reaction.
o Need to make an –OH leave, it doesn’t matter which one, so convert
it into a good leaving group by protonation.

50. 20.1.7.2.3.1 – Carboxylic acid - Reactions - Involving OH group of
the carboxylic acid - Preparation of esters - Mechanism
• Step 5:
o Use the electrons of an adjacent oxygen to help push out the
leaving group, a neutral water molecule.
• Step 6:
o An acid/base reaction.
o Deprotonation of the oxonium ion reveals the carbonyl in the
ester product.

51. 20.1.7.2.4 – Carboxylic acid - Reactions - Involving OH group of
the carboxylic acid - Preparation of amides
• Carboxylic acids react with ammonia to form ammonium salts, which on
heating produce acid amides.
CH3COOH + NH3 2CH3COONH4
AmmoniaAcetic acid
Ammonium
acetate
CH3COONH4 CH3COONH2 + H2O
Ammonium
acetate
Sodium
acetate
Water

52. • The reactions that involve OH
group of the carboxylic acid are
preparation reactions for various
derivatives of carboxylic acids.
20.1.7.2.5 – Carboxylic acid - Reactions - Involving OH group of
the carboxylic acid - Summary

53. 20.1.7.3.1 – Carboxylic acid - Reactions - Involving carboxylic
group - Reduction to alcohols
• Carboxylic acids, acid halides, esters, and amides are easily reduced by
strong reducing agents, such as lithium aluminum hydride (LiAlH4).
• The carboxylic acids, acid halides, and esters are reduced to alcohols, while
the amide derivative is reduced to an amine.
• Carboxylic acids are less reactive to reduction by hydride than aldehydes,
ketones and esters.
• Carboxylic acids are reduced to primary alcohols.
• As a result of their low reactivity, carboxylic acids can only be reduced by
LiAlH4 to form primary alcohol.
CH3COOH + 4[H] CH3CH2OH + H2O
Acetic acid ethanol
LiAlH4

54. 20.1.7.3.2 – Carboxylic acid - Reactions - Involving carboxylic
group - Decarboxylation
• Decarboxylation is the loss of the acid functional group as carbon dioxide from a carboxylic acid.
• This is an elimination reaction.
• The reaction product is usually a halo-compound or an aliphatic or aromatic hydrocarbon.
• Simple carboxylic acids rarely undergo decarboxylation.
• Carboxylic acids with a carbonyl group at the 3-position readily undergo thermal decarboxylation, e.g.,
derivatives of malonic acid.
• The reaction proceeds via a cyclic transition state giving an enol intermediate that tautomerizes to the
carbonyl.
Propanedioic acid
(Malonic acid)
Carboxylic
acid
Alkane
Carbon
dioxide

55. 20.1.7.3.2.1 – Carboxylic acid - Reactions - Involving carboxylic
group - Decarboxylation - Mechanism
• Step 1:
o Remember curly arrows flow....
o Start at the protonation of the carbonyl,
o break the O-H bond and form the p bond,
o break the C-C and
o make the C=C.
o Note the concerted nature of this reaction and the cyclic
transition state.
• Step 2:
o Tautomerization of the enol of the carboxylic acid leads to the
acid product (not shown here)

56. 20.1.8 – Carboxylic acid - Derivatives
• The carboxylic acid derivatives are a family of closely related functional groups:
o Each contain a C=O group with a heteroatom attached.
o Note : this is what distinguishes them from aldehydes and ketones.
• They can all be prepared from the "parent" carboxylic acid (shown earlier)
• On hydrolysis (reaction with H2O) they all convert back to the parent carboxylic acid.
• They share a common reactivity pathway with nucleophiles: nucleophilic acyl substitution.
• Reactivity order : acyl chloride > anhydride > thioester > ester = carboxylic acid > amide >
carboxylate
• The most important things to know about carboxylic acid derivatives are:
o How to prepare the derivatives from the carboxylic acid itself.
o The relative reactivity of the carboxylic acid derivatives.
o That hydrolysis of derivatives gets you back to the carboxylic acid.
o The mechanism of nucleophilic acyl substitution.

