Transcript 無投影片標題 - Tsuen Wan Government Secondary School

1
Chapter 24
An Introduction to Organic Chemistry
24.1
What are organic compounds?
24.2
Introducing organic chemistry
24.3
Organic molecules represented by structural formulae
24.4
Saturated and unsaturated hydrocarbons
24.5
Classification of organic compounds
24.6
Naming of organic compounds
24.7
Structural formulae from IUPAC names
CONTENTS OF CHAPTER 24
2
24.1
WHAT ARE ORGANIC COMPOUNDS?
Figure 24.2
24.1
A collection of substances containing organic compounds.
WHAT ARE ORGANIC COMPOUNDS?
3
ORGANIC COMPOUNDS are carbon compounds.
A24.1
CO, CO2, Na2CO3, KHCO3, H2O, NH3, KOH, HCl, HNO3, NaCl.
(Other answers may be given.)
24.1
WHAT ARE ORGANIC COMPOUNDS?
4
24.2
INTRODUCING ORGANIC CHEMISTRY
WHAT IS ORGANIC CHEMISTRY?
ORGANIC CHEMISTRY is a branch of chemistry focusing on
carbon compounds.
24.2
INTRODUCING ORGANIC CHEMISTRY
5
Figure 24.3
24.2
Organic chemistry is often studied as a separate branch of chemistry.
INTRODUCING ORGANIC CHEMISTRY
6
GENERAL CHARACTERISTICS OF ORGANIC
COMPOUNDS
Constituent elements and bonding in organic compounds
Almost all organic compounds contain hydrogen besides carbon.
Most organic compounds are covalent compounds. Some
consist of simple molecules. Others consist of very large
molecules (macromolecules).
24.2
INTRODUCING ORGANIC CHEMISTRY
7
Figure 24.4
Most organic compounds consist of molecules:
(a) Hexane consists of simple molecules.
24.2
INTRODUCING ORGANIC CHEMISTRY
(b) Starch consists of macromolecules.
8
A24.2
Tetrachloromethane CCl4.
(Other answers may be given.)
Reactions of organic compounds
In general, reactions involving organic compounds have the
following in common:

The reactions are usually slow (when compared with common
inorganic reactions).

