Download Chapter 12 Organic Compounds with Oxygen and Sulfur

Chapter 12 Organic Compounds
with Oxygen and Sulfur
1
Alcohols
An alcohol contains a hydroxyl group (–OH) that replaces a
hydrogen atom in a hydrocarbon.
A phenol contains a hydroxyl group (–OH) attached to a
benzene ring.
2
Naming Alcohols
The names of alcohols
• in the IUPAC system replace the -e with -ol
• with common names use the name of the alkyl group
followed by alcohol
Formula
IUPAC
CH4
methane
CH3─OH
methanol
CH3─CH3
ethane
CH3─CH2─OH
ethanol
Common Name
methyl alcohol
ethyl alcohol
Naming Alcohols
4
Naming of Alcohols
Step 1 Name the longest carbon chain with the –OH group.
Name an aromatic alcohol as a phenol.
CH3CH2CH2OH
propanol
OH
CH3CHCH2CH3
CH3
butanol
OH
CH3CHCH2CH2CHCH3
6
5 4
3
2
1
5
hexanol
Naming of Alcohols
Step 2
Number the chain starting at the end closer to the
–OH.
CH3CH2CH2OH
1-propanol
OH
CH3CHCH2CH3
CH3
2-butanol
OH
CH3CHCH2CH2CHCH3
6
5
4
3
2 1
6
2-hexanol
Naming of Alcohols
Step 3
Give the location and name of each substituent
relative to the –OH group.
CH3CH2CH2OH
1-propanol
OH
CH3CHCH2CH3
CH3
2-butanol
OH
CH3CHCH2CH2CHCH3
6
5 4
3
2
1
7
5-methyl-2-hexanol
Some Typical Alcohols
OH
|
“Rubbing alcohol” CH3—CH—CH3
2-propanol (isopropyl alcohol)
Antifreeze HO—CH2—CH2—OH
1,2-ethanediol (ethylene glycol)
OH
|
Glycerol
HO—CH2—CH—CH2—OH
1,2,3-propanetriol
8
Learning Check
Name the following compounds:
1. CH3—CH2—CH2—CH2—OH
2.
OH CH3
|
|
CH3—CH—CH—CH2—CH3
OH
3.
9
Solution
Step 1 Name the longest carbon chain with the –OH group.
Name an aromatic alcohol as a phenol.
1. CH3—CH2—CH2—CH2—OH
butanol
OH CH3
|
|
2. CH3—CH—CH—CH2—CH3
pentanol
OH
3.
cyclopentanol
10
Solution
Step 2
Number the chain starting at the end closer to the
–OH.
1. CH3—CH2—CH2—CH2—OH
1-butanol
OH CH3
|
|
2. CH3—CH—CH—CH2—CH3
2-pentanol
OH
3.
cyclopentanol
11
Solution
Step 3
Give the location and name of each substituent
relative to the –OH group.
1. CH3—CH2—CH2—CH2—OH
1-butanol
OH CH3
|
|
2. CH3—CH—CH—CH2—CH3
3-methyl-2-pentanol
OH
3.
cyclopentanol
12
Phenols in Medicine
Phenol is
• the IUPAC name for benzene with a hydroxyl group
• used in antiseptics and disinfectants
OH
OH
OH
OH
OH
CH2CH2CH2CH2CH2CH3
Phenol
Resorcinol
4-Hexylresorcinol
13
Derivatives of Phenol
Compounds of phenol are the active ingredients in the essential
oils of cloves, vanilla, nutmeg, and mint.
14
Naming Phenols
Step 1 Name the longest carbon chain with the –OH group.
Name an aromatic alcohol as a phenol.
OH
OH
Cl
Br
phenol
phenol
15
Naming Phenols
Step 2
Number the chain starting at the end closer to the
–OH.
OH
OH
1
1
3
4
Cl
Br
phenol
phenol
16
Naming Phenols
Step 3
Give the location and name of each substituent
relative to the –OH group.
OH
OH
1
1
3
4
Cl
Br
3-chlorophenol
4-bromophenol
17
Thiols
Thiols
• contain sulfur
• are similar to alcohols
• contain a thiol (–SH) group
• often have strong odors
• are found in cheese, onions, garlic,
and oysters
• are used to detect gas leaks
18
Thiols
Thiols are named in the IUPAC system by adding thiol to
the alkane name of the longest carbon chain.
