Unit 3 Organic
Chemistry
Chemistry 2202
Introduction

Organic Chemistry is the study of the
molecular compounds of carbon.
eg. CH4

CH3OH
CH3NH2
Organic compounds exclude oxides
of carbon and ions containing carbon.
ie. CO, CO2, KCN, CaCO3
are NOT organic compounds!!
History of Organic Chemistry
Organic chemistry can be traced back
to ancient times when medicine men
extracted chemicals from plants and
animals to treat members of their
tribes
 Organic chemistry was first defined
as a branch of modern science in the
early 1800's by Jon Jacob Berzelius

Berzelius believed in Vitalism organic compounds could only
originate from living organisms
through the action of some vital force
 organic compounds originate in living
or once-living matter
 inorganic compounds come from
"mineral" or non-living matter


In 1828, Friedrich Wöhler
discovered that urea - an organic
compound - could be made by
heating ammonium cyanate (an
inorganic compound).
NH4OCN(aq)  (NH2)2CO(s)
inorganic
organic
organic chemistry branched into
disciplines such as polymer
chemistry, pharmacology,
bioengineering and petro-chemistry
 98% of all known compounds are
organic


The huge number of organic
compounds is due mainly to the
ability of carbon atoms to form stable
chains, branched chains, rings,
branched rings, multiple rings, and
multiple bonds (double and triple
bonds) to itself and to many other
non-metal atoms.
Sources of Organic Compounds
1. Carbonized Organic Matter
- fossil fuels such as coal, oil, and
natural gas
- basis for the petrochemical industry
2. Living Organisms
eg: - penicillin from mold
- ASA from the bark of a willow tree
3. Invention
- antibiotics, aspirin, vanilla flavoring,
and heart drugs are manufactured
from organic starting materials
- plastics
Structural Isomers

Structures that have the same molecular
formula but different structural formulas
are called structural isomers
eg. C4H10
Practice: Draw all structural isomers
of C5H12 and C6H14
Structural Isomers

structural isomers have the same
chemical formula but have different
chemical and physical properties.
Classifying Organic Compounds
Organic
Compounds
Hydrocarbons
Hydrocarbon
Derivatives
hydrocarbons consist of carbon and
hydrogen atoms only
eg. Methane - CH4
 hydrocarbon derivatives have one
or more hydrogen atoms replaced by
another nonmetallic atom
eg. bromomethane - CH3Br
methanol - CH3OH

Hydrocarbons
Aliphatic
Hydrocarbons
Aromatic
Hydrocarbons
(benzene based)
AlkAnes
AlkEnes
AlkYnes
aliphatic hydrocarbons have carbon
atoms bonded in chains or rings with
only single, double, or triple bonds
 aromatic hydrocarbons contain at
least one 6 carbon benzene ring

Aliphatic Hydrocarbons
1. Alkanes

Alkanes are hydrocarbons that have
only single bonds between carbon
atoms

general formula CnH2n+2
eg. C3H8
C6H14
IUPAC
prefixes
Prefix
meth
eth
prop
but
pent
hex
hept
oct
non
dec
# of carbon
atoms
1
2
3
4
5
6
7
8
9
10
Complete this methane
ethane
table for the
first 10 alkanes propane
CH4

A series of compounds which differ by
the same structural unit is called a
homologous series
eg. each successive member of the
alkanes increases by CH2
Representing Alkanes (4 ways)
1. Structural formulas
eg. propane
H
H
H
H–C–C–C–H
H
H
H

Hydrogen atoms may be omitted from
structural formulas
eg. propane
–C–C–C–
2. Condensed Structural Formula
eg. propane
CH3-CH2-CH3
3. Line Structural Diagrams
eg: propane
(the endpoint of each segment is a
carbon atom)
4. Expanded Molecular Formulas
eg. propane
CH3CH2CH3
Alkyl Groups
An alkyl group has one less hydrogen
than an alkane.
 General Formula: CnH2n + 1
 To name an alkyl group, use the
prefix to indicate the # of carbon
atoms followed by the suffix –yl
eg. -C7H15 heptyl

Alkyl Groups
methyl -CH3
ethyl -C2H5 or -CH2CH3
propyl -C3H7 or -CH2CH2CH3
Alkyl Groups

Branched alkanes are alkanes
that contain one or more alkyl
groups
eg.
Naming Branched Alkanes
1. Find
the longest continuous chain of
carbons and name it using the alkane
name. This is the parent chain.
2. Number
the carbons in the parent
chain starting from the end closest to
branching. These numbers will
indicate the location of alkyl groups.
Naming Branched Alkanes
3.
List the alkyl groups in alphabetical
order. Use Latin prefixes if an alkyl
group occurs more than once.
(di = 2, tri = 3, tetra = 4, etc.)
4.
Use a number to show the location of
each alkyl group on the parent.
Naming Branched Alkanes
5.
Use commas to separate numbers,
and hyphens to separate numbers
and letters.
Naming Branched Alkanes
eg.
ethyl
7
6
5
4
3
2
1
methyl
4-ethyl-3-methylheptane
Naming Branched Alkanes
Practice:

p. 336 - 339 #’s 5 - 11
Alkenes and Alkynes
saturated compounds contain only
single bonds between carbon atoms
eg. alkanes
 saturated compounds have the
maximum number of hydrogen atoms
bonded to carbon atoms

