Download CHE1502 TL 102 0 B 2021

CHE1502/102/0/2021
Tutorial Letter 102/0/2021
General Chemistry 2
CHE1502
Year module
Department of Chemistry
This tutorial letter contains important information about the CHE1502 module.
BARCODE
1.
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CHE1502/102/0/2021
2.
QUESTIONS FOR ASSIGNMENT 2
ASSIGNMENT 02
UNIQUE NUMBER:
868636
DUE DATE:
05 July 2021
ANSWER ALL QUESTIONS
The multiple choice questions have FOUR possible answers. In each case, provide only
ONE answer to each question.
TOPICS: Alkyl Halides: Nucleophilic substitution reactions and mechanisms of alkyl
halides - SN1 and SN2.
The following series of questions covers the topic of “Alkyl Halides”
1.
Which of the following IS NOT A CORRECT presentation of electron movement/flow?
(1)
(2)
3
(3)
H2O
O
H
H
(4)
2.
Which of the following reactions will NOT take place?
(1)
CH3CH2CH2Br
NaN3
CH3CH2CH2N3
ethanol -water
(2)
CH3CH2CH2Br
NaI
CH3CH2CH2I
acetone
(3)
CH3CH2CH2Br
NaSCH3
CH3CH2CH2CH3
(4)
O
CH3CH2CH2Br
3.
O
CH3CH2CH2OCCH3
What is the product of the nucleophilic substitution reaction of CH3(CH2)2CH2Br with the
iodide ion?
(1) CH3(CH2)2CH2I
(2) CH2I(CH2)2CH2Br
4
CH3CONa
CHE1502/102/0/2021
(3)
CH3CH2CHICH3
(4) CH3CH2CHICH2Br
4.
5.
Alkyl halides can undergo nucleophilic substitution reactions. Which of the following
statements is CORRECT?
(1)
The second order nucleophilic substitution reactions involve inversion of
configuration at the central atom.
(2)
Tertiary alkyl halides are unlikely to undergo SN1 type reactions.
(3)
Unless resonance stabilization is observed, primary alkyl halides are unlikely to
undergo second order nucleophilic substitution.
(4)
The strength of the nucleophile does not play a role in the order of the nucleophilic
substitution reaction.
Which of the following statements pertaining to an SN2 reaction is INCORRECT?
(1)
The nucleophile attacks the carbon from the side of the molecule opposite the
group being displaced, that is, opposite to the leaving group.
6.
(2)
The rate of the reaction is dependent of the concentration of the nucleophile.
(3)
The reaction proceeds with simultaneous bond formation and bond breaking.
(4)
Bulky groups around the reaction site speeds up the reaction.
Which of the following species will react the fastest with CH3CH2CH2-I in a nucleophilic
substitution reaction?
(1)
(CH3)3CO
(2)
HO
(3)
H2O
(4)
CH3CO2
5
7.
Which of the following nucleophilic substitution reactions will TAKE PLACE THE
FASTEST?
(1)
CH2OH
CH2Br
OH
+
H2O
(2)
CH3
HO
Br
CH3
OH
+
Br
+
Br
H2O
(3)
H
HO
Br
H
OH
H2O
(4)
CH3CH2Br
OH
CH3CH2OH
H2O
8.
Identify the product of the following reaction:
(1)
6
+
Br
Br
CHE1502/102/0/2021
(2)
(3)
(4)
9.
If the substrate, CH3CHBrCH2CH3, is replaced by CH3CHFCH2CH3 in a nucleophilic
substitution reaction, then
10.
(1)
the rate at which each reaction takes place is the same.
(2)
the reaction will take place at a much faster rate.
(3)
the rate of the reaction will be twice as fast.
(4)
the reaction will not take place.
What is the major product of the following reaction?
7
(1)
(2)
(3)
(4)
11.
Which of the following reactions DOES NOT proceed via an SN2 reaction mechanism?