19
Ethers
An ether
• contains an –O– between two carbon groups
• has a common name that gives the alkyl names of the
attached groups, followed by ether
CH3OCH3
CH3CH2OCH3
20
Learning Check
Write the structure of the following:
A. 3-pentanol
B. ethanethiol
C. diethyl ether
21
Solution
A. 3-pentanol
OH
|
CH3CH2CHCH2CH3
B. ethanethiol
CH3CH2SH
C. diethyl ether
CH3CH2OCH2CH3
22
Ethers as Anesthetics
Anesthetics
• inhibit pain signals to the brain
• like diethyl ether, CH3CH2OCH2CH3, were used for over
a century, but caused nausea and were flammable
• developed by the 1960s were nonflammable
Cl F
F
Cl F
H
HCCOCH
F F
F
Ethrane (enflurane)
23
HCCOCH
H F
H
Penthrane
Classification of Alcohols
Classification of alcohols is
• determined by the number of alkyl groups attached to the
carbon bonded to the hydroxyl
• primary (1), secondary (2), or tertiary (3)
Primary (1)
1 group
H
|
CH3—C—OH
|
H
24
Secondary (2)
2 groups
CH3
|
CH3—C—OH
|
H
Tertiary (3)
3 groups
CH3
|
CH3—C—OH
|
CH3
Solubility of Alcohols in Water
Alcohols
• contain polar OH groups and
form hydrogen bonds with other
alcohol molecules
• that have one to three carbons are
soluble in water
• solubility in water decreases with
increasing number of carbons
25
Solubility of Ethers in Water
Ethers
• do not have a polar OH group,
but have a COC group
• do not form hydrogen bonds
• with less than four carbons are
slightly soluble in water
• with more than four carbons are
not soluble in water
26
Solubility of Phenols
Phenols
• are slightly soluble in water
• have an OH group that can form hydrogen bonds with water
• can react with water to produce phenoxide ions
• were once used as antiseptics
OH
O-
+ H2O
+ H3O+
27
Learning Check
Indicate whether each of the following is soluble in water
and explain why.
A. CH3CH2CH2CH2CH2CH2OH
B. CH3OCH2CH3
C. CH3CH2OH
28
Solution
Indicate whether each of the following is soluble in water
and explain why.
A. CH3CH2CH2CH2CH2CH2OH
Not soluble
Alcohols with long carbon chains (nonpolar) are not soluble.
B. CH3OCH2CH3
Slightly soluble
Ethers with less than four carbons are only slightly
soluble in water.
C. CH3CH2OH
Soluble
Short-chain alcohols form hydrogen bonds with water.
29
Dehydration of Alcohols
Alcohols undergo
• dehydration when heated with an acid catalyst
• the loss of –H and –OH from adjacent carbon atoms,
producing an alkene
H OH
| |
H—C—C—H
| |
H H
alcohol
30
H+, heat
H—C=C—H + H2O
| |
H H
alkene
Oxidation of 1 Alcohols
Alcohols undergo oxidation, increasing the number of
carbon and oxygen bonds.
Primary alcohols are oxidized to produce an aldehyde.
1 bond to O
H OH
| |
H—C—C—H
| |
H H
1 alcohol
31
2 bonds to O
H O
| ||
H—C—C—H
|
oxidation
H
aldehyde
Oxidation of 1 Alcohols
Alcohols undergo oxidation, increasing the number of
carbon and oxygen bonds.
Aldehydes can further oxidize to produce a carboxylic acid.
1 bond to O
H O
| ||
H—C—C—H
|
H
aldehyde
32
2 bonds to O
H O
| ||
H—C—C—OH
|
oxidation
H
carboxylic acid
Oxidation of 2 Alcohols
Secondary alcohols are oxidized to produce a ketone.
To indicate the process of oxidation, [O] is placed over the
reaction arrow.
1 bond to O
H OH H
| | |
H—C—C—C—H
| | |
H H H
2 alcohol
33
2 bonds to O
[O]
H O H
| || |
H—C—C—C—H
|
|
H
H
ketone
Oxidation of Tertiary 3 Alcohols
Tertiary (3) alcohols do not readily oxidize.
