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1
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Chapter 10 Introduction to Organic
Chemistry: Alkanes
___________________________________
___________________________________
___________________________________
10.1
Organic Compounds
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___________________________________
___________________________________
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2
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Organic Chemistry
___________________________________
___________________________________
___________________________________
An organic compound
•
•
•
•
___________________________________
is a compound made from carbon atoms.
has one or more C atoms.
has many H atoms.
may also contain O, S, N, and halogens.
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2
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3
Organic Compounds
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Typical organic compounds
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•
•
•
•
•
___________________________________
have covalent bonds.
have low melting points.
have low boiling points.
are flammable.
are soluble in nonpolar
solvents.
• are not soluble in water.
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___________________________________
oil (organic) and water (inorganic)
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4
Organic vs. Inorganic
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___________________________________
___________________________________
• Propane, C3H8, is an
organic compound used
as a fuel.
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___________________________________
• NaCl, salt, is an
inorganic compound
composed of Na+ and
Cl− ions.
___________________________________
Why is propane organic,
but NaCl is not?
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5
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Comparing Organic and Inorganic
Compounds
___________________________________
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___________________________________
___________________________________
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6
Learning Check
___________________________________
___________________________________
___________________________________
Identify each characteristic as most typical of compounds
that are 1) inorganic or 2) organic.
___________________________________
___________________________________
A.
B.
C.
D.
E.
F.
has a high melting point.
is not soluble in water.
has a formula CH3─CH2─CH3.
has a formula MgCl2.
burns easily in air.
has covalent bonds.
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7
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Solution
___________________________________
___________________________________
___________________________________
Identify each characteristic as most typical of compounds
that are 1) inorganic or 2) organic.
1
2
2
1
2
2
A.
B.
C.
D.
E.
F.
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___________________________________
has a high melting point.
is not soluble in water.
has a formula CH3─CH2─CH3.
has a formula MgCl2.
burns easily in air.
has covalent bonds.
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8
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Writing Formulas for Alkanes
___________________________________
___________________________________
In organic compounds,
• carbon has 4 valence electrons and hydrogen has 1.
•
•C•
•
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___________________________________
___________________________________
H•
___________________________________
• carbon achieves an octet by forming four bonds.
H
H
••
H:C:H
••
H
H
C
H
H
CH4, methane
8
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9
Tetrahedral Structure of Carbon
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___________________________________
___________________________________
VSEPR theory
predicts that a
carbon atom with
four single,
covalent bonds has
a tetrahedral
shape.
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10
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Organic Molecules
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___________________________________
___________________________________
In organic molecules,
• valence electrons are shared.
• covalent bonds form between carbon atoms.
H
••
H
••
H:C:C:H
••
H
H
••
H
H
H
C
C
H
H
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___________________________________
___________________________________
H
Ethane, CH3─CH3
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11
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Tetrahedral Structure of Carbon
___________________________________
___________________________________
___________________________________
In molecules with
two or more carbon
atoms, each
carbon atom with
four single bonds
has a tetrahedral
shape.
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___________________________________
Chapter 10 Introduction to Organic
Chemistry: Alkanes
___________________________________
___________________________________
___________________________________
10.2
Alkanes
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___________________________________
___________________________________
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13
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Structural Formulas
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___________________________________
___________________________________
Alkanes are written with structural formulas that are
• expanded to show each bond.
• condensed to show each carbon atom and its
attached hydrogen atoms.
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___________________________________
Expanded
H
H
C
Condensed
CH4 , methane
H
H
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14
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Expanded and Condensed
Structures
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___________________________________
___________________________________
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15
Structural Formulas
___________________________________
___________________________________
___________________________________
Condensed formulas are written for expanded
structural formula by showing each carbon and the
attached hydrogen atoms.
Expanded
Condensed
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___________________________________
___________________________________
H H H H
│ │ │ │
H─C ─C ─C ─C ─ H
│ │ │ │
H H H H
CH3─CH2─CH2─CH3
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Names of Alkanes
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___________________________________
The names of alkanes
• are determined by the IUPAC (International Union of
Pure and Applied Chemistry) system.
• end in –ane.
• with 1-4 carbons in a chain use prefixes as follows:
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___________________________________
___________________________________
___________________________________
Name
# Carbons
1
Condensed Structural
Formula
CH4
Ethane
2
CH3―CH3
Propane
3
CH3―CH2―CH3
Butane
4
CH3―CH2―CH2―CH3
Methane
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Names of Alkanes
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___________________________________
___________________________________
Alkanes with 5-10 carbon atoms in a chain use Greek prefixes.
