Aldehyde ketones and carboxylic group that specify the groups and their drives derivatives

1. Aldehydes, ketones
and
carboxylic acids
By –
Mr. Pranav A.
Galgale
PGT Chemistry
book 2

2. Organic Compounds having >C=O group are called carbonyl compounds. It's general formula is Cn H2nO (n = 1, 2, 3......)
Carbonyl compounds are grouped into two categories.
C = O
H
Aldehydes (also known as formyl group). It is a monovalent group (only one bond to get attached with carbon
chain)
Ketones C = O its both the valencies are satisfied by alkyl group. It is a bivalent group.
– C – OH
||
O
– C – NH2
||
O
– C – O – R
||
O
– C – X
||
O
– C = OH
|
O
–
+
– C = NH2
|
O
–
+
– C = O – R
|
O
–
+
– C = X
|
O
–
+
– C –
||
O
These groups contain but still they are not considered as carbonyl compounds as carbonyl group take part in resonance

3. Nomenclature of aldehydes and ketones
The common names of most aldehydes are derived from the common names of the corresponding carboxylic acids by replacing
the ending –ic of acid with aldehyde.
Names are given from name of source in Latin or in Greek
e.g.
Formaldehyde – Derived from formic acid present in ant sting (Greek: Forma – Ant)
Propionaldehyde – Derived from propionic acid (Greek: Propion – Butter)
Butyraldehyde – Derived from buyric acid (Greek: Butyr – Butter)
The location of the substituent in the carbon chain is indicated by Greek letters a, b, g, d, etc.
Nomenclature of aldehydes
Common system

4. Nomenclature of ketones
The common names of ketones are derived by naming two alkyl or aryl groups bonded to the carbonyl group. The locations of
substituents are indicated by Greek letters, a, a’, b, b’ and so on….
e.g.
C – C – C – C – C
||
O
a a’
b b’
IUPAC names
Aldehydes –e of alkanes replaced by –al
In case of aldehyde group attached to cycloalkanes or benzene ring then word carbaldehyde is used as suffix in both the systems
Ketones –e of alkanes replaced by –one
Remember priority series:
– SO3H used as suffix (sulphonic acid)
– COOH used as suffix (–oic acid)
Rest for all functional groups used as prefix
If aldehyde and ketone both groups are
there, then name aldehydic group is written
in suffix (–al) and name of ketone is used
as prefix (–oxo)

5. CH3 – C – H
||
O
– C – H
||
O
CH3 – CH = CH – CH2
|
CHO
|
CHO
CH3
CHO
NO2
1
2
3
4
5
1
2
Common system IUPAC system
Acetaldehyde Ethanal
Cyclohexanecarbaldehyde Cyclohexanecarbaldehyde
pent – 3 – enal
2 – methylcyclopentanecarbaldehyde
o - nitrobenzaldehyde
o - nitrobenzenecarbaldehyde
4 - nitrobenzaldehyde
o - nitrobenzenecarbaldehyde
________
b – methylcyclopentanecarbaldehyde
Aldehydes
a
b

6. CH2 = CH – CHO
CH3 – CH2 – CH2 – CH2 – CHO
CHO
CHO
Common system IUPAC system
Acrolein Prop-2-enal
Valeraldehyde Pentanal
Phthaldehyde Benzene-1,2-dicarbaldehyde

7. – C –
||
O
| |
CH3 – CH CH – CH3
CH3 CH3
CH3 – C – CH3
||
O
– C –
||
O
||
O
CH3 – CH2
CH2 – C – H
CH3 – C – CH2 – CH2 – CH3
||
O
||
O
OCH3
Common system IUPAC system
Ketones
Acetone Propanone
Methyl n – propyl ketone Pentan – 2 – one
Di isopropyl ketone 2,4 – dimethylpentan – 3 – one
1
2
3
4
5
3 – oxopentanal
1
2
3
4
5
2 – methoxycyclohexanone
b – methoxycyclohexanone
a b
________

8. Lone pair of electrons
p
p
Lone pair of electrons
s
Unhybridised p orbital of oxygen
Unhybridised p orbital of carbon
These two sp2 hybridised orbitals
of carbon available for formation
of s bond
Structure of functional group

9. C O
p
p
s
s
s Hybridisation of carbonyl ‘C’ – sp2
Hybridisation of ‘O’ – sp2
s
p
O
C
120o
120o
120o
C O
s
p
p

10. General Methods of Preparation :
For both Aldehydes and Ketones :
Oxidation of primary alcohols gives aldehyde and oxidation of secondary alcohols gives Ketones. Here, (K2Cr2O7 / H2SO4) is a
strong oxidising agent.
1. By Oxidation of Alcohols :
By K2Cr2O7 / H2SO4 :
[O]
K2Cr2O7 / H2SO4 (dil)
R – C – H
||
O
Aldehyde
1o alcohol
R – CH2 – OH
CH – OH
R
R’
2o alcohol
O
K2Cr2O7 / H2SO4 (conc.)
C = O
R
R’
Ketone

11. Aldehydes are quite susceptible to further oxidation to acids -
R – CH2 – OH
[O]
R – C – H
||
O
[O]
R – C – OH
||
O
Thus oxidation of primary alcohols is made at the temperature much above the boiling point of aldehyde and thus aldehydes
are vapourised out and prevented from being oxidised.
1° alcohol Aldehydes
2° alcohol ketones
PCC (Pyridinium chloro chromate) in CH2Cl2
PDC (Pyridinium di chromate) in CH2Cl2
Jones reagent (CrO3+H2SO4) in acetone
IMPORTANT
Mild Oxidising Agent:
1o alcohols will get oxidised with CrO3/Pyridine, Collin's reagent Ag/O2 at 250oC
Selective oxidising agents

12. When the vapours of a primary or a secondary alcohol are passed over heated copper at 573 K, dehydrogenation takes place and an
aldehyde or a ketone is formed while tertiary alcohols undergo dehydration.
2. Dehydrogenation reaction
CH3 – CH2 – OH
Cu
573K
CH3 – CHO
CH – OH
CH3
CH3
Cu
573K
C = O
CH3
CH3

13. This reaction is used to determine the position of double bond in alkene.
3. By Ozonolysis of alkenes :
R – CH = CH2
O3
R – C CH2
| |
O O
O
Ozonide
R – CHO + HCHO
CH = CH2
R
R’
O3
R – C CH2
| |
O O
O
R’
C = O
R
R’
+ HCHO
Branched alkenes Ketones
Unbranched alkenes Aldehydes
Zn dust
H2O
Zn dust
H2O