OH
CH3CCH3
CH3
3 alcohol
34
[O]
no product
no H to oxidize
no reaction
Oxidation and Reduction
In an oxidation,
• there is an increase in the number of C–O bonds
• there is a loss of H
In a reduction,
• there is a decrease in the number of C–O bonds
• there is a gain of H
35
Methanol Poisoning
Methanol
• is also known as methyl alcohol
• is highly toxic and found in windshield washer fluid, Sterno,
and paint strippers
• is rapidly absorbed and oxidized to formaldehyde and then
formic acid
O
O
[O]
[O]
CH3OH
HCH
HCOH
methyl alcohol formaldehyde
36
formic acid
Ethanol, CH3CH2OH
Ethanol
• acts as a depressant and 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
37
Effect of Alcohol on the Body
38
Oxidation of Thiols
When thiols undergo oxidation,
• an H atom is lost from each of two –SH groups
• the product is a disulfide
• protein in hair is cross-linked by disulfide bonds found in the
amino acid cysteine
39
Learning Check
Give the primary product for the reaction of
2-propanol when it undergoes
A. oxidation
B. dehydration
40
Solution
OH
CH3CHCH3 = 2-propanol = C3H8O
A. oxidation
OH
2CH3CHCH3 + 9O2
B. dehydration
OH
CH3CHCH3
41
[O]
H+, heat
O
CH3CCH3 + 6CO2 + 8H2O
CH3CH=CH2 + H2O
Carbonyl Group in Aldehydes
and Ketones
A carbonyl group
• consists of a carbon-oxygen polar
double bond
• has a very electronegative oxygen
atom
• has two lone pair electrons on the
O atom
• has partial positive charge on C
and partial negative charge on O
O
C
42
Carbonyl Group in Aldehydes
and Ketones
A carbonyl group
• in an aldehyde is attached
to at least one H atom
• in a ketone is attached to
two carbon groups
43
Naming Aldehydes
An aldehyde
• has an IUPAC name in which the -e in the alkane name is
changed to -al
• has a common name for the first four aldehydes that use the
following prefixes:
1 carbon, form
2 carbons, acet
3 carbons, propion
4 carbons butyr
followed by aldehyde
44
Naming Aldehydes
45
Naming Aldehydes
46
Naming Aldehydes
Give the IUPAC name for the following aldehydes:
O
||
CH3CH2CH2CHCH
|
CH3
O
C
H
Cl
Cl
47
Naming Aldehydes
Step 1 Name the longest carbon chain containing the
carbonyl group by replacing the e in the
alkane name with al.
O
O
||
CH3CH2CH2CHCH
|
CH3
pentanal
48
C
H
Cl
Cl
benzaldehyde
Naming Aldehydes
Step 2 Name and number substituents by counting the
carbonyl group as carbon 1.
O
||
CH3CH2CH2CHCH
|
CH3
2-methylpentanal
O
C
H
Cl
Cl
3,4-dichlorobenzaldehyde
49
Aldehydes in Flavorings
Several naturally occurring aldehydes are used as
flavorings for foods and fragrances.
O
O
C
C
H
H
vanillin
HO
OCH3
benzaldehyde
(almonds)
O
C
HC
C
H
H
cinnamaldehyde
cinnamon
50
Naming Ketones
When naming the following ketones
• in the IUPAC system, the -e in the alkane name is replaced
with -one
• with a common name, the alkyl groups attached to the
carbonyl group are named alphabetically, followed by
ketone
O
CH3 CCH3
propanone
(dimethyl ketone)
51
O
CH3CCH2CH3
2-butanone
(ethyl methyl ketone)
Naming Ketones
52
Naming Ketones
Name the following ketones using the IUPAC system.
O
||
CH3CH2CHCH2CCH3
|
CH3
O
CH3
CH3
53
Naming Ketones
Step 1 Name the longest carbon chain that contains the
carbonyl group by replacing the e in the alkane name
with one.
O
O
||
CH3CH2CHCH2CCH3
|
CH3
hexanone
54
CH3
CH3
pentanone
Naming Ketones
Step 2 Number the carbon chain starting from the end nearer
the carbonyl group and indicate its location.
O
||
CH3CH2CHCH2CCH3
|
CH3
2-hexanone
O
CH3
CH3
pentanone
55
Naming Ketones
Step 3 Name and number any substituents on the carbon chain.
O
||
CH3CH2CHCH2CCH3
|
CH3
4-methyl-2-hexanone
O
CH3
CH3
2,3-dimethylcylcopentanone
56
Ketones in Common Use
Acetone (propanone) is a solvent
used in nail polish remover.
Butanedione is the butter
flavoring used in margarine.