57. 20.1 - Carboxylic acid
Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
Federal Board of Intermediate and Secondary
Education (FBISE)
Chemistry F.Sc
II

58. Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
20.2 – Acyl halides
Federal Board of Intermediate and Secondary
Education (FBISE)
Chemistry F.Sc
II

59. 20.2.1 – Acyl chlorides - Conversion to other derivatives
• Acyl chlorides are the most
reactive of the carboxylic acid
derivatives and therefore can be
readily converted into all other
carboxylic acid derivatives
through nucleophilic
substitution.
• They are sufficiently reactive that
they react quite readily with cold
water and hydrolyze to the
carboxylic acid.
• The HCl by-product is usually
removed by adding a base such
as pyridine, C6H5N, or triethyl
amine, Et3N.
Acid
anhydride
Esters
Acids
Amides

60. 20.2.1 – Acyl chlorides - Friedel Craft’s acylation of benzene
• Overall transformation : Ar-H to Ar-COR (a ketone)
• Named after Friedel and Crafts who discovered the reaction.
• Reagent: normally the acyl halide (e.g. usually RCOCl) with aluminum trichloride, AlCl3, a Lewis acid catalyst.
• The AlCl3 enhances the electrophilicity of the acyl halide by complexing with the halide.
• Electrophilic species: the acyl cation or acylium ion (i.e., RCO+ ) formed by the "removal" of the halide by the
Lewis acid catalyst.
• Friedel-Crafts reactions are limited to arenes as they are more reactive than mono-halobenzenes.
• Other sources of acylium can also be used such as acid anhydrides with AlCl3.
• Note how the reaction can still be reviewed as a Nucleophilic Acyl Substitution of the acyl halide since overall
we have a nucleophile (here the π bond of an aromatic ring) replaces the leaving group (chloride) at the
electrophilic C=O.
Benzene Acyl
chloride
Ketone

61. 20.2 - Acyl halides
Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
Federal Board of Intermediate and Secondary
Education (FBISE)
Chemistry F.Sc
II

62. Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
20.3 – Acid anhydrides
Federal Board of Intermediate and Secondary
Education (FBISE)
Chemistry F.Sc
II

63. 20.3.1 – Acid anhydrides - Conversion to other derivatives
• Acid anhydrides are the
second most reactive of the
carboxylic acid derivatives
and can therefore, be fairly
readily converted into the
other less reactive
carboxylic acid derivatives.
• A base in often added to
neutralize the carboxylic
acid by-product that is
formed.
Esters
Acids
Amides

64. 20.3 - Acid anhydrides
Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
Federal Board of Intermediate and Secondary
Education (FBISE)
Chemistry F.Sc
II

65. Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
20.4 – Esters
Federal Board of Intermediate and Secondary
Education (FBISE)
Chemistry F.Sc
II

66. 20.4.1 – Esters - Conversion to other derivatives
• Esters can be converted into
other esters (transesterification),
the parent carboxylic acid
(hydrolysis) or amides.
• Trans-esterification: Heat
with alcohol and acid catalyst.
• Hydrolysis: Heat with aq. acid
o base (e.g. aq. H2SO4 or aq.
NaOH) (see next slide for more
details)
• Amide preparation: Heat
with the amine.
o methyl or ethyl esters are the most
reactive esters.
Esters
Acids
Amides

67. 20.4.2 – Esters - Hydrolysis
• Carboxylic esters hydrolyze to the parent
carboxylic acid and an alcohol.
• Reagents :
o aqueous acid (e.g. H2SO4) with heat, or
o aqueous NaOH with heat (known as
"saponification").
• These mechanisms are among some of
the most studied in organic chemistry.
• Both are based on the formation of a
tetrahedral intermediate, which then
dissociates.
• In both cases it is the C-O bond between
the acyl group and the oxygen that is
cleaved.
An ester A carboxylate
salt
A base An alcohol
Butyl
acetate
Acetic
acid
Water 1-butanol
Ethyl
acetate
Sodium
acetate
Sodium
hydroxide
ethanol
An ester A carboxylic
acid
Water An
alcohol

