Announcements & Agenda (03/09/07)
Exam next Wednesday!
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Covers Ch 7, 8, 10-12 (not 12.6, on Exam 3)
Practice Exam Posted!
Review Monday @ 6:30p (Room TBA)
Come visit Bob!!!
Today
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Quiz!
Properties & Reactions of Alcohols (12.1-12.3)
Ethers & Thiols (12.1-12.3)
Aldehydes & Ketones (12.4-12.5) (?)
1
Last Time: Aromatic Compounds
“Special Conjugation”
One Important Example: Benzene (Know This One!)
• a ring of 6 C & 6 H atoms.
• a flat ring structure drawn with three double bonds.
• represented by 2 structures because electrons are
shared among all the C atoms.
By the way, aromatics are called as such b/c many of
them have noticeable odors!
2
Last Time: A color debate!
Highly conjugated pi bonds!
CH2
CH3
H3C
CH2
N
N
Fen+
N
N
H3C
HO
It’s the HEME in
hemoglobin!!!
CH3
O
HO
O
Note: Highly conjugated molecules are
typically colored!
3
Last Time: Polymerization
In polymerization, small repeating units
called monomers join to form a long chain
polymer.
H
H
+
C C
H
H
H
H
C C
H
H
+
H
H
monomer unit repeats
C C
H
H
Ethylene monomers
chain continues
H H H
H H H
C C C
C C C
H H H
H nH H
chain continues
Polyethylene
4
Last Time: Alcohols
An alcohol contains a hydroxyl group (—OH)
attached to a carbon chain.
•
occur in many important molecules like sugars and -ol
compounds (cholesterol, menthol, etc.)
A phenol contains a hydroxyl group (—OH) attached
to a benzene ring.