Organic chemistry is the study of the
properties of the compounds of
carbon.
Just about everything in this world has
carbon, C, in it!
Learning Objectives
a. Organic molecules form the basis for life and
include many natural products with medicinal
properties.
b. After the structure of a biologically active
compound is determined, organic chemists can
often synthesize the compound, as well as new
derivatives with more powerful activities.
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Learning Objectives (cont)
c. Most organic compounds contain a
hydrocarbon framework containing chains of
carbon atoms and bonded hydrogen atoms
(“hydrocarbons”).
d. Hydrocarbons are classified according to types
of carbon-carbon bonds. Alkanes contain only
single bonds, alkenes contain at least one
double bond, alkynes contain at least one triple
bond, and aromatics are rings that contain
alternating single and double bonds.
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Learning Objectives (cont)
e. Adding different atoms or groups of atoms
(functional groups) to a hydrocarbon results in
new classes of compounds with distinctive
chemical properties.
f. The geometric arrangement of atoms within an
organic compound determines its activity.
g. Two mirror-image molecules (enantiomers) with
the same chemical formula and connections of
the atoms can have different biological activities.
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•
General Properties of Organic Compounds
a. Review of Carbon
1. Carbon has four electrons in its outer shell and
therefore can form four covalent bonds.
b. Polarity
1. Organic molecules contain many nonpolar C-H bonds
and are therefore generally hydrophobic.
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Three ways
in which carbon can fulfill its octet
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Effect of differences in electronegativity
on charge distribution
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•
General Properties of Organic Compounds
c. Intermolecular Forces
1. Small hydrocarbons interact through relatively weak
London forces and therefore tend to be gases at room
temperature.
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Melting and Boiling
Points of Hydrocarbons
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•
General Properties of Organic Compounds
c. Intermolecular Forces
3. Large hydrocarbons and those containing bonded
polar atoms are often liquids or solids at room
temperature.
4. Organic molecules containing bonded polar atoms
are generally more water soluble than those
containing only carbon and hydrogen. (Like dissolves
like.)
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Water Solubility of
Alcohols vs. Alkanes
OH groups can make a molecule, with less than 8 carbons, water soluble
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•
Natural Products
a. Some compounds found in nature (natural
products) have interesting properties, such as
medicinal activity.
b. Once the structure of a natural product is
determined, chemists may seek to synthesize the
compound in the laboratory.
c. Parent compounds, like salicin, serve as the
structural basis for new synthetic molecules
(derivatives or analogues).
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Synthesis of Derivatives
The willow tree, source of the
active ingredient of aspirin
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The Pacific
yew tree, source of taxol
A molecule with powerful
Anticancer activity!
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•
Types of Hydrocarbons
a. Alkanes: contain only single carbon-carbon
bonds
b. Alkenes: contain at least one double carboncarbon bond
c. Alkynes: contain at least one triple carboncarbon bond
d. Aromatics: ringed hydrocarbons with alternating
single and double bonds between carbons.
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Examples of Straight-Chain Alkanes
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Reduction of
hydrocarbons vs. oxidation
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Reactivity of Alkanes
Hydrocarbon + O2  carbon dioxide + water + heat energy
D
Ex. CH4 + 2O2  CO2 + 2H2O
D
Heat released is 802 kJ/mol
of methane
Effect of partially oxidizing a hydrocarbon, let’s look at the
combustion reaction of CH3OH (methanol), in which 1 H has
been replaced by an –OH group.
2CH3OH + 3O2  2CO2 + 4H2O
D
Heat released is 640 kJ/mol
of methanol
(1.5 moles of O2 required to with 1 mole of CH3OH!)
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These reactions illustrates two important principles.
1st, the more reduced a molecule, the more energy is released
during oxidation on a molar basis.
Methane is fully reduced and gives off more energy during
combustion than methanol.
2nd, the number of oxygen molecules required to react with a
fuel molecule gives an estimate of how much energy is
available.
More highly reduced molecules require more oxygen during
combustion and produce more energy.
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Examples of cycloalkanes
C5H10
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Cyclopentane
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The simplest alkene, ethylene
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Saturated fats contain three
alkane chains, unsaturated fats three alkene chains
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Cis and trans refer to
different geometries in two isomers
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Trans Fatty Acids
in Some Common Food Products
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The formation of
trans double bonds, hydrogenation
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Polymerization:
white plastic water bottles
monomers
Credit: Courtesy of Nalgene
The simplest alkyne, acetylene
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Aromatics Compounds,
Polycyclic Aromatic Hydrocarbons (PAH’s)
Benzene
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Naphthalene, in mothballs
Anthracene, in insecticides and wood
preservatives
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Bioaccumulation of
Polycyclic Aromatic Hydrocarbons
A process by which
chemical contamination
increases within organisms
higher up the food chain.
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•
Functional Groups are groups of atoms that
contribute to the properties of an organic compound
a.
b.
Organic Halides ex. CH3-X (X = Cl, Br, I, or F)
Oxygen-Containing Functional Groups
1.
2.
3.
4.
5.
Ethers
Aldehydes
Ketones
Carboxylic Acids
Esters
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•
•
Functional Groups
Nitrogen-Containing Functional Groups
1. Amines
2. Amides
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Alcohols and Ethers
An alcohol contains the
hydroxyl (-OH) functional
group.
In an ether, an oxygen
atom is bonded to two
carbon atoms.
–C–O–C– .
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Publishing as Benjamin Cummings
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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.
In a ketone, the carbon of the
carbonyl group is attached to
two other carbon atoms.
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Publishing as Benjamin Cummings
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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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Publishing as Benjamin Cummings
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Amines and Amides
In amines, the functional
group is a nitrogen atom.
|
—N —
In amides, the hydroxyl
group of a carboxylic acid is
replaced by a nitrogen
group.
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Publishing as Benjamin Cummings
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Functional Groups
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Functional Groups Cont.
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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
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O
║
5) CH3─C─O─CH3
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Solution
1) CH3─CH2─CH2─OH
2) CH3─O─CH2─CH3
alcohol
ether
3) CH3─CH2─NH2
amine
O
║
4) CH3─C─OH
carboxylic acid
O
║
5) CH3─C─O─CH3
ester
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Polymerization of Teflon
Teflon frying pan
Credit: Royalty Free/Alamy
Problematic
Organic Halides Are No Longer Widely
Used
Examples of Polyhydroxy Alcohols
Examples of Phenols
Examples of Aldehydes
Acetone (A Ketone) is produced
during normal metabolism of fats
A common household
Product: nail polish remover.
Acetone can be produced
during
metabolism
of fats, particularly in cases
of starvation or serious
diabetes.
Examples of Carboxylic Acids
•
Isomers
a. Isomers have the same chemical formula but
different arrangements of atoms.
Ex. Ethanol (C2H5O) vs. dimethyl ether or Octane (C8H18) vs isooctane
b. One type of isomers is a pair of enantiomers,
molecules that are “handed”.
c. Enantiomers often have different biological
activities.
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Enantiomers
Enantiomers are like a pair
of gloves: similar shapes that
have “handedness” and are
Nonsuperimposable
R vs S enantiomers
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Key Words
•
•
•
•
•
•
•
•
Organic chemistry
Hydrophobic
Parent compound
Derivative/analogue
Hydrocarbons
Alkanes
Alkenes
Alkynes
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•
•
•
•
•
•
•
•
Aromatic
Saturated
Cycloalkanes
Unsaturated
Cis isomer
Trans isomer
Polymer
Monomer
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