68. 20.4.2 – Esters - Hydrolysis - Under basic conditions
• The mechanism shown in the next slide leads to acyl-oxygen cleavage (see
step2).
• The mechanism is supported by experiments using 18O labeled compounds
and esters of chiral alcohols.
• This reaction is known as "saponification" because it is the basis of making
soap from glycerol triesters in fats.

69. 20.4.2 – Esters - Hydrolysis - Under basic conditions -
Mechanism
• Step 1:
o The hydroxide nucleophiles attacks at the electrophilic C of the
ester C=O, breaking the π bond and creating the tetrahedral
intermediate.
• Step 2:
o The intermediate collapses, reforming the C=O results in the loss
of the leaving group the alkoxide, RO–, leading to the carboxylic
acid.
• Step 3:
o An acid / base reaction.
o A very rapid equilibrium where the alkoxide, RO– functions as a
base deprotonating the carboxylic acid, RCOOH, (an acidic work
up would allow the carboxylic acid to be obtained from the
reaction).

70. 20.4.2 – Esters - Hydrolysis - Under acidic conditions
• Note that the acid catalyzed mechanism is the reverse of the Fischer
esterification.
• The mechanism shown below also leads to acyl-oxygen cleavage (see step 5).

71. 20.4.2 – Esters - Hydrolysis - Under acidic conditions -
Mechanism
• Step 1:
o An acid/base reaction.
o Since we only have a weak nucleophile and a poor electrophile we need to
activate the ester.
o Protonation of the ester carbonyl makes it more electrophilic.
• Step 2:
o The water O functions as the nucleophile attacking the electrophilic C in the
C=O, with the electrons moving towards the oxonium ion, creating the
tetrahedral intermediate.
• Step 3:
o An acid/base reaction.
o Deprotonate the oxygen that came from the water molecule to neutralise the
charge.
• Step 4:
o An acid/base reaction.
o Need to make the -OCH3 leave, but need to convert it into a good leaving
group first by protonation.

72. 20.4.2 – Esters - Hydrolysis - Under acidic conditions -
Mechanism
• Step 5:
o Use the electrons of an adjacent oxygen to help "push out" the
leaving group, a neutral methanol molecule.
• Step 6:
o An acid/base reaction.
o Deprotonation of the oxonium ion reveals the carbonyl C=O
in the carboxylic acid product and regenerates the acid
catalyst.

73. 20.4.3 – Esters - Reduction
• Carboxylic esters are reduced give 2 alcohols, one from the alcohol portion of the ester and
a 1° alcohol from the reduction of the carboxylate portion.
• Esters are less reactive towards Nu than aldehydes or ketones.
• They can only be reduced by LiAlH4 but NOT by the less reactive NaBH4.
• The reaction requires that 2 hydrides (H–) be added to the carbonyl group of the ester
• The reaction proceeds via a aldehyde intermediate which then reacts with the second
equivalent of the hydride reagent (review)
• Since the aldehyde is more reactive than the ester, the reaction is not normally used as a
preparation of aldehydes .

74. 20.4.3 – Esters - Reduction - Mechanism
• Step 1:
o The nucleophilic H from the hydride reagent adds to the electrophilic C in the polar carbonyl
group of the ester.
o Electrons from the C=O move to the electronegative O creating the tetrahedral intermediate a
metal alkoxide complex.
• Step 2:
o The tetrahedral intermediate collapses and displaces the alcohol portion of the ester as a
leaving group, in the form of the alkoxide, RO-.
o This produces an aldehyde as an intermediate.
• Step 3:
o Now we are reducing an aldehyde
o The nucleophilic H from the hydride reagent adds to the electrophilic C in the polar carbonyl
group of the aldehyde.
o Electrons from the C=O move to the electronegative O creating an intermediate metal
alkoxide complex.
• Step 4:
o This is the work-up step, a simple acid/base reaction.
o Protonation of the alkoxide oxygen creates the primary alcohol product from the intermediate
complex.

