introduction to organic chemistry
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Chapter 24. Introduction to Organic Chemistry. 24.1 What is Organic Chemistry? 24.2 The Unique Nature of Carbon 24.3 Classification of Organic Compounds. 24.1 What is Organic Chemistry (SB p.2). Organic Chemistry: The chemistry of the compounds of carbon. - PowerPoint PPT PresentationTRANSCRIPT
New Way Chemistry for Hong Kong A-Level Book 3A1
Introduction to Organic Chemistry
24.124.1 What is Organic Chemistry?What is Organic Chemistry?
24.224.2 The Unique Nature of CarbonThe Unique Nature of Carbon
24.324.3 Classification of Organic CompoundsClassification of Organic Compounds
Chapter 24Chapter 24
New Way Chemistry for Hong Kong A-Level Book 3A2
24.1 What is Organic Chemistry (SB p.2)
Organic Chemistry: The chemistry of the compounds of carbon
Carbon compounds: DNA, proteins in our body, carbohydrates, wool, cotton, petrol, medicines, pesticides, etc.
Organic chemicals
• make our life easy
• but also cause serious environmental problems
(e.g. organic compounds used as aerosol propellent damage the ozone layer, insecticide is harmful to human
New Way Chemistry for Hong Kong A-Level Book 3A3
24.1 What is Organic Chemistry (SB p.3)
Development of Organic Chemistry as a ScienceDevelopment of Organic Chemistry as a Science
In the past …,ChemistryChemistry
Organic Compounds
Organic Compounds
obtained from living
organisms
Inorganic CompoundsInorganic
Compounds
obtained from non-living sources
New Way Chemistry for Hong Kong A-Level Book 3A4
(Inorganic compound) (Organic compound)
In 1828, Wohler (a German chemist)
Redefining …...
Organic chemistry is the study of carbon compounds except carbon monoxide, carbon dioxide, carbonates, hydrogencarbonates, carbides and cyanide.
Organic chemistry is the study of carbon compounds except carbon monoxide, carbon dioxide, carbonates, hydrogencarbonates, carbides and cyanide.
24.1 What is Organic Chemistry (SB p.3)
New Way Chemistry for Hong Kong A-Level Book 3A5
24.1 What is Organic Chemistry (SB p.4)
Natural Sources of Organic CompoundsNatural Sources of Organic Compounds
Crude oil / coal
Fractional distillation / destructive distillation
Alkanes / Alkenes / Alkynes / Aromatic hydrocarbons
Living things Carbohydrates / Proteins / Fats / Vitamins / Antibiotics
New Way Chemistry for Hong Kong A-Level Book 3A6
24.2 The Unique Nature of Carbon (SB p.5)
Ability to CatenateAbility to Catenate
Carbon atoms can link themselves together to form chains of varying length, branched chains and rings of different sizes
Catenation:The ability of atoms in forming stable bonds with itself and joining up in chains or rings.
e.g.
New Way Chemistry for Hong Kong A-Level Book 3A7
24.2 The Unique Nature of Carbon (SB p.5)
Ability to Form Multiple BondsAbility to Form Multiple Bonds
• Each carbon atom has four unpaired electrons when excited
• tend to form 4 covalent bonds
Carbon (ground state)
Carbon (excited state)
• Electronic configuration of carbon (ground state) : 1s22s22p2
New Way Chemistry for Hong Kong A-Level Book 3A8
24.2 The Unique Nature of Carbon (SB p.6)
Single bond Double bond Triple bond
New Way Chemistry for Hong Kong A-Level Book 3A9
Example 24-1Example 24-1Would you expect silicon, which is just below carbon in the Periodic Table, to catenate to form diverse molecular structures? Explain your answer.
Answer
24.2 The Unique Nature of Carbon (SB p.6)
Solution:
Silicon, unlike carbon, does not catenate to form diverse molecular structures. Carbon is able to catenate because carbon atoms have a relatively small atomic size. This enables a carbon atom to form strong covalent bonds with other carbon atoms. However, due to the greater atomic size of silicon, its ability to catenate is much lower than that of carbon.
New Way Chemistry for Hong Kong A-Level Book 3A10
Check Point 24-1 Check Point 24-1
Would you expect sulphur, which has an electronegativity value very close to carbon, to catenate? Why?
Answer
The electronic configuration of sulphur is 1s22s22p63s23p4. It has only two unpaired electrons. Its atomic s
ize is larger than that of carbon. So it has a much low
er tendency to catenate than carbon.