14. (a) Hydration : With dil H2SO4 & 1% HgSO4 at 60 – 80oC.
4. From Alkyne:
CH ≡ CH + H2O CH2 = C – H
|
O – H
H2SO4 & 1% HgSO4
Enol form
CH3 – C – H
||
O
Keto form
Keto – enol tautomerism
CH3 – C ≡ CH + H2O
H2SO4 & 1% HgSO4
CH2 = C – CH3
|
O – H
CH3 – C – CH3
||
O
Acetylene Aldehydes
Other alkynes Ketones

15. Preparation of Aldehydes (specifically)
Acyl chloride (acid chloride) is hydrogenated over catalyst, palladium on barium sulphate. This reaction is called Rosenmund
reduction.
Cl
O
C
||
H2
Pd – BaSO4
O
C – H
||
Nitriles are reduced to corresponding imine with stannous chloride in the presence of hydrochloric acid, which on hydrolysis
give corresponding aldehyde. This reaction is called Stephen reaction.
R – C ≡ N + SnCl2 + HCl
Cyanide stannous chloride
R – CH = NH
H3O +
R – CHO
Immine
1. From acyl chloride (acid chloride)
2. From nitriles and esters
HCHO cannot be prepared by this reaction

16. Alternatively, nitriles are selectively reduced by Di-isoButylaluminium hydride, (DIBAL – H) to imines followed by hydrolysis
to aldehydes:
R – CN
1. DIBAL – H
2. H2O
R – CHO
If double bond is present then that double bond is not reduced by DIBAL – H
CH3 – CH2 – CH = CH – CN
1. DIBAL – H
2. H2O
CH3 – CH2 – CH = CH – CHO
Similarly, esters are also reduced to aldehydes with DIBAL-H.
CH3– C – O – C2H5
||
O
1. DIBAL – H
2. H2O
CH3 – CHO + C2H5OH

17. Aromatic aldehydes (benzaldehyde and its derivatives) are prepared from aromatic hydrocarbons
3. From hydrocarbons
Strong oxidising agents oxidise toluene and its derivatives to benzoic acids.
As aldehyde group can undergo oxidation easily, methyl group attached to benzene ring first get converted to intermediate that is
difficult to oxidise and then finally it is converted to aldehydic group.
(i) By oxidation of methylbenzene (toulene)
CS2 H3O +
CH3
+ CrO2Cl2
Toulene
CH(OCrOHCl2)2
Chromium complex
H
O
C
||
Benzaldehyde
(a) Use of chromyl chloride (CrO2Cl2):
Chromyl chloride oxidises methyl group to a chromium complex, which on hydrolysis gives corresponding benzaldehyde. This is known
as Etard reaction.

18. (b) Use of chromic oxide (CrO3):
Toluene or substituted toluene is converted to benzylidene diacetate on treating with chromic oxide in acetic anhydride. The
benzylidene diacetate can be hydrolysed to corresponding benzaldehyde
Toulene
CH3
+ CrO3 +
CH3 – C – O
O
CH3 – C – O
H3O +
D
CHO
CH
Benzylidene diacetate
O – C – CH3
||
O
O – C – CH3
||
O
CH
Benzylidene diacetate
O – C – CH3
||
O
O – C – CH3
||
O

19. Side chain chlorination of toluene gives Benzal chloride, which on hydrolysis gives benzaldehyde. This is a commercial method
of manufacture of benzaldehyde.
(ii) By side chain chlorination followed by hydrolysis
CH3
Toulene
Cl2 / hn
CHCl2
Benzal chloride
H2O
373 K
CHO

20. When benzene or its derivative is treated with carbon monoxide and hydrogen chloride in the presence of anhydrous aluminium
chloride or cuprous chloride, it gives benzaldehyde or substituted benzaldehyde.
(iii) By Gatterman – Koch reaction
CO / HCl
Anhyd. AlCl3 / CuCl2
CHO
Preparation of ketones
1. From acyl chlorides
Treatment of acyl chlorides with dialkylcadmium, prepared by the reaction of cadmium chloride with Grignard reagent, gives
ketones.
+ CdCl2 R2Cd + 2 Mg
Cl
X
+ R2Cd + CdCl2
2 R’ – C – Cl
||
O
Acyl chloride
R – Mg – X
Grignard’s reagent
2 R’ – C – R
||
O
Ketone

21. Treating a nitrile (cyanide) with Grignard reagent followed by hydrolysis yields a ketone.
2. From nitriles
CH3 – CH2 – C ≡ N + C6H5MgBr
Anhyd. AlCl3
CS2
CH3 – CH2 – C
N – Mg – Br
C6H5
H3O+
CH3 – CH2 – C
O
C6H5
When benzene or substituted benzene is treated with acid chloride in the presence of anhydrous aluminium chloride, it gives the
corresponding ketone. This reaction is known as Friedel-Crafts acylation reaction.
3. From benzene or substituted benzenes
+ R – C – Cl
||
O
C
||
– R
O
Dry ether
4. From dry distillation of acids
Ca(OH)2
Dry distillation
R – C – OH
||
O
R – C – R
||
O

22. DO IT YOURSELF…..
+ C2H5 – C – Cl
||
O
1.
Anhyd. AlCl3
CS2
?
2. (C6H5CH2)2Cd + 2CH3COCl ?
3. CH3 – C ≡ C – H
Hg+, H2SO4
?
4. CH3
NO2
1. CrO2Cl
2. H3O+
?

23. Physical Properties
1. Physical states
Methanal is a gas at room temperature.
Ethanal is a volatile liquid.
Other aldehydes and ketones are liquid or solid at room temperature.
2. Boiling points
The boiling points of aldehydes and ketones are higher than hydrocarbons and ethers of comparable molecular masses. It is
due to weak molecular association in aldehydes and ketones arising out of the dipole-dipole interactions. Also, their boiling
points are lower than those of alcohols of similar molecular masses due to absence of intermolecular hydrogen bonding.
d+ d-
C = O
d+ d-
C = O
Dipole – dipole interaction

24. 3. Solubility
The lower members of aldehydes and ketones such as methanal, ethanal and propanone are miscible with water in all
proportions, because they form hydrogen bond with water.
C = O
d+ d-
H – O
H
d+ d-
d+
d-
d+
However, the solubility of aldehydes and ketones decreases rapidly on increasing the length of alkyl chain. All aldehydes and
ketones are fairly soluble in organic solvents like benzene, ether, methanol, chloroform, etc.
The lower aldehydes have sharp pungent odours. As the size of the molecule increases, the odour becomes less pungent
and more fragrant. In fact, many naturally occurring aldehydes and ketones are used in the blending of perfumes and flavouring
agents.
4. Odour

25. Chemical Reactions the aldehydes and ketones undergo nucleophilic addition reactions.
(i) Mechanism of nucleophilic addition reactions
C O
d+ d-
sp2
Planar
C
O
_
Nu
sp3
Tetrahedral
Nu
_
C
O
_
Nu
Slow step
H+
Fast step
C
OH
Nu