75. 20.4.4 – Esters - Reactions with RLi and RMgX
• Carboxylic esters, R'CO2R'', react with 2 equivalents of organolithium or
Grignard reagents to give tertiary alcohols.
• The tertiary alcohol that results contains 2 identical alkyl groups (from R in
the scheme).
• The reaction proceeds via a ketone intermediate which then reacts with the
second equivalent of the organometallic reagent.
• Since the ketone is more reactive than the ester, the reaction cannot be used
as a preparation of ketones.

76. 20.4.4 – Esters - Reactions with RLi and RMgX - Mechanism
• Step 1:
o The nucleophilic C in the organometallic reagent adds to the electrophilic C in the polar
carbonyl group of the ester.
o Electrons from the C=O move to the electronegative O creating the tetrahderal
intermediate, a metal alkoxide complex.
• Step 2:
o The tetrahedral intermediate collapses and displaces the alcohol portion of the ester as
a leaving group, in the form of the alkoxide, RO–.
o This produces a ketone as an intermediate.
• Step 3:
o The nucleophilic C in the organometallic reagent adds to the electrophilic C in the polar
carbonyl group of the ketone.
o Electrons from the C=O move to the electronegative O creating an intermediate metal
alkoxide complex.
• Step 4:
o This is the work-up step, a simple acid/base reaction.
o Protonation of the alkoxide oxygen creates the alcohol product from the intermediate
complex.

77. 20.4 - Esters
Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
Federal Board of Intermediate and Secondary
Education (FBISE)
Chemistry F.Sc
II

78. Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
20.5 – Amides
Federal Board of Intermediate and Secondary
Education (FBISE)
Chemistry F.Sc
II

79. 20.5.1 – Amides - Conversion to other derivatives
• Amides are the least reactive of the neutral carboxylic acid derivatives.
• The only interconversion reaction that amides undergo is hydrolysis back to
the parent carboxylic acid and the amine.
• Reagents:
o Strong acid (e.g. H2SO4) or
o Strong base (e.g. NaOH) / heat.
AcidsAmides

80. 20.5.2 – Amides - Hydrolysis
• Amides hydrolyze to the parent carboxylic acid and the appropriate amine.
• The mechanisms are similar to those of esters.
• Reagents :
o Strong acid (e.g. H2SO4) / heat (preferred) or
o Strong base (e.g. NaOH) / heat.
• Reaction under acidic conditions:
o Note that the acid catalysed mechanism is analogous to the acid catalysed
hydrolysis of esters.
o The mechanism shown below proceeds via protonation of the carbonyl, not the
amide N (see step 1).

81. 20.5.2 – Amides - Hydrolysis - Under acidic conditions -
Mechanism
• Step 1:
o An acid/base reaction.
o Since we only have a weak nucleophile and a poor electrophile we need to activate
the amide.
o Protonation of the amide carbonyl makes it more electrophilic.
• Step 2:
o The water O functions as the nucleophile attacking the electrophilic C in the C=O,
with the electrons moving towards the oxonium ion, creating the tetrahedral
intermediate.
• Step 3:
o An acid/base reaction.
o Deprotonate the oxygen that came from the water molecule to neutralize the charge.
• Step 4:
o An acid/base reaction.
o Need to make the -NH2 leave, but need to convert it into a good leaving group first
by protonation.

82. 20.5.2 – Amides- Hydrolysis - Under acidic conditions -
Mechanism
• Step 5:
o Use the electrons of an adjacent oxygen to help "push out" the
leaving group, a neutral ammonia molecule.
• Step 6:
o An acid/base reaction.
o Deprotonation of the oxonium ion reveals the carbonyl in the
carboxylic acid product and regenerates the acid catalyst.

