1 lecture 4 alcohols, phenols, and thiols alcohols, phenols, and thiols copyright © 2007 by pearson...
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Lecture 4 Alcohols, Phenols, and Thiols
Alcohols, Phenols, and Thiols
Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings
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Midterm II Outcome
0%
5%
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15%
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> 90 80-90 70-79 50-70 < 50
Score on Test
% S
tuden
t
Class Average: 75High Score: 103Low Score: 32
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Alcohols and Phenols
An alcohol contains A hydroxyl group
(—OH) attached to a carbon chain.
A phenol contains A hydroxyl group
(—OH) attached to a benzene ring.
Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings
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Alcohols are classified By the number of alkyl groups attached to the carbon
bonded to the hydroxyl. As primary (1°), secondary (2°), or tertiary (3°).
Primary (1º) Secondary (2º) Tertiary (3º)1 group 2 groups 3 groups H CH3 CH3
| | | CH3—C—OH CH3—C—OH CH3—C—OH
| | | H H CH3
Classification of Alcohols
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Classify each alcohol as (P) primary, (S) secondary, or (T) tertiary.
OH |
1. CH3—CH—CH2—CH3
2. CH3—CH2—CH2—OH
OH |
3. CH3—CH2—C—CH2—CH3 |
CH3
Learning Check
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Naming Alcohols
The names of alcohols In the IUPAC system replace -e of alkane name with -ol. that are common names use the name of the alkyl group
followed by alcohol. Formula IUPAC Common Name
CH4 methane
CH3─OH methanol methyl alcohol
CH3─CH3 ethane
CH3─CH2─OH ethanol ethyl alcohol
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More Names of Alcohols
In IUPAC names for longer carbon chains, the chain is
numbered from the end nearest the ─OH group.
CH3─CH2─CH2─OH 1-propanol
OH │CH3─CH─CH2─CH3 2-butanol
CH3 OH │ │CH3─CH─CH2─CH2─CH─CH3 5-methyl-2-
hexanol6 5 4 3 2 1
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Some Typical Alcohols
OH |“rubbing alcohol” CH3—CH—CH3
2-propanol (isopropyl alcohol)
antifreeze HO—CH2—CH2—OH
1,2-ethanediol (ethylene glycol) OH
| glycerolHO—CH2—CH—CH2—OH
1,2,3-propanetriol
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Learning Check
Give the IUPAC name for each of the following:
1. CH3—CH2—CH2—CH2—OH
OH CH3 | |2. CH3—CH—CH—CH2—CH3
3.
OH
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Write the structure of the following:
A. 3-pentanol
B. ethyl alcohol
C. 3-methylcyclohexanol
Learning Check
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Naming Phenols
To name a phenol with two substituents, Assign C-1 to the carbon attached to the –OH. Number the ring to give the lowest numbers. Use prefixes o, m, and p for common names.
OH
Cl
OHOH
Br
Phenol 3-chlorophenol 4-bromophenol (m-chlorophenol) (p-bromophenol)
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Phenols in Medicine
Phenol Is the IUPAC name for benzene with a hydroxyl
group. Is used in antiseptics and disinfectants.
phenol resorcinol 4-hexylresorcinol
OH
OH
CH2CH2CH2CH2CH2CH3
OH OH
OH
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Derivatives of Phenol
Compounds of phenol are the active ingredients in the essential oils of cloves, vanilla, nutmeg, and mint.
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Write the structure of each of the following:
A. 3-pentanol
B. ethyl alcohol
C. p-methylphenol
Learning Check
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Thiols
Thiols Are carbon compounds
that contain a –SH group.
Are named in the IUPAC system by adding thiol to the alkane name of the longest carbon chain.
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In thiols with long carbon chains, the chain is numbered to locate the –SH group.
CH3—CH2—CH2—SH 1-propanethiol
SH |
CH3—CH—CH3 2-propanethiol
Naming Thiols
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Thiols
Thiols Often have
strong odors. Are used to
detect gas leaks. Are found in
onions, oysters, and garlic.