26. Aldehydes are generally more reactive than ketones in nucleophilic addition reactions
(ii) Reactivity
Because ketones have two alkyl groups
That’s why more stearic hindrance is present
In ketone.
Ketones show lesser reactivity because
+I effect increases electron density on
carbonyl carbon. So partial positive charge
on carbon decreases
R C R
O Due to this partial positive charge
on this ‘C’ decreases
+ I + I
|
C
O
H
|
C
O
H
||
C
O
H
+
–
||
C
O
H
+
–
||
C
O
H
+
–
||
C
O
H
–
+
Aromatic aldehydes
Positive charge get developed on ortho and para position due to decrease in electron density on these positions.
Because of – M or – R effect of carbonyl group as it is EWG.
But lesser reactivity towards nucleophilic reactions than aliphatic aldehydes

27. In general,
Aliphatic Aldehydes > Aromatic aldehydes > Aliphatic Ketone > Aromatic ketone
Reactivity toward nucleophilic reactions decreases

28. Some important examples of nucleophilic addition and nucleophilic addition-elimination reactions
(a) Addition of hydrogen cyanide (HCN):
Aldehydes and ketones react with hydrogen cyanide (HCN) to yield cyanohydrins.
Cyanide and hydroxyl both groups
This reaction occurs very slowly with pure HCN. Therefore, it is catalysed by a base and the generated cyanide ion (CN-)
Mechanism
HCN
Base
+ OH
–
CN
–
+ H3O +
C = O CN
–
+ C
O
CN
–
C
O
CN
–
H
+
+ C
OH
CN
Tetrahedral complex
Cyanohydrin

29. C = O NaHSO3
+ C
O Na
SO3H
– +
(b) Addition of sodiumhydrogensulphite:
Proton transfer
C
OH
SO3Na
The hydrogensulphite addition compound is water soluble and can be converted back to the original carbonyl compound by
treating it with dilute mineral acid or alkali. Therefore, these are useful for separation and purification of aldehydes.
Hydrogensulphite addition compound
(Crystalline)
Aldehydes react with one molecule of monohydric alcohol in the presence of dry hydrogen chloride to yield alkoxyalcohol
intermediate, known as hemiacetals, which further react with one more molecule of alcohol to give a gem – dialkoxy compound
known as acetal
(c) Addition of alcohols:
C = O
R
H
R’OH
HCl gas
C
R
H OH
O R’
Hemiacetal
C
R
H O R’
O R’
Hemiacetal

30. Ketones react with ethylene glycol under similar conditions to form cyclic products known as ethylene glycol ketals.
C = O
R
R
CH2 – OH
+ |
CH2 – OH
HCl gas R
R
C
O
O
– CH2
– CH2
+ H2O
ethylene glycol ketal
(d) Addition of ammonia and its derivatives:
C = O C = NH H2O
+
C
OH
N – H
H
|
N – H
+
|
H
|
H

31. C = O H2 N – R
+ C = N – R Substituted imine (Schiff’s base)
C = O H2 N – H
+ C = N – H Imine
1o amine
C = O H2 N – OH
+
Hydroxyl amine
C = N – OH Oxime
C = O H2 N – NH2
+
Hydrazine
C = N – NH2 Hydrazone
H2 N –
+
C = O
– H2O
– H2O
– H2O
– H2O
– H2O
C = N– Phenyl hydrazone
Phenyl hydrazine

32. C = O H2 N – NH –
+ – NO2
O2N
– H2O
C = N – NH – – NO2
O2N
C = O H2 N – NH – C – NH2
+
||
O
– H2O
C = N – NH – C – NH2
||
O
2,4-DNP-derivatives are yellow, orange or red solids, useful for characterisation of aldehydes and ketones.

33. Aldehydes and ketones are reduced to primary and secondary alcohols
respectively by sodium borohydride (NaBH4) or lithium aluminium hydride
(LiAlH4) as well as by catalytic hydrogenation
2. Reduction
LiAlH4 / THF or Ether
R – CH2 – OH
Primary alcohols
C = O
H
Aldehydes
R
C = O
R’
Ketones
R NaBH4 / THF or Ether
CH – OH
R’
Secondary alcohols
R
H2 / Pt
H2 / Pd
H2 / Ni
(i) Reduction to alcohols:
LiAlH4 NaBH4
Strong reducing agent Weak reducing agent
THF or ether used as
solvent
Aldehydes
Ketones
Carboxylic acids
Acid chlorides
Nitriles
Esters
Nitro compounds
THF or ether used as
solvent
Aldehydes
Ketones
Acid chlorides
Conjugate double
bond gets reduced
Conjugate double
bond does not get
reduced
Isolated double bond
does not get reduced
Isolated double bond
does not get reduced

34. The carbonyl group of aldehydes and ketones is reduced to CH2 group in these reactions.
(ii) Reduction to hydrocarbons:
Reduction to hydrocarbons
Clemmensen reduction
Carbonyl group is reduced to CH2 group on treatment with zinc amalgam and concentrated
hydrochloric acid
C = O
HCl
Zn – Hg
CH2
Wolff – Kishner reduction
C = O
– H2O
NH2 NH2
C = N – NH2
Heat
KOH / Ethylene glycol
CH2
C = O
420 K
Red P
CH2

35. 3. Oxidation Aldehydes differ from ketones in their oxidation reactions.
Aldehydes Ketones
Easily oxidised to carboxylic acids on treatment with common
oxidising agents (strong or mild)
Cannot be oxidise easily and vigorous oxidation is required
Oxidation occurs at room temperature Oxidation occurs at high temperature
Cleavage of C – C bond does not take place Cleavage of C – C bond takes place
Oxidising agents
Strong Mild
Nitric acid Tollen’s reagent
Potassium permanganate Fehling’s solution
Potassium dichromate
Only strong oxidising agents are required.
Only one carboxylic acid gets formed
Mixture of carboxylic acids (having lesser carbon in each
than the parent ketone) gets formed

36. Aldehydes Ketones
C = O
H
Aldehydes
R [O]
R – COOH
CH3 – CH2 – CHO
[O]
CH3 – CH2 – COOH
CH3 – CH2 – C – CH2 – CH2 – CH3
||
O
[O]
CH3 – COOH + HOOC – CH2 – CH2 – CH3
CH3 – CH2 – C – CH2 – CH2 – CH3
||
O
[O]
CH3 – CH2 – COOH + CH3 – CH2 – COOH

37. DISTINGUISHING TESTS BETWEEN ALDEHYDES AND KETONES
1. Tollens test (Oxidation by Tollen’s reagent)
Bernhard Tollens (1841-1918) was a Professor of Chemistry at the University of Gottingen, Germany.
Tollen’s reagent is ammoniacal AgNO3 solution. When aldehydes are heated with Tollens reagent, aldehydes gets oxidised to
carboxylate ion and Tollens’ reagent gets reduced into bright silver mirror.
2 AgNO3 + 2NH4OH Ag2O + 2NH4NO3 + H2O
Ag2O + 4NH4OH 2 [ Ag (NH3)2] OH + 3H2O
–
+
RCHO + 2 [ Ag (NH3)2] + 3 OH RCOO + 2Ag ↓ + 2H2O + 4 NH3
+ – –
silver mirror
Only aldehydes show this test positive. Ketones do not show this test positive.

