Chemistry 101 H
Introduction to Organic
Chemistry
This presentation was created by
Professor Carl H. Snyder
Chemistry Department
University of Miami
Coral Gables, FL 33124
CSnyder@miami.edu
Copyright 2004 by Carl H. Snyder,
University of Miami. All rights reserved.
Chapter 6 - Introduction to
Organic Chemistry
“Organic” in Everyday Life
What do we mean by organic foods?
organic gardening?
organic pesticides?
“Organic” and “Vital Force”
Before 19th Century, belief was:
Compounds present in plants and animals required a “vital (life) force” for their creation.
1828, Friedrich Wohler carried out a laboratory synthesis of urea , a biological product formerly believed to be a product of the “vital force”.
Wohler’s laboratory synthesis of urea signalled the beginning of the end of the “vital force” theory.
“Organic” in Chemistry
All organic compounds contain carbon.
If a compound contains carbon, it’s an organic compound.
Inorganic compounds do not contain carbon.
The Hydrocarbon Family
1

Our Most Common Hydrocarbons
Gasoline is our most common consumer product consisting principally of hydrocarbons.
Others include: mineral oil lubricating oil petroleum jelly
Methane
Methane, CH
4
, is the simplest member of the hydrocarbon family
Four hydrogen atoms form four covalent bonds with one carbon atom
Methane and The Tetrahedral
Carbon
The stereochemistry of methane is tetrahedral .
Four hydrogens lie at the apexes of a tetrahedron.
The carbon lies at the center of the tetrahedron.
The Methyl Free Radical
The distinguishing characteristic of a free radical is that it contains an unpaired electron.
Ethane
The 3-Dimensional Structure of Ethane
The combination of 2 methyl free radicals forms ethane .
Ethane can be formed in a variety of other ways as well.
2

Three Ways to Draw the
Structure of Ethane
The first shows explicitly the C-C and all the C-H bonds.
The second shows explicitly only the C-C bond..
The third is the most common way of drawing ethane’s structure.
Space-filling Models of
Methane and Ethane
Propane and The Alkanes methane , CH
4 ethane , C
2
H
6 propane , C
3
H
8 are the first 3 members of the alkane family.
All alkanes have the general formula C n
H
2n+2
From One Methane to One
Ethane
All 4 hydrogens of methane are mutually equivalent.
Replacing any one of methane’s hydrogens with a methyl group gives rise to the same ethane molecule.
From One Ethane to One Propane
Propane - Two Different Kinds of Hydrogens
The propane molecule contains two different kinds of hydrogens:
The methyl group's 6 primary (1 o ) hydrogens
The methylene group’s 2 secondary (2 o ) hydrogens
All six of ethane’s hydrogens are mutually equivalent.
Replacing any one of ethane’s hydrogens with a methyl group gives rise to the same propane molecule.
3

From One Propane to Two
Different Butanes
Replacing a 1 o
H with a methyl group gives butane
Replacing a 2 o
H with a methyl group gives isobutane.
Isomers
Butane, C
4
H
10
, and isobutane,
C
4
H
10
, are isomers .
The First Five Alkanes - A
Summary
The First 10 Straight-Chain
Alkanes
The C
5
H
12
Alkanes - Structures
Left: pentane , the only straight-chain pentane
Center: isopentane , a pentane with one branch
Right: neopentane , a pentane with two branches
Isomeric Alkanes
By one estimate, there are as many possible isomers of C
100
H universe.
202
as there are atoms in the
4

IUPAC - #1 IUPAC - #2
IUPAC - #3 IUPAC - #4
IUPAC - #5 Alkenes
5

Ethene, or Ethylene
The C-C Single
Bond and The C=C
Double Bond
Covalent bonding in ethane and in ethene
(ethylene).
Removal of a molecule of hydrogen from ethane produces ethene (IUPAC), or ethylene (common).
Where Is The Double Bond?
Give the C=C double bond the number held by the lower numbered carbon.
If the C=C bond lies between C#1 and C#2, we have 1-butene .
If between C#2 and
C#3, we have 2-butene .
Alkynes - Ethyne, or
Acetylene
An alkyne contains a triple bond.
Alkanes, Alkenes, and Alkynes
A Summary
Saturation and Unsaturation
6

Saturation and Unsaturation in
Ethane and Ethylene
H
2
can be added to C=C double (and triple) bonds.
Cycloalkanes
Aromatic Compounds
Addition of H
2
O to C=C
Water can be added to C=C
The product is an alcohol.
Benzene, An Aromatic
Hydrocarbon
Left: All bonds and all atoms are shown
Center: Only C-C and C=C bonds are shown
Right: The 6 electrons of the C=C system appear as a circle.
Some Important Aromatic
Compounds
7

The Hydrocarbon Family
A Burning Candle
The Chemistry of a Charcoal
Grill
As the carbon of the charcoal briquettes in a backyard grill burns:
One atom of carbon and one diatomic molecule of oxygen combine to form one molecule of carbon dioxide:
1C + 1O
2
---> 1CO
2 or more simply
C + O
2
---> CO
2
The reaction releases heat.
Balanced Equations
Carbon dioxide formation:
C + O
2
---> CO
2
C + O=O ---> O=C=O
Carbon monoxide formation:
2 C + O
2
---> 2 CO
C, C, O=O ---> CO, CO
End - Chapter 6
8