CHEMISTRY 102
Elementary Organic Chemistry with Applications
Course Description: This course will focus on introductory principles of organic
chemistry and then build on these concepts to gain an understanding of biological
chemistry. The course is especially appropriate for persons planning careers in the life
sciences.
Instructor: Prof. Paul G. Seybold, Office hours: Mon., Wed., Fri.: 9:00 – 9:40 am and
after class; other times by arrangement. Room 219 Oelman Hall. (937) 775-2407,
paul.seybold@wright.edu
Lab Director: Mr. Kirby Underwood, 428 Oelman Hall, (937) 775-3012
Textbooks: Essentials of General, Organic, and Biological Chemistry by H. Stephen
Stoker (2003) Houghton Mifflin (lecture): Laboratory Guide for Chemistry (2nd Edition)
by David A. Grossie and Andrea Burns (2005), Hayden McNeil Publ. (lab).
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10–1
Suggestions: It is strongly suggested that students read the chapter to be covered before
each class. Keep up with the lectures and do the problems in each chapter.
Supplementary material will be provided during the lecture, so it is important to attend
class. When you have questions, ask your instructor or TA for help.
Lab Reports: Laboratory attendance is a requirement for CHM 102. You are expected
to actively participate in lab. The teaching assistant will inform you about expectations
for the lab report. Lab reports are due at the start of the next lab session. Each lab report
is worth 10 points. A penalty of 2 points per day will be assessed for late lab reports.
Grading: Three hour exams and a final exam will be given; the hour exam with the
lowest grade or a missed hour exam will be dropped. Because you can drop one exam,
make-up exams are not available. The final exam is comprehensive for all material
covered in this class and cannot be dropped. Should an emergency arise requiring you
to miss the final exam, you must contact your instructor beforehand (no exceptions)
explaining your absence and then provide written documentation of the emergency.
Grading System: Each hour exam (best two out of three) counts 100 points, the final
exam 150 points, and lab 100 points, for a total of 450 points. A = 400-450 points, B =
350-399, C = 300-349, D = 250-299, F less than 250.
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10–2
Exam Schedule
See the Syllabus for the dates of these exams.
First Hour Exam (Chaps. 10, 11, 12)
Second Hour Exam (Chaps. 13, 14, 15)
Third Hour Exam (Chaps. 16, 17)
Two-hour Final Exam (Comprehensive)
Note: There are no make-up exams. The lowest score of
the three hour exams will be dropped; if you miss an hour
exam, that will be your dropped exam. You must take the
final exam.
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10–3
The CHM 102 lecture slides and
syllabus are available online
• Go to the lecturer’s home page:
www.chm.wright.edu/seybold/
• Open “Courses”
• Open “Chemistry 102”
• Last year’s exams are also given in this folder
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10–4
NOTE 1: There are NO LABS this week. The
first lab (next week) is Experiment 25.
NOTE 2: If you miss a lecture, please contact a
fellow student, not the lecturer.
The will to succeed is important, but what's even more
important is the will to prepare.
-
--Bobby Knight
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10–5
Study Advice
 Work with others. If possible, study with a friend or
group.
 Start early to go over the material. If possible read the
course material before each lecture.
 Practice. Solve the problems in the text, do the practice
quizzes, and try last year’s exams.
 Ask questions. Ask your friends, ask your TA, ask
your professor.
 Get a good night’s sleep. Recent research shows that
sleep helps consolidate learning.
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10–6
We have these and many other interesting topics to
explore, but first we must undergo …
BOOT CAMP!
… wherein we go over the basics of the classes of
organic compounds and how they are named.
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10–7
Chapter Ten
Organic Chemistry
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10–8
• Saturated Hydrocarbons
10.1 Organic and Inorganic
Compounds
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10–9
10.1 Organic and Inorganic Molecules
The term organic derives from organism. Thus, organic
compounds were historically derived from organisms or
from living sources.
The term inorganic derives from inanimate. Thus,
inorganiccompounds were historically derived from
inanimate ornon-living sources.
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10–10
10.1 Organic and Inorganic Molecules
Chemists once believed that a “vital force” supplied by a
living organism was necessary to form an organic compound.
