Transcript Hein and Arena

Chapter 11 Outline
11.1 Alcohols, Ethers, and
Related Compounds
11.6 Reduction of Aldehydes
and Ketones
11.2 and 11.3 Preparation
11.7 Reactions of Alcohols
with Aldehydes and Ketones
and Reactions
11.4 Aldehydes and Ketones
11.5 Oxidation of Aldehydes
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11.1
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Examples of
complex org. cpds.
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Are these org. cpds?
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11.1: Alcohols, Ethers, and Related Compounds
Naming Alcohols
• When the IUPAC rules are used to name an alcohol, the
main chain (the longest continuous carbon chain carrying
the -OH group) is numbered from the end nearer the -OH
and named by replacing the “e” ending on the name of the
corresponding hydrocarbon by adding “ol;” (i.e. methane to
methanol).
• When a parent chain contains more than two carbon atoms,
the position of the -OH group must be specified with a
number.
• Any alkyl groups (branches) attached to the main chain are
identified by name, position, and number of appearances.
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Alcohols
Thiols
Ethers
Sulfides
Disulfides
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Classification of alcohols: 1, 2, and
3 Alcohols
• Primary alcohol (1) - the “C” atom
carrying the -OH group is attached to one
other “C” atom.
• Secondary alcohol (2) - the “C” atom
carrying the -OH group is attached to two
other “C” atoms.
• Tertiary alcohol (3) - the “C” atom
carrying the -OH group is attached to three
other “C” atoms.
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H-binding in alcohols:
Compared to hydrocarbons with a similar
molecular weight, alcohols have relatively high
boiling points.
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• The boiling points of ethers, thiols,
sulfides, and disulfides are much lower
than those of alcohols with similar
molecular weights, because none of these
compounds are able to form hydrogen
bonds to like molecules.
• Ether molecules are slightly polar as a
consequence of the C-O-C linkage, but the
dipole-dipole attractions that occur between
ether molecules are not strong enough to
raise boiling points much above those of
similar sized hydrocarbons.
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Example:
Which of the following molecules
can form hydrogen bonds to another
molecule of the same type?
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Exercise:
Predict which molecule has the
higher boiling point?
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11.2 and 11.3: Preparation of alcohols and their
reactions
Alcohols can be prepared using a
nucleophilic substitution reaction, in which
an electron-rich atom or group of atoms,
called a nucleophile, replaces a leaving
group, an easily replaced atom or group of
atoms. Chlorine, bromine, and iodine are
common leaving groups used in organic
chemistry.
(See next slide for reaction to form alcohols)
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Nucleophilic
Substitution rxns.
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Exercise:
Draw the organic product of each
nucleophilic substitution reaction.
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Rxn for making
alcohols from
alkenes:
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11.3: Oxidation of alcohols
Oxidation – gaining more “O’s”, losing “H’s”
Reduction – gaining more “H’s”, losing “O’s”
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Exercise:
Draw the product expected from each
reaction.
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Exercise:
In Chapter 15 we will study the citric acid cycle, a series
of reactions involved in making compounds that can be
used in a separate process to manufacture an energy-rich
compound called ATP. A reaction early in the citric acid
cycle involves the oxidation of an alcohol. Of the two
reactants shown below (each is a reactant somewhere in
the cycle), which can be oxidized?
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Dehydration rxn of
alcohols:
Alcohols -----> alkenes
(lost of OH and H or H2O ---> get
a double bond on the product)
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Oxidation of thiols by I2:
The oxidation of thiols produces a different type of
product than obtained from the oxidation of alcohols. On
treatment with the oxidizing agent I2, two thiol
molecules combine to form a disulfide. The loss of
hydrogen atom by each thiol is evidence that oxidation
has taken place.
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11.4: Aldehydes and Ketones; Naming Aldehydes and
Ketones
• When naming aldehydes and ketones according to the
IUPAC rules, the carbonyl (C=O) must be part of the
main chain, which is numbered from the end nearer this
C=O group.
• Since the carbonyl carbon atom of an aldehyde is always
in position number 1, its position is not specified in the
name.
• For ketones, however, the position of the carbonyl
carbon is given, unless the molecule is small enough
that there is no question as to where the C=O is located.
• Parent chains are named by dropping the final “e” from
the name of the corresponding hydrocarbon and adding
“al” for aldehydes or “one” for ketones.
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IUPAC names vs. common names of
aldehydes and ketones:
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General physical properties of aldehydes and ketones:
• Aldehydes and ketones have much lower boiling
points than alcohols with a similar molecular
weight.
• The differences in boiling points is due to the fact
that alcohols can form hydrogen bonds while
aldehydes and ketones cannot.
• The C=O is slightly polar, which allows an aldehyde
or ketone to interact with one another through
dipole-dipole forces.
The polarity of the carbonyl group and its ability to
form hydrogen bonds with water molecules allows small
aldehydes and ketones to be highly water soluble (“like
dissolves like”).
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11.5 : Oxidation of Aldehydes
Aldehyde
O
C H
[O]
[O]
carboxylic acid
O
C O H
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11.6: Reduction of Aldehydes and Ketones
Reactant
(more O’s, less H’s)
Product
(more H’s, less O’s; gaining more H’s)
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Examples:
Draw the alcohol product expected
from each reduction reaction.
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Exercises:
What is the organic reactant that would undergo the reaction
below to give the product shown in each reaction?
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11.7: Reactions of Alcohols with Aldehydes and Ketones
(Hemiacetal and Hemiketals)
When an aldehyde or ketone is reacted
with one alcohol molecule a hemiacetal
is formed.
(Hemiacetals formed from ketones are
also known as hemiketals).
A hemiacetal consists of a carbon atom
that is attached to both -OH and -OC.
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These are
hemiacetals and
hemiketals! How do
I recognize them?
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(Acetals and ketals)
When two alcohol molecules react with
an aldehyde or ketone in the presence of
H+, an acetal forms.
An acetal consists of a carbon atom that
is attached to two -OC groups.
(Acetals formed from ketones are also
known as ketals).
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These are acetals
and ketals! How
do I know?
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Exercises:
Draw the organic product of each reaction.
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Exercises: (More Practice make you better!)
Draw the missing reactant for each reaction.
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Drugs in the Environment
What functional groups are present on these
drug molecules?
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