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Chapter 8 Lecture
Basic Chemistry
Fourth Edition
Chapter 8 Chemical Reactions
8.4 Functional Groups and Reactions of
Organic Compounds
Learning Goal Classify organic
molecules according to their functional
groups; draw the condensed structural
formulas for products of reactions of
organic compounds.
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The propane from the torch
undergoes combustion, which
provides energy to solder metals.
Organic Reactions, Combustion
The most common type of reaction that organic
compounds undergo is combustion.
Hydrocarbons are carbon-hydrogen compounds
• used as fuels; gasoline is a mixture of different
hydrocarbons
• burned in the presence of oxygen to produce
carbon dioxide, CO2, water, and energy
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Combustion of Alkanes
Propane, a hydrocarbon with three carbon atoms,
is used as fuel in portable heaters and barbeques.
The balanced reaction for combustion of
propane, C3H8, is
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Covalent Bonds in Organic Compounds
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Functional Groups
Organic compounds are organized according to
their functional groups, specific groups of
atoms that undergo characteristic chemical
reactions.
Compounds with the same functional group have
similar chemical properties.
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Functional Groups, Alkenes
Organic compounds that contain carbon-carbon
double bonds are called alkenes.
The simplest alkene contains two carbons:
ethene,
In ethene, each carbon is attached to
• a double bond
• two hydrogen atoms, with single bonds
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Functional Groups, Alkenes
Ethene is a plant
hormone that
promotes the
ripening of fruit
such as bananas
and avocados.
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Fruit that is picked early is ripened by
exposure to ethene.
Chemistry Link to the Environment
Many insects emit very small quantities of
chemicals called pheromones to send messages
to other members of the same species.
Pheromones can be used
• as a signal of danger
• to mark a trail
• to attract members of the opposite sex
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Chemistry Link to the Environment
One such communication chemical is called
bombykol, emitted by female silkworm moths.
Bombykol
• attracts male silkworm moths
• contains two double bonds and an alcohol
group
• can be made by scientists and used as a
nontoxic pesticide
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Chemistry Link to the Environment
Bombykol attracts male silkworm moths.
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Hydrogenation of Alkenes
Alkenes undergo
• addition reactions, where atoms are added to
each side of the double bond
• hydrogenation reactions, where hydrogen
atoms are added to each side of the double
bond, turning the alkene into an alkane
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Hydrogenation of Alkenes
Hydrogenation reactions require a catalyst such
as platinum (Pt), nickel (Ni), or palladium (Pd)
to speed up the reaction.
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Functional Groups, Aromatic Compounds
In 1825, Michael Faraday isolated benzene, a
hydrocarbon with the formula C6H6.
Because molecules that contain benzene often
have fragrant odors, they are called aromatic
compounds.
Benzene is a six-carbon ring
with alternating single and
double bonds.
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Functional Groups, Aromatic Compounds
Benzene molecules are often represented by a
hexagon with a circle in the center.
One example of an aromatic compound, thymol,
is found in thyme.
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Functional Groups, Alcohols
In an alcohol, a hydroxyl (—OH) group replaces
a hydrogen in a hydrocarbon.
Ethanol
• has the formula
• has been known since prehistoric times as an
intoxicating product
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Functional Groups, Alcohols
Ethanol (ethyl alcohol), CH3CH2OH, is formed
by the fermentation of grains, sugars, and
starches.
Ethanol is used as a solvent for perfumes,
varnishes, and some medicines, such as tincture
of iodine.
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Combustion of Alcohols
Alcohols burn with oxygen to produce carbon
dioxide and water.
Desserts may be prepared
by pouring liquor on
fruit or ice cream and
lighting it.
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A flaming dessert is prepared using a
liquor containing ethanol that
undergoes combustion.
Functional Groups, Aldehydes, and Ketones
Aldehydes and ketones contain a carbonyl group
(C O), which is a carbon atom attached to an
oxygen atom with a double bond.
• In an aldehyde, the carbon atom of the
carbonyl group is also bonded to a
hydrogen atom.
• In a ketone, the carbon atom of the
carbonyl group is bonded to two
other carbon atoms.
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Functional Groups, Aldehydes, and Ketones
Aldehydes and ketones are often found in food
flavorings such as vanilla, cinnamon, and
spearmint.
Formaldehyde, the
simplest aldehyde, is
a colorless gas with
a pungent odor, used
as a germicide and as
a way to preserve
biological specimens.
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Functional Groups, Aldehydes, and Ketones
The simplest ketone, known as acetone or
propanone, is a liquid with a mild odor. It is
widely used as a solvent in cleaning fluids, paint,
and nail polish removers.
In the body, acetone may be produced in
uncontrollable diabetes,
fasting, and with highprotein diets when large
amounts of fats are
metabolized for energy.
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Functional Groups, Carboxylic Acids
In a carboxylic acid, the functional group is the
carboxyl group, which is a combination of the
carbonyl and hydroxyl groups.
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Functional Groups, Carboxylic Acids
The functional group in the formula for a
carboxylic acid can be drawn as follows:
Acetic acid, CH3−−COOH,
and water form a solution
called vinegar, used in
food preparation.
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Functional Groups, Esters
Esters are similar to carboxylic acids, except the
hydrogen atom attached to the oxygen is replaced
by a carbon atom.
The functional group in an ester can be drawn as
follows:
or
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CH3—COO—CH3
Functional Groups, Esters
Many fragrances found in perfumes and flowers
are due to esters.
Esters are also responsible for the odor and
flavorings in oranges, bananas, pears,
pineapples, and strawberries.
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Esters such as ethyl butanoate
provide the odor and flavor of
many fruits such as pineapples.
Chemistry Link to Health
In the 1800s, chemists discovered that salicin,
found in willow tree bark, was responsible for
the relief of pain.
When ingested, the
body converts salicin
to salicylic acid,
which irritates the
stomach lining.
The discovery of salicin in the leaves
and bark of the willow tree led to the
development of aspirin.
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Chemistry Link to Health
In 1899, the Bayer Chemical Company produced
an ester of salicylic acid called acetylsalicylic
acid (aspirin), which is less irritating to the
stomach.
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Functional Groups, Amines
Amines are derivatives of ammonia, NH3, in
which the nitrogen atom is attached to one, two,
or three carbon atoms.
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Functional Groups, Amines
Amines are responsible for fish odor. As the
proteins in fish decay, they produce putrescine
and cadaverine, which have a particularly
pungent and offensive odor.
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Functional Groups, Amides
In an amide, the hydroxyl group of a carboxylic
acid is replaced by a nitrogen group.
Compounds that contain
amides are used to reduce
fever and relieve pain.
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Classes of Organic Compounds
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Classes of Organic Compounds
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Learning Check
Classify each of the following as alcohol, alkene,
aldehyde, ketone, carboxylic acid, ester, amide,
or amine:
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Solution
Classify each of the following as alcohol, alkene,
aldehyde, ketone, carboxylic acid, ester, amide,
or amine:
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