38. 2. Fehling’s test (Oxidation by Fehling’s reagent)
Fehling A – Aqueous CuSO4 Fehling B – Alkaline sodium potassium tartarate (Rochelle salt)
These two solutions are mixed in equal amounts. On heating aldehyde with this solution a reddish brown precipitate of Cu2O
is formed and aldehyde is oxidised to corresponding carboxylate anion.
RCHO + 2 Cu + 5 OH RCOO + Cu2O ↓ + 3H2O
2+ – –
reddish brown ppt
Aromatic aldehydes do not show this test

39. 3. Haloform test
Aldehydes and ketones having at least one methyl group linked to the carbonyl carbon atom (methyl ketones) are oxidised by
sodium hypohalite (Cl2, Br2 or I2 in presence of NaOH) to give sodium salts of corresponding carboxylic acids having one carbon
atom less than that of carbonyl compound.
The methyl group is converted to haloform. (Chloroform, bromoform or iodoform)
This oxidation does not affect a carbon-carbon double bond, if present in the molecule.
CH3 – C –
||
O
CH3 – CH –
|
OH
Then only this test is positive
(Exception – Ethanol)
R – C – CH3
||
O
NaOX
R – C – O Na
||
O
– +
+ CH3 – X
Haloform
X = Cl, Br, I

40. COMMON EXAMPLES OF HALOFORM TEST
Remember only CH3 – C –
||
O
CH3 – CH –
|
OH
and show this test positive. Only exception is ethanol
1. Ethanol and methanol
CH3 – CH2 – OH
Ethanol
CH3 – OH
Methanol
Positive Negative
2. Acetaldehyde and formaldehyde
CH3 – C – H
||
O
H– C – H
||
O
Positive Negative
3. Acetaldehyde and benzaldehyde
CHO
CH3 – C – H
||
O
Positive Negative
4. Acetophenone and benzaldehyde
CHO
C – CH3
O
Positive Negative
5. Acetone and propanal
CH3 – C – CH3
||
O
CH3 – CH2– C – H
||
O
Positive Negative
6. pentan-2-one and pentan-3-one
7. Isopropyl alcohol and n – propyl alcohol
CH3 – CH2– CH2 – C – CH3
||
O
CH3 – CH2– C – CH2 – CH3
||
O
Positive
Negative
CH3 – CH – CH3
|
OH
CH3 – CH2 – CH2 – OH
Positive
Negative

41. SOME IMPORTANT PROBLEMS
Problem 1 How can you perform following conversions?
(a) But-2-ene to ethanal
CH3 – CH = CH – CH3
1. O3
2. Zn/H2O
2 CH3 – CHO
(b) Cyclohexanol to cyclohexanone
|
OH
K2Cr2O7 / H2SO4
||
O
Here you can use mild oxidising agents like
1. PCC in CH2Cl2
2. PDC in CH2Cl2
3. Jones reagent (CrO3+H2SO4) in acetone
4. CrO3/Pyridine
5. Collin's reagent Ag/O2 at 250oC
(c) Butyne to Butan-2-one
CH3 – CH2 – C ≡ CH
HgSO4 / H2SO4
CH3– CH2 – C – CH3
||
O
CHO
NO2
(d) p – nitrotoulene to p – nitrobenzaldehyde
CH3
NO2
1. CrO2Cl2 / CS2
2. H3O +
Here you can also use
1. chromic oxide (CrO3) with acetic anhydride followed by hydrolysis
2. Side chain chlorination followed by hydrolysis at 373 K
(Commercial method) (Benzal chloride formed as intermediate)
Etard reaction – Chromium complex is formed as intermediate

42. Problem 2 How can you perform following conversions?
(a) Propanone to propene
(b) Propanal to butanone
(c) Benzaldehyde to benzophenone
CH3 – C – CH3
||
O
LiAlH4
CH3 – CH – CH3
|
OH
H2SO4
CH3 – CH = CH2
CH3 – CH2– C – H
||
O
+ CH3 MgBr
Dry ether
CH3 – CH2– C – H
|
O Mg Br
|
CH3
CH3 – CH2– CH
|
OH
|
CH3
Mg
Br
OH
+
CH3 – CH2– CH – CH3
|
OH
K2Cr2O7 / H2SO4
CH3 – CH2 – C – CH3
||
O
CHO
KMnO4 / OH -
COOH
Ca(OH)2
Dry distillation
C
||
O
H3O +

43. Problem 3 Complete the following reactions
(d) Benzaldehyde to a hydroxyphenylacetic acid
HCN / OH -
C – CN
OH
H –
C
O
H –
H3O +
C – COOH
OH
H –
Alc. KOH
D
A
1. O3
2. Zn / H2O
B + C
Alc. KOH
D
O3
+
CH3 – C– CH2 – CH3
|
CH3
|
Cl
CH3 – C CH – CH3
| |
O O
O
CH3
Zn / H2O
CH3 – C – CH3
||
O
B
CH3 – C – H
||
O
C
CH3 – C = CH – CH3
|
CH3
A
CH3 – C– CH2 – CH3
|
CH3
|
Cl
(a)

44. Alc. KCN
A
1. SnCl2 / HCl
2. H3O+
B
CH3 – CH – CH3
|
I
Alc. KCN 1. SnCl2 / HCl
2. H3O+
CH3 – CH – CH3
|
CN
A
CH3 – CH – CH3
|
CHO
B
1. CrO2Cl2 / CS2
2. H3O +
CH3
CH3
1. CrO2Cl2 / CS2
2. H3O +
A
CHO
CHO
A
CH3 – CH – CH3
|
I
(b)
CH3
CH3
(c)

45. + H2
Pd / BaSO4
(CH3)2CH – CHO
(CH3)2CH – CHO
CH3 – CH – C – Cl
||
O
|
CH3
(d)
A + H2
Pd / BaSO4
+ NaOI A + B
CH3 – C – C – CH3
||
O
|
CH3
|
CH3
(e)
CH3 – C – C – CH3
||
O
|
CH3
|
CH3
+ NaOI CH3 – C – C – O Na
||
O
|
CH3
|
CH3
– +
A
+ CHI3
B