(1)
(CH3)2CHBr + NaCN
(CH3)2CHCN
+
NaBr
(2)
OCH3
I
+ CH3OH
+
HI
+
NaBr
(3)
Br
I
+ NaI
(4)
CH3CH2Br + NaSH
8
CH3CH2SH
+
NaBr
CHE1502/102/0/2021
12.
Which of the following species can react as a nucleophile to react in an SN1-type reaction?
(1) (CH3)2C=O
(2) H2O
(3) CN(4) CH3Cl
13.
Consider the following reaction:
Which of the following steps is NOT PART of the mechanism of the reaction?
(1)
(2)
CH3
H3C
H2O
+
Cl
+
HCl
O
Cl
H
H
(3)
CH3
CH3
O
H
H
Cl
OH
9
(4)
CH3
CH3
H2O
O
H
14.
15.
H
Which of the following alkyl halides will undergo hydrolysis the fastest?
(1)
(CH3)3Cl
(2)
(CH3)3Br
(3)
(CH3)3F
(4)
(CH3)3I
Alkyl halides may undergo nucleophilic substitution reaction according to the following
general reaction:
R
70% H2O
X
R
OH
+
HX
30% CH3OH
Which of the following substrates reacts the SLOWEST under similar reaction conditions?
(1)
CH3
Ph
C
Cl
CH3
(2)
Br
Ph
C
H
10
CH3
CHE1502/102/0/2021
(3)
Br
(4)
16.
Which of the following reactions will NOT take place?
(1)
I
Li
+
+
CH3Li
CH3I
(2)
Br
SH
+
NaSH
(3)
Br
OMe
+ Na OMe
MeOH
(4)
CH3
CH3
CH3OH
Br
OCH3
11
17.
Which of the following reactions proceeds via an SN1 reaction mechanism?
(1)
(2)
CH3CH2Br + NaSH
CH3CH2SH
(CH3)2CHBr + NaCN
(CH3)2CHCN
+
NaBr
(3)
+
NaBr
(4)
18.
Consider the following species:
Which statement below is INCORRECT?
(1)
Ethanol promotes nucleophilic substitution reaction via the SN2 mechanism.
(2)
Ethoxide is a better nucleophile than ethanol.
(3)
Ethoxide promotes nucleophilic substitution reaction via the S N2 mechanism.
(4)
Ethanol and ethoxide can act as nucleophiles.
TOPICS: Alcohols: Structure and nomenclature; physical properties; classification of alcohols
as primary, secondary, or tertiary; stereochemistry: 3-dimensional representations of
simple organic molecules, chirality and R- and S-configurations;
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CHE1502/102/0/2021
selected reactions of alcohols: oxidation reactions and the reactions of alcohols to
form alkyl halides, ethers and alkenes.
The following series of questions cover the topic of “Alcohols”
19.
Which of the following statements is INCORRECT?
(1)
The following compounds are classified as secondary alcohols
OH
CH3
(2)
CH
CH2CH3
and
OH
The following compound is classified as a phenol
OH
CH3
(3)
The following compound is (R)-hexan-3-ol
CH2CH3
H
CH3CH2CH2
(4)
C
OH
The following compound is classified as an enol
OH
13
20.
Consider the following compounds:
CH3
OH
CH3CH2CHCH3
A
;
CH3
C
CH3
OH ; CH3
C
CH3
CH3
B
C
CH2OH
;
Which statement regarding the above compounds is INCORRECT?
21.
22.
14
(1)
The compound, A, is a chiral compound.
(2)
Compounds C and D are primary alcohols.
(3)
All of the compounds contain a poor leaving group.
(4)
Compound B is a quaternary alcohol.
Name the following compound according to the IUPAC rules:
(1)
2-Bromo-2,3-dimethylhexan-5-ol
(2)
1-Bromo-1,1,2-trimethylpentan-4-ol
(3)
5-Bromo-4,5-dimethylhexan-2-ol
(4)
5-Bromo-4,5,5-trimethylpentan-2-ol
Name the following compound according to the IUPAC nomenclature:
CH3CH2CH2CH2OH
D
CHE1502/102/0/2021
23.
