TMK SK025: Chapter 11 Introduction to Organic Chemistry

Tutorial CHAPTER 11: Introduction to Organic Chemistry

11.1 & 11.2: Molecular and Structural Formula & Functional groups and homologous series.

1. (a) Define term structural formula.
Structural formula is a chemical formula which shows how the atoms in a molecule
are bonded to each other.

(b) Draw condensed structure
i. CH3CH(CH3)CH2OH

ii. CH3CH(CH3)CO CH(CH3) CH2CH3

iii. HC CH2
HC CH2

iv. CH3CH(Cl)CH2COOH

(c) Draw skeletal structure and classify each C 10
i. ii.
40 20 OH
2o O
1o 2o 1o 10 20 20

10

iii.

2o 2o 2o OH

1o
Br O

3. (a) Define

Functional group is an atom or group of atoms in an organic molecule which
characterized the molecule and enables the molecule to react in specific ways
(determine its chemical properties).

Homologous series is a series of compounds where each member differs from the
next member by a –CH2– group.

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Tutorial CHAPTER 11: Introduction to Organic Chemistry

(b) i. circle and name functional group

CH 2OH
hydroxyl

aromatic ring NCH3
H

amino

ii.
alkoxy

CH 2OCH 3

aromatic ring NHCOCH 3
amide

iii.

carbonyl halogen

O C-C double bond Cl carboxyl
COOH

CC H

C-C triple bond C
O

aromatic ring C O carbonyl

O

ester

11.3: Isomerism

1. (a) Define
Isomerism are the existence of chemical compound that have the same molecular
formula but different molecular structures or different arrangements of atoms in
space.

(b) Draw constitutional isomers and identify type of isomer.

1 H3C CH2 2 H3C CH2 3 H3C CH2

CH2 CH2 CH OH
CH2 CH2 H3C HC
HO H3C CH2
OH

CH3

4 H3C CH2 5 H3C HC 6 H3C CH2

CH CH3 CH2 HO C CH3
H3C
HO CH2 HO CH2

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Tutorial CHAPTER 11: Introduction to Organic Chemistry

OH 8 H3C CH3 9 H3C CH2
CH2
7 H3C HC H3C C O
CH2 CH2
CH CH3
H3C HO

CH3

10 H3C CH2 11 CH3 12 CH3
CH2
H2C H3C HC H3C HC
O CH2 O

CH3 H3C O H3C CH2

Functional group isomers: 1&9, 2&10, 3&11, 4&12, etc.
Positional isomers: 1&2, 5&6, 9&10, 9&12, etc.
Chain isomers: 2&8, 3&4, 9&11, 10&12, etc
*Any other combination are accepted.

2. (a) Requirement for cis-trans isomerism.
(b) • Has restricted rotation site at C = C double bond in alkenes or at C – C single

bond in cyclic compounds.
• Each carbon atom at a site of restricted rotation has two different groups attached

to it.

cis-trans isomer

i, ii, v and vii can exists as a pair of cis-trans isomers

i. Cl H
CC
HH
CC H Cl
t rans-isomer
Cl Cl
cis-isomer Cl H
CC
ii.
H Br
HH t rans-isomer
CC

Cl Br
cis-isomer

v. CH3 H
CC
HH
CC H CH2 CH3
t rans-isomer
CH3 CH2 CH3
cis-isomer Br H

vii.

Br Br

HH H Br
cis-isomer t rans-isomer

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Tutorial CHAPTER 11: Introduction to Organic Chemistry

3. (a) Structural features for optically active molecule
• Molecule contains a chiral carbon or chiral centre (chirality center).
• The molecule and its mirror image molecule are not superimposable to each

other.

(b) chiral C
CH3*CH(Br)CH2CH3

(c) Enantiomers

CH3 CH3

HC CH
Br CH2CH3 CH3CH2 Br

enantiomer

(d) Optically active compound
i. Not optically active
ii. Optically active
iii. Not optically active
iv. Optically active

11.4 Reactions in organic compounds

1. (a) Definition
Electrophile :
Nucleophile : a species that can accept an electron pair.
an electron-rich species that can donate a pair of electrons to form a
bond.

(b) Classify
Nucleophile : NH3, NO2-, PCl3
Free radical : Br.
Electrophile : NO2+, BF3, CO2, H2O

(c) (i) Nucleophilic site : CH2=CH2 Electrophile : H2O
(ii) Electrphilic site : CH3Cl Nucleophile : OH-

2. Increasing order of stability

H C+ H CH3 H CH3
CH3CHC+ H CH3C+ CH2CH3 < CH3C+ CH2CH3

H< H< IV II

III I

• Alkyl group is the electron donating group that increases the stability of a carbocation
• The greater number of alkyl groups on the carbon atom bearing the positive charge, the

more stable is the carbocation.
• Number of alkyl groups on the positively charge carbon atom of structure II > IV > I > III.
• Stability of structure III < I < IV < II.

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Tutorial CHAPTER 11: Introduction to Organic Chemistry

3.

H
H3C C
i. H radical

ii. CH3O- carbanion
iii. CH3+ carbocation
4. Type of reaction
(a) Nucleophilic substitution reaction.
(b) Electrophilic addition reaction.
(c) Rearrangement reaction.
(d) Elimination reaction.
(e) Free radical substitution reaction.
(f) Electrophilic substitution reaction.
(g) Elimination reaction.

