About aldehydes,ketones & carboxylic acids

4.  Aldehydes, ketones and carboxylic acids
are widespread in plants and animal
kingdom.

5.  They play an important role in biochemical
processes of life.
 They add fragrance and flavour to nature,
for example, vanillin (from vanilla beans),
salicylaldehyde (from meadow sweet) and
cinnamaldehyde (from cinnamon) have very
pleasant fragrances.

10.  They are used in many food products and
pharmaceuticals to add flavours. Some of
these families are manufactured for use
as solvents (i.e., acetone) and for
preparing materials like adhesives, paints,
resins, perfumes, plastics, fabrics, etc.

11.  Aldehydes and ketones having at least one
α-hydrogen undergo a reaction in the
presence of dilute alkali as catalyst to
form β-hydroxy aldehydes (aldol) or β-
hydroxy ketones (ketol), respectively.
This is known as Aldol reaction.

12.  In presence of base [dil.
NaOH,KOH,Na2CO3, ,Ba(OH)2]

16. Methods of preparation of
aldehydes and ketones
Dry distillation of carboxylic acid
Rosenmund’s reduction and
stephen’s reduction
Preparation of benzaldehyde:
Etard’s reaction & Gatterman
koch reaction

17. Preparation of ketones:
From Acyl chloride and from
benzene
Properties 01:
Nucleophilic addition – Addition
of HCN , alcohols
Properties 02 :
Addition of ammonia & ammonia
derivatives
Properties 03:
Reduction of aldehydes and
ketones

18. Properties 04 :
Tollen’s test (silver mirror
test) & Fehling’s test
Haloform reaction /
iodoform reaction/
iodoform test

20.  Rosenmund’s reduction:
Partial reduction acid halide to aldehyde.
H2
Acid halide Aldehyde
Lindlar’s
catalyst

21. CATALYST :
1. Pd / BaSO4
2.Pd / CaCO3
In presence of quinoline
Or
Sulphur Or Pb (OAC)2

22. O Pd / BaSO4 O
R-C-Cl + H2 R-C-H + HCl
Poisoned by
suphur

23. O Pd / BaSO4 O
CH3-C-Cl + H2 CH3-C-H + HCl
Poisoned by
ethanoyl sulphur acetaldehyde
chloride

24. O Pd / BaSO4 O
Cl C + H2 Cl- C-H + HCl
Poisoned by
benzoyl sulphur benzaldehyde
chloride

25.  Formaldehyde cannot be prepared by
rosenmund’s reduction.
O
H-C-H

26. Methanoyl chloride is highly unstable
O
H-C-Cl
H2/Lindlar’s
catalyst
O
H-C-H

27. 1. SnCl2/ HCl
 Alkane nitrile Aldehyde
(cyanide) 2. H2O / H+

28. 1. SnCl2/ HCl
 R-C=N R-CH=NH
(nitrile) (imine)
2. H2O / H+
R-CHO

29. 1. SnCl2/ HCl
 CH3-C=N CH3-CH=NH
(ethane nitrile) (imine)
2. H2O / H+
(Acetaldehyde) CH3-CHO

30.  SnCl2 + 2HCl SnCl4 + 2H+
 Sn+2 Sn +4 +2e-

31. 2e-
 CH3-C=N CH3-C=N
2H+
CH3-CH=NH
(imine)

32. H-OH O-H
 CH3-CH=NH CH3-CH-NH2
H+
-NH3
CH3-C-H
O

33.  Benzonitrile
C=N CH=NH
CHO 2.H2O/ H+
1. SnCl2/ HCl

34.  In NCERT book they give as AlH(i-bu)2.

35.  R-CO-Cl ------------------------- RCHO
 R-C=N ----------------------------RCHO
 R-COO-R’----------------------- RCHO + R’OH