(1)
(2S)-3-bromo-5,6-dimethyloctan-2-ol
(2)
(2R)-3-bromo-5,6-dimethyloctan-2-ol
(3)
(2S)-3-bromo-6-ethyl-5-methylheptan-2-ol
(4)
(2R)-3-bromo-6-ethyl-5-methylheptan-2-ol
Name the following compound according to the IUPAC nomenclature:
OH
H
HOCH2CH2
24.
H
(1)
trans-3-(2-hydroxyethyl)cyclohexanol
(2)
(1R, 3S)-3-(2-hydroxyethyl)cyclohexanol
(3)
(1S, 3R)-3-(2-hydroxyethyl)cyclohexanol
(4)
cis-1-(2-hydroxyethyl)cyclohexan-3-ol
Which of the following compound is the MOST ACIDIC alcohol derivative?
(1)
CH3CH2OH
(2)
CH3
CH3
C
CH2OH
CH3
15
(3)
Br
CH2CH2
OH
(4)
OH
25.
26.
Methanol, CH3OH, is a good solvent for polar substances because:
(1)
Methanol undergoes dipole-dipole interactions.
(2)
Methanol is able to form hydrogen bonds with the polar substances.
(3)
There are weak ion-dipole interactions in methanol.
(4)
The van der Waals forces in methanol cause repulsion.
The following compounds are possible products in an elimination reaction.
Which compound, according to Saytzeff’s rule, will be the major product?
(1)
(2)
(3)
(4)
16
CHE1502/102/0/2021
27.
What is the MAJOR product formed in the following reaction?
CH3
CH3
CH
CH
CH3
H2SO4
H2O
OH
(1)
CH3
CH3
CH
CH
CH2
(2)
CH3
CH3
C
CH
CH3
(3)
CH3
CH2
C
CH2CH3
(4)
CH3
CH3
C
H
CH3
28.
The dehydration of alcohols in the presence of a strong acid is a regioselective and
stereoselective reaction. What is the MAJOR product formed in the following reaction?
OH
CH3
C
CH2CH2CH3
H2SO4
heat
H
17
(1)
(2)
CH3
CH3
CH
C
CH3
(3)
CH3
H
C
C
H
CH2CH3
(4)
CH3
CH2CH3
C
C
H
29.
H
t-Butanol undergoes dehydration reactions in the presence of dilute sulphuric acid at
80 OC. Which of the following steps is NOT APPLICABLE in the reaction mechanism?
(1)
(2)
CH3
CH3
H
CH3
C
CH3
18
O
H
slow
CH3
C
CH3
+
H2O
CHE1502/102/0/2021
(3)
HSO4
CH3
CH3
H
H
CH2
C
fast
O
CH2
H
CH3
+ H2SO4
C
CH3
(4)
CH3
H
C
CH2
H +
CH3
30.
fast
O
H
CH3
C
CH2
+
H3O
CH3
What is the MAJOR product formed in the following reaction?
CH3
CH3
C
CH3
CH
OH
CH3
H3PO4
heat
(1)
CH3
CH3
C
CH
CH2
CH3
(2)
CH3
CH3
C
CH3
C
CH3
19
(3)
CH2
CH3
C
CH3
CH
CH3
(4)
CH3
H
C
CH2
CH
31.
CH3
CH2
What is the MAJOR product formed in the following reaction?
CH2CH2CH3
CH3CH2
C
CH
H
CH3
OH
(1)
CH2CH2CH3
CH3CH2
C
CH
CH2
H
(2)
CH2CH2CH3
CH3
CH
C
CH2
CH
CH
CH3
(3)
CH3
CH2
C
H
20
CH2
CH3
CH3
H2SO4
150OC
CHE1502/102/0/2021
(4)
CHCH2CH3
C
CH3CH2
32.