46. NH2NHCONH2
A
CHO
NH2NHCONH2
CH = N – NHCONH2
A
CHO
(f)
||
O
|
CHO
||
O
|
COO
–
A
||
O
|
CHO
(g)
[ Ag (NH3)2] OH
–
+
[ Ag (NH3)2] OH
–
+

47. REACTIONS DUE TO a HYDROGEN
Aldehydes or ketones having at least one a hydrogen show aldol condensation reaction in presence of dilute alkali [e.g.
NaOH, Na2CO3 or Ba(OH)2].
Aldol condensation
– C– C– C – C – C – C –
||
O
|
|
H
H
|
|
H
H
H – C – H
||
O
a a'
a
CHO
– C– C– C – C – H
||
O
|
|
H
H
Two molecules of same aldehydes or ketones with a hydrogen condense together (combine together) to form b – hydroxy
aldehyde or b – hydroxy ketone which undergo dehydration to form a , b unsaturated aldehydes or ketones.
–– C –– C ––
||
O
|
H
This a hydrogen becomes acidic because electron density around this hydrogen
decrease due to – I effect of carbonyl carbon. So it can be easily given out as H + in
solution if we use base which can extract this proton
carbonyl group is EWG and shows – I effect.
(a) Simple aldol or self aldol condensation

48. After the removal of H+ the carbanion formed is stable due to resonance.
–– C –– C ––
||
O
|
H
B
–– C –– C ––
||
O
–
carbanion
+ BH
–– C –– C ––
||
O
–
–– C = C ––
|
O
–
CH3 – C
||
O
|
H
H – CH2 – C – H
||
O
CH2 – C – CH2 – C – H
|
OH O
||
|
H
a
b
b – hydroxy aldehyde (aldol)
a
b a
b
a , b – unsaturated aldehyde
–H2O
D
OH
–
CH2 – CH – CH – C – H
|
OH O
||
|
H
CH2 – CH = CH – C – H
O
||
Mechanism

49. CH3 – C
||
O
|
CH3
H – CH2 – C – CH3
||
O
OH
–
CH3 – C – CH2 – C – CH3
|
OH O
||
|
CH3
CH3 – C – CH – C – CH3
|
OH O
||
|
CH3
|
H
–H2O
D
CH3 – C = CH – C – CH3
O
||
|
CH3
b – hydroxy ketone (ketol)
a
b
a
b
a , b – unsaturated ketone

50. CH3 – C – CH3
||
O
CH3 – CH2– C – H
||
O
+
(b) Crossed aldol condensation
Simple aldol or self aldol products
CH3 – C – CH3
||
O
CH3 – C – CH3
||
O
+
OH
–
CH3 – C – CH2 – C – CH3
|
OH O
||
|
CH3
–H2O
D
CH3 – C = CH – C – CH3
O
||
|
CH3
Four products are possible
CH3 – CH2– C – H
||
O
CH3 – CH2– C – H
||
O
+ CH3 – CH2– C – CH – C – H
|
OH
|
H
||
CH3
|
O
OH
–
–H2O
D
CH3 – CH2– C = C – C – H
|
H
||
CH3
|
O

51. CH3 – CH2– C – H
||
O
OH
–
CH3 – CH2– C – CH2 – C – CH3
|
OH
|
H
||
O
CH3 – C – CH3
||
O
+
–H2O
D
CH3 – CH2– C = CH – C – CH3
|
H
||
O
Crossed aldol products
CH3 – C – CH3
||
O
CH3 – CH2– C – H
||
O
+ CH3 – C – CH – C – H
|
OH O
||
|
H3C
|
CH3
OH
–
–H2O
D
CH3 – C = C – C – H
O
||
|
H3C
|
CH3
In case of crossed aldol condensation, any one aldehyde or ketone has a hydrogen and other does not have a carbon then also
reaction is possible as given below.
CHO
CH3 – C – CH3
||
O
+
OH
–
CH – CH2 – C – CH3
||
|
OH O
–H2O
D
CH = CH – C – CH3
||
O

52. Cannizzaro reaction
Aldehydes which do not have any a H atom such as HCHO, C6H5CHO undergo self oxidation and self reduction on treatment with
conc. Alkali. In this, one molecule is reduced to alcohol and another molecule gets oxidised into salt of carboxylic acid.
HCHO + HCHO
Conc. KOH
CH3OH + HCOOK
CHO CHO
+
Conc. NaOH
CH2OH COONa
+
Self Cannizzaro reaction
Crossed Cannizzaro reaction
+ HCHO
CHO
Conc. NaOH
CH2OH
+ HCOONa
In case of crossed Cannizzaro of any aldehyde and formaldehyde always oxidation of formaldehyde takes place i.e. always salt
of formic acid gets formed

53. Electrophilic substitution reactions (aromatic aldehydes and ketones)
In case of aromatic aldehydes and ketones, they undergo electrophilic substitution reaction at meta position because – CHO is
EWG and shows – R effect. As all EWG are meta directing, so substitution occurs at meta position. (Electron density decreases
on ortho and para position so, positive charge gets developed.)
|
C
O
H
|
C
O
H
||
C
O
H
+
–
||
C
O
H
+
–
||
C
O
H
+
–
||
C
O
H
–
+
(a) Halogenation
CHO
+ Cl2
FeCl3
CHO
Cl
+ HCl
COCH3
+ Cl2
FeCl3
COCH3
Cl
+ HCl

54. (b) Nitration
CHO
Conc. HNO3 + Conc.H2SO4
Nitrating mixture
CHO
NO2
(c) Sulphonation
CHO
Fuming H2SO4
CHO
SO3H
COCH3
Fuming H2SO4
COCH3
SO3H

55. USES OF ALDEHYDES AND KETONES
1. 40% HCHO is known as formalin used in preservation of biological specimens
2. Formaldehyde is also used as disinfectant
3. Acetaldehyde is sued for silvering mirrors
4. Benzaldehyde is used in perfume industry
6. Many aldehydes and ketones like vaniline (used as vanilla flavour), cinnamaldehyde (used as cinnamon flavour) used for flavour
5. Acetone is used as solvent in industries as well as paints

56. CARBOXYLIC ACIDS
Large number of carboxylic acids are found in nature. Some higher members of aliphatic carboxylic acids (C12 – C18) known as
fatty acids.
Carbon compounds containing a carboxyl functional group, –COOH are called as carboxylic acids.
The carboxyl group, consists of a carbonyl group attached to a hydroxyl group, hence its name carboxyl.
Carboxylic acids
Aliphatic (RCOOH)
Aromatic (ArCOOH)
Alkyl group attached to – COOH group
Aromatic ring attached to – COOH group