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Learning Check
Draw the structure of each compound.
A. 2-butanethiol
B. 2-methyl-1-butanol
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Learning Check
Name each of the following compounds: OH | A. CH3—CH2 —CH—CH3
CH3
| B. CH3—CH2—CH—CH2—CH2—OH
C. CH3—CH2—CH2—SH
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Pause: Group Activity
Do the following problems on ALE 4 Problem # 1, parts A to F Problem # 2, parts A to D
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Ethers
Ethers Contain an ─O─ between two carbon groups. That are simple are named by listing the alkyl names in
alphabetical order followed by ether
CH3─O─CH3 CH3─CH2─O─CH3
dimethyl ether ethyl methyl ether
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IUPAC Names for Ethers
In the IUPAC system, the shorter alkyl group and the oxygen are named as an alkoxy group attached to the longer alkane.
methoxy propane
CH3—O—CH2—CH2—CH3
1 2 3
Numbering the longer alkane gives
1-methoxypropane
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Ethers as Anesthetics
Anesthetics Inhibit pain signals to the brain. Such as ethyl ether CH3─CH2─O─CH2─CH3 were used
for over a century, but caused nausea and were flammable.
Developed by 1960s were nonflammable. Cl F F Cl F H │ │ │ │ │ │ H─C─C─O─C─H H─C─C─O─C─H │ │ │ │ │ │ F F F H F H
Ethane(enflurane) Penthrane
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MTBE
Methyl tert-butyl ether CH3
│
CH3─O─C─CH3
│ CH3
Is one of the most produced organic chemicals.
Is a fuel additive
Is used to improve gasoline combustion.
Use is questioned since the discovery that MTBE has contaminated water supplies.
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Learning Check
Draw the structure of each compound.
A. diethyl ether
B. ethyl methyl ether
C. 2-methoxybutane
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Cyclic Ethers
A cyclic ether Contains an O atom in a carbon ring. Is called a heterocyclic compound. Typically has 5 (furan) or 6 atoms (pyran) in the
ring.
O O O
furan tetrahydrofuran pyran 1,4-dioxane
O
O
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Dioxins
Dioxins are A group of ethers that are highly toxic. Formed during forest fires and as industrial by-
products. Often carcinogenic.
Cl
Cl Cl
OCH2 OHC
O
Cl
Cl
O
O
Cl
Cl
2,4,5-trichlorophenoxyacetic acid 2,3,7,8-tetrachlorodibenzodioxin(2,4,5-T; agent orange) (TTCC, “dioxin”)
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Learning Check
Name each of the following:
1.
2. O
O
OCH3
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Pause: Group Activity
Do the following problems on ALE 4 Problem # 1, parts G to I Problem # 2, parts E to F
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Lecture 4
13.3
Physical Properties of Alcohols,
Phenols, and Ethers
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Boiling Points of Alcohols
Alcohols Contain a strongly
electronegative O in the OH groups.
Form hydrogen bonds between alcohol molecules.
Have higher boiling points than alkanes and ethers of similar mass.
Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings
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Boiling Points of Ethers
Ethers Have an O atom, but
no H is attached. Cannot form hydrogen
bonds between ether molecules.
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Solubility of Alcohols and Ethers in Water Alcohols and ethers are more soluble in water than
alkanes because the oxygen atom hydrogen bonds with water.
Alcohols with 1-4 C atoms are soluble, but alcohols with 5 or more C atoms are not.
Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings
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Comparing Solubility and Boiling Points
Compound Molar Boiling Soluble
Mass Point (°C) in Water?
Alkane CH3─CH2─CH3 44 -42 No
Ether CH3─O─CH3 46 -23 Yes
Alcohol CH3─CH2─OH 46 78 Yes
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Solubility of Phenol
Phenol Is soluble in water. Has a hydroxyl group that ionizes slightly (weak
acid). Is corrosive and irritating to the skin.