CH2CH3
Consider the following reaction:
CH3
CH3
C
CH3
OH
+
H
Cl
CH3
CH3
C
+
Cl
H2O
CH3
Which of the following steps is NOT APPLICABLE in the stepwise mechanism of the reaction?
(1)
CH3
CH3
C
CH3
fast
H
OH
Cl
CH3
CH3
C
H
+
O
CH3
Cl
H
(2)
CH3
Cl
CH3
C
CH3
CH3
H
fast
O
CH3
Cl
C
H
+
H2O
CH3
(3)
CH3
CH3
C
CH3
CH3
Cl
fast
CH3
C
Cl
CH3
21
(4)
CH3
CH3
H
O
C
CH3
33.
CH3
slow
CH3
H
C
H2O
+
CH3
Which of the following reactions is INCORRECT as indicated by the mechanism of the
reaction and the major product formed in the reaction?
(1)
Via the SN1 reaction mechanism:
(2)
Via the SN2 reaction mechanism:
(3)
Via the SN2 reaction mechanism:
CH3CH2CH2CH2CH2OH + HCl
(4)
CH3CH2CH2CH2CH2Cl
Via the SN2 reaction mechanism:
CH3CH2
22
→
OH
+
HBr
CH3CH2Br
+
H2O
+ H2O
CHE1502/102/0/2021
34.
Which of the following reactions will NOT take place as shown?
(1)
HBr
CH2 OH
CH3
CH2Br
CH3
(2)
OH
HBr
H2 O
Br
(3)
OH
H2SO4
heat
(4)
CH3
CH3
CH3
H2SO4
C OH
H2 O
CH3
35.
CH3
CH3
C O C CH3
CH3
CH3
Heating ethanol with sulphuric acid at 140 OC produces diethyl ether. Which of the
following reaction steps is NOT APPLICABLE in the reaction pathway?
(1)
H
CH3CH2
O
+
H
H
O
SO2OH
fast
CH3CH2
+ HSO4
O
H
23
(2)
H
CH3
CH2
fast
O
CH3CH2
+
H2O
SN1
H
(3)
CH3CH2
CH3CH2
H
O
+
H
CH2
slow
O
O
SN2
CH3
CH2CH3 +
H2 O
H
H
(4)
H
CH2CH3
CH3CH2 O
H
+
fast
CH2CH3
O
CH3CH2OCH2CH3 + CH3CH2 O
H
H
36.
Alkyl halides can be prepared by the reaction of alcohols with hydrogen halides. Which of
the following reactions will NOT take place?
(1)
CH3
CH3
o
CH3
C
OH
+
25 C
HCl
CH3
CH3
C
Cl
+
H2O
CH3
(2)
OH +
HF
25oC
F
+
H2O
(3)
CH3
24
CH2
(CH2)4 CH2
OH + HBr
125o
CH3
CH2
(CH2)4 CH2Br +H2O
CHE1502/102/0/2021
(4)
Br
OH
+
37.
HBr
100
o
+ H2O
What is the MAJOR product formed in the following reaction?
OH
H2SO4
H2O
(1)
(2)
(3)
(4)
25
38.
Which of the following alcohols is oxidized to a ketone when reacted with Na2Cr2O7 in a
mixture of sulphuric acid and water?
(1)
(2)
(3)
(4)
39.
Which of the following reactions will NOT take place?
(1)
O
K2Cr2O7
F CH2CH2CH2 OH
H2SO4 / H2O
F CH2CH2 C
OH
(2)
OH
Na2Cr2O7
O
H2SO4 / H2O
(3)
O
PCC
OH
CH2Cl2
26
H
CHE1502/102/0/2021
(4)
OH
O
PCC
CH2Cl2
TOPICS:
Ethers: Structure of ethers, nomenclature of ethers, chemical and physical
properties of ethers, synthesis of ethers, reactions of ethers
The following series of questions cover the topic of “Ethers”
40.
Consider the compounds, dimethyl ether and ethanol. Which of the following statements is
INCORRECT?