In most cases, organic compounds can burn to give carbon
dioxide and water.
24.2
INTRODUCING ORGANIC CHEMISTRY
9
Figure 24.5
Ethanol, an organic compound,
burns to form carbon dioxide
and water.
24.2
INTRODUCING ORGANIC CHEMISTRY
10
UNIQUENESS OF CARBON
Carbon has the unique property of forming a very large number of
compounds (over 4 000 000). There are three reasons for this:
(1) Carbon atoms can form strong single, double and triple
covalent bonds with other carbon atoms.
(2) Each carbon atom can form four single covalent bonds.
(3) Carbon can form strong bonds with other elements.
24.2
INTRODUCING ORGANIC CHEMISTRY
11
24.2
INTRODUCING ORGANIC CHEMISTRY
12
24.3
ORGANIC MOLECULES REPRESENTED
BY STRUCTURAL FORMULAE
Table 24.1
Structures of a butane molecule and a 2-methylpropane molecule, as represented by
formulae and models.
24.3
ORGANIC MOLECULES REPRESENTED BY STRUCTURAL
FORMULAE
13
Table 24.2
Structural formulae and models of some organic compounds.
24.3
ORGANIC MOLECULES REPRESENTED BY STRUCTURAL
FORMULAE
14
A24.3
24.3
ORGANIC MOLECULES REPRESENTED BY STRUCTURAL
FORMULAE
15
24.4
SATURATED AND UNSATURATED
HYDROCARBONS
Hydrocarbons may be saturated or unsaturated. Hydrocarbons
containing only single bonds are said to be saturated. Those
containing one or more carbon-carbon multiple bonds (C = C,
C  C) are unsaturated. For example,
24.4
SATURATED AND UNSATURATED HYDROCARBONS
16
24.5
CLASSIFICATION OF ORGANIC
COMPOUNDS
FUNCTIONAL GROUP
Figure 24.7
Structural formulae and models of butane, but-1-ene and butan-1-ol.
24.5
CLASSIFICATION OF ORGANIC COMPOUNDS
17
A FUNCTIONAL GROUP is an atom or group of atoms
responsible for most of the chemical properties of a compound.
A24.4
(a) Yes. They have the same functional group (–OH).
(b) A < B < C < D in boiling point. Van der Waals’ forces are
greater between larger molecules.
HOMOLOGOUS SERIES
The hydrocarbons methane, ethane, propane and butane belong
to the same homologous series — the alkane series.
24.5
CLASSIFICATION OF ORGANIC COMPOUNDS
18
Table 24.3
Names, formulae and models of the four hydrocarbons present in natural gas.
24.5
CLASSIFICATION OF ORGANIC COMPOUNDS
19
A HOMOLOGOUS SERIES is a family of compounds all having
the same general formula and with adjacent members differing by
a – CH2 – unit. The individual members of a homologous series
are referred to as HOMOLOGUES.
A24.5
(a) Put n = 5 in CnH2n+2.
The molecular formula is C5H12.
(b) Put n = 11 in CnH2n+2.
The molecular formula is C11H24.
24.5
CLASSIFICATION OF ORGANIC COMPOUNDS
20
Another homologous series is the alkanol (alcohol) series,
with the general formula CnH2n+1OH.
Figure 24.8
Methanol and ethanol are the first
two members of the alkanol series.
24.5
CLASSIFICATION OF ORGANIC COMPOUNDS
21
24.5
CLASSIFICATION OF ORGANIC COMPOUNDS
22
Table 24.4
Some common functional groups and homologous series, with the first member in each
series shown.
24.5
CLASSIFICATION OF ORGANIC COMPOUNDS
23
A24.6
(a) A and C; alkanoic acid series
(b)
H
H
H
H
H
O
H— C— C— C— C— C— C— O— H
H
24.5
H
H
H
H
CLASSIFICATION OF ORGANIC COMPOUNDS
24
24.6
NAMING OF ORGANIC COMPOUNDS
NAMING ALKANES BY THE IUPAC SYSTEM
Naming straight-chain alkanes
All alkanes have names ending with the suffix -ane.
24.6
NAMING OF ORGANIC COMPOUNDS
25
Table 24.5
Structural formulae and names of the 10 simplest straight-chain alkanes.
24.6
NAMING OF ORGANIC COMPOUNDS
26
Alkyl groups
Alkyl groups are derived from alkanes by the removal of a
hydrogen atom. They are often represented by the symbol R—.
Table 24.6
Some alkyl groups and their parent alkanes.
24.6
NAMING OF ORGANIC COMPOUNDS
