HALOALKANES AND ALCOHOLS
HALOALKANES
1
Name the following compounds according to IUPAC rules and classify them as
primary, secondary or tertiary haloalkane.
[5]
IUPAC name
Compound
(a)
(c)
1, 2 or 3
CH3CI(CH3)CH2CH2CH3
Cl
(b)
CH3C(F)(CH3)CH3
Class of R-X
2-iodo-2-methylpentane
2
1-chloro-2-methylbutane
1
2-fluoro-2-methylpropane
3
3-bromo-2-methylhexane
2
Br
(d)
1.4(c)
2
Draw the structural formula of the following compounds.
IUPAC name
(a)
tetrachloromethane
[3]
Structure
CCl4
4-bromo-3-methyl-2-pentene
(b)
CH3
CH3CH
C
CHCH3
Br
(c)
3-phenyl-2-chlorohexane
CH3C(Br)2CH3
1.4(c)
HALOALKANES AND ALCOHOLS
3
State why haloalkanes are more reactive than alkanes toward substitution.
[1]
Haloalkanes are polar compounds or C-X bond in haloalkanes are
polar [1]
1.4(f)
4
Complete the table below by drawing the structure of organic product for
each of the following reactions.
[4]
Reaction
Organic
product
and hot ethanolic NH3
(a)
F
NH2
F
NH2
(b)
CH3CH2Br and hot NaOH(aq)
CH3CH2OH
(c)
H3CHICH3 and hot ethanolic KCN
CH3CHCNCH3
Cl
(d)
CH3
CH2 C
C CH3 and hot ethanolic NaOH
CH3
CH3
CH3
1.4(g)
5
Based on the following information, draw the structural formulas of the
compounds A, B, D and E.
[4]
(a)
Hydrocarbon A reacts with Cl2 gas when exposed to sunlight to form
B. Compound B reacts further with hot ethanolic KCN to form
CH3CH2CN.
A
(b)
CH3CH3
B
CH3CH2Cl
Compound D reacts with hot NaOH(aq) to form E. Compound E forms
ethene in the presence of concentrated H2SO4 at 180 C.
D
CH3CH2Cl
E
CH3CH2OH
1.4(g)
HALOALKANES AND ALCOHOLS
6
Describe the SN2 reaction mechanism in the hydrolysis of chloromethane.
[3]
-
H
H
H
C
Cl
HO
C
H
HO
C
H
H
HO
H
H
[1]
H
+
-
Cl
H
[1]
[1]
1.4(h)
7
(a)
A haloalkane, C4H9Br has two isomers. Isomer Q can rotate planepolarized light. Another isomer, R is an optically inactive compound
that reacts with hot ethanolic potassium hydroxide to form compound
S. S reacts with hot acidified potassium permanganate (VII) to yield
compound T which resists oxidation together with CO2 and water.
Draw the structural formula for Q, R, S and T.
[4]
CH3
Q
CH3CH2CHBrCH3
S
CH2
C
CH3
O
R
CH3CBr(CH3)CH3
T
CH3
C
CH3
1.4(g)
(b)
Compare the reactivity when C4H9I and C4H9Br are hydrolyzed by hot
NaOH(aq) in terms of C-X bond strength.
[2]
C4H9I is more reactive [1] because I is less electronegative
than Br or size of I is larger than Br thus making C-I bond
become weaker [1].
1.4(i)
HALOALKANES AND ALCOHOLS
8
(a)
An organic compound A decolorizes bromine (in CH2Cl2) to form B.
Compound A also reacts with hydrogen chloride to form compound
C, C3H7Cl which is the major product according to Markovnikov’s rules.
Compound C is converted to D, C4H7N when reacted with hot ethanolic
KCN.
Draw the structural formula of A, B, C and D.
(b)
A
CH2=CHCH3
B
CH2(Br)CH(Br)CH3
C
CH3CH(Cl)CH3
D
CH3CH(CN)CH3
[4]
1.4(g)
Compare the reactivity when C3H7F and C4H9Cl are hydrolyzed by hot
NaOH(aq) in terms of C-X bond strength.
[2]
C3H7F is less reactive [1] because F is very electronegative than
Cl or size of F is smaller than Cl thus making C-F bond become
stronger [1].
1.4(i)
9
Reactions of 2-bromobutane are shown in the reaction scheme below.
(a)
Draw the structural formula of the following compounds.
(i)
compound R
CH3CH2CHCH3
NH2
(ii)
[2]
compound S
CH3CH2CHCH3
CN
1.4(g)
HALOALKANES AND ALCOHOLS
(b)
State the type of reaction for I, II and III.
(i)
(ii)
(iii)
Reaction I Reaction II Reaction III -
[3]
Addition
Substitution
Elimination
1.4(g)
(c)
(d)
(i)
State the significance of reaction IV.
To increase the number of carbon in the chain
(ii)
State the reagent and nucleophile in this reaction.
