Download Alcohols, Phenols, and Thiols

Alcohols, Phenols, and
Thiols
• An alcohol contains a hydroxyl group (–OH) attached to a
carbon chain.
• A phenol contains a hydroxyl group (–OH) attached to a
benzene ring.
• A thiol contains a thiol group (–SH) attached to a carbon
chain.
1
Guide to Naming Alcohols
2
Naming Alcohols
The names of alcohols
• in the IUPAC system, replace -e of the alkane name with
-ol.
• that are common names, use the name of the alkyl group
followed by alcohol.
Formula
CH4
IUPAC
Methane
Common Name
CH3─OH
Methanol
Methyl alcohol
CH3─CH3
Ethane
CH3─CH2─OH
Ethanol
Ethyl alcohol
3
Naming Alcohols
When an alcohol contains a chain with three or more carbon
atoms, the chain is numbered to give the position of the −OH
group and any substituents on the chain.
Formula
CH3─CH2─CH2─OH
IUPAC
Common Name
1-Propanol
Propyl alcohol
2-Propanol
Isopropyl alcohol
OH
CH3─CH─CH3
4
Naming Alcohols
In IUPAC names for longer carbon chains, the chain is
numbered from the end nearer the –OH group.
5
Naming Alcohols
We can also draw skeletal structures for alcohols.
CH3─CH2─CH2─OH
OH
CH3─CH─CH2─CH3
OH
OH
1-Propanol
2-Butanol
6
Some Typical Alcohols
Rubbing alcohol:
2-Propanol (isopropyl alcohol)
Antifreeze:
1,2-Ethanediol (ethylene glycol)
Glycerol:
1,2,3-Propanetriol
© 2013 Pearson Education, Inc.
Chapter 11, Section 4
7
Learning Check
Give the IUPAC name for each of the following.
A. CH3—CH2—CH2—CH2—OH
B.
© 2013 Pearson Education, Inc.
Chapter 11, Section 4
8
Learning Check
Give the IUPAC name for each of the following.
Step 1 Name the longest carbon chain attached to
the −OH group by replacing the -e in the
corresponding alkane name with -ol .
A. CH3—CH2—CH2—CH2—OH
butanol
pentanol
B.
© 2013 Pearson Education, Inc.
Chapter 11, Section 4
9
Learning Check
Give the IUPAC name for each of the following.
Step 2 Number the chain starting at the end closer
to the −OH group.
A. CH3—CH2—CH2—CH2—OH
4
3
2
1
butanol
B.
pentanol
1
© 2013 Pearson Education, Inc.
2
3
4
5
Chapter 11, Section 4
10
Learning Check
Give the IUPAC name for each of the following.
Step 3 Give the location and name of each
substituent relative to the −OH group.
A. CH3—CH2—CH2—CH2—OH
4
3
2
1
butanol
B.
3-methyl-1-pentanol
1
© 2013 Pearson Education, Inc.
2
3
4
5
Chapter 11, Section 4
11
Learning Check
Draw the condensed structural formula of the
following.
A. 3-Pentanol
B. Propanol
C. 3-Methylcyclohexanol
12
Solution
Draw the condensed structural formula of the following.
A. 3-Pentanol
B. Propanol
CH3—CH2—CH2—OH
C. 3-Methylcyclohexanol
OH
CH3
© 2013 Pearson Education, Inc.
Chapter 11, Section 4
13
Phenol
Phenol
• is the IUPAC name for benzene with a hydroxyl group.
• is used in antiseptics and disinfectants.
Phenol
© 2013 Pearson Education, Inc.
Chapter 11, Section 4
14
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 substituents the lowest
numbers.
Phenol
© 2013 Pearson Education, Inc.
3-chlorophenol
Chapter 11, Section 5
3-methylphenol
15
Learning Check
Name the following phenol.
OH
Cl
© 2013 Pearson Education, Inc.
Chapter 11, Section 5
16
Solution
Name the following phenol.
Step 1 Name an aromatic alcohol
as a phenol.
-phenol
OH
1
2
Step 2 Number the chain starting
3
at the end closer to the
−OH group. (In phenol,
carbon number one is the −OH group.)
Step 3 Give the location and name of each
substituent relative to the −OH group.
3-Chloro-phenol
© 2013 Pearson Education, Inc.
Chapter 11, Section 5
Cl
17
Derivatives of Phenol
Compounds of phenol are the active ingredients in the
essential oils of cloves, vanilla, nutmeg, and mint.
18
Thiols
Thiols
• are organic compounds
that contain a –SH
group.
• are named in the
IUPAC system by
adding thiol to the
alkane name of the
longest carbon chain.