41.
(1)
Molecules of dimethyl ether form strong hydrogen bonds with each other
(2)
Ethanol has the higher boiling point
(3)
Dimethyl ether has the lower boiling point
(4)
Molecules of ethanol form strong hydrogen bonds with each other.
Which of the following reactions will NOT take place?
(1)
(2)
(3)
OH
NaH
O
CH3Br
CH3
THF
27
(4)
NaOH
CH3CH2OH
42.
CH3Br
CH3CH2
O
CH3
Which of the following reactions will NOT produce the final product as shown?
(1)
O Na
+
CH3CH2O Na
+
CH3CH2Br
O CH2CH3
(2)
Br
O CH2CH3
(3)
CH3
CH2 O CH
CH3
CH2Cl
CH3
CH O Na
+
CH3
(4)
CH3 CH3
CH3 CH3
CH3CH2
C
C
(i) NaH
OH
(ii) CH3Br
CH3CH2
CH3 H
43.
C
OCH3
CH3 H
What are the MAJOR products formed in the reaction of 2-methoxybutane with excess
HBr?
CH3
CH
CH2CH3
HBr (excess)
heat
OCH3
(1)
CH3
CH CH2CH3
OH
28
C
+
CH3
Br
CHE1502/102/0/2021
(2)
+
(3)
CH3
CH CH2CH3
+
CH3
Br
Br
(4)
CH3
44.
CH3
+
OH
Br
Which of the following reaction steps is NOT APPLICABLE in the cleavage of diethyl ether
with excess hydrogen bromide?
(1)
(2)
CH3CH2
slow
O
H
CH3CH2OH
+
CH3CH2
CH3CH2
(3)
29
(4)
TOPICS:
Amines: Structure of amines, nomenclature of amines, classification of amines,
chemical and physical properties of amines, reactivity and basicity of amines,
synthesis of amines, reactions of amines
The following series of questions cover the topic of “Amines”
45.
46.
Name the following compound according to the IUPAC rules:
(1)
3-chloro-3-methyl-1-methylaminopentane
(2)
N-methyl-3-chloro-3-methylpentan-1-amine
(3)
1-methyl 3-chloro-3-methylpentan-1-amine
(4)
(3-chloro-3-methylpentyl) methyl amine
The structure of N-ethyl-3,3-dimethyl-1-butanamine is:
(1)
H
N
NH2
30
CHE1502/102/0/2021
(2)
NH2
(3)
N
(4)
N
H
47.
Which of the following amines is LEAST SOLUBLE in water?
(1)
CH3CH2NH2
(2)
CH3NHCH3
(3)
NH2
(4)
CH3CH2
N
CH2CH3
CH2CH3
31
48.
Which of the following compounds is classified as a tertiary amine?
(1)
H
CH3 CH2
N
CH3
(2)
N
CH3
CH3
(3)
CH2CH3
CH3CH2
N
H
H
Br
(4)
NH2
49.
Consider the compounds, propan-1-ol (CH3CH2CH2OH) and propan-1-amine
(CH3CH2CH2NH2). Which of the following statements is INCORRECT?
32
(1)
Propan-1-ol has a higher boiling point than propan-1-amine
(2)
The O-H bond is more polar than the N-H because oxygen is more electronegative
than nitrogen.
(3)
Alcohols form stronger hydrogen bonds than amines and have higher boiling
points.
(4)
Propan-1-amine has a higher boiling point than propan-1-ol.
CHE1502/102/0/2021
50.
Which of the following reactions will take place?
(1)
+
Br
NH3
(2)
OH
NH2
+
NH3
+
H2 O
(3)
CH3CH2CH2Br + 2NH3 → CH3CH2CH2NH2 + NH4+ Br -
(4)
TOTAL = [100]
The content of the Tutorial Letter 102 for the CHE1502/2021 module was compiled by
Professor GJ Summers and Professor CA Summers
------------------------------------------------------------------------------------------------------------------------------
33