Tutorial Kit (Chemistry-300 L)-Vol. 2

122 Pages·2016·3.19 MB·English

by  Henry Okodua

COVENANT

UNIVERSI TY

ALPHA SEMESTER TUTORIAL KIT

(VOL. 2)

P ROG RAMME: CH EMI ST RY

300 LEVEL

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DISCLAIMER
The contents of this document are intended for practice and learning purposes at the undergraduate
level. The materials are from different sources including the internet and the contributors do not in
any way claim authorship or ownership of them. The materials are also not to be used for any
commercial purpose.

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LIST OF COURSES
CHM312: Organic Chemistry
CHM315: Unit Operations/Heat Transfer
CHM317: Environmental Chemistry
CHM332: Industrial Inorganic Chemistry
CHM333: Instrumental Method of Analysis
CHM334: Applied Spectroscopy
CHM356: Metallurgy and Metal Fabrication

*Not included

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COVENANT UNIVERSITY
CANAANLAND, KM 10, IDIROKO ROAD
P.M.B 1023, OTA, OGUN STATE, NIGERIA.

TITLE OF EXAMINATION: BSc EXAMINATION
COLLEGE: Science and Technology
DEPARTMENT: Chemistry
SESSION: 2015/2016 SEMESTER:
ALPHA
COURSE CODE: CHM 312 CREDIT UNIT: 3
COURSE TITLE: Organic Chemistry
INSTRUCTION: Attempt any FOUR (4) Questions TIME:
3 HOURS
PLEASE START THE RESPONSE TO EACH QUESTION ON A NEW PAGE OF THE
ANSWER BOOKLET

1. (a) Describe the Haworth synthesis of
Naphthalene.

(5 marks)

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Haworth Synthesis
• Naphthalene can be synthesized by treating
benzene with succinic anhydride in the
presence in the presence of AlCl .
3
O
O C
COOH
O AlCl3 Zn/Hg COOH
HCl 3-Phenyllpropa-
Benzene O 3-Benzoylpropa- noic acid
Succinic noic acid
anhydride Conc. H2SO4
Pd/C or Zn/Hg
Selenium HCl O
dehydrogenation
Naphthalene 1,2,3,4-Tetrahydro
naphthalene

(b) Showing the appropriate equation, give the final products of sulfonation of anthracene
both at low and high
temperature.

(5 marks)
Sulphonation
SO3H SO3H
exceLsosw CToenmcp. eHr2aStuOre4 Anthracene-1,8-disulphonic acid
eHxcigehs sT eCmonpce.r aHt2uSreO4 HO3S SO3H
Anthracene-2,7-disulphonic acid

(c) Give the IUPAC names of the following compounds:

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(i) Br O (ii) CH (iii) O O (iv) O
3
CH C CH O CH C C C
3
H C CH Br H C CH C H C O CH H C NH
3 2 3 2 3 3 3 2
O

(2 marks)
(i) 3-bromobutanoyl bromide; (ii) isobutyl acetate or 2-methylpropyl ethanoate or -
bromobutyryl bromide; (iii) acetic anhydride; (iv) acetamide
(d) Give the general products formed during the hydrolysis, alcoholysis, and aminolysis of
acid
halides.

(3 marks)
Hydrolysis, alcoholysis and aminolysis of acid chloride will give the products:
carboxylic acid, ester and amide respectively as shown in the figure below;
Acid Chloride Reactions (1)
O
HO
2 R C OH + HCl acid
O
R'OH
O R C OR' + HCl ester
R C Cl O
R'NH
2 R C NHR' + HCl amide
O O
R'COOH
R C O C R' + HCl
acid anhydride
=>
Chapter 21 16
(e) Complete the following reactions:
(i) CH CH COOH + NaOH ?
3 2

CH3―CH2―COOH + NaOH CH3―CH2―COO Na+ + H2O
sodium propanoate

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O
C
(ii) OCH3 HCl +
H O
2

(2.5 marks)

[Total
17.5
marks]

2. (a) Write structures for the following bicyclic
alkanes:

(3 marks)
(i) bicyclo[1.1.0]butane; (ii) 2-chlorobicyclo[3.2.0]heptane; (iii) 7-
methylbicyclo[2.2.1]heptane
H C
Cl 3

(b) (i) Draw the Newman projections for rotation about the C―C bond in
chloroethane and clearly label the most stable conformer and the least stable
conformer

(2 marks)
Cl
CCllH
H H
H H H
HH HH
H
H
more stable

The barrier to rotation about the C―C bond in chloroethane is 18.0 kJ/mol.

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(ii) What energy value can you assign to an H―Cl eclipsing interaction given that
H―H eclipsing interaction is 4
kJ/mol?

(2 marks)
18 = 𝑥 +4+4 = 𝑥+8
𝑥 = 18−8 = 10 kJ/mol
(iii) Sketch a diagram of potential energy versus angle of rotation about the C―C
bond of
chloroethane.

(2 marks)
18 kJ/mol
E
0 60 120 180 240 300 360
Degrees of Rotation 

(iv) Label the energy barrier to rotation on your
diagram

(1 mark)
See diagram above
(c) (i) The relative basicities of some nitrogen-containing compounds are as follows:
CHNH > NH > CHNH. Explain why these compounds behave as
2 5 2 3 6 5 2
bases.

(2 marks)
There is a lone pair of electrons on nitrogen that can be donated to a proton
(ii) Using diagrams, explain why aniline (CHNH) is more acidic than ammonia
6 5 2
(NH).
3

(2 marks)
The lone pair of electrons on nitrogen is delocalized into the benzene ring, which
means that the lone pair of electrons is not available for donation to a proton.

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+
NH2 NH2

(d) This question is about Diels-Alder reaction, a [4+2] cycloaddition reaction involving a
diene and a dienophile. Use curly arrows to describe the mechanism of the reaction
between 1,3-butadiene and propanal to give cyclohex-3-ene carbaldehyde.

(3.5 marks)
CH
2 CH
2
H H
CH
2
O O
[Total
17.5
marks]

3. (a) An aldol addition product loses water to form an aldol condensation product. Give the
mechanism of reaction for aldol condensation of propanal
(CHCHCHO).
3 2

(10 marks)
Aldol condensation is an organic reaction in which an enol or an enolate ion reacts with
a carbonyl compound to form a β-hydroxyaldehyde or β-hydroxyketone, followed by a
dehydration to give a conjugated enone.

(b) Briefly define the following terms showing the equation of reactions
(i). Claisen condensation
(ii). Malonic ester synthesis

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(iii). Aldol condensation
(iv). Aldol addition reaction
(v). Enol

(7.5 marks)
[Total
17.5
marks]
The Claisen condensation is a carbon–carbon bond forming reaction that occurs between two esters or one ester and another
carbonyl compound in the presence of a strong base, resulting in a β-keto ester or a β-diketone.

Aldol condensation is an organic reaction in which an enol or an enolate ion reacts with a
carbonyl compound to form a β-hydroxyaldehyde or β-hydroxyketone, followed by a
dehydration to give a conjugated enone.

Aldol addition
In the aldol reaction, two molecules of an aldehyde or ketone react with each other in the
presence of a base to form a -hydroxy carbonyl compound.

Malonic Ester Synthesis

Four basic step in reaction
1. Enolate formation (strong base)
2. Enolate alkylation (alkyl halide)
3. Ester hydrolysis (aqueous acid)
4. Decarboxylation (heat)
Enols are isomers of aldehydes or ketones in which one alpha hydrogen has been removed
and placed on the oxygen atom of the carbonyl group. The molecule has a C═C and an ―OH

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