57
Physical Properties
The polar carbonyl group provides dipole-dipole interactions.
+ -
+ -
C=O
C=O
Because the electronegative oxygen atom forms hydrogen
bonds with water molecules, aldehydes and ketones with one
to four carbons are very soluble.
58
Solubility of Aldehydes and Ketones in Water
59
Solubility in Water
The electronegative O atom of the carbonyl group of aldehydes
and ketones forms hydrogen bonds with water.
60
Oxidation of Aldehydes
Primary alcohols can be oxidized to aldehydes, which can
be easily oxidized to carboxylic acids.
Secondary alcohols can be oxidized to ketones, which
cannot be further oxidized.
61
Tollens’ Test
In Tollens’ test,
• Tollens’ reagent, which contains Ag+, oxidizes aldehydes but
not ketones.
• Ag+ is reduced to metallic Ag, which appears as a “mirror”
in the test tube.
62
Tollens’ Test
63
Benedict’s Test
In Benedict’s test, Benedict’s reagent, which contains Cu2+,
reacts with aldehydes that have an adjacent OH group.
Monosaccharide sugars typically have this aldehyde –
adjacent hydroxide arrangement.
64
Benedict’s Test
In Benedict’s test,
• an aldehyde is oxidized to a
carboxylic acid, while Cu2+
is reduced to give red
Cu2O(s).
The blue Cu2+ in Benedict’s solution forms a brick-red
solid of Cu2O in a positive test for many sugars and
aldehydes with adjacent hydroxyl groups.
65
Reduction of Aldehydes and Ketones
Aldehydes and ketones can be reduced by sodium borohydride,
NaBH4, or H2.
The reduction of aldehydes and ketones decreases the number of
carbon–oxygen bonds by addition of hydrogen or loss of oxygen.
66
Isomers
Molecules are structural isomers when they have the same
molecular formula, but different bonding arrangements.
67
Stereoisomers
Stereoisomers have identical molecular formulas, but they
are not structural isomers.
In stereoisomers, the atoms are bonded in the same
sequence but differ in the way they are arranged in space.
When stereoisomers have mirror images that are different,
they are said to have “handedness.”
68
Chiral Molecules Have Handedness
Chiral molecules
• have the same number of atoms
arranged differently in space
• have one or more chiral carbon
atoms, each of which is bonded to
four different groups
• are like your hands
Try to superimpose your thumbs,
palms, back of hands, and little fingers.
69
Some Everyday Chiral and
Achiral Objects
70
Chiral Carbon Atoms Are Mirror Images
• The mirror images of chiral compounds cannot be
superimposed.
• When the H and I atoms are aligned, the Cl and Br atoms
are on opposite sides.
71
Achiral Structures Are Superimposable
When the mirror image of an achiral structure is rotated, the
structure can be aligned with the initial structure. Thus this
mirror image is superimposable.
72
Learning Check
Identify each as a chiral or an achiral compound.
Cl
Cl
H
C
C H3
C H 2C H 3
A.
H
C
Cl
C H3
H
C
H
Br
B.
C.
C H3
73
Solution
Identify each as a chiral or an achiral compound.
Cl
Cl
H
C
C H3
H
C
Cl
C H3
H
C
C H3
H
Br
A.
B.
C.
chiral
achiral
chiral
C H 2C H 3
74
Fischer Projections
A Fischer projection
• is a two-dimensional representation of a three-dimensional
molecule
• places the most oxidized group at the top
• uses vertical lines in place of dashes for bonds that go back
• uses horizontal lines in place of wedges for bonds that
come forward
75
Drawing Fischer Projections
76
D and L Notations
• By convention, the letter L is assigned to the structure with
the –OH on the left.
• The letter D is assigned to the structure with the –OH on
the right.
77
Learning Check
Indicate whether each pair is a mirror image that cannot be
superimposed (enantiomers).
CH2OH
A.
B.
H
H
C
CH3
CH2OH
and
CH3 C
Br
Br
Cl
Cl
C
H
CH3
and
CH3 C
H
H
H
78
Solution
Indicate whether each pair is a mirror image that cannot be
superimposed (enantiomers).
CH2OH
A.
B.
H
H
C
CH3
CH2OH
and
CH3 C
Br
Br
Cl
Cl
C
H
CH3
and
CH3 C
H
Yes
No
H
H
79
Concept Map – Organic Molecules
with O and S
80