However, Friedrick Wöhler showed in 1828 that an organic
compound, urea, could be made from inorganic compounds.
NH4Cl + AgNCO
inorganic
inorganic
ammonium chloride silver cyanate
H2NCONH2 + AgCl
organic
urea
inorganic
silver chloride
Reaction of two chemicals from inanimate sources produced a
chemical normally found in living organisms. The “vital force”
theory was therefore abandoned.
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10–11
An Historical Aside
Serendipity: “A lucky accident” (the term was first coined by Horace
Walpole in 1754)
Many of the most famous discoveries in science have come about by
accident. Wöhler’s discovery was an accident. He was actually trying to
prepare the inorganic compound ammonium cyanate when he made urea-and in so doing he demonstrated for the first time that “organic” compounds
could be synthesized in the laboratory. Wöhler expressed his excitement in a
famous 1828 letter to J. Berzelius:
I can no longer, so to speak, hold my chemical water and must tell you
that I can make urea without needing a kidney, whether of man or dog;
the ammonium salt of cyanic acid is urea.
This discovery reinforces the famous words of Louis Pasteur: “Chance
favors only the prepared mind.” Wöhler’s mind was prepared, and he became
famous.
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10–12
10.1 Organic and Inorganic Molecules
•
Organic chemistry: The chemistry of carbon
compounds, including hydrocarbons and
hydrocarbon derivatives.
•
Exceptions: CO, CO2, Na2CO3, etc. are
normally considered as inorganic
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10–13
Sheer numbers is one reason why organic chemistry
is a separate field of chemical study. More than 33
million compounds are now known (May, 2008),
and roughly 90% of them are organic compounds.
Note that the text’s Figure 10.1, showing 8.5 million
compounds, is quite outdated. In fact, 2 million new
compounds are reported each year!
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10–14
10.2 Bonding Characteristics of
the Carbon Atom
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10–15
Carbon has four valence electrons and always forms
compounds with four bonds attached to each carbon atom.
C
one double bond
and two single bonds
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C
two double bonds
C
one triple bond
and one single bond
10–16
•
•
Organic molecules have covalent bonds.
Organic molecules contain polar covalent
bonds when carbon bonds to an
electronegative (electron-attracting) element
on the right side of the periodic table.
Ionic bonds, NaCl
Na+ and ClNonpolar covalent
bonds: H-H, equally
shared electrons
Polar Covalent bonds,
CH3Cl: unequally
shared electrons
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10–17
•
Carbon can form multiple covalent bonds by
sharing more than two electrons with a
neighboring atom.
•
Organic molecules have specific threedimensional shapes or conformations.
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10–18
•
•
Organic molecules often contain hydrogen,
nitrogen, and oxygen in addition to carbon.
Nitrogen can form single, double, or triple
bonds to carbon; oxygen can form single and
double bonds.
O
H C N
hydrogen cyanide
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H H
formaldehyde
10–19
10.2 Families of Organic Molecules: Functional groups
• More than 33 millions organic compounds, are
known today. They are classified into just a few
general families on the basis of their chemical
composition
• Functional group: A group of atoms within a
large molecule that has a characteristic structure
and chemical behavior. Functional groups allow us
to group vast number of organic molecules into few
classes. See Table 10.1.
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10–20
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10–21
• In Table 10.1, the first four families are
hydrocarbons – organic compounds that
contain only carbon and hydrogen.
- Alkanes have only single bonds.
- Alkenes contain a carbon-carbon double
bond functional group.
- Alkynes contain a carbon-carbon triple bond
functional group.
- Aromatic compounds contain a sixmembered ring of carbon atoms with three
alternating double bonds.
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10–22
•
•
In Table 10.1, the next four families have functional
groups that contain only single bonds and have a
carbon atom bonded to an electronegative atom.
- Alkyl halides have a carbon-halogen bond (the
“halogens are” F, Cl, Br, and I);
- Alcohols have a carbon-oxygen (-OH) bond;
- Ethers have two carbons bonded to the same
oxygen atom (R-O-R’); and
- Amines have a carbon-nitrogen bond.