OH O-
+ H2O + H3O+
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Learning Check
Which compound would have the higher boiling
point? Explain.
ethyl methyl ether or 1-propanol
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Learning Check
Which compound would be more soluble in water?
Explain.
ethanol or 2-pentanol
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Pause: Group Activity
Do the following problems on ALE 4 Problem # 3 Problem # 4
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Lecture 4
13.4
Reactions of Alcohols and Thiols
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Combustion of Alcohols
Combustion is the reaction of an alcohol
with O2 to produce CO2 and H2O.
2CH3OH + 3O2 2CO2 + 4H2O + Heat
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Dehydration of an alcohol occurs When heated with an acid catalyst. With the loss of —H and —OH from adjacent carbon
atoms. H OH
| | H+, heatH—C—C—H H—C=C—H + H2O
| | | | H H H H
alcohol alkene
Dehydration of Alcohols
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Learning Check
Write the equations for the reactions when
2-propanol undergoes:
1. combustion
2. dehydration
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Formation of Ethers
Ethers form when dehydration takes place at low temperature.
H+
CH3—OH + HO—CH3 CH3—O—CH3 + H2O
two methanol dimethyl ether
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Oxidation and Reduction
In the oxidation of an organic compound There is an increase in the number of C—O
bonds. There is a loss of H.
In the reduction of an organic compound There is an decrease in the number of C—O
bonds. There is a gain of H.
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Oxidation and Reduction
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When a primary alcohol is oxidized [O], One H is removed from the –OH. Another H is removed from the carbon bonded to the OH. An aldehyde is produced.
[O] Primary alcohol Aldehyde
OH O | [O] ||
CH3—C—H CH3—C—H + H2O |
H Ethanol Ethanal (ethyl alcohol) (acetaldehyde)
Oxidation of Primary (1) Alcohols
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Oxidation of Secondary (2) AlcoholsWhen a secondary alcohol is oxidized [O], One H is removed from the –OH. Another H is removed from the carbon bonded to the OH. A ketone is produced. [O] secondary alcohol ketone OH O
│ [O] ║ CH3—C—CH3 CH3—C—CH3 + H2O
│ H
2-propanol (isopropyl alcohol) 2-propanone(dimethyl ketone, “acetone”)
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Oxidation of Tertiary (3)Alcohols
Tertiary alcohols do not readily oxidize. [O]
Tertiary alcohol no reaction OH │ [O]
CH3─C─CH3 no product │ CH3 no H on the C-OH to oxidize
2-methyl-2-propanol
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Select the compound that would result for each reaction
of CH3—CH2—CH2—OH.
O
||1) CH3—CH=CH2 2) CO2 + H2O 3) CH3—CH2—C—H
A. H+, heat
B. [O]
C. O2, heat
Learning Check
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Oxidation of Ethanol in the Body
In the body, Ethanol is oxidized by enzymes in the liver. Aldehyde product impairs coordination. O O ║ ║
CH3─CH2─OH CH3─C─H CH3─C─OH ethyl alcohol acetaldehyde acetic acid
2CO2 + H2O
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Ethanol Acts as a depressant. Kills or disables more
people than any other drug. Is metabolized at a rate of
12-15 mg/dL per hour by a social drinker.
Is metabolized at a rate of 30 mg/dL per hour by an alcoholic.
Ethanol CH3─CH2─OH
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Effect of Alcohol on the Body
TABLE 13.2
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Learning Check
Select the product for the oxidation of OH │ [O]
CH3—CH—CH2—CH3
O ║
1) CH3—CH=CH—CH3 2) CH3—C—CH2 —CH3
OH │
3) CO2 + H2O 4) CH3—CH—CH2—CH3
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Oxidation of Thiols
When thiols undergo oxidation, An H atom is lost from each of two –SH groups. The product is a disulfide.
[O]
CH3—SH + HS—CH3 CH3—S—S—CH3 + H2O
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Pause: Group Activity
Do the following problems on ALE 4 Problem # 5