# Carbons
Structural Formula
Name
Pentane
5
Hexane
6
CH3CH2CH2CH2CH2CH3
Heptane
7
CH3CH2CH2CH2CH2CH2CH3
Octane
8
CH3CH2CH2CH2CH2CH2CH2CH3
Nonane
9
CH3 CH2 CH2CH2CH2CH2CH2CH2CH3
Decane
10
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CH3CH2CH2CH2CH3
___________________________________
___________________________________
CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3
17
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18
Learning Check
___________________________________
___________________________________
___________________________________
A. Write the condensed formula for:
H H
H
H
H
___________________________________
___________________________________
H
C
C
C
C
C
H
___________________________________
H
H
H
H
H
B. What is its molecular formula?
C. What is its name?
18
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19
___________________________________
Solution
___________________________________
___________________________________
A. CH3─CH2─CH2─CH2─CH3
___________________________________
___________________________________
B. C5H12
___________________________________
C. pentane
___________________________________
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20
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Writing Structural Formulas
___________________________________
___________________________________
Carbon atoms in a chain
•
•
•
•
___________________________________
___________________________________
maintain tetrahedral shape.
are connected in a zigzag pattern.
are drawn as 2-dimensional.
can be written in several conformations.
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20
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21
Some Structures for Butane
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___________________________________
___________________________________
___________________________________
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22
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Hexane Has Six Carbon Atoms
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___________________________________
Hexane
• is an alkane with six carbon atoms in a continuous
chain.
• has a “zigzag” look because each carbon atom is at
the center of a tetrahedron.
• is represented by a ball-and-stick model as shown
below.
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23
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Learning Check
___________________________________
___________________________________
___________________________________
Write the condensed structural formula for
___________________________________
A. ethane.
___________________________________
___________________________________
B. heptane.
23
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24
Solution
___________________________________
___________________________________
___________________________________
Write the condensed structural formula for
A. ethane
___________________________________
CH3─CH3
___________________________________
___________________________________
B. heptane CH3─CH2─CH2─CH2─CH2─CH2─CH3
24
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___________________________________
Cycloalkanes
___________________________________
___________________________________
___________________________________
Cycloalkanes
___________________________________
• are cyclic alkanes.
___________________________________
• have two hydrogen atoms fewer than the open
chain.
___________________________________
• are named by using the prefix cyclo- before the
name of the alkane chain with the same number of
carbon atoms.
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26
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Cycloalkanes
___________________________________
___________________________________
The structural formulas of cycloalkanes are usually
represented by geometric figures.
___________________________________
___________________________________
___________________________________
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27
More Cycloalkanes
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Learning Check
___________________________________
___________________________________
___________________________________
Name the following.
___________________________________
A. CH3─CH2─CH2─CH3
___________________________________
___________________________________
B.
C. CH3─CH2─CH2─CH2─CH2─CH2─CH2─CH3
D.
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29
___________________________________
Solution
___________________________________
___________________________________
___________________________________
Name the following:
A. CH3─CH2─CH2─CH3
B.
___________________________________
butane
___________________________________
cyclopropane
___________________________________
C. CH3─CH2─CH2─CH2─CH2─CH2─CH2─CH3 octane
D.
cyclohexane
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30
___________________________________
Chapter 10 Introduction to Organic
Chemistry: Alkanes
___________________________________
___________________________________
___________________________________
10.3
Alkanes with Substituents
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___________________________________
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30
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31
___________________________________
Isomers of Butane
___________________________________
___________________________________
___________________________________
Isomers
• have the same
molecular formula.
• have different atom
arrangements.
• of butane (C4H10) are a
straight chain and a
branched chain.
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___________________________________
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32
___________________________________
Alkyl groups
___________________________________
___________________________________
Alkyl groups are
• alkanes that are missing one H.
• substituents attached to carbon chains.
• named with a –yl ending.
___________________________________
___________________________________
___________________________________
___________________________________
CH3
CH3
methyl
CH2
ethyl
32
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33
Naming Substituents
___________________________________
___________________________________
___________________________________
___________________________________
In the IUPAC system,
• a carbon branch is
named as an alkyl
group.
• halogen atoms are
named as halo.
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___________________________________
33
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34
___________________________________
Guide to Naming Alkanes
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___________________________________
___________________________________
___________________________________
___________________________________
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34
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35
___________________________________
Alkanes with Substituents
___________________________________
___________________________________
___________________________________
CH3
CH3 CH
___________________________________
methylpropane
CH3
___________________________________
___________________________________
methyl groups
CH3
CH3
CH3 CH CH2 CH CH3
2,4-dimethylpentane
35
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36
Naming Alkanes
___________________________________
___________________________________
Give the name of
STEP 1:
CH3 CH3
⎢
⎢
CH3─CH─CH─CH3
___________________________________
___________________________________
___________________________________
Name the longest continuous chain.