37.  1. From methyl benzene / toluene
Using Chromyl chloride CrO2Cl2

38. CH3 CHO
1.CrO2Cl2/CS2
2.H2O/H+
Benzaldehyde

39. CH3 CH(OCrCl2OH)2
2CrO2Cl2/CS2
CHO Chromium
complex
H2O/H+ (brown)

41.  With dialkyl cadmium
R2Cd

42. O O
2R’-C-Cl + R2Cd 2 R’-C-R+
CdCl2

44.  Addition of ammonia and its is derivatives
 Ammonia : NH3
 Ammonia derivatives : NH2-Z
1. Hydroxyl amine : NH2-OH
2. Hydrazine : NH2-NH2
3. Phenyl hydrazine : NH2-NH-
4. 2,4-Dinitrophenyl hydrazine
NH2-NH-

47.  Aldehydes are easily oxidized to
corresponding carboxylic acids.
 R-CHO RCOOH
ALDEHYDES CARBOXYLIC
ACIDS

48.  HNO3
 Acidified K2Cr2O7
 Acidified KMnO4

49.  Tollen’s reagent
 Fehling’s reagent
 Also oxidize aldehydes into
carboxylic acids

50.  Ketones are oxidised only in vigrous
conditions
 Ie,. Strong oxidizing agent in very
high temperature.
 They are not oxidized by mild
oxidizing agent.

51.  It is ammonical silver nitrate

52.  Freshly prepared tollen’s reagent
 R-CHO +2 Ag(NH3)2
+
+ 3OH-
metallic silver
RCOO- + 2Ag + 4NH3 + 2H2O

53.  Showing test tube of tollen test having silver
sticking to the sides.
 This indicates completion of reaction
 It looks like silver mirror
 Silver deposits as mirror

57.  Both aliphatic as well as aromatic
aldehyde show positive silver mirror
test
 CH3-CHO +2 Ag(NH3)2 +
+
+ 3OH-
CH3-COO- + 2Ag + 4NH3 + 2H2O

58. CHO
2 Ag(NH3)2 +
+
+ 3OH-
COO-
+ 2Ag + 4NH3 + 2H2O

59.  Ketones do not give tollen’s test
 Except : - hydroxy ketone
 Alpha - hydroxy ketone will give
tollen’s test.

60.  Gives positive result for silver mirror test
O O
CH3-C-CH-CH3 Ag + CH3-C-C-CH3
OH O

61.  Formic acid also gives positive
tollen’s test
 HCOOH CO2 + H2O + Ag

62.  So, the test to distinguish between
formic acid and other acid is
tollen’s test.

63.  Terminal alkynes do react with
tollen’s reagent but do not form
silver mirror.

64. H-C=C-H H-C=C--Ag+

66. Fehling’s solution A
Aq copper sulphate
(CuSO4.5H2O)
Blue colour
Fehling’s solution B
Sodium potassium
tartarate

69.  Aliphatic aldehydes react reacts
with fehling’s solution to give
reddish brown precipitate.
 Fehling’s test is not applicable for
aromatic aldehydes.

71.  Aromatic aldehydes cannot be
oxidized by fehling’s solution.
 Ketones do not give fehling test

72.  Tollen’s reagent >Fehling’s reagent
 Tollen’s reagent is strong oxidizing
agent compared to fehling’s.

74.  CHCl3 (chloroform)
 Colourless liquid with pleasant smell.
 CHBr3 (bromoform)
 Colourless liquid with sweet smell
 CHI3 (iodoform)
 Pale yellow crystalline solid (yellow
precipitate)
 With hospital like smell (antiseptic smell)

75. O
CH3-C-H + X2 + NaOH CHX3

76. O
CH3-C-H +3X2 + 4NaOH CHX3 +
HCOONa +3NaX
+3H2O

77. O
CH3-C-CH3 +3X2 + 4NaOH CHX3
+ CH3COONa +3NaX +3H2O

78.  It is a property of aldehydes and
ketones which contain O
–C-CH3
OR
a methyl group

79. 3. Methyl alkyl ketones

80. 4. Formaldehyde

81. 5.benzaldehyde

82. 6. benzophenone

83. 7.Benzophenone

84.  Certain aldehydes & ketones (a-
methyl group ) on treatment with
I2/NaOH gives yellow precipitate
with antiseptic smell.

85.  Formaldehyde & acetaldehyde
 Acetone & benzophenone

86.  Ans : iodoform test