Reagent :
KCN in ethanol
Nucleophile :
CN- or cyanide ion
[2]
1.4(g)
Name the type of reaction and a reagent that is needed for reaction
VII.
[2]
Reduction
(e)
[1]
1.4(g)
reagent : LiAlH4 in ether
Name the reagent and condition for reaction V.
Reagent : dilute H2SO4
Condition : heat
1.4(g)
[2]
1.4(g)
HALOALKANES AND ALCOHOLS
ALCOHOLS
1
Name the following compounds according to IUPAC rules.
[4]
1.5(b)
2
The following names of organic compounds are incorrect. Draw the structural
formula and give the correct IUPAC names.
[3]
Incorrect name
Structure
IUPAC name
(a)
4-butanol
CH3CH2CH2CH2OH
1-butanol
(b)
1,1-dimethyl-2pentanol
(c)
CH3CH2CH2CHOHCHCH3
CH3
1-chloro-3-propanol
CH2ClCH2CH2OH
2-methyl-3hexanol
3-chloro-1propanol
1.5(b)
3
Write the equation for each of the following reactions.
(a)
2-butanol heated with acidified KMnO4 solution.
OH
CH3CHCH2CH3
(b)
+
KMnO4/H
heat
O
CH3CCH2CH3
+
Mn2+
2-propanol reacts with concentrated H2SO4 at 180 C.
OH
CH3CHCH3
conc H2SO4
1800C
CH2CHCH3
+
H2O
[3]
HALOALKANES AND ALCOHOLS
(c)
2-phenyl-1-ethanol reacts with PCl5
CH2CH2OH
CH2CH2Cl
PCl5
rt
+
HCl
+ POCl3
1.5(f)
4
Draw the structure of the organic product for each of the following reactions.
State the relevant observations for each reaction.
[6]
(a)
(b)
1,2-ethanediol reacts with sodium metal
ONa
ONa
CH2
CH2
Ethanoic acid is heated with 2-methyl-1-butanol in the presence of
dilute H2SO4
O
CH3C
(c)
Gas bubbles formed
CH3
Sweet smelling odor formed
OCH2CHCH2CH3
2-methyl-1-propanol heated with acidified K2Cr2O7
CH3
CH3CHCOOH
Orange solution change to green
1.5(g)
HALOALKANES AND ALCOHOLS
5
The reaction scheme below shows the reactions of alcohol P.
+
KMnO4 / H
2 CH3 COOH
heat
conc. H2 SO4 Q
C4 H8
o
180 C
P
-
KMnO4 / OH
C4 H10 O
cold
CH3 CHOHCHOHCH3
+
HCOOH/H
heat
(a)
R
Draw the structural formula of compound P, Q and R in the box
provided.
[3]
Compound P
Compound Q
CH3
OH
CH3CHCH2CH3
Compound R
CH3CH
P
CHCH3
Q
CH3CH2CH
O
O
C
H
R
1.5(f)
(b)
Classify alcohol P into primary, secondary or tertiary alcohol. [1]
Secondary alcohol
1.5(c)
HALOALKANES AND ALCOHOLS
6
The reaction scheme below shows the reactions of alcohol A.
Draw the structural formula of compounds A, B, C, D and E in the box
provided.
[5]
Compound A
Compound B
CH3
CH3CHCHCH3
ONa
Compound D
Compound E
Compound C
HALOALKANES AND ALCOHOLS
7
Suggest a chemical test to distinguish between the following compounds.
State the reagents, conditions and observation.
[6]
a)
2-methyl-1-propanol and 2-methyl-2-propanol
Reagent:
KMnO4/H+
[1]
Condition:
Heat
[1]
Observation:
2-methyl-1-propanol decolorizes purple solution
of
KMnO4
whereas 2-methyl-2-propanol does not decolorize purple color
KMnO4
[1]
Or Lucas test
Reagent:
HCl/ZnCl2 [1]
Condition:
rt
[1]
Observation:
2-methyl-1-propanol gives no cloudiness within 10-15 minutes
while 2-methyl-2-propanol gives rapid cloudiness [1]
1.5(h)
b)
1-butanol and 2-propanol
Reagent:
HCl/ZnCl2 [1]
Condition:
rt
[1]
Observation:
2-propanol forms cloudy solution within 5-10
minutes while 1-butanol gives no cloudiness [1]
1.5(h)
8
Suggest a chemical test to distinguish between the following compounds.
State the reagents, conditions and observation.
[6]
(a)
ethanol and 1-propanol
Reagent:
I2/NaOH [1]
Condition:
heat
[1]
Observation:
Ethanol
forms
yellow
precipitate
with
antiseptic smell whereas 1-propanol does not form yellow
precipitate with antiseptic smell[1]
1.5(f)
b)
hexane and hexanol
Reagent:
PCl5 [1]
Condition:
rt
[1]
Observation:
Hexanol forms white fume while hexane does
not form white fume[1]
1.5(f)