24.2 The Unique Nature of Carbon (SB p.7)
New Way Chemistry for Hong Kong A-Level Book 3A11
24.3 Classification of Organic Compounds (SB p.7)
Functional GroupsFunctional Groups
The compounds in a particular family are characterized by the presence of a certain arrangement of atoms called a functional group
A functional group is defined as an atom or a group of atoms that effectively determines the chemical properties of an organic compound.
A functional group is defined as an atom or a group of atoms that effectively determines the chemical properties of an organic compound.
New Way Chemistry for Hong Kong A-Level Book 3A12
have similar chemical properties because they contain the same functional group –OH. They are classified into the same homologous series — Alcohols.
e.g.
and
24.3 Classification of Organic Compounds (SB p.7)
New Way Chemistry for Hong Kong A-Level Book 3A13
24.3 Classification of Organic Compounds (SB p.8)
FamilyGeneral formula
Functional group
Specific example
Formula IUPAC name
Alkane RHC – H and C – C bonds
CH3CH3 Ethane
Alkene
RCH = CH2
RCH = CHR
R2C = CHR
R2C = CR2
CH2 = CH2 Ethene
AlkyneRC CH
RC CR– C C – HC CH Ethyne
Aromatic hydrocarbon
ArH Aromatic ring Benzene
Haloalkane RX CH3Cl Chloromethane
R = CnH2n+1 –
New Way Chemistry for Hong Kong A-Level Book 3A14
24.3 Classification of Organic Compounds (SB p.8)
FamilyGeneral formula
Functional group
Specific example
Formula IUPAC name
Alcohol ROH CH3OH Methanol
Ether R – O – R CH3 – O – CH3 Methoxymethane
Aldehyde Methanal
Ketone Propanone
R = CnH2n+1 –
New Way Chemistry for Hong Kong A-Level Book 3A15
24.3 Classification of Organic Compounds (SB p.8)
FamilyGeneral formula
Functional group
Specific example
FormulaIUPAC name
Carboxylic acid Ethanoic acid
Amine
RNH2
R2NH
R3N
CH3NH2 Methylamine
Nitrile RC N – C N CH3CN Ethanenitrile
EsterMethyl ethanoate
Acyl halideEthanoyl chloride
R = CnH2n+1 –, X = F, Cl, Br or I
New Way Chemistry for Hong Kong A-Level Book 3A16
24.3 Classification of Organic Compounds (SB p.9)
Family General formulaFunctional
group
Specific example
FormulaIUPAC name
Amide Ethanamide
Acid anhydrid
e
Ethanoic anhydride
R = CnH2n+1 –
New Way Chemistry for Hong Kong A-Level Book 3A17
24.3 Classification of Organic Compounds (SB p.9)
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.
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.
CH3CH2CH2CH3C4H10Butane4
CH3CH2CH3C3H8Propane3
CH3CH3C2H6Ethane2
CH4CH4Methane1
Structural formulaCondensed structural formula
Molecular formula
IUPAC name
Number of carbon atom(s)
New Way Chemistry for Hong Kong A-Level Book 3A18
24.3 Classification of Organic Compounds (SB p.10)
Number of carbon atom(s)
IUPAC name
Molecular formula
Condensed structural formula
Structural formula
1 Methanol CH3OH CH3OH
2 Ethanol C2H5OH CH3CH2OH
3 Propanol C3H7OH CH3CH2CH2OH
4 Butanol C4H9OH CH3CH2CH2CH2OH
New Way Chemistry for Hong Kong A-Level Book 3A19
24.3 Classification of Organic Compounds (SB p.10)
Members in the same series can be represented by a general formula.