The remaining families have functional groups that
contain a carbon-oxygen double bond; aldehydes,
ketones, carboxylic acids, anhydrides, esters, and
amides.
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10–23
10.3 Hydrocarbons and
Hydrocarbon Derivatives
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10–24
A hydrocarbon contains only carbon and hydrogen.
CH3-CH2-CH3
propane
A hydrocarbon derivative contains carbon and hydrogen
and one or more additional elements.
CH3-CH2-CH2-Cl
1-chloropropane
A saturated hydrocarbon contains only carbon–carbon
single bonds.
An unsaturated hydrocarbon contains one or more carbon
–carbon multiple bonds; double bonds, triple bonds, or both.
CH3-CH=CH2
propene
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10–25
Figure 10.2
A summary of classification terms for
organic compounds.
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10–26
Practice Problems and Questions
• What is the difference between a saturated
and an unsaturated hydrocarbon?
• What is the difference between a
hydrocarbon and a hydrocarbon derivative?
• What elements are commonly found in
hydrocarbon derivatives?
N, O, S, P, F, Cl, and Br.
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10–27
10.4 Alkanes: The Simplest
Saturated Hydrocarbons
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10–28
An alkane is a saturated hydrocarbon in which the
carbon atom arrangement is not cyclic.
CH3-CH2-CH3
propane
H2C
H2C
H2
C
C
H2
CH2
CH2
cyclohexane
acyclic
cyclic
Cn H2n+2
Cn H2n
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10–29
Ball-and-stick models showing the molecular
structures of (a) methane, (b) ethane, and (c)
propane, the three simplest alkanes.
The geometrical arrangement around each carbon atom
is tetrahedral.
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10–30
Practice problems
• How many carbon atoms are there in propane?
• How many carbon-carbon bonds are there in
propane?
• How many carbon-hydrogen bonds are there in
propane?
• Suppose an alkane has four carbon atoms. How
many hydrogen atoms would it have?
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10–31
10.5 Structural Formulas
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10–32
10.5 Drawing Organic Structures
•Expanded structure: shows in two
dimensions all atoms in a molecule and
all the bonds connecting them.
H H H
H C C C H
H H H
propane
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10–33
• Condensed structure: uses groupings of
atoms, in which central atoms and the atoms
connected to them are written as a group, to
convey molecular structural information.
CH3-CH2-CH3
propane
• Skeletal structure: focuses on the
backbone or arrangement of atoms only.
C-C-C-C-C
pentane
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10–34
10.6 Structural Isomerism
a.k.a. Constitutional Isomers
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10–35
ISOMERS
These are compounds with same molecular
formula but different connections. They have
different properties
Consider the pentanes (all C5H12):
C-C-C-C-C
“normal”
C
|
C-C-C-C
“branched”
BP = 36.°
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BP = 28°
C
|
C-C-C
|
C
BP = 9.5° C
10–36
•There is only one possible way that the
carbons in methane (CH4), ethane (C2H6),
and propane (C3H8) can be arranged.
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10–37
However, the carbons in butane (C4H10)
can be arranged in two ways; four carbons
in a row (linear alkane) or a branching
(branched alkane). These two structures
are the structural isomers for butane. The
number of possible structures increases
rapidly with the number of carbons in the
molecule.
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10–38
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10–39
Space-filling models and skeletal formulas for the
three isomeric (C5H12) alkanes.
C-C-C-C-C
C
C
C
C
C
C
C
C
C
C
Structural Isomers
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10–40
Selected Physical Properties of C4 and C5 Alkanes.
Branching lowers boiling point and density.
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10–41
Number of Structural
Isomers Possible for
Alkanes of Various
Carbon-Chain Lengths.
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10–42
•Different structural isomers are in effect
different compounds. They have different
structures, different physical properties such
as melting point and boiling point, and may
have different physiological properties.
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10–43
10.7 Conformations of Alkanes
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10–44
The Shapes of Organic Molecules
•
Molecules joined by a carbon-carbon single
bonds are free to spin around the bond, giving
rise to an infinite number of possible three
dimensional geometries, or conformations.