57. NOMENCLATURE AND STRUCTURE OF CARBOXYL GROUP
Common system
Large number of carboxylic acids are known by their common names because many of the are naturally occurring.
The common names end with the suffix –ic acid and have been derived from Latin or Greek names of their natural sources.
For example
Formic acid HCOOH First obtained from red ants (Latin: formica means ant)
Acetic acid CH3COOH First obtained from vinegar (Latin: acetum, means vinegar)
Butyric acid CH3CH2CH2COOH First obtained from rancid butter (Latin: butyrum, means butter)

58. IUPAC system
Aliphatic carboxylic acids are named by replacing the ending –e in the name of the corresponding alkane with – oic acid.
Presence of one –COOH group – oic acid
Presence of two –COOH group dicarboxylic acid
Presence of three –COOH group tricarboxylic acid
Remember priority series
1. f any other functional group present along with – COOH
group then that group gets lesser priority and can be used as
prefix of that group.
2. Only sulphonic acid has higher priority than that of –
COOH group and can be used as suffix.

59. Common name
Compound IUPAC name
CH3COOH
CH3CH2COOH
CH3 – CH – CH – CH2 – COOH
|
OH
1
2
3
4
5
Acetic acid Ethanoic acid
Propionic acid Propanoic acid
Isobutyric acid 2 – methyl propanoic acid
CH3 – CH – COOH
|
CH3
2
3 1
CH3 – CH – CH2 – CH2 – CH2 – COOH
|
Cl
2
3
4
5
6 1
5 – chloro hexanoic acid
______
5 – chloro hexanoic acid
CH3 – CH = CH – CH2 – CH2 – COOH
2
3
4
5
6 1
______
______
3 – hydroxy pentanoic acid

60. Common name
Compound IUPAC name
COOH
|
CH3
COOH
2
1
COOH
COOH
1
2
2 – methyl cyclopentane carboxylic acid
CH2 – CH2 – COOH
2
3 1
______
3 – phenyl propanoic acid
______
______
Benzoic acid
Phthalic acid Benzene –1–2–dicarboxylic acid

61. Common name
Compound IUPAC name
Salicylic acid
Anisic acid
COOH
OH
1
2
COOH
OCH3
1
2
3
4
Dibasic acids
COOH
COOH
|
COOH
COOH
|
CH2
|
2 – hydroxy benzoic acid
4 – methoxy benzoic acid
Oxalic acid
Malonic acid
Ethanedioic acid
Propanedioic acid

62. COOH
CH2
|
CH2
|
CH2
|
COOH
|
COOH
CH2
|
CH2
|
COOH
|
Succinic acid
Common name
Compound IUPAC name
Butanedioic acid
Glutaric acid Hexanedioic acid

63. STRUCTURE OF CARBOXYL GROUP
C
O H
O
sp2 hybridisation
sp3 hybridisation
sp2 hybridisation
120o
C
O H
O
Resonance structures:
C
O H
O
-
+ C
O H
O
-
+

64. METHODS OF PREPARATION OF CARBOXYLIC ACIDS
1. From primary alcohols and aldehydes (by oxidation)
Primary alcohols
Oxidising agents
Aldehydes
1. KMnO4 in alkaline medium [KMnO4 / OH -]
Followed by hydrolysis
2. KMnO4 in acidic medium [KMnO4 / H+]
3. K2Cr2O7 in acidic medium [K2Cr2O7 / H+]
1. CrO3
2. Pyridinium chloro chromate (PCC)
3. Pyridinium dichromate (PDC)
4. Jones reagent (CrO3+H2SO4) in acetone
CH3 – CH2 – CH2 – OH
1. KMnO4 / OH -
2. H3O+
CH3 – CH2 – COOH
CH3 – CH – CH2 – CHO
CH3
|
PCC
CH3 – CH – CH2 – COOH
CH3
|

65. Primary and secondary alkyl groups are oxidised in this manner while tertiary group is not affected.
2. From alkylbenzenes
Aromatic carboxylic acids can be prepared by vigorous oxidation of alkyl benzenes with chromic acid or acidic or alkaline
potassium permanganate.
The entire side chain is oxidised to the carboxyl group irrespective of length of the side chain.
CH3
KMnO4 – KOH
Heat
COO K
– +
H3O+
COOH
CH2 – CH2 – CH3
KMnO4 – KOH
Heat
COO K
– +
H3O+
COOH

66. Nitriles are hydrolysed to amides and then to acids in the presence of H+ or OH– as catalyst.
3. From nitriles and amides
R – CN
H + or OH–
H2O
R – C – NH2
||
O
H + or OH–
D
R – C – OH
||
O
CONH2
H + or OH–
D
COOH
Grignard reagents react with carbon dioxide (dry ice) to form salts of carboxylic acids which in turn give corresponding carboxylic
acids after acidification with mineral acid.
4. From Grignard reagents
R Mg X + O = C = O
Dry ether
R– C
O
O Mg
_ +
H3O+
R – C – OH
||
O
Mg
X
OH
+

67. Anhydrides are hydrolysed to corresponding acid(s) with water.
5. From acyl halides and anhydrides
Acid chlorides when hydrolysed with water give carboxylic acids or more readily hydrolysed with aqueous base to give carboxylate
ions which on acidification provide corresponding carboxylic acids.
C6H5 – C
O
C6H5 – C
O
O
||
||
R – C – Cl
||
O
H2O
OH / H2O
_
R – C – O
||
O
_
+ Cl
_ H3O+
R – C – OH
||
O
+ HCl
R – C – OH
||
O
H2O
2 C6H5– C – OH
||
O C6H5 – C
O
C2H5 – C
O
O
||
||
H2O
C6H5– C – OH
||
O
C2H5– C – OH
||
O
+

68. 6. From esters
COOC2H5 COOH
+ C2H5OH
H3O+

69. PHYSICAL PROPERTIES
Aliphatic carboxylic acids up to nine carbon atoms are colourless liquids at room temperature with unpleasant odours.
The higher acids are wax like solids and are practically odourless due to their low volatility.
1. Physical states
2. Boiling point
R C
O
OH
d –
d+
C R
O
OH
d+
d –
Intermolecular H – bonding
Carboxylic acids have highest boiling point among all functional groups in organic compounds.

70. 3. Solubility
R C
O
OH
d –
d+
H – O
H
d+ d-
d+
H – O
H
d+
d-
d+
Benzoic acid, the simplest aromatic carboxylic acid is nearly insoluble in cold water.
Simple aliphatic carboxylic acids having upto four carbon atoms are miscible in water due to the formation of hydrogen
bonds with water.
The solubility decreases with increasing number of carbon atoms. Higher carboxylic acids are practically insoluble in
water due to the increased hydrophobic interaction of hydrocarbon part.
Carboxylic acids are also soluble in less polar organic solvents like benzene, ether, alcohol, chloroform, etc.

