Download Introduction to organic chemistry

Introduction to
Organic Chemistry
What is Organic Chemistry?
The Unique Nature of Carbon
Classification of Organic Compounds
Factors Affecting the Physical Properties of
Organic Compounds
1
New Way Chemistry for Hong Kong A-Level Book 3A
Organic Chemistry
2
•
Chemistry of the compounds present
in living organisms.
•
They all contain carbon.
•
Organic Chemistry is the Chemistry
of Carbon.
New Way Chemistry for Hong Kong A-Level Book 3A
In 1828, Professor Wohler who was at the
time finishing up his post-doctoral work as
a student, succeeded in synthesizing in the
laboratory an organic compound previously
observed in living tissue as Urea. Student
Wohler made this organic compound from
non-living chemical substance, Ammonium
Cyanate. He evaporated a solution of
Ammonium Cyanate to produce Urea.
NH4NCO
heat
2HN
C NH2
O
3
New Way Chemistry for Hong Kong A-Level Book 3A
Development of Organic Chemistry
as a Science
Organic Chemistry has undergone a
substantial change since then. There are
well over a 40 millions synthetic organic
compounds. Organic Chemistry is defined as
the Chemistry of Carbon and its compounds.
• Organic compound:
• hydrobarbons
• one functional compounds
• many functional compounds
• heterocyclic compounds
4
New Way Chemistry for Hong Kong A-Level Book 3A
Development of Organic Chemistry
as a Science
Organic chemistry is the study of carbon
compounds (except CO, CO2, carbonates,
hydrogencarbonates, carbides and cyanides)
obtained from natural sources or
synthesized in the laboratories.
5
New Way Chemistry for Hong Kong A-Level Book 3A
Classification of
Organic
Compounds
6
New Way Chemistry for Hong Kong A-Level Book 3A
Functional Groups
•
7
Organic compounds are classified by
the the presence of characteristic
functional groups.
New Way Chemistry for Hong Kong A-Level Book 3A
Functional Groups
A functional group is defined as an
atom or a group of atoms that
effectively determines the chemical
properties of an organic compound.
8
New Way Chemistry for Hong Kong A-Level Book 3A
Functional Groups
9
New Way Chemistry for Hong Kong A-Level Book 3A
Functional Groups
10
•
Propane does not react with sodium
•
Ethanol and propan-1-ol react with
sodium to give hydrogen gas
New Way Chemistry for Hong Kong A-Level Book 3A
Homologous Series
A homologous series is a series of
compounds that have the same functional
group, and each member differs from
the next member by a – CH2 – unit in
their formulae.
CH4
C2H6
CH2
11
C3H8
CH2
C4H10
CH2
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Number
of carbon
atom(s)
IUPAC
name
Molecular
formula
Condensed
structural
formula
1
Methane
CH4
CH4
2
Ethane
C2H6
CH3CH3
3
Propane
C3H8
CH3CH2CH3
4
Butane
C4H10
CH3CH2CH2CH3
12
12
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New Way Chemistry for Hong Kong A-Level Book 3A
Structural
formula
The first four members of straight-chain alkanes
Number
of carbon
atom(s)
IUPAC
name
Molecular
formula
Condensed
structural
formula
1
Methanol
CH3OH
CH3OH
2
Ethanol
C2H5OH
CH3CH2OH
3
Propan-1ol
C3H7OH
CH3CH2CH2OH
4
Butan-1ol
C4H9OH
CH3CH2CH2CH2OH
13
13
New Way Chemistry for Hong Kong A-Level 3A
New Way Chemistry for Hong Kong A-Level Book 3A
Structural
formula
The first four members of straight-chain alcohols
Homologous Series
• Members in the same series can be
represented by a general formula.
e.g. alkanes: CnH2n+2
alkenes: CnH2n
alkynes: CnH2n-2
14
New Way Chemistry for Hong Kong A-Level Book 3A
Homologous Series
• Members in the same series can be
represented by a general formula.