•
Fig 10.2 The structure of butane can be shown in
several different ways.
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10–45
• At any moment, however, most
molecules are in the least
crowded conformation.
• As long as any two structures
show
identical
connections
between atoms, they represent
identical compounds no matter
how the structures are drawn.
C-C-C-C-C-C
C-C-C-C-C
C
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These two are identical
molecules, but are shown in
two different conformations.
10–46
How are these compounds
named?
IUPAC Nomenclature
for Alkanes
IUPAC = International Union of Pure and Applied
Chemistry
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10–47
IUPAC Names for the First Ten
Continuous-Chain Alkanes.
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10–48
• Substituents: An atom or group of
atoms attached to a parent
compound.
• Alkyl group: A hydrocarbon
substituent formed by removing a
hydrogen atom from an alkane.
• Example: Remove one hydrogen
atom from CH4 (methane)  -CH3 (a
methyl group) substituent.
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10–49
Some alkyl substituents
•
•
•
•
•
•
•
Methyl -CH3
Ethyl -CH2CH3
Propyl -CH2CH2CH3
Butyl -CH2CH2CH2CH3
Pentyl -CH2CH2CH2CH2CH3
Hexyl -CH2CH2CH2CH2CH2CH3
Heptyl -CH2CH2CH2CH2CH2CH2CH3
Etc.
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10–50
• Both methane (CH4) and ethane (CH3CH3) have only one type of hydrogen. It
does not matter which of the hydrogens in
methane or in ethane is removed, this will
produce the same methyl or ethyl group.
• But propane (CH3-CH2-CH3) has two
distinct locations for its hydrogens.
Removing a hydrogen from one of the outer
CH3 groups produces a propyl group,
whereas removal of a hydrogen from the
inner CH2 produces an isopropyl group.
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10–51
No swimming allowed!
Ethane Lakes on Titan!
Titan is the largest of the planet
Saturn’s 60 moons. It has a hazy
atmosphere composed mainly of
N2 and hydrocarbons. The
surface temperature is only about
-180 °C (or -292 °F) with a pressure
of 1.5 atm. Recently it has been
found that there are “lakes” of
liquid ethane (containing
dissolved methane and N2) on
Titan.
Note: The boiling point of
ethane is -88.6 °C.
Saturn and some of its moons
See Nature 454, 587, 607 (2008)
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10–52
• Primary carbon atom: A carbon atom
with one other carbon attached to it.
• Secondary carbon atom: A carbon
atom with two other carbons attached to
it.
• Tertiary carbon atom: A carbon atom
with three other carbons attached to it.
• Quaternary carbon atom: A carbon
atom with four other carbons attached
to it.
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10–53
Naming Alkanes
The system of naming (nomenclature)
used now is devised by the International
Union of Pure and Applied Chemistry, or
IUPAC. In the IUPAC system for organic
compounds, a name has three parts;
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10–54
• Straight chain alkanes are named by
counting the number of carbon atoms and
adding the family suffix –ane.
• Branched chain alkanes can be named
following four steps:
• Step 1: Name the longest chain. Find
the longest continuous chain of carbons,
and name the chain according to the
number of carbon atoms it contains.
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10–55
• Step 2: Number the carbon atoms in the
main chain, beginning at the end near the
first branch point.
• Step 3: Identify the branching substituents,
and number each according to its point of
attachment to the main chain.
• Step 4: Write the name as a single word,
using hyphens to separate the numbers
from the different prefixes and commas to
separate numbers if necessary. Cite
different substituents in alphabetical order.
Use di-, tri-, etc for two or three identical
substituents present in the molecule.
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10–56
Example: Octane Numbers
The octane numbers for gasoline tell how smoothly a fuel
works in an auto engine. The scale runs from 0 for nheptane to 100 for “isooctane”. Octane has 18 different
structural isomers. The IUPAC name for “isooctane” is
2,2,4-trimethylpentane:
C C
|
|
C-C-C-C-C
|
C
2,2,4-trimethylpentane
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10–57
Gasoline is a blend of
different hydrocarbons
The blend consists of (1) alkanes, (2) alkenes, and (3)
aromatic compounds. In general the more branched
alkanes have higher octane numbers than straight-chain
alkanes. Alkenes and aromatics tend to burn better (have
higher octane numbers) than alkanes.