27
A24.7
(a) (i)
Hexyl
(ii) Octyl
(b) (i)
CH3(CH2)3CH2—
(ii) CH3(CH2)5CH2—
Naming branched-chain alkanes
The IUPAC name for a branched-chain alkane consists of 2 parts:
(1) The prefixes which indicate the alkyl group substituents
(2) The ‘ root’ which indicates the parent alkane (the main
carbon chain).
24.6
NAMING OF ORGANIC COMPOUNDS
28
That is,
Prefixes
Root
(alkyl groups) (main carbon chain)
The basic IUPAC rules of naming can be illustrated by the
example below:
24.6
NAMING OF ORGANIC COMPOUNDS
29
The name of the compound is:
A24.8
(a) 2,3-dimethylbutane
(b) 4-ethyl-3-methylheptane
24.6
NAMING OF ORGANIC COMPOUNDS
30
NAMING HALOGEN-SUBSTITUTED ALKANES
A24.9
2-bromo-1-iodo-3-methylpentane
NAMING ALKENES
Alkenes have the general formula CnH2n. We can name them with
the same general rules for alkanes, but using the suffix -ene
instead of -ane.
24.6
NAMING OF ORGANIC COMPOUNDS
31
For example,
24.6
NAMING OF ORGANIC COMPOUNDS
32
24.6
NAMING OF ORGANIC COMPOUNDS
33
A24.10
(a) 2-methylbut-2-ene
(b) chloroethene
24.6
NAMING OF ORGANIC COMPOUNDS
34
NAMING ALKANOLS
Alkanols have the general formula CnH2n+1OH or ROH, where R–
is an alkyl group.
Names of some alkanols are given below:
CH3OH (methaneol) methanol;
3
2
1
CH3CH2CH2OH propan-1-ol
3
2
CH3CH2OH ethanol
1
CH3CHCH3
propan-2-ol
OH
24.6
NAMING OF ORGANIC COMPOUNDS
(not propan-3-ol, as the lowest possible
numeral is given to the –OH group)
35
CH3
1CH
2
3
3— C— CH3
2-methylpropan-2-ol
OH
A24.11
(a) Butan-1-ol
(b) 4-chlorobutan-2-ol
(not 1-chlorobutan-3-ol)
24.6
NAMING OF ORGANIC COMPOUNDS
36
NAMING ALKANOIC ACIDS
Alkanoic acids have the general formula CnH2n+1COOH or
R COOH, where R– is an alkyl group or hydrogen.
Names of some alkanoic acids are given below:
HCOOH (methaneoic acid) methanoic acid
CH3COOH ethanoic acid
CH3CH2COOH propanoic acid
CH3CH2CH2COOH butanoic acid
3
2
1
CH3CHCOOH 2-methylpropanoic acid
CH3
24.6
NAMING OF ORGANIC COMPOUNDS
37
A24.12
3-chlorobutanoic acid.
24.6
NAMING OF ORGANIC COMPOUNDS
38
24.7
STRUCTURAL FORMULAE FROM IUPAC
NAMES
24.7 STRUCTURAL FORMULAE FROM IUPAC NAMES
39
24.7 STRUCTURAL FORMULAE FROM IUPAC NAMES
40
A24.13
24.7 STRUCTURAL FORMULAE FROM IUPAC NAMES
41
A model of butane.
24.7 STRUCTURAL FORMULAE FROM IUPAC NAMES
42
A model of but-1-ene.
24.7 STRUCTURAL FORMULAE FROM IUPAC NAMES
43
A model of butan-1-ol.
24.7 STRUCTURAL FORMULAE FROM IUPAC NAMES
44
A model of butanoic acid.
24.7 STRUCTURAL FORMULAE FROM IUPAC NAMES
45
SUMMARY
1.
Organic compounds are carbon compounds.
2.
Almost all organic compounds contain hydrogen besides
carbon. Many contain oxygen too. They are usually covalent
compounds.
3.
In general, reactions involving organic compounds are slow.
In most cases, organic compounds can burn to give carbon
dioxide and water.
SUMMARY
46
4.
5.
Carbon forms a very large number of organic compounds
because

carbon can form strong bonds with itself and with other
elements

each carbon atom can form 4 single covalent bonds
Saturated hydrocarbons are compounds (with carbon and
hydrogen only) containing only single bonds.
Unsaturated hydrocarbons are compounds (with carbon and
hydrogen only) containing one or more carbon-carbon
multiple bonds (C=C or CC).
6.
A functional group is an atom or group of atoms responsible
for most of the chemical properties of a compound.
SUMMARY
47
7.
A homologous series is a family of compounds having the
same general formula with adjacent members differing by a
– CH2 – unit. See Table 24.4 on p. 29.
8.
Organic compounds are usually named by the IUPAC system
of naming. For rules and examples, refer to pp. 30 – 37.
SUMMARY