___________________________________
CH3 CH3
⎢
⎢
CH3─CH─CH─CH3
butane
36
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37
___________________________________
Naming Alkanes
___________________________________
___________________________________
Give the name of
CH3 CH3
⎢
⎢
CH3─CH─CH─CH3
___________________________________
___________________________________
___________________________________
___________________________________
CH3 CH3
⎢
⎢
CH3─CH─CH─CH3
1
2
3 4
STEP 3: Locate substituents and name.
2,3-dimethylbutane
STEP 2:
Number chain.
37
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38
___________________________________
Learning Check
___________________________________
___________________________________
___________________________________
Write the name of
___________________________________
Cl CH3
⎢
⎢
CH3─CH2─CH─CH─CH3
___________________________________
___________________________________
38
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39
Solution
___________________________________
___________________________________
STEP 1:
Longest chain is pentane.
STEP 2:
Number chain from end nearest substituent.
Cl CH3
⎢
⎢
CH3─CH2─CH─CH─CH3
5
4
3
2
1
___________________________________
___________________________________
___________________________________
___________________________________
STEP 3: Locate substituents and name alphabetically.
3-chloro-2-methylpentane
39
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40
___________________________________
Learning Check
___________________________________
___________________________________
___________________________________
Give the IUPAC name for each of the following:
A.
B.
___________________________________
CH3
CH3
|
|
CH3─CH─CH2 ─CH─CH3
___________________________________
___________________________________
Cl
CH3
|
|
CH3─CH2─CH─CH2─C─CH2─CH3
|
Cl
40
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41
___________________________________
Solution
___________________________________
___________________________________
A.
CH3
CH3
|
|
CH3─CH─CH2 ─CH─CH3
1
B.
2
3
4
___________________________________
___________________________________
2,4-dimethylpentane
___________________________________
5
___________________________________
Cl
CH3 more substituents on C3
|
|
CH3─CH2─CH─CH2─C─CH2─CH3
|
Cl
7
6
5
4
3
2
1
3,5-dichloro-3-methylheptane
41
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___________________________________
Guide to Drawing Alkane
Formulas
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
42
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43
___________________________________
Learning Check
___________________________________
___________________________________
___________________________________
Draw the condensed structural formula for
3-bromo-1-chlorobutane.
___________________________________
___________________________________
___________________________________
43
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44
___________________________________
Solution
___________________________________
___________________________________
3-bromo-1-chlorobutane
STEP 1: Longest chain has 4 carbon atoms.
C─C─C─C
STEP 2: Number chain and add substituents.
Br
⎢
C ─ C ─ C ─ C ─ Cl
4 3 2
1
STEP 3: Add hydrogen to complete 4 bonds to each C.
Br
⎢
CH3─CH─CH2─CH2─Cl
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___________________________________
___________________________________
___________________________________
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45
___________________________________
Naming Cycloalkanes with
Substituents
___________________________________
___________________________________
___________________________________
The name of a substituent is placed in front of the
cycloalkane name.
___________________________________
CH3
methylcyclobutane
chlorocyclopentane
___________________________________
___________________________________
Cl
45
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46
___________________________________
Learning Check
___________________________________
___________________________________
___________________________________
Name each of the following.
1.
2.
___________________________________
CH3
___________________________________
___________________________________
CH2─CH3
46
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47
___________________________________
Solution
___________________________________
___________________________________
___________________________________
Name each of the following.
___________________________________
1. methylcyclopropane
___________________________________
___________________________________
2. ethylcyclohexane
47
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48
___________________________________
Chapter 10 Introduction to Organic
Chemistry: Alkanes
___________________________________
___________________________________
___________________________________
10.4
Properties of Alkanes
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___________________________________
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49
___________________________________
Some Properties of Alkanes
___________________________________
___________________________________
___________________________________
Alkanes are
• nonpolar.
• insoluble in water.
• less dense than water.
• flammable in air.
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50
___________________________________
Some Properties of Alkanes
___________________________________
___________________________________
___________________________________
Alkanes with 1-4 carbon
atoms are
• methane, ethane,
propane, and butane.
• gases at room
temperature.
• used as heating fuels.
___________________________________
___________________________________
___________________________________
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51
Some Properties of Alkanes
___________________________________
___________________________________
___________________________________
Alkanes with 5-8 carbon atoms are
• liquids at room temperature.
• pentane, hexane, heptane, and octane.
• very volatile.
• used to make gasoline.
___________________________________
___________________________________
___________________________________
Alkanes with 9-17 carbon atoms
• are liquids at room temperature
• have higher boiling points.