Compound
n-octane
3-methylheptane
2,3-dimethylhexane
2,2,4-trimethylpentane
Octane number
0
35
79
100
Note that these are all octanes with the formula C8H18.
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10–58
Cycloalkanes
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10–59
A cycloalkane is a saturated hydrocarbon in which the
carbon atoms are connected to one another in a cyclic (ring)
arrangement.
Three-dimensional representations of the
structures of simple cycloalkanes.
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10–60
Cycloalkanes
• Cycloalkanes: An alkane that contains a ring of
carbon atoms. Ring sizes from 3 carbons to 30 or
higher are known.
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10–61
• Cyclopropanes and cyclobutanes are less
stable since the C-C-C bond angles are 60o and
90o respectively, much compressed from the
normal tetrahedral bond angle of 109.5o.
• Cyclopentane has nearly ideal bond angle,
and as a result it is stable.
• Cyclohexane has a puckered non-planar
structure called a chair conformation. In chair
conformation, the carbon atoms have 109o
bond angles and ths compound is very stable.
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10–62
Cycloalkanes have the general formula CnH2n.
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10–63
Drawing Cycloalkanes
• Cycloalkanes are represented by polygons. A
triangle represents cyclopropane, a square
represents cyclobutane, a pentagon represents
cyclopentane, and so on.
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10–64
• Line structure: A shorthand way of
drawing structures in which atoms
aren’t shown; instead a carbon atom is
understood to be at each intersection
of lines and hydrogens are filled
mentally.
=
H2C
H2C
H2
C
C
H2
CH2
CH2
cyclohexane
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10–65
• Cycloalkanes are named by a straightforward
extension of the rules for open-chain alkanes. In
most cases, only two steps are needed:
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10–66
• Step 1: use the cycloalkane name as
the parent.
• Step 2: Number the substituents starting
at the group that has alphabetical priority,
and proceed around the ring in the
direction
that
gives
the
second
substituent the lower possible number.
CH3
CH2CH3
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10–67
Isomerism in Cycloalkanes
CH3
H3C
CH3
all C5H10
same molecular formula
H3C
but different structures
H2C
CH3
CH3
= structural isomers
H3C
CH3
Capable of cis-trans isomers
Cis-trans isomers are compounds that have the same
molecular formula, but different arrangements of atoms
in space because of restricted rotation around bonds.
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10–68
Cis = on the same side, Trans = across
CH3
CH3
H
cis-1,2-dimethylcyclopropane
H
Geometrical isomers
CH3
H
H
trans-1,2-dimethylcyclopropane
CH3
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10–69
More on Cis-Trans Isomers
Most commonly encountered in ethene (ethylene)
Cl
Cl
\
/
C===C
/
\
H
H
(Cis)
Cl
H
\
/
C===C
/
\
H
Cl
(Trans)
These are called cis- and trans-dichloroethene
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10–70
Sources for Alkanes and
Cycloalkanes
Where do they come from?
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10–71
A rock formation like this is needed for the trapping of
petroleum and natural gas. This is the major source of
both alkanes and cycloalkanes.
Commercial natural gas is 90% methane and 10% ethane.
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10–72
The complex
hydrocarbon mixture
present in petroleum
is separated into
simpler mixtures by
means of a
fractionating column.
Separated components of
petroleum are isolated by
fractional distillation.
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10–73
Physical Properties of Alkanes
and Cycloalkanes
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10–74
•
•
•
•
•
•
The first four alkanes, methane, ethane,
propane, and butane are gases.
Alkanes with 5-15 carbon atoms are liquids.
Alkanes with 16 or more carbon atoms are
low melting waxy solids.
Alkanes are insoluble in water but soluble in
nonpolar organic solvents, including other
alkanes.
Alkanes are generally less dense than water
as result they float on water.
Low molecular-weight alkanes are volatile
and their vapors are highly flammable.