83. 20.5.3 – Amides - Reduction
• Amides, RCONR'2, can be reduced to the amine,
RCH2NR'2 by conversion of the C=O to –CH2–.
• Amides can be reduced by LiAlH4 but NOT the less
reactive NaBH4
• Typical reagents: LiAlH4/ether solvent followed by
aqueous work-up.
• Note that this reaction is different to that of other
C=O compounds which reduce to alcohols.
• The nature of the amine obtained depends on the
substituents present on the original amide.
• Look at the N substituents in the following
examples (those bonds don't change !)
• R, R' or R" may be either alkyl or aryl substituents.
• In the potential mechanism note that it is an O
system that leaves.
• This is consistent with O systems being better
leaving groups than the less electronegative N
systems.

84. 20.5.3 – Amides - Hydrolysis - Under acidic conditions -
Mechanism
• Step 1:
o The nucleophilic H from the hydride reagent adds to the
electrophilic C in the polar carbonyl group of the ester.
o Electrons from the C=O move to the electronegative O creating the
tetrahedral intermediate, a metal alkoxide complex.
• Step 2:
o The tetrahedral intermediate collapses and displaces the O as part of
a metal alkoxide leaving group, this produces a highly reactive
iminium ion an intermediate.
• Step 3:
o Rapid reduction by the nucleophilic H from the hydride reagent as it
adds to the electrophilic C in the iminium system.
o π electrons from the C=N move to the cationic N neutralising the
charge creating the amine product.

85. 20.5 - Amides
Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
Federal Board of Intermediate and Secondary
Education (FBISE)
Chemistry F.Sc
II

86. Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
20.6 – Nitriles
Federal Board of Intermediate and Secondary
Education (FBISE)
Chemistry F.Sc
II

87. 20.6.1 – Nitriles - Introduction
• Nitriles typically undergo nucleophilic addition to give products that often undergo a
further reaction.
• The chemistry of the nitrile functional group, C≡N, is very similar to that of the carbonyl,
C=O of aldehydes and ketones. Compare the two schemes:
• vs
• However, it is convenient to describe nitriles as carboxylic acid derivatives because:
o The oxidation state of the C is the same as that of the carboxylic acid derivatives.
o Hydrolysis produces the carboxylic acid
• Like the carbonyl containing compounds, nitriles react with nucleophiles via two
scenarios:
o Strong nucleophile reactions.
o Weak nucleophile reactions.

88. 20.6.2 – Nitriles - Reactions with strong nucleophiles
• Strong nucleophiles (anionic) add directly to the C≡N to form an
intermediate imine salt that protonates (and often reacts further) on work-
up with dilute acid.
• Examples of such nucleophilic systems are :
o RMgX,
o RLi,
o RC≡CM,
o LiAlH4

89. 20.6.3 – Nitriles - Reactions with weaker nucleophiles
• Weaker nucleophiles (neutral) require that the C≡N be activated prior to
attack of the Nu.
• This can be done using a acid catalyst which protonates on the Lewis basic N
and makes the system more electrophilic.
• Examples of such nucleophilic systems are : H2O, ROH.
• The protonation of a nitrile gives a structure that can be redrawn in another
resonance form that reveals the electrophilic character of the C since it is a
carbocation.

90. 20.6.4 – Nitriles - Hydrolysis
• Nitriles, RC≡N, can be hydrolyzed to carboxylic acids, RCOOH via the
amide, RCONH2.
• Reagents :
o Strong acid (e.g., H2SO4) or
o Strong base (e.g. NaOH) / heat.

91. 20.6.4 – Nitriles - Hydrolysis - Under acidic conditions -
Mechanism
• Step 1:
o An acid/base reaction. Since we only have a weak nucleophile so
activate the nitrile, protonation makes it more electrophilic.
• Step 2:
o The water O functions as the nucleophile attacking the electrophilic C
in the C≡N, with the electrons moving towards the positive center.
• Step 3:
o An acid/base reaction.
o Deprotonate the oxygen that came from the water molecule.
o The remaining task is a tautomerisation at N and O centers.
• Step 4:
o An acid/base reaction.
o Protonate the N gives us the -NH2 we need.

