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ORGANIC CHEMICAL REACTIONSUnit
3
307Doc Scientia - IEB Senior Chemistry Answer Book
Exercise 42: Page 372
1. B
2
Reaction General reaction typeSpecific
reaction type
2.1 CH2Cℓ–CH2Cℓ → CH2=CHCℓ + HCℓ Elimination Dehydrohalogenation
2.2 CH2=CH2 + Cℓ2 → CH2Cℓ–CH2Cℓ Addition Halogenation
2.3 CH3CH2OH → CH2=CH2 + H2O Elimination Dehydration
2.4 C2H6 → CH2=CH2 + H2 Elimination Dehydrogenation
2.5 CH3CH2Br + H2O → CH3CH2OH + HBr Substitution Hydrolysis
3.1 Ethane reacts with bromine.
3.2 Propene reacts with hydrogen gas with Pt as catalyst.
3.3 Butane reacts with bromine.
C CH H+ +C C
H H Br
H H H
H H
H
H
Br Br BrH
+ +Br Br BrHH HC CC CC CC C
H HH H
H H
H HH HH HH H
H HH Br
H HC CC CC CH
H H
H HH
H HHH
H HH H
+Pt
ORGANIC CHEMISTRY
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3.4 Ethene reacts with water that contains concentrated H2SO4 as catalyst.
3.5 1 mol of but-1-ene reacts with water.
4.1 When longer chains of hydrocarbons are divided into shorter chains.
4.2 To obtain a larger percentage of usable products from the heavier fractions of crude oil. OR Shorter chains are mixed with fuel to enrich it. OR Shorter chains burn more evenly.
5.1
5.2 High temperatures and high pressure
5.3 Smaller, more usable molecules are manufactured, which are used in the production of various products.
6.
Propene
C CH H O+C C
H H
H H H
H H
H
H H
OH2SO4
CC CH H+C C C C
H H H HO H
H
HH H H
CH H
H H
H HH
OH2SO4
C C
H
H H
H
HH
+ +
H
H
H
H
C C
H
H
H
H
C C
hexane (C6H14) ethane
high temp.
highpressure
ethene ethene
H C CC C C C
H HH
H
HH HH HH
H H H
H CC C
HH
HH
H
ORGANIC CHEMICAL REACTIONSUnit
3
309Doc Scientia - IEB Senior Chemistry Answer Book
7.1
7.2 The ethene released by the banana ages the cabbage and lettuce. OR Lettuce and cabbage will change colour. OR Lettuce and cabbage will go bad and rot.
7.3 CnH2n
7.4 A: Substitution: halogenation/bromination B: Addition: hydrogenation D: Addition: hydration G: Substitution: hydrolysis
7.5
7.6 HBr
7.7.1 E: concentrated and dissolved in ethanol. G: diluted with water.
7.7.2 Dehydrohalogenation
8.1 Contains a double bond between two carbon atoms.
8.2
8.3 Addition: hydrohalogenation
8.4
Propan-2-ol Propan-1-ol
H
H
H
H
C C
C C
H
H H
H
HH
+ H H
H
H
H
H
C CPt
C C CH HOR+C C C CC C
H H HBr HH Br
H H H H
H H H
H H
H HH H
H Br
major product minor product
ORC H
H
C C
HO
H
H
H
H H
major product
C H
H
C C
H HO
H
H
H H
minor product
ORGANIC CHEMISTRY
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Doc Scientia - IEB Senior Chemistry Answer Book
8.5 Hydrolysis
8.6.1 Water
8.6.2 H2SO4/H3PO4
8.6.3 Addition: hydration
8.7.1 Propene
8.7.2 Elimination: dehydrohalogenation
9.
3-bromo-3-methylpentane 2-bromo-3-methylpentane
10.1 CH3CHCℓCH3 + NaOH → CH3CHOHCH3 + NaCℓ
10.2 CH2BrCH3 CH2=CH2 + HBr
11.1.1 Substitution: halogenation
11.1.2 Sunlight/heat
11.2
12.1 A: Brown colour disappears and the mixture becomes colourless. B: The colour stays brown at first and does not change immediately.
12.2 Addition: halogenation
12.3 3-chloroprop-1-ene
C
H
C
H
C C HC
CH
H
H HH
H
H BrH HH
C
H
C
H
C C HC
CH
H
H HH
H
Br HH HH
OR
NaOHΔ
C Cℓ
F
Cℓ
F
ORGANIC CHEMICAL REACTIONSUnit
3
311Doc Scientia - IEB Senior Chemistry Answer Book
12.4
IUPAC name: 1,2-dibromo-3-chloropropane
12.5 Solution A is unsaturated. There is a double bond between the two C atoms. Solution B is saturated. All C-C bonds are single bonds. Unsaturated compounds are more reactive than saturated compounds.