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10–75
Properties of Alkanes
•Melting points and boiling points of straight chain
alkanes increases with molecular size.
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10–76
Trends in normal boiling points for continuous-chain
alkanes, 2-methyl branched alkanes, and
unsubstituted cycloalkanes as a function of the
number of carbon atoms present.
cyclic have higher
boiling points
branching
lowers
boiling point
30 deg. increase for each additional C
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10–77
Chemical Properties of Alkanes
and Cycloalkanes
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10–78
Reactions of Alkanes
• Alkanes don’t react with acids, bases, or most
other common laboratory reagents. Their only
major reactions are with oxygen and with halogens.
• Combustion: Reaction of alkanes with oxygen,
producing carbon dioxide and water.
• Halogenation: This reaction normally involves
replacement of a hydrogen by a chlorine or bromine.
Initiation of this reaction requires heat or light.
Complete chlorination of methane produces carbon
tetrachloride.
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10–79
Examples
Combustion: Reaction with oxygen
12 CO2 + 14 H2O + energy
2 C6H14 + 19 O2
Halogenation = a substitution reaction in which a halogen
atom replaces a hydrogen atom.
R H
+
alkane
H H
H C C H +
H H
X2
halogen
Br2
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heat or
light
R X
+
halogenated
alkane
H H
H C C Br
H H
H X
hydrogen
halide
+
HBr
10–80
In an substitution reaction, an incoming atom or group
of atoms (represented by the orange sphere) replaces
a hydrogen atom in the molecule.
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10–81
Chemistry at a Glance:
Properties of Alkanes and Cycloalkanes
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10–82
What you should know from this chapter
--Organic chemistry is the study of carbon-containing
compounds.
--Originally it was thought that only living things could make
“organic” compounds, but in 1828 F. Wöhler produced urea
from two inorganic chemicals.
--The carbon atom has a unique ability to form bonds to other
elements and itself.
--Chemical bonds can be ionic, covalent, of polar covalent.
--The great majority of the more than 31 million chemical
compounds known today are organic compounds.
--Hydrocarbons are compounds containing only hydrogen and
carbon.
--A functional group is a group of atoms that has a
characteristic structure and chemical reactivity.
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-- Saturated hydrocarbons are hydrocarbons with only carboncarbon single bonds.
-- Unsaturated hydrocarbons contain one or more C-C multiple
(double or triple) bonds.
-- Alkanes are saturated hydrocarbons Their general formula is
CnH2n+2, where n = 1, 2, 3, etc.
-- You should be able to name the first ten alkanes.
-- Alkenes have one or more C-C double bonds.
-- Alkynes contain one or more C-C triple bonds.
-- Cycloalkanes are alkanes that have ring shapes.
-- You should be able to name different alkanes and cycloalkanes
with up to 10 carbons, using the IUPAC nomenclature.
-- You should understand that these molecules have 3dimensional shapes in space.
-- Isomers are compounds that have the same molecular formula
but different structures.
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-- These compounds can be pictured by various means
including structural formulas, ball and spoke models, and
space-filling models.
-- Cis-trans isomers are defined by whether substituents are
on the same side (cis) or opposite sides (trans) of a plane
in the molecule.
-- The boiling and melting points of alkanes increase with the
number of carbon atoms. Methane, ethane, propane, and
butane are gases, and normal alkanes with 5-15 carbon
atoms are liquids.
-- Alkanes are not soluble in water, but are soluble in non-polar
organic solvents. They generally are lighter than water and
float as films on top of water.
-- They are not toxic.
-- They react mainly with oxygen (combustion reaction) and
halogens (halogenation reaction).
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--Understand that hydrocarbons are obtained in nature from
natural gas and petroleum deposits trapped under rock
formations.
-- Appreciate that hydrocarbons have great economic
importance, both as the components of natural gas, gasoline,
and heating oil, but also as the raw material for much of the
chemical industry, including plastics.
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To Do List
• Read chapter 10!!
• Do additional problems
• Do practice test T/F
• Do practice test MC
• Review Lecture notes for
Chapter Ten
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