92. 20.6.4 – Nitriles - Hydrolysis - Under acidic conditions -
Mechanism
• Step 5:
o Use the electrons of an adjacent O to neutralize the positive at
the N and form the π bond in the C=O.
• Step 6:
o An acid/base reaction.
o Deprotonation of the oxonium ion reveals the carbonyl in the
amide intermediate....halfway to the acid.....

93. 20.6.5 – Nitriles - Reduction
• The nitrile, RC≡N, gives the 1° amine
by conversion of the C≡N to -CH2-
NH2
• Nitriles can be reduced by LiAlH4 but
NOT the less reactive NaBH4
• Typical reagents : LiAlH4/ether
solvent followed by aqueous work-up.
• Catalytic hydrogenation (H2/catalyst)
can also be used giving the same
products.
• R may be either alkyl or aryl
substituents.

94. 20.6.6 – Nitriles - Reaction with RLi or RMgX
• Nitriles, RC≡N, react with Grignard reagents or organolithium reagents to
give ketones.
• The strongly nucleophilic organometallic reagents add to the C≡N bond in a
similar fashion to that seen for aldehydes and ketones.
• The reaction proceeds via an imine salt intermediate that is then hydrolyzed
to give the ketone product.
• Since the ketone is not formed until after the addition of water, the
organometallic reagent does not get the opportunity to react with the ketone
product.
• Nitriles are less reactive than aldehydes and ketones.

95. 20.6.6 – Nitriles - Reaction with RLi or RMgX - Mechanism
• Step 1:
o The nucleophilic C in the organometallic reagent adds to theelectrophilic C in
the polar nitrile group.
o Electrons from the C≡N move to the electronegative N creating an
intermediate imine salt complex.
• Step 2:
o An acid/base reaction.
o On addition of aqueous acid, the intermediate salt protonates giving the
imine.
• Step 3:
o An acid/base reaction.
o Imines undergo nucleophilic addition, but require activation by protonation
(i.e., acid catalysis).
• Step 4:
o Now the nucleophilic O of a water molecule attacks the electrophilic C with
the π bond breaking to neutralize the change on the N.

96. 20.6.6 – Nitriles - Reaction with RLi or RMgX
• Step 5:
o An acid/base reaction.
o Deprotonate the O from the water molecule to neutralize the positive
charge.
• Step 6:
o An acid/base reaction.
o Before the N system leaves, it needs to be made into a better leaving
group by protonation.
• Step 7:
o Use the electrons on the O in order to push out the N leaving group, a
neutral molecule of ammonia.
• Step 8:
o An acid/base reaction.
o Deprotonation reveals the carbonyl group of the ketone product.

97. • Define steric effect.
• What is alcohol’s reactivity order?
• How oxonium ion creates the tetrahedral intermediate?
• Define tautomerization.
• Define saponification.
20.6.7 – Nitriles - Quick quiz

98. 20.6 - Nitriles
Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
Federal Board of Intermediate and Secondary
Education (FBISE)
Chemistry F.Sc
II

99. • Carboxylic acid occurrence
o Sorbic acid is found in berries from rowan tree.
o Caprylic acid is present in coconut and in milk.
o Lauric acid is also present in coconut.
o Myristic acid is present in nutmeg.
o Arachidic acid is present in peanut oil.
o Citric acid is present in citrus fruits, e.g., in lemon, orange and grape.
o Tartaric acid is present in tamarind and wine.
o Lactic acid is found in apples, tomatoes, molasses and sour milk.
o Acetic acid is found in grapes and vinegar.
o Malic acid is present in green apples and plums.
o Benzoic acid is found in berries.
o Butyric acid is present in rancid butter.
o Caproic acid is present in goat fat.
o Palmitic acid is present in palm oil.
o Stearic acid is present in waxes, animal fats and oils.
o Amino acids are the building blocks of proteins.
o Acetoacetic acid pyruvic acid are the acids of biochemical significance.
Society, Technology and Science

