CARBONYL COMPOUNDS AND PHENOL
EXPERIMENT
11
EXPERIMENT 11
CARBONYL COMPOUNDS AND PHENOL
11
OBJECTIVE(S):To study the properties of carbonyl and phenol
A.
REACTIONS OF CARBONYL COMPOUNDS
DATA/RESULTS:
Test
Observation
Ethanal
Propanone
Benzaldehyde
1
Brady’s reagent
Yellow orange
precipitate is formed
Yellow orange
precipitate is formed
Yellow orange
precipitate is formed
2
K2Cr2O7(aq)
Orange colour of
K2Cr2O7(aq) turns
green
Orange colour of
K2Cr2O7(aq) remains
Orange colour of
K2Cr2O7(aq) turns
green
3
Tollen’s reagent
Silver mirror is
formed on the wall of
the test tube/grayish
black precipitate
The solution remains
colourless
Silver mirror is
formed on the wall of
the test tube/grayish
black precipitate
4
Fehling’s reagent
Blue colour
Blue colour remains
Blue colour remains
Yellow precipitate
with anticeptic smell
is formed
Colourless solution
changes to brick red
5
Iodoform test
Yellow precipitate
with anticeptic smell
is formed
[any one correct testing and observations √1M]
CARBONYL COMPOUNDS AND PHENOL
EXPERIMENT 11
DATA/RESULTS:
Observation
Test
Unknown
1
Brady’s reagent
Yellow orange precipitate is formed
2
K2Cr2O7(aq)
Orange colour remains
3
Tollen’s reagent
The solution remains colourless
4
Fehling’s reagent
Blue colour remains
5
Iodoform test
Yellow precipitate with antiseptic smell is
formed
Class/Family of unknown: Ketone @ aldehyde
[any one correct testing and observations √1M]
B.
REACTIONS OF PHENOL
DATA/RESULTS
Test
Observations
Phenol
1
Addition of
water
2
Acidity
(a) Litmus paper
Emulsion (cloudiness) is formed and colourless homogeneous solution
formed in hot water bath.
(a)Blue litmus paper turns red
(b) (i) NaOH
(ii) HCl
(b)(i) homogeneous solution formed
(ii) emulsion formed
3
Iron(III) chloride
Blue violet/purple solution formed
4
Bromine water
White precipitate formed/ brown colour of bromine discharged
CARBONYL COMPOUNDS AND PHENOL
EXPERIMENT 11
[any one correct testing and observations √1M]
DISCUSSIONS:
Reaction of carbonyl compound
1.
Brady’s Reagent [√1M for equation OR observation]
a. Ethanal
O2 N
O
CH3 CH
+
O2 N
NH2 NH
NO2
CH3 CH
NNH
N2 O + H2 O
ethanal-2,4-dinitrophenylhydrazone
(yellow precipitate )
b. Propanone
O2 N
O
CH3 CCH3 +
O2 N
NO2
NH2 NH
CH3 C(CH3 )
NNH
N2 O
+ H O
2
propanone-2,4-dinitrophenylhydrazone
(yellow precipitate)
c. Benzaldehyde
O2 N
C6H5COH
+
O2 N
NH2 NH
NO2
C6H5CH
NNH
N2 O
+ H O
2
benzaldehyde-2,4-dinitrophenylhydrazone
(yellow precipitate)
2.
K2Cr2O7 [√1M for equation OR observation]
a. Ethanal
O
CH CH
3
K C r O /H +/w ar m
2 2 7
O
CH CO
H
+ 3Cr3+ (green/blue)
ethanoic acid
b. Benzaldehyde
O
O
CH
COH
+
K2 Cr2 O7 /H /warm
+ Cr3+ (green/blue)
benzoic acid
CARBONYL COMPOUNDS AND PHENOL
3.
EXPERIMENT 11
Tollen’s reagent [√1M for equation OR observation]
a. Ethanal
O
O
CH3 CH
+
+
2 [Ag(NH3 )2 ]
+
-
-
3 OH
CH3 CO
2Ag(s)+ 4NH3
+
+
H2 O
Silver mirror
b. Benzaldehyde
O
O
CH
CO
-
+
+
2 [Ag(NH3 )2 ]
+
-
3 OH
+
2Ag(s)+ 4NH3
+
H2 O
Silver mirror
4.
Fehling’s reagent [√1M for equation OR observation]
~ positive for aliphatic aldehyde
a. Ethanal
O
O
CH3 CH
5.
+
2Cu2+
+
-
5OH
+ Cu2 O (s)
Brick red precipitate
-
CH3 CO
+
3 H2 O
Iodoform test [√1M for equation OR observation]
a. Ethanal
O
CH3 CH
O
+
3I 2
+
4
NaOH
CH3 CONa
+
3 NaI
+ H2 O
+ CHI3
Yellow precipitate with antiseptic smell
CARBONYL COMPOUNDS AND PHENOL
EXPERIMENT 11
b. Propanone
O
O
CH3 CCH3 +
3I2
+
4
NaOH
CH3 CONa
+
3 NaI
+ H2 O
+ CHI3
Yellow precipitate with antiseptic smell
Reaction of Phenol
1.
Addition of water:
Phenol partially soluble in water. √1M
2.
Acidity
(a)
phenol is an acidic compound
C6H5OH + H2O ⇌ C6H5O- + H3O+
phenoxide ion
(b) (i) C6H5OH + NaOH  C6H5O- + Na+ + H2O
phenoxide ion(soluble)
(ii) C6H5O-
+ H+  C6H5OH
cloudy as phenol precipitate out
3. Iron (III) chloride
OH
OH
FeCl3
+ FeCl3 →
CARBONYL COMPOUNDS AND PHENOL
EXPERIMENT 11
Blue violet soln
4.
Bromine in water [√1M for equation OR observation]
OH
OH
Br
Br
Br2 (aq)
Br
White ppt (2,4,6-tribromophenol)
CONCLUSION:
1. Carbonyl compounds undergo nucleophilic addition reaction
2. Aldehyde can be oxidized/reducing agent to carboxylic acid whereas ketones cannot
be oxidized
3. Ethanal and propanone can be distinguish from benzaldehyde by using Iodoform
test due to the carbonyl group being bonded to the methyl group
4. Phenol is an acidic compound which partially soluble in water.
REFLECTION:
‘He knows that which goes into the earth and that which comes forth from it, and that which
descend from the heaven and that which ascends to it. And He is the Most Merciful, the
Oft¬Forgiving ‘ (34:2)
Allah knows everything that happens around us, we as the caliph should observe the
change in the reaction to know actually happening.
REFERENCES:
1. Tan Yin Toon, Chemistry for Matriculation Semester 2, Oxford Fajar Sdn.Bhd.
(pg. 219-250)
2.
Holy Quran; Text and Translation by Abdullah Yusuf Ali (pg 416)
CARBONYL COMPOUNDS AND PHENOL
EXPERIMENT 11
TOTAL MARKS 10