e.g. General formula of alkanes: CnH2n+2
General formula of alcohols: CnH2n+1OH
Functional group of an organic compound
Chemical
properties
Members of a homologous series have similar chemical properties
New Way Chemistry for Hong Kong A-Level Book 3A20
The physical properties change gradually along the homologous
series
e.g. the longer the carbon chain in molecule ( or the greater the
molecular mass)
the greater the attractive force between molecules
the higher the melting point and boiling point
24.3 Classification of Organic Compounds (SB p.10)
New Way Chemistry for Hong Kong A-Level Book 3A21
24.3 Classification of Organic Compounds (SB p.11)
Number of carbon atom(s)
Molecular formula
State (at room temperature
and pressure)
Melting point (°C)
Boiling point (°C)
Density of solid / liquid at 20°C
(g cm–3)
1
2
3
4
5
6
7
8
9
10
CH4
C2H6
C3H8
C4H10
C5H12
C6H14
C7H16
C8H18
C9H20
C10H22
Gas
Gas
Gas
Gas
Liquid
Liquid
Liquid
Liquid
Liquid
Liquid
–183
–172
–188
–135
–130
–95
–31
–57
–54
–30
–161
–89
–42
0
36
69
98
126
151
174
–
–
–
–
0.626
0.657
0.684
0.703
0.718
0.730
Some physical properties of the first 20 members of straight-chain alkanes
New Way Chemistry for Hong Kong A-Level Book 3A22
24.3 Classification of Organic Compounds (SB p.11)
Number of carbon atom(s)
Molecular formula
State (at room temperature
and pressure)
Melting point (°C)
Boiling point (°C)
Density of solid / liquid at 20°C
(g cm–3)
11
12
13
14
15
16
17
18
19
20
C11H24
C12H26
C13H28
C14H30
C15H32
C16H34
C17H36
C18H38
C19H40
C20H42
Liquid
Liquid
Liquid
Liquid
Liquid
Liquid
Liquid
Solid
Solid
Solid
–26
–10
–7
–3
10
18
22
28
32
37
196
216
233
260
271
287
302
316
330
344
0.740
0.749
0.753
0.761
0.769
0.773
0.778
0.777
0.777
0.785
Some physical properties of the first 20 members of straight-chain alkanes
New Way Chemistry for Hong Kong A-Level Book 3A23
Example 24-2Example 24-2Identify the functional group(s) in the following compound:
(a)
Answer
24.3 Classification of Organic Compounds (SB p.11)
Solution:
(a) Carbon-carbon double bond ( ) and chloro ( ) group
New Way Chemistry for Hong Kong A-Level Book 3A24
Example 24-2Example 24-2Identify the functional group(s) in the following compound:
(b)
Answer
24.3 Classification of Organic Compounds (SB p.11)
Solution:
(b) Carbonyl group ( )
New Way Chemistry for Hong Kong A-Level Book 3A25
Example 24-2Example 24-2Identify the functional group(s) in the following compound:
(c)
Answer
24.3 Classification of Organic Compounds (SB p.12)
Solution:
(c) Amino group ( ) and carboxyl
group ( )
New Way Chemistry for Hong Kong A-Level Book 3A26
Example 24-3Example 24-3To which homologous series does each of the following compounds belong?
(a)
Answer
24.3 Classification of Organic Compounds (SB p.12)
Solution:
(a) Ester
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Example 24-3Example 24-3To which homologous series does each of the following compounds belong?
(b)
Answer
Solution:
(b) Amide
24.3 Classification of Organic Compounds (SB p.13)
New Way Chemistry for Hong Kong A-Level Book 3A28
Example 24-3Example 24-3To which homologous series does each of the following compounds belong?
(c)
Answer
Solution:
(c) Acid anhydride
24.3 Classification of Organic Compounds (SB p.13)
New Way Chemistry for Hong Kong A-Level Book 3A29
Example 24-4Example 24-4State whether each of the following pairs of compounds belongs to the same homologous series. Explain your answers.
(a)
AnswerSolution:
(a) No, the first one is a carboxylic acid and the second one is an ester.
24.3 Classification of Organic Compounds (SB p.13)
New Way Chemistry for Hong Kong A-Level Book 3A30
Example 24-4Example 24-4State whether each of the following pairs of compounds belongs to the same homologous series. Explain your answers.
(b)
AnswerSolution:
(b) Yes, both of them are alcohols.
24.3 Classification of Organic Compounds (SB p.13)
New Way Chemistry for Hong Kong A-Level Book 3A31
Example 24-4Example 24-4State whether each of the following pairs of compounds belongs to the same homologous series. Explain your answers.
(c)
AnswerSolution:
(c) No, the first one is an amide and the second one is an amine.
24.3 Classification of Organic Compounds (SB p.13)
New Way Chemistry for Hong Kong A-Level Book 3A32
Check Point 24-2 Check Point 24-2
(a) Name the homologous series of organic compounds that contain the element oxygen in their functional groups.
Answer
(a) Alcohol, ether, aldehyde, ketone, carboxylic acid,
ester, acyl halide, amide and acid anhydride
24.3 Classification of Organic Compounds (SB p.14)
New Way Chemistry for Hong Kong A-Level Book 3A33
Check Point 24-2 Check Point 24-2
(b) Identify and name the functional groups in glucose which has the structure:
Answer
24.3 Classification of Organic Compounds (SB p.14)
(b) – OH (hydroxyl) and – O – (oxy) groups
New Way Chemistry for Hong Kong A-Level Book 3A34
Check Point 24-2 Check Point 24-2
(c) Identify and name the functional groups in the following compound:
Answer
24.3 Classification of Organic Compounds (SB p.14)
(c) – Br (bromo), (aldehyde),
(acyl chloride) and
(carbon-carbon double bond) group
New Way Chemistry for Hong Kong A-Level Book 3A35
The END