e.g. alkanols: CnH2n+1OH
alkanals: CnH2n+1CHO
alkanoic acids: CnH2n+1COOH
15
New Way Chemistry for Hong Kong A-Level Book 3A
Homologous Series
Functional group
of an organic
compound
Chemical
properties
Members of a homologous series
have similar chemical properties
16
New Way Chemistry for Hong Kong A-Level Book 3A
Homologous Series
• The physical properties change gradually
along the homologous series
• e.g. the longer the carbon chain in the
molecule ( or the greater the
molecular mass)
 the greater the attractive force
between molecules
 the higher the melting point,
boiling point and density
17
New Way Chemistry for Hong Kong A-Level Book 3A
Some physical properties of the first 20 members of
straight-chain alkanes
State (at
Number
room
Density of
of
Molecular
Melting
Boiling
temperature
solid / liquid at
point (°C) point (°C)
carbon formula
20°C (g cm–3)
and
atom(s)
pressure)
1
CH4
Gas
–183
–161
–
2
C 2H 6
Gas
–172
–89
–
3
C 3H 8
Gas
–188
–42
–
4
C4H10
Gas
–135
0
–
5
C5H12
Liquid
–130
36
0.626
6
C6H14
Liquid
–95
69
0.657
7
C7H16
Liquid
–91
98
0.684
8
C8H18
Liquid
–57
126
0.703
9
C9H20
Liquid
–54
151
0.718
18 10
C10H22
–30
174
0.730
NewLiquid
Way Chemistry for Hong
Kong A-Level 3A
18
New Way Chemistry for Hong Kong A-Level Book 3A
Some physical properties of the first 20 members of
straight-chain alkanes
State (at
Number
room
Density of
of
Molecular
Melting
Boiling
temperature
solid / liquid at
point (°C) point (°C)
carbon formula
20°C (g cm–3)
and
atom(s)
pressure)
11
C11H24
Liquid
–26
196
0.740
12
C12H26
Liquid
–10
216
0.749
13
C13H28
Liquid
–7
233
0.753
14
C14H30
Liquid
–3
260
0.761
15
C15H32
Liquid
10
271
0.769
16
C16H34
Liquid
18
287
0.773
17
C17H36
Liquid
22
302
0.778
18
C18H38
Solid
28
316
0.777
19
C19H40
Solid
32
330
0.777
19 20
C20H42
37Kong A-Level 344
0.785
NewSolid
Way Chemistry for Hong
3A
19
New Way Chemistry for Hong Kong A-Level Book 3A
Factors Affecting the
Physical Properties of
Organic Compounds
20
New Way Chemistry for Hong Kong A-Level Book 3A
Main Factors Affecting the
Physical Properties of Organic
Compounds
1. Structure of the functional group
1.1 Dipole moment of the molecule
1.2 Formation of hydrogen bonding
2. Length of carbon chains (London
dispersion forces)
21
New Way Chemistry for Hong Kong A-Level Book 3A
Structure of Functional Group
• Molecules having a polar functional
group have a higher b.p. than others
with a non-polar functional group of
similar molecular masses
 Stronger intermolecular attraction
among molecules
22
New Way Chemistry for Hong Kong A-Level Book 3A
Structure of Functional Group
Molecule
Molecules
with polar
functional
groups
Molecules
with nonpolar
functional
groups
23
23
Relative
molecular
mass
Boiling point
(oC)
CH3CH2CH2OH
60
97.2
CH3CH2CH2NH2
59
48.6
64.5
12.5
CH3CH2COOH
60
141
CH3CH2CH2CH3
58
-0.5
CH3CH2CH=CH2
56
-6.2
CH3CH2CCH
54
8.1
CH3CH2Cl
New Way Chemistry for Hong Kong A-Level Book 3A
Dipole Moment of Molecule
• Tetrachloromethane has 4 polar bonds
in the molecule
• M.p. and b.p. are very low
 the molecule is non-polar
 the molecule is tetrahedrally
symmetrical
 the dipole moments of the
C  Cl bond cancel each other
24
New Way Chemistry for Hong Kong A-Level Book 3A
Examples of Polar Molecules
with Net Dipole Moment
25
New Way Chemistry for Hong Kong A-Level Book 3A
Examples of Non-polar Molecules
with No Net Dipole Moment
26
New Way Chemistry for Hong Kong A-Level Book 3A
Solubility of Organic Molecules
• Depends on the polarity of organic
molecules and the solvent
• Non-polar or weakly polar compounds
dissolve readily in non-polar or weakly
polar solvents
• Highly polar compounds dissolve readily
in highly polar solvents
• “Like dissolves like”
27
New Way Chemistry for Hong Kong A-Level Book 3A
Solubility of Organic Molecules
Hexane in
tetrachloromethane
28
Hexane in water
New Way Chemistry for Hong Kong A-Level Book 3A
Why is Hexane Insoluble in Water?