71. CHEMICAL REACTIONS OF CARBOXYLIC ACIDS
Acidity of carboxylic acids
Carboxylic acids react with active metals like sodium, potassium etc. to give hydrogen gas
2 R – C – OH + 2 Na
||
O
R – C – O Na
||
O
_ +
+ H2
2
Carboxylic acids react with alkalis to form salt and water (neutralisation reaction)
R – C – OH + NaOH
||
O
R – C – O Na
||
O
_ +
+ H2O
Carboxylic acids react with weaker bases like sodium carbonate, sodium bicarbonate etc. to form salt and carbon
dioxide is evolved
R – C – OH + NaHCO3
||
O
R – C – O Na
||
O
_ +
+ H2O + CO2

72. Carboxylic acids dissociate in water to give resonance stabilised carboxylate anions and hydronium ion.
R – C – OH + H2O
||
O
R – C – O
||
O
_
+ H3O +
R C
O
O
_ R C
O
O
_
R C
O
O
-
Carboxylate ion
Resonance structures of carboxylate ion
Resonance hybrid

73. Now, consider the same reaction,
R – C – OH + H2O
||
O
R – C – O
||
O
_
+ H3O +
Equilibrium constant for this reaction can be given as,
K =
[RCOO ] . [H3O+]
_
[RCOOH] . [H2O]
∴ K [H2O] =
[RCOO ] . [H3O+]
_
[RCOOH]
∴ Ka=
[RCOO ] . [H3O+]
_
[RCOOH]
pKa = – log10 Ka
Remember
Higher Ka Value stronger is the acid
Higher pKa value weaker is the acid
For strong acid pKa < 1
For moderately strong acid 5 > pKa > 1
For weak acid 15 > pKa > 5
For extremely weak acids pKa > 15

74. EFFECT OF SUBSTITUENTS ON THE ACIDITY OF CARBOXYLIC ACIDS
If EWG group is attached to R chain in – COOH group then acidity of carboxylic acid increases
EWG C
O
O
-
– I
Case 1:Acidity of carboxylic acid depends upon which EWG group is attached to – COOH
Increase in acidity of acid is in order.
Ph < I < Br < Cl < F < CN < NO2 < CF3
e.g. Arrange the following acids in increasing order of acidic strength
CH3 – CH2 – CH – CH2 – COOH
|
NO2
(I)
CH3 – CH2 – CH – CH2 – COOH
|
I
(II)
CH3 – CH2 – CH – CH2 – COOH
|
F
(III)
CH3 – CH2 – CH – CH2 – COOH
|
(IV)

75. Case 2: Acidity of carboxylic acid depends upon no. of EWG attached to carbon chain
No. of EWG increases acidity of acid also increases
e.g. Arrange the following acids into their increasing order of acidic strength
F – C – CH2 – COOH
F
|
F
|
(I)
CH2 – CH2 – COOH
|
F
(II)
CH – CH2 – COOH
|
F
|
F
(III)
CH3 – CH2 – COOH
(IV)
Case 3: Acidity of carboxylic acid depends upon position of EWG in carbon chain.
CH3 – CH2 – CH2 – CH – COOH
|
CN
(I)
CH3 – CH – CH2 – CH2 – COOH
CN
|
(II)
CH2 – CH2 – CH2 – CH2 – COOH
CN
|
(III)
CH3 – CH2 – CH – CH2 – COOH
CN
|
(IV)
e.g. Arrange the following acids into their increasing order of acidic strength

76. If EDG group is attached to R chain in – COOH group then acidity of carboxylic acid decreases
EDG C
O
O
-
+ I
e.g. groups like – R, – OR etc.
CH3 – C – CH2 – COOH
CH3
|
CH3
|
(I)
CH2 – CH2 – COOH
|
CH3
(II)
CH – CH2 – COOH
|
CH3
|
CH3
(III)
CH3 – CH2 – COOH
(IV)
e.g. Arrange the following acids into their increasing order of acidic strength
Same can be applied for aromatic acids as well.

77. 1. Formation of anhydride
Carboxylic acids on heating with mineral acids such as H2SO4 or with P2O5 give corresponding anhydride
CH3 C
O
OH
+ C CH3
O
H
O
H+
, D
Or P2O5 , D
CH3 C
O
C CH3
O
O
2. Esterification
R – OH + R’ COOH
H+
R COOR’ + H2O

78. 3. Reactions with PCl5, PCl3 and SOCl2
R – C – OH + PCl5
||
O
R – C – Cl + POCl3 + HCl
||
O
3 R – C – OH + PCl3
||
O
3 R – C – Cl + H3PO3
||
O
The hydroxyl group of carboxylic acids, behaves like that of alcohols and is easily replaced by chlorine atom on treating
with PCl5, PCl3 or SOCl2.
R – C – OH + SOCl2
||
O
R – C – Cl + SO2 + HCl
||
O

79. Carboxylic acids react with ammonia to give ammonium salt which on further heating at high temperature give amides.
4. Reaction with ammonia
CH3– C – OH + NH3
||
O
D
– H2O
COOH
COOH
+ NH3
D
– 2H2O
CH3 – C – O NH4
||
O
– +
Ammonium acetate
CH3– C – NH2
||
O
Acetamide
COO NH4
COO NH4
– +
– +
Ammonium phthalate
Strong heating
– NH3
Phthalamide
C – NH2
C – NH2
||
O
||
O
C
C
||
O
||
O
NH
Phthalimide

80. Carboxylic acids are reduced to primary alcohols by lithium aluminium hydride or better with diborane.
5. Reduction
Diborane reduces carboxylic acid and unsaturation selectively. Diborane does not reduce functional groups such as ester,
nitro, halo, etc.
RCOOH RCH2OH
1. LiAlH4
2. H3O+
RCOOH RCH2OH
B2H6
Carboxylic acids lose carbon dioxide to form hydrocarbons when their sodium salts are heated with sodalime (NaOH and CaO in
the ratio of 3 : 1). The reaction is known as decarboxylation.
6. Decarboxylation
RCOONa
NaOH & CaO
Heat
RH + Na2CO3
Alkali metal salts of carboxylic acids also undergo decarboxylation on electrolysis of their aqueous solutions and form hydrocarbons
having twice the number of carbon atoms present in the alkyl group of the acid. The reaction is known as Kolbe electrolysis