100. • The carboxylic acid, 3-methyl-3-hexanoic acid is one of the compounds
associated with the odor of human perspiration.
• The vinegaroon (whip-tail scorpion) expels a spray of acetic acid to repel
predators.
• Flavors of some esters:
o Amyl acetate Banana
o Isobutyl formate Raspberry
o Benzyl acetate Jasmine
o Ethyl butyrate Pineapple
o Amyl butyrate Apricot
o Octyl acetateOrange
• Proteins are peptides consisting of amino acids, and some proteins have been
identified with molecular mass in excess of 10000.
Society, Technology and Science

101. • Carboxylic acid as food preservatives
o Formic acid is used as preservative for silage (including fresh hay) and other
livestock feed.
o Boric acid was used as a food preservative in caviar (a product made from salt-
cured fish eggs) but its use has now been banned.
o Benzoic acid is used as a preservative in jams, beer, preserved fruits, pickles,
fruit juice, dessert, sauces and syrups.
o Acetic acid is used as a preservative in fish fingers, butter, margarine, processed
cheese, curry powder and cooking oil.
o Lactic acid is used as a preservative in beer, tinned foods especially vegetables
and fruit.
o Propionic acid is used as a preservative in dairy products, particularly in cheese
and in baking products.
Society, Technology and Science

102. • Taste of different esters
o Ester flavors are in a range of fruity, sugary and sweet that occur in many beer
types as a normal part of their brewing process.
o Ethyl formate gives raspberries their characteristic taste.
o Ethyl acetate has a bittersweet, wine-like burning taste.
o Isoamyl acetate has a taste reminiscent of pears or bananas.
o Ethyl propionate has rum like taste (rum is distilled alcoholic beverage made
from sugar cane byproducts).
o Ethyl butyrate, found in pineapples, tastes like sugary water.
o Ethyl valerate has apple like taste.
o Ethyl hexanoates also has an apple like flavor.
o Ethyl heptanoate, found in pineapples, has sweet taste.
Society, Technology and Science

103.  Carboxylic acids are the most acidic of the common organic functional groups.
 The COOH unit is planar and consistent with sp2 hybridization and a resonance interaction of the lone
pairs of the hydroxyl oxygen with the π system of the carbonyl.
 The most important reactions of carboxylic acids converts them into carboxylic acid derivatives such as
acyl halides, esters and amides via nucleophilic acyl substitution reactions.
 Esters can also be made from other carboxylic acid derivatives, especially acyl halides and anhydrides by
reacting them with the appropriate alcohol in the presence of a weak base.
 Loss of carbon dioxide is called decarboxylation.
 Simple carboxylic acids rarely undergo decarboxylation.
 Esters and carboxylic acids are less reactive towards nucleophiles than aldehydes or ketones.
 Carboxylic esters, R’CO2R’’, react with two equivalents of organolithium or Grignard’s reagent to give
tertiary alcohols.
 Amides hydrolyze to the parent carboxylic acid and the appropriate amine.
 Amides can be reduced by LiAlH4 but not with the less reactive NaBH4.
 The chemistry of the nitrile functional group, C≡N, is very similar to that of the carbonyl C=O of aldehydes
and ketones.
 Nitriles, RC≡N, react with Grignard reagents or organolithium reagents to give ketones.
Key Points

104. 1. A carboxylic acid contains
functional group
a. A hydroxyl group
b. A carboxyl group
c. A hydroxyl and carboxyl group
d. A carboxyl and aldehyde group
2. From the following carboxylic
acids, which acids have higher
acidity
1. Ethanoic acid
2. Propanoic acid
3. Chloroethanoic acid
4. Nitroethanoic acid
1. Select the right answer from the choices given
3. Which reagent is used to reduce a
carboxylic acid?
a. He/Ni
b. H2/Pt
c. NaBH4
d. LiAlH4
4. Stronger acid is
1. CH3COOH
2. HCOOH
3. CH3CH2COOH
4. CH3CH2CH2COOH