• are found in kerosene, diesel, and jet fuels.
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___________________________________
Some Properties of Alkanes
___________________________________
___________________________________
Alkanes with 18 or more carbon atoms
• have high molar masses.
• are waxy solids at room temperature.
• used in waxy coatings of fruits and
vegetables.
___________________________________
___________________________________
___________________________________
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53
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Combustion
___________________________________
___________________________________
___________________________________
In combustion reactions,
• alkanes react with oxygen.
• CO2, H2O, and energy are produced.
• Alkane + O2
CO2 + H2O + heat
___________________________________
___________________________________
___________________________________
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54
Learning Check
___________________________________
___________________________________
___________________________________
Write a balanced equation for the
complete combustion of propane.
___________________________________
___________________________________
___________________________________
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55
___________________________________
Solution
___________________________________
___________________________________
___________________________________
Unbalanced equation
C3H8 + O2
___________________________________
CO2 + H2O
___________________________________
Balance C
C3H8 + O2
3CO2 + H2O
___________________________________
Balance H
C3H8 + O2
3CO2 + 4H2O
Balance O
C3H8 + 5O2
3CO2 + 4H2O (Balanced)
55
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56
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Chapter 10 Introduction to Organic
Chemistry: Alkanes
___________________________________
___________________________________
10.5
Functional Groups
___________________________________
___________________________________
___________________________________
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56
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57
Elements in Organic Compounds
___________________________________
___________________________________
___________________________________
In organic molecules, carbon atoms bond
• with four bonds.
• mostly with H and other C atoms.
• sometimes to O, N, S.
• sometimes to halogens F, Cl, and Br.
___________________________________
___________________________________
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Functional Groups
___________________________________
___________________________________
___________________________________
Functional groups are
• a characteristic feature of organic molecules that
behave in a predictable way.
• composed of an atom or group of atoms.
• groups that replace a hydrogen atom in the
corresponding alkane.
• a way to classify families of organic compounds.
___________________________________
___________________________________
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___________________________________
Alkenes, Alkynes, and Aromatic
Compounds
___________________________________
___________________________________
___________________________________
Alkenes contain a double bond between adjacent
carbon atoms.
Alkynes contain a triple bond.
Aromatic compounds contain a ring of six carbon
atoms called benzene.
___________________________________
___________________________________
___________________________________
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60
___________________________________
Comparing Alkenes, Alkynes,
and Aromatic Compounds
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
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61
___________________________________
Alcohols and Ethers
___________________________________
___________________________________
___________________________________
An alcohol contains the
hydroxyl (-OH) functional
group.
___________________________________
___________________________________
A thiol contains the thiol
(-SH) functional group.
___________________________________
An ether contains an
oxygen atom bonded to
two carbon atoms.
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Aldehydes and Ketones
___________________________________
___________________________________
An aldehyde contains a
carbonyl group (C=O), which
is a carbon atom with a double
bond to an oxygen atom. The
carbonyl is attached to a
hydrogen.
___________________________________
___________________________________
___________________________________
___________________________________
In a ketone, the carbon of the
carbonyl group (C=O) is
attached to two carbon atoms.
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63
Carboxylic Acids and Esters
___________________________________
___________________________________
___________________________________
Carboxylic acids contain the
carboxyl group, which is a
carbonyl group attached to a
hydroxyl group.
O
║
— C—OH
An ester contains the
carboxyl group between
carbon atoms.
___________________________________
___________________________________
___________________________________
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64
___________________________________
Amines and Amides
___________________________________
___________________________________
___________________________________
In amines, the functional
group is a nitrogen atom.
|
—N —
___________________________________
___________________________________
___________________________________
Amines
In amides, the hydroxyl
group of a carboxylic acid
is replaced by a nitrogen
group.
Copyright © 2009 by Pearson Education, Inc.
An amide
64
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65
___________________________________
Summary of Functional Groups
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
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65
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66
Learning Check
___________________________________
___________________________________
___________________________________
Classify each of the following as: alcohol, ether,
aldehyde, ketone, carboxylic acid, ester, amine, or
amide.
1) CH3─CH2─CH2─OH
2) CH3─O─CH2─CH3
3) CH3─CH2─NH2
O
║
4) CH3─C─OH
___________________________________
___________________________________
___________________________________
O
║
5) CH3─C─O─CH3
66
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67
___________________________________
Solution
___________________________________
___________________________________
1) CH3─CH2─CH2─OH
2) CH3─O─CH2─CH3
3) CH3─CH2─NH2
alcohol
ether
amine
___________________________________
O
║
4) CH3─C─OH
carboxylic acid
O
║
5) CH3─C─O─CH3
ester
___________________________________
___________________________________
___________________________________
67