81. Carboxylic acids having an α-hydrogen are halogenated at the a-position on treatment with chlorine or bromine in the presence
of small amount of red phosphorus to give a-halocarboxylic acids. The reaction is known as Hell-Volhard-Zelinsky reaction.
7. Halogenation
R – CH2 – COOH
1. X2 / Red phosphorus
2. H3O+
R – CH – COOH
|
X
(X = Cl, Br)
Aromatic carboxylic acids undergo electrophilic substitution reactions in which the carboxyl group acts as a deactivating and
meta-directing group. They however, do not undergo Friedel-Crafts reaction because the carboxyl group is deactivating and the
catalyst aluminium chloride (Lewis acid) gets bonded to the carboxyl group.
8. Electrophilic substitution of aromatic acids
COOH
NO2
COOH
HNO3 + H2SO4
COOH
Br
COOH
Br2 / FeBr3

82. 1. Hexanedioic acid is used in the manufacture of nylon-6, 6.
2. Esters of benzoic acid are used in perfumery.
3. Sodium benzoate is used as a food preservative.
4. Higher fatty acids are used for the manufacture of soaps and detergents.
USES OF CARBOXYLIC ACIDS

83. IMPORTANT
PROBLEMS FOR
BOARD EXAM

84. Q.1 Write the structures of products of the following reactions
O
+ HO – NH2
H+
O
H2 N – NH –
+ – NO2
O2N
H2N – NH – C – NH2
||
O
R – CH = CH – CHO +

85. Q. 2. Write chemical reactions to affect the following transformations:
(i) Butan-1-ol to butanoic acid
(ii) Benzyl alcohol to phenylethanoic acid
(iii) 3-Nitrobromobenzene to 3-nitrobenzoic acid
CH3 – CH2 – CH2 – CH2 – OH
[O]
CH3 – CH2 – CH2 – COOH
CH2 – OH
Mg
Ether
CH2 – Br CH2 – CN
KCN
CH2 – COOH
1. Reduction
2. H3O+ D
Br
NO2
Mg Br
NO2
Dry ice (CO2)
Dry Ether
C
NO2
O Mg Br
O
C
NO2
OH
O
HBr
H3O+
Mg
Br
OH
+

86. (vi) Butanal to butanoic acid.
(iv) 4-Methylacetophenone to benzene-1,4-dicarboxylic acid
(v) Cyclohexene to hexane-1,6-dioic acid
COCH3
CH3
KMnO4 / KOH
COOK
COOK
H3O+
COOH
COOH
benzene-1,4-dicarboxylic acid
Terephthalic acid
KMnO4 / H2SO4
Heat
COOH
COOH
CH3 – CH2 – CH2 – CHO
[O]
CH3 – CH2 – CH2 – COOH

87. Q. 3 Show how each of the following compounds can be converted to benzoic acid.
(i) Ethylbenzene
(ii) Acetophenone
(iii) Bromobenzene
C2H5
KMnO4 / KOH
COOK
H3O+
COOH
COCH3
1. KMnO4 / OH
_
2. Hydrolysis
COOH
+ CH3COOH
Br
Mg
Ether
Mg Br
Dry ice (CO2)
Dry Ether
C
O Mg Br
O
C
OH
O
H3O+
Mg
Br
OH
+

88. (iv) Phenylethene (Styrene)
CH = CH2
KMnO4 / KOH
COOK
H3O+
COOH

89. Q. 4 Predict the products formed when cyclohexanecarbaldehyde reacts with following reagents.
(i) PhMgBr and then H3O+
(ii) Tollens’ reagent
C
O H
+ PhMgBr
Dry
Ether
C
Br Mg O H
Ph
H3O+
C
HO H
Ph
Mg
Br
OH
+
C
O H
Tollen’s reagent
Ammoniacal solution of AgNO3
C
O O
_
+ 2 Ag ↓ + 4NH3 + 2H2O

90. (iii) Semicarbazide and weak acid
C
O H
(iv) Excess ethanol and acid
H2N – NH – C – NH2
||
O
+
H+
C
O H
C2H5 – OH
C2H5 – OH
H+
C H
OC2H5
C2H5 O
+ H2O
(v) Zinc amalgam and dilute hydrochloric acid
C
O H
Zn – Hg / HCl
CH3

91. Q. 5. Which of the following compounds would undergo aldol condensation, which the Cannizzaro reaction and which neither?
Write the structures of the expected products of aldol condensation and Cannizzaro reaction.
(i) Methanal
(ii) 2-Methylpentanal
(iii) Benzaldehyde
(iv) Benzophenone
(viii) Butan-1-ol
(ix) 2,2-Dimethylbutanal
(v) Cyclohexanone
(vi) 1-Phenylpropanone
(vii) Phenylacetaldehyde
HOME WORK

92. Q. 6 How will you convert ethanal into the following compounds?
(ii) But-2-enal
(iii) But-2-enoic acid
(i) Butane-1,3-diol
CH3 – CHO
Dil. NaOH
Self aldol
CH3 – CH – CH2 – CHO
|
OH
CH3 – CH – CH2 – CH
|
OH
|
OH
D
– H2O
CH3 – CHO
Dil. NaOH
Self aldol
CH3 – CH – CH2 – CHO
|
OH
NaBH4
CH3 – CH = CH – CHO
D
– H2O
CH3 – CHO
Dil. NaOH
Self aldol
CH3 – CH – CH2 – CHO
|
OH
CH3 – CH = CH – CHO
Mild oxidising agent
CH3 – CH = CH – COOH

93. Q. 7. How will you bring about the following conversions in not more than two steps?
(i) Propanone to Propene
(ii) Benzoic acid to Benzaldehyde
(iii) Ethanol to 3-Hydroxybutanal
CH3 – C – CH3
||
O
CH3 – CH – CH3
|
OH
CH3 – CH = CH2
COOH
NaBH4 H2SO4
D
SOCl2
COCl CHO
Pd / BaSO4
H2
CH3 – CH2 – OH
[O]
CH3 – CHO CH2 – C – CH2 – C – H
|
OH O
||
|
H
Dil. NaOH
Self aldol

94. (iv) Benzene to m-Nitroacetophenone
(v) Benzaldehyde to Benzophenone
CH3COCl / Anhyd. AlCl3
Friedel – Craft acylation
C – CH3
||
O
HNO3 + H2SO4
C – CH3
||
O
NO2
(vi) Bromobenzene to 1-Phenylethanol
COOH
CHO
[O] SOCl2
COCl
Anhyd. AlCl3
C
||
O
Br
Mg
Ether
Mg Br
1. CH3CHO
2. H2O
H3C – C – H
|
OH
Mg
Br
OH
+

95. (viii) Benzoic acid to m- Nitrobenzyl alcohol
(vii) Benazaldehyde to α-Hydroxyphenylacetic acid
CHO CH – CN
|
OH
CH – COOH
|
OH
NaCN / HCl H+ / HCl
COOH
HNO3 + H2SO4
COOH
NO2
B2H6
CH2OH
NO2