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Tutorial CHAPTER 11: Introduction to Organic Chemistry

MEKA 11

1. Classify X and Y Y: 2o carbon
X: 3o carbon

2. Classify C b) 1o C: 3, 2o C: 6, 3o C: 3
a)

1o

3o
2o 2o

2o 3o 2o

1o 3o 2o 1o
2o

3. Condensed structure
a) CH3CH(Br)CH(Br)CH3
b)
(CH3)2C CCl 2
c)

CH2CH2CH(OH)CH3
C CH(CH2CH3)

CH(CH3)2

d) CH3CH2O(CH2)2COOH

4. Skeletal structure
a)

O

b)

NH

5. Circle functional group

HOH2C amino
hydroxyl CH2 CHCOOH

NH2 carboxyl
aromatic ring

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Tutorial CHAPTER 11: Introduction to Organic Chemistry

6. chiral C and enantiomer

a) CH3*CH(OH)CH2CH3

CH 2CH 3 CH 2CH 3

HC CH
HO CH3 H3C OH

enantiomer

b)
*CHClCH 3

HC CH
Cl CH3 H3C Cl

enant iom er

c)

CH3CH CHC* HCH3

CH2NH2

CH CHCH3 HC CHCH3

HC CH2NH2 CH
CH2NH2 CH3
H3C

enant iomer

7. type of isomerism
a) Structural isomers
b) Diastereomers

8. a) Optically active
Yes.
• It has a chiral carbon which is a carbon atom that is bonded to four different
atoms/groups of atoms.
• It has the ability to rotate plane-polarised light.

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Tutorial CHAPTER 11: Introduction to Organic Chemistry

b) enantiomers

C6H5 C6H5
* *C H
HC NC OH
HO CN
enantiomer

c) Characteristic of optically active compound:
• Has chiral carbon which is a carbon atom that is bonded to four different
atoms/groups of atoms.
• It has the ability to rotate plane-polarised light.

9. Escending order of stability CH3

CH3 < CH3CH2 < (CH3)2CH <

10. identify nucleophile and electrophile
nucleophiles: CH3O-, NH3
electrophiles: AlCl3, C6H5N2+

11. Type of reaction
a) Elimination reaction
b) Free radical substitution reaction.
c) Electrophilic addition reaction.

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Tutorial CHAPTER 11: Introduction to Organic Chemistry

KUMBE 11

1. circle and name functional group O carbonyl

a)

O carbonyl

C
H

C-C double bond

HO C-C double bond carbonyl
hydroxyl
O
b)
CH2CHO carbonyl
amino

H2NH2C

O

alkoxy CH2CH2OH hydroxyl

c)

aromatic ring

carboxyl amide CH2 ester

O O CH O
C CH3
HO C CH2 C O
N

C

H2N CH3 H

amino

2. Isomeric pair
a)
CH3CH2CH CH2

Chain isomer:

H3C C CH2

CH3

Positional isomer:
CH3CH CHCH3

Functional group isomer:

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Tutorial CHAPTER 11: Introduction to Organic Chemistry

b) CH3CH(CH3)CH(CH3)CH3

Chain isomer:
CH3CH2CH2CH2CH2CH3

Positional isomer:
CH3C(CH3)2CH2CH3

Functional group isomer:
NONE

c) CH3CH2CH2CH2CH2OH

Chain isomer:
CH3CH(CH3)CH2CH2OH

Positional isomer:
CH3CH(OH)CH2CH2CH3

Functional group isomer:
CH3CH2CH2CH2OCH3

3. cis-trans isomer CH2CH3 H3C H
a)
CC
H3C
H CH2CH3
CC t ran s-isom er

HH
cis-isomer

b) OH
H
H
H H

OH OH
t ran s-iso mer
OH
cis-isomer

c) molecule X:
• has restricted rotation site (C-C double bond)
• Each C at the restricted rotation site bonded with two different group of atoms.
CH3CH CHCH3

H3C CH3 H3C H

CC CC

HH H CH3
cis-isomer t ran s-iso mer

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Tutorial CHAPTER 11: Introduction to Organic Chemistry

5. C5H10- Cycloalkane
a) Structural isomer

b) diastereomer(cis-trans) of A;
• Has two branches at different C.
6. a)
b) HH H CH3
c)
CH3 CH3 CH3 H
d) cis-isomer t ran s-iso mer

Name functional group

COOH - carboxylic acid.
OH – hydroxyl group.

Define chiral centre
Carbon atom that attached to four different atoms or groups of atoms.

Enantiomers

CH3 CH3

HC CH
HO COOH HOOC OH

enantiomer

Optically active compound
Lactic acid has a chiral carbon which is a carbon atom that is bonded to four
different atoms/groups of atoms. It has the ability to rotate plane-polarised light.

8. Difference between hemolytic cleavage and heterolytic cleavage

Homolytic cleavage Heterolytic cleavage
occur in non polar bond involving two Occurs in a polar bond involving two
atoms of similar electronegativity. atoms of different electronegativity.
Single bond break symmetrically. Single bond breaks unsymmetrically.
Free radicals are formed. Cation and anion are formed.

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Tutorial CHAPTER 11: Introduction to Organic Chemistry

9. Increasing order of stability

(a)

CH3 H H3C

H3C < H2C C CH3 < C CH2CH3 < C CH2CH3

H H3C H3C IV

I II III

• The presence of alkyl group increase the stability of free radical.
• The greater number of alkyl groups on the carbon free radical atom, the more stable

is the free radical.
• Number of alkyl groups on the carbon free radical atom of structure I < II < III < IV.
• Stability of structure I < II < III < IV.

(b)

+ +
<
H3C <

+ III
I II

• The presence of alkyl group increase the stability of a carbocation.
• The greater number of alkyl groups on the positively charge carbon atom, the more

stable is the carbocation.
• Number of alkyl groups on the positively charges carbon atom of structure I < II <

III.
• Stability of structure I < II < III.

10. type of reaction
(a) electrophilic substitution reactions
(b) electrophilic addition reactions.
(c) nucleophilic substitution reactions.
(d) i. Free radical substitution
ii. Elimination
iii. Electrophilic addition reaction

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