29
New Way Chemistry for Hong Kong A-Level Book 3A
Formation of Hydrogen Bonding
• Molecules having OH or  NH2 groups
are able to form hydrogen bonds
• Hydrogen bonds affect the physical
properties of alcohols and amines with
low molecular masses
30
New Way Chemistry for Hong Kong A-Level Book 3A
Formation of Hydrogen Bonding
• Also affect the solubility of a molecule
• Molecules with OH groups are able
to form hydrogen bonds with
surrounding water molecules
 Soluble in water
31
New Way Chemistry for Hong Kong A-Level Book 3A
Length of Carbon Chains
• Molecules with higher molecular masses
have higher m.p., b.p. and density
 Higher molecular masses
 Large molecular sizes
 Stronger London dispersion
forces among molecules
32
New Way Chemistry for Hong Kong A-Level Book 3A
Length of Carbon Chains
• Molecules with branched chains
 b.p. and density lower than its
straight-chain isomer
 Straight-chain isomers have greater
surface area in contact with each other
 Greater attractive force among the
molecules
33
New Way Chemistry for Hong Kong A-Level Book 3A
Classification of Organic
Compounds
34
New Way Chemistry for Hong Kong A-Level Book 3A
Family
General
formula
Functional
group
Alkane
RH
(Nil)
Alkene
RCH = CH2
RCH = CHR
R2C = CHR
R2C = CR2
Alkyne
RC  CH
RC  CR
Aromatic
hydrocarbon
ArH
Carboncarbon
double bond
–CC–
Carboncarbon triple
bond
Example
Formula
IUPAC name
CH3CH3
Ethane
CH2 = CH2
Ethene
HC  CH
Ethyne
Benzene
Phenyl group
35
35
R = CnH2n+1 –New Way Chemistry for Hong Kong A-Level 3A
New Way Chemistry for Hong Kong A-Level Book 3A
Example
Formula
IUPAC name
Family
General
formula
Functional
group
Haloalkane
RX
X
halo group
CH3Cl
Chloromethane
Alcohol
ROH
 OH
hydroxyl group
CH3OH
Methanol
Ether
RO  R
O
oxy group
CH3  O 
Methoxymethane
CH3
Aldehyde
Methanal
R = CnH2n+1 –
36
carbonyl group
New Way Chemistry for Hong Kong A-Level Book 3A
Family
General
formula
Functional
group
Example
Formula
IUPAC name
Ketone
Propanone
carbonyl group
Carboxylic
acid
Ethanoic acid
carboxyl group
Amine
Nitrile
RNH2
R2NH
R 3N
RCN
CH3NH2
Methylamine
CH3CN
Ethanenitrile
amino group
CN
nitrile group
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R = CnH2n+1 –New WayNewChemistry
for Hong Kong A-Level Book 3A
37
37
Family
General
formula
Functional
group
Example
Formula
IUPAC name
Methyl
ethanoate
Ester
ester group
Ethanoyl
chloride
Acyl halide
acyl halide
group
Amide
Ethanamide
amide group
38
38
New Way Chemistry for Hong Kong A-Level 3A
New Way Chemistry for Hong Kong A-Level Book 3A
R = CnH2n+1 –
Family
Acid
anhydride
39
General
formula
Functional
group
Example
Formula
IUPAC name
acid anhydride
group
New Way Chemistry for Hong Kong A-Level Book 3A
Ethanoic
anhydride
R = CnH2n+1 –
The END
40
New Way Chemistry for Hong Kong A-Level Book 3A