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ORGANIC CHEMISTRY

By
Mubarak O
...
e
...


– Other type of organic compounds

Classification of Organic Compounds
Functional groups are structural units that determine the chemical reactivity of a
molecule under a given set of conditions
...


Classification of Organic Compounds

Classification of Organic Compounds

Classification of Organic Compounds

•DO YOU
HAVE ANY
QUESTION?

STUDY QUESTIONS
1
...


3
...


A cyclic compound is:
(a)
an open chained compound
(b)
An unsaturated hydrocarbon
(c)
A straight chained hydrocarbon
(d)
A closed chain compound
An alicyclic compound is an:
(a)
Aliphatic straight chain compound
(b)
Aromatic straight chain compound
(c)
Aliphatic cyclic compound
(d)
Aromatic cyclic compound
Cycloheptene is an example of
(a)
Heterocyclic compound
(b)
Polycyclic compound
(c)
Saturated hydrocarbon
(d)
Unsaturated hydrocarbon
Which of the following is an example of heterocyclic compound?
(a)
Cyclohexane
(b)
Furan
(c)
Benzene
(d)
Naphthalene

•Nomenclature of
Organic compounds
•Homologous series of
Organic Compounds

Nomenclature of Organic compounds
Homologous series of Organic Compounds
–
–
–
–

At the end of this topic you should be able to:
Identify
Provide systematic Names and
Discuss
• the various classes of organic compounds based on their
homologous series i
...

– Alkanes
» Cycloakanes
» Alkyhalide (Haloalkanes)
– Alkenes
– Alkynes
– Alkanol (Alcohols)
– Alkanoic acids (Carboxylic acids)
– Alkanals and Alkanones
– Alkanoate (Esters)

• etc

Nomenclature of Organic compounds
Homologous series of Organic Compounds
• HOMOLOGOUS SERIES
• The organic compounds which are structurally similar
having same functional groups, combinedly gives a series
known as homologous series and the members as
homologues
...
The two adjacent members are differ by a –CH2 – group or 14
atomic mass unit
...
All the members of a series have same
i
...
general methods of preparation and
iii
...


iii
...


Nomenclature of Organic compounds
Homologous series of Organic Compounds

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkanes

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkanes

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkanes

• As the number of carbons in an alkane increases
beyond three, the number of possible structures
increases
...

• Both of these structures fulfill the requirement that
each carbon forms four bonds and each hydrogen
forms only one bond
...

• In fact, isobutane got its name because it is an “iso”mer of
butane
...
”
• Thus, the name isobutane tells you that the compound is a
four-carbon alkane with an iso structural unit
...

• Isopentane, as its name indicates, has an iso structural
unit and five carbon atoms
...

• The structural unit with a carbon surrounded by four
other carbons is called “neo
...

• But we cannot name the other two without defining
names for new structural units
...

• Two of them can be named as (heptane and
isoheptane) without defining new structural units
...


Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkanes

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkanes

• The number of constitutional isomers increases rapidly as
the number of carbons in an alkane increases
...

• That way, only the rules have to be learned
...


Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkanes

• This method of nomenclature is called systematic
nomenclature
...

• The IUPAC rules have been continually revised by the
commission since then
...

• Before we can understand how a systematic name for an
alkane is constructed, we must learn how to name alkyl
substituents
...

• A propyl group is obtained when a hydrogen is removed
from a primary carbon of propane
...


Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkanes

• There are four alkyl groups that contain four carbon atoms
...

• A sec-butyl group has a hydrogen removed from a
secondary carbon (sec-, often abbreviated s-, stands for
secondary)
• A tert-butyl group has a hydrogen removed from a tertiary
carbon (tert-, sometimes abbreviated t-, stands for tertiary)
...

• This chain is called the parent hydrocarbon
...
”
• For example, a parent hydrocarbon with eight carbons would be called octane
...


Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkanes

•DO YOU HAVE
ANY QUESTION?