19
Naming Thiols
In thiols with long carbon chains, the chain is numbered to
give the −SH group the lowest possible number.
20
Sources of Thiols
Thiols
• often have strong odors.
• are used to detect gas leaks.
• are found in onions, oysters, and garlic.
21
Ethers
• Ethers consist of an oxygen atom that is connected
by single bonds to two carbon groups (alkyl or
aromatic).
• Simple ethers are named by listing the alkyl names
in alphabetical order followed by ether
CH3─O─CH3
methyl
© 2013 Pearson Education, Inc.
CH3─CH2─O─CH3
methyl
ethyl
Chapter 11, Section 4
methyl
22
Ethers as Anesthetics
Early anesthetics, such as diethyl ether
CH3─CH2─O─CH2─CH3,
• worked by inhibiting pain signals to
the brain.
• caused nausea and were flammable.
23
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
O
O
Furan
Tetrahydrofuran
Pyran
1,4-Dioxane
© 2013 Pearson Education, Inc.
Chapter 11, Section 5
24
Classifying Alcohols
Alcohols can be classified as
• primary (1), which has one alkyl group
attached to the carbon with the −OH group,
• secondary (2), which has two alkyl groups
attached to the carbon with the −OH group,
or
• tertiary (3), which has three alkyl groups
attached to the carbon with the −OH group.
25
Classifying Alcohols
26
Learning Check
Classify each of the following alcohols as
primary, secondary, or tertiary.
A. 2-propanol
B. 1-butanol
OH
C.
OH
D.
27
Solution
Classify each of the following alcohols as
primary, secondary, or tertiary.
A. 2-propanol
secondary
B. 1-butanol
primary
OH
C.
tertiary
OH
D.
secondary
28
Boiling Points of Alcohols
Alcohols
• form hydrogen bonds
between alcohol
molecules.
• have higher boiling
points than alkanes and
ethers of similar mass.
29
Boiling Points of Ethers
Ethers
• have an O atom, but
no H is attached.
• cannot form
hydrogen bonds
between ether
molecules.
• have boiling points
similar to alkanes of
similar mass.
30
Solubility of Alcohols and
Ethers in Water
Alcohols and ethers are more soluble in water than
are alkanes because the oxygen atom can form
hydrogen bonds with water.
Alcohol
Solubility in H2O
1–3 carbon atoms
completely soluble
4 carbon atoms
slightly soluble
5 or more carbon atoms insoluble
Ethers containing up to 4 carbon atoms are slightly
soluble in water.
31
Solubility of Alcohols and
Ethers in Water
32
Combustion of Alcohols
Combustion is the reaction of an alcohol with O2 to
produce CO2, H2O and energy.
© 2013 Pearson Education, Inc.
Chapter 11, Section 4
33
Dehydration of Alcohols
Dehydration of an alcohol occurs
• when heated with an acid catalyst, H+
• with the loss of –H and –OH from adjacent carbon atoms to
form water
alcohol
alkene
34
Saytzeff’s Rule
According to Saytzeff’s rule, the dehydration of a
secondary alcohol favors the product in which hydrogen is
removed from the carbon atom in the chain with the smaller
number of H atoms
35
Learning Check
Write the equations for the reactions when 2propanol undergoes _______.
A. combustion
B. dehydration
36
Solution
Write the equations for the reactions when 2-propanol
undergoes _______.
A. combustion
B. dehydration
37
Formation of Ethers
Ethers form when dehydration occurs at lower
temperatures, (130 C) in the presence of an
acid catalyst.
two methanol molecules
dimethyl ether
38
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 a decrease in the number of C–O
bonds.
• there is a gain of H.
39
Oxidation and Reduction
An alcohol is more oxidized than an alkane; an aldehyde or
ketone is more oxidized than an alcohol; a carboxylic acid is
more oxidized than an aldehyde.
40
Oxidation of Primary (1) Alcohols
Primary alcohols are oxidized to form aldheydes.
Ethanol (ethyl alcohol)
Ethanal (acetaldehyde)
41
Oxidation of Secondary (2) Alcohols
Secondary alcohols are oxidized to form ketones.
2-Propanol (isopropyl alcohol)
2-Propanone(dimethyl ketone,
“acetone”)
42
Oxidation of Tertiary (3)
Alcohols
Tertiary alcohols do not readily oxidize.
There is no H on the C–OH to oxidize.
2-Methyl-2-propanol
43
Oxidation of Ethanol in the Body
In the body,
• ethanol is oxidized by enzymes in the liver.
• aldehyde product impairs coordination.
44
Learning Check
Select the product from the oxidation of _______.
Solution
Select the product from the oxidation of _______.
Answer is B.
46