Alkenes and Alkynes

unsaturated compounds contain
double or triple bonds between
carbon atoms
eg. alkenes and alkynes
Alkenes and Alkynes
 General
Formulas:
 Alkenes
CnH2n
 Alkynes
CnH2n - 2
Naming Alkenes and Alkynes
1.
Name the longest continuous chain
that contains the double/triple bond.
Use the smallest possible number to
indicate the position of the double or
triple bond.
Naming Alkenes and Alkynes
2.
Branches are named using the same
rules for alkanes. Number the
branches starting at the same end
used to number the multiple bond.
Naming Alkenes and Alkynes
p. 347 #’s 17 - 19
 p. 354 #’s 28 & 29

Cyclic Hydrocarbons

Pp. 356 – 358
 questions 30 & 31
3-ethyl-1-methylcyclopentane
cyclopentane
2
1
ethyl
3
methyl
1-ethyl-3-methylcyclopentane
methyl
1,2,3,4-tetramethylcyclohexane
Aromatic Compounds
Aromatic hydrocarbons contain at
least one benzene ring.
 The chemical formula for benzene,
C6H6 , was determined by Michael
Faraday in 1825.
 Structural formula was determined by
August Kekulé in 1865.

Aromatic Compounds

benzene ring consists of six carbon
atoms, each of which is bonded to a
hydrogen atom
(Try to draw this!!)

C6H6 can be drawn with alternating
single and double bonds.
Aromatic Compounds
While C=C double bonds are shorter
than C-C single carbon bonds, x-ray
crystallography shows that all six C-C
bonds in benzene are the same
length.
 Benzene molecules behave like
alkanes in chemical reactions, not like
the alkenes

Aromatic Compounds
Kekulé thought benzene could exist in
two forms and used the idea of
resonance to explain its structure.
 The resonance structure is an
average of the electron distributions.

Aromatic Compounds
or
Aromatic Compounds
bonding electrons that were thought
to be in the double bonds are
delocalized and shared equally over
the 6 carbon atoms
 the bonds in benzene are like “1 ½”
bonds – somewhere between single
and double.

Naming Aromatic Compounds
an alkyl benzene has one or more H
atoms replaced by an alkyl group.
 name the alkyl groups, using
numbers where necessary, followed
by the word benzene.

Aromatic Compounds
methylbenzene
ethylbenzene
propylbenzene
Aromatic Compounds
1,3-dimethylbenzene
1,4-dimethylbenzene
1,2-dimethylbenzene
Aromatic Compounds
ortho- means positions 1 and 2 and is
represented by an italicized "o"
 meta- means positions 1 and 3 and is
represented by an italicized "m"
 para- means positions 1 and 4 and is
represented by an italicized "p"

Aromatic Compounds
m-dimethylbenzene
p-dimethylbenzene
o-dimethylbenzene
Aromatic Compounds
Benzene is treated as a branch if it is
not attached to the terminal carbon of
an alkyl group
 Benzene as a branch is called phenyl

Aromatic Compounds
CH3
CH2
CH2
CH3 CH CH3
2-phenylpropane
propylbenzene
Aromatic Compounds
CH3 CH2 CH2 CH CH CH3
CH2
CH3
Aromatic Compounds
CH3
CH2
CH2 CH3
CH3 CH2 CH2 CH CH2 CH CH CH3
Aromatic Compounds

p. 361 #’s 32 – 35
Hydrocarbons Practice
pp. 363, 364
#’s 4 – 9
 Test!!

Hydrocarbon Derivatives
Hydrocarbon Derivatives have one
or more H atoms replaced by another
nonmetallic atom
 Types of derivatives:
 alcohols
 carboxylic acids
 ethers
 organic halides
 aldehydes
 esters
 ketones

Hydrocarbon Derivatives
A functional group is the reactive
group of atoms that gives a family of
derivatives its distinct properties.
 The general formula for a derivative is

R - functional group
where R stands for any alkyl group.
Bonded to
Hydrocarbon Derivatives
eg. ALCOHOLS
ethanol
propanol
hydroxyl
group
R-OH
C2H5OH
carboxyl
C3H7OH group
CARBOXYLIC ACIDS
R-COOH
ethanoic acid
CH3COOH
propanoic acid
C2H5COOH
Hydrocarbon Derivatives

Types of derivatives (See p. 378)
 Alcohols – pp. 386 - 388
 Ethers – pp. 394 – 396
 Aldehydes & Ketones – pp. 402,403
 Carboxylic Acids – pp.405, 406
 Alkyl Halides – pp. 390, 391
 Esters – pp. 410, 411