13.1
13.2
14.1 Substitution
14.2
15.1 P. Q.
C CH H+C C C C
BrCℓ Br Cℓ
H H H H
H H
H H
Br Br
HH CC O CC H H H
HH
O
HH
H
H
H
+H2SO4
H CC OC
HH
H HH
H
H
H
ORH
HH C
C
C
C
C
C
CC C
C
CC H
H
H
H
HH H
H
H
H
HH
HH
Br
Br
HH HH
H
H HH
HBr
+
+
KOH in ethanol
Δ
major product
minor product
C CH H
H H
ethene
C C
H H
H
HOH
H
ethanol
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15.2 Y
15.3 Dehydrohalogenation
15.4 X: Dilute strong base in water, mild heat Y: Concentrated strong base in ethanol, strongly heated.
15.5 P: Alkenes Q: Alcohols
16.1 Heat or light energy must be added.
16.2 Substitution
16.3
bromomethane dibromomethane tribromomethane tetrabromomethane
17.1
17.2
17.3
C Br
H
H
H C Br
Br
Br
HC Br
H
Br
H C Br
Br
Br
Br
C C C H
H
H
H H HPt
H
H
propene propane
addition:hydrogenation+ H CC HC
HH
H HH
H
C HC Cℓ
H
H
H Cℓ
H
H
light energy+ C HC H
H
H
H Cℓ
Cℓ
H
+
chloroethane
substitution:halogenation
C C C CC C H
H H Br H
H H H H
H H HH Br
H
H
+
2-bromopropanepropene
addition:hydrohalogenation
major product
ORGANIC CHEMICAL REACTIONSUnit
3
313Doc Scientia - IEB Senior Chemistry Answer Book
17.4
17.5
17.6
17.7
17.8
elimination: dehydrohalogenation
C C C C
H
H
H H
H
HH H
+
1-bromobutane but-1-ene
C CC C
H
H H
H
H H
H
Br
H H NaOH in
ethanol
high heat
H Br
C CC CC CCℓ
H H
H H H
H HH HCℓ
H Cℓ Cℓ
H H
+
propene 1,2-dichloropropane
addition:halogenation
C CC C Na
H
H H
H
H O
H
H
Br
H
H H
+
2-bromobutane butan-2-olsubstitution: hydrolysis
C CC C
H
H H
H
H Br
H
H
H H
+H2O
mildheat
H
Na O
C C C C H
H
H
H H O
H H H
H H
+
butan-2-olbut-2-ene
elimination: dehydration
C CC C
H
H H
H
H
H
HO H
H H
H2SO4
heat
major product
H2SO4(c)C C C H
H
H
H H O
H H
H
+
addition: hydration
C CC
O
H
H
H H
H
HH
H
propenepropan-2-ol
orH3PO4
major product
ORGANIC CHEMISTRY
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Doc Scientia - IEB Senior Chemistry Answer Book
18.1
18.2 Propan-2-ol For propan-2-ol, the position of the hydroxyl is in the centre of the molecule, while it is at the end for propan-1-ol. The propan-1-ol molecule has stronger London forces due to its longer non-polar tail, than propan-2-ol has. The net intermolecular forces for propan-1-ol are stronger than for propan-2-ol and the boiling point of propan-2-ol is therefore lower.
18.3 Dehydration
18.4 Propene
18.5 Haloalkanes OR alkyl halides
18.6 Dilute base/NaOH/KOH/aqueous base/NaOH/KOH/NaOH/KOH in water OR H2O
18.7.1 Dehydrohalogenation OR Dehydrobromination
18.7.2 CH3CHBrCH3 CH3CH=CH2 + HBr (Condensed formulae are deduced from the structural formulae.)
18.8 Hydrogenation
18.9
C C C
H H H
H
O HHH
H
C CC
HHH
H
H H
NaOH
C CC
H
H H
H
Br H
H
H
+ +KOH in ethanol
Δ; refluxC C C H NaH
H
H
H O BrO
H H HNa
H
+
C CC CC CH
H H
HH H H
HH HH
H H H
H H
+Pt, Pd, Ni
ORGANIC CHEMICAL REACTIONSUnit
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315Doc Scientia - IEB Senior Chemistry Answer Book
19.1.1 Ethanoic acid
19.1.2 Methylpropane
19.2 Base/basic/alkaline Compound A is acidic – it will neutralise an alkali/a base. Thus, a wasp sting is alkaline (basic).
19.3
20.1 A saturated hydrocarbon contains only carbon and hydrogen and all of the bonds between carbon atoms are single bonds.
20.2 CH3CH2CH=CH2 + H2 CH3CH2CH2CH3
21.1 3-ethylpentane
21.2 Methyl propanoate
22.1
22.2 Addition
22.3
22.4.1 Compounds with the same molecular formula, but different structural formulae
22.4.2 B: Butan-2-ol C: Methylpropan-2-ol
22.4.3 A
22.4.4 The intermolecular forces weaken as the molecule branches, because the surface area and therefore the London forces, decrease. A has no branches, and therefore has the strongest intermolecular forces and also the higher boiling point because more energy is needed to overcome the IMF’s.
+C OC C H C
H HH HH H
H HH HH H
HH HC C O C
O
H2SO4O
H
HC CC C C H
H H HH H H
H H HH H H
H C OC
O
+heat
O H
C CC CCC O
H H H
HH
H HH
H HHH
H HHHH H
+ O
H
H
C CH2SO4
Pt