105. 5. Acetamide is prepared by
a. Heating ammonium acetate
b. Heating methyl cyanide
c. Heating ethyl acetate
d. The hydrolysis of methyl cyanide
6. Carboxylic acids react with metal
to form salts with the evolution of
a. CO2
b. H2
c. CO
d. CH4
1. Select the right answer from the choices given
7. Ethane-1,2-dioic acid is also called
a. Benzoic acid
b. Oxalic acid
c. Formic acid
d. Melonic acid
8. Carboxylic acid can be prepared by
the action of Grignard’s reagent
with
a. O2
b. CO2
c. KCl
d. N2

106. 9. The IUPAC name for formic acid
is
a. Methanoic acid
b. Acetic acid
c. Ethanoic acid
d. Butanoic acid
10.The reaction of alcohol with
acetic acid is known as
a. Saponification
b. Esterification
c. Ammonolysis
d. Hydrolysis
1. Select the right answer from the choices given
11. Esters are formed by the reaction
of carboxylic acids with
a. Alcohols
b. Ethers
c. Aldehydes
d. Alkyl halides
12. Which one of the following has
both hydroxyl and carboxylic acid
groups?
a. phenol
b. Picric acid
c. Phthalic acid
d. Salicylic acid

107. 13.Which of the following can not be
prepared directly from acetic acid
a. Acetamide
b. Acetyl chloride
c. Acetic anhydride
d. Ethyl acetate
14.Reaction between caustic soda
and a fat is called
a. Esterification
b. Hydrogenation
c. Neutralization
d. Saponification
1. Select the right answer from the choices given
15. When a carboxylic acid reacts
with alcohol, it produces a new
class of compounds
a. Ether
b. Esters
c. Anhydrides
d. Amide

108. 1. What are aliphatic and aromatic carboxylic acids?
2. Give probable mechanism of alkaline hydrolysis of an ester. (20.4.2)
3. A carboxylic acid does not form phenyl hydrazone when treated with
phenyl hydrazine. Explain.
2. Give short answers to the following questions
+

109. 4. Give the mechanism for the acid catalyzed hydrolysis of a nitrile,
RC N.
5. Why acetic acid is often called glacial acetic acid?
6. What is use of esters?
7. How may nitriles be converted into carboxylic acids?
8. What are acidic mino acids? Give examples.
9. What happens when ammonium acetate and calcium acetate are heated?
10.How does carboxylic acid exist in non-polar solvent?
2. Give short answers to the following questions

110. 1. How will you prepare carboxylic acid from
i. Alkyl nitrile
ii. Hydrolysis of esters
2. Give the reaction of acetic acid with the following along with mechanism.
i. SOCl2
ii. Ethanol
iii. NH3
3. Give the reaction of amine with Grignard’s reagent and its mechanism.
4. What happens when the following compounds are heated?
i. Calcium acetate
ii. Sodium formate and soda lime
iii. Ammonium acetate
5. What is vinegar? Describe how vinegar is prepared from ethanol.
6. Write down the mechanism of the following reactions.
i. Between acetic acid and ethanol.
ii. Between acetic acid and ammonia.
iii. Between acetic acid and thionyl chloride.
3. Give detailed answers to the following questions

111. 7. How would you the convert the following?
i. Acetic acid into acetamide.
ii. Acetic acid into acetone.
8. How amides are reduced with LiAlH4? Give mechanism.
9. What is Friedel & Craft’s reaction? Explain their mechanism.
10.Give mechanism for reaction for acid catalyzed esterification.
3. Give detailed answers to the following questions

112. 20 - Carboxylic acid and functional derivatives
Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
Federal Board of Intermediate and Secondary
Education (FBISE)
Chemistry F.Sc
II