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkanes_Study Questions

• Write a structure for each of the following
compounds:
• a
...
isopentyl fluoride
• c
...
neopentyl chloride
• e
...
n-octyl bromide

•Nomenclature
of Alkanes

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkanes

• The systematic name of an alkane is obtained using
the following rules:
 Determine the number of carbons in the longest continuous
carbon chain
...

 The name that indicates the number of carbons in the
parent hydrocarbon becomes the alkane’s “last name
...

 The longest continuous chain is not always a straight chain;
sometimes you have to “turn a corner” to obtain the
longest continuous chain
...

• The chain is numbered in the direction that gives the substituent as low a
number as possible
...


Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkanes

• If more than one substituent is attached to the parent hydrocarbon,
the chain is numbered in the direction that will result in the lowest
possible number in the name of the compound
...

• In the following example, the correct name (5-ethyl-3-methyloctane)
contains a 3 as its lowest number,
• while the incorrect name (4-ethyl-6-methyloctane) contains a 4 as its
lowest number:

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkanes

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkanes

• When both directions lead to the same lowest
number for one of the substituents,
• the direction is chosen that gives the lowest
possible number to one of the remaining
substituents
...


Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkanes

• If a compound has two or more chains of the same
length, the parent hydrocarbon is the chain with the
greatest number of substituents

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkanes

• Names such as “isopropyl,” “sec-butyl,” and “tertbutyl” are acceptable substituent names in the IUPAC
system of nomenclature
• but systematic substituent names are preferable
...

• This means that the carbon that is attached to the
parent hydrocarbon is
• always the number 1 carbon of the substituent
...

• Write a structure for each of the following compounds:
• a
...
isopentyl fluoride
• c
...
neopentyl chloride
• e
...
n-octyl bromide

•Cycloalkanes

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Cycloalkanes

• Cycloalkanes are alkanes with their carbon atoms
arranged in a ring
...

• This means that the general molecular formula for a
cycloalkane is CnH2n
• Cycloalkanes are named by adding the prefix “cyclo” to
the alkane name that signifies the number of carbon
atoms in the ring
...

• Skeletal structures show the carbon–carbon bonds as lines, but do
not show the carbons or the hydrogens bonded to carbons
...

• Each vertex in a skeletal structure represents a carbon
...


Nomenclature of Organic compounds
Homologous series of Organic Compounds_Cycloalkanes

• Acyclic molecules can also be represented by skeletal
structures
...

• Again, each vertex represents a carbon, and carbons are
assumed to be present where a line begins or ends
...

• In that case, the substituent is the parent hydrocarbon and
the ring is named as a substituent
...


Nomenclature of Organic compounds
Homologous series of Organic Compounds_Cycloalkanes

• If the ring has two different substituents, they are
cited in alphabetical order and the number 1
position is given to the substituent cited first
...

• The substituent given the number 1 position is the one that
results in a second substituent getting as low a number as
possible
...


•ANY
QUESTIONS?

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Physical Properties of Alkanes

• Alkanes are non – polar compounds
• They have low melting and boiling points
• The melting and boiling points increases with increase in
molecular weight
• e,
...
e
...


Nomenclature of Organic compounds
Homologous series of Organic Compounds_Chemical Properties of Alkanes

• Alkanes are normally referred to as “Paraffin” because of their
inert nature
• Latin: Parum affinis, not enough affinity
• Halogenation: Alkanes do react with chlorine or bromine to form
alkyl chlorides or alkyl
• bromides
...


Nomenclature of Organic compounds
Homologous series of Organic Compounds_Chemical Properties of Alkanes
mechanism for the monochlorination of methane

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Chemical Properties of Alkanes

• Combustion, a reaction with oxygen that takes
place at high temperatures and converts alkanes
to carbon dioxide and water
...
Wt
Alkanes are subjected to high temp & pressures in
the presence of a catalyst to yield low fragments
alkanes
A lk a n e

4 0 0 -6 0 0 o C w ith o r
w ith o u t c a ta ly s t

H 2 + s m a lle r a lk a n e s + a lk e n e s

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Sources & Preparation of Alkanes

• The main souces of Alkanes industrially is
Petroleum and Natural Gas
• Alkanes can be prepared by any of the following
methods
– Hydrogenation of alkenes

C

H

n 2 n + H
A lk e n e

2

P t, P d o r N i

C nH 2n+
A lk a n e

2

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Sources & Preparation of Alkanes

– Reduction of alkyl halides
a R -X + M g

b

R - X + Z n + H

R - M g X
G rig n a rd
re a g e n t
+

H

2

O

R - H + Z n

R - H

2 +

+ X

-

H y d ro ly s is o f G rig n a rd re a g e n t

R e d u c tio n b y m e ta l &

a c id

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Sources & Preparation of Alkanes

• Coupling of alkyl halides with organometallic componds

i
R L
X

C
u
X
R
-i
L

Atu
l lh
k i
y m
l
i

Ri
C
u
2L
Lm
ii
tu
h
dy p
ik p
al e
l c r
o
`
R
X

R
-`
R

Methane
• The simplest member of alkanes
• Obtained mainly from petroleum and natural gas
• It can be prepared by heating anhydrous sodium
ethanoate with an alkali
N a+
-

O-

+

O
O

so d iu m e th a n o a te

N a+

OH-

so d iu m h y d ro x id e
fro m s o d a lim e

-O

N

a+

N a+

+
O

s o d iu m c a rb o n a te

CH4

m e th a n e

Methane
•
•
•
•
•

A colourless and odourless gas
Slightly soluble in water
Less dense than water
Neutral to litmus
Nonpolar

Methane

• It burns in oxygen to form carbon IV oxide & water

C 2)
H O
4
(+ (
g
)
2
g

2( C
H O
O 2
+(
2)
l
g
)

m
ee
tn
h
a

• It undergoes substitution reaction, reacting with chlorine to form
chloromethanes
C H

4 (g )

+

C l2

+e
c h lo ro m e th a n
C l

(g )

m e th a n e

+
c h lo ro m e th a n e

C l2

C l

H C l

+
d ic h lo ro m e th a n e
C l

(g )

C l

H C l
C l

+
d ic h lo ro m e th a n e
C l

C l2

C l

(g )

+

C l

H C l

C l

tric h lo ro m e th a n e
C l

C l
C l

+
C l

tric h lo ro m e th a n e

C l2

(g )

C l

C l
C l

te tra c h lo ro m e th a n e

+

H C l

Methane
• It is used in as fuel either by itself or in a mixture
of other gases
• It is used for producing
– Hydrogen
– Carbon black
– Carbon sulphides
– Alkynes
– Chloroform

STUDY QUESTIONS
• Convert the following condensed structures into
skeletal structures (remember that condensed
structures show atoms but few, if any, bonds,
whereas skeletal structures show bonds but few, if
any, atoms):

STUDY QUESTIONS
• Give the systematic name for each of the following compounds:

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkylhalides
• Alkyl halides are compounds in which a hydrogen of an alkane has been
replaced by a halogen
...

• Primary alkyl halides have a halogen bonded to a primary carbon
• Secondary alkyl halides have a halogen bonded to a secondary
• carbon
• Tertiary alkyl halides have a halogen bonded to a tertiary carbon

Nomenclature of Organic compounds
Homologous series of Organic Compounds_Alkylhalides

• The common names of alkyl halides consist of the
name of the alkyl group, followed by the name of
the halogen—with the “ine” ending of the halogen
name replaced by “ide” (i
...
, fluoride, chloride,
bromide, iodide)
...

• The substituent prefix names for the halogens end with “o” (i
...
,
“fluoro,” “chloro,” “bromo,” “iodo”)
...


STUDY QUESTIONS
• Draw the structures and name the four
constitutional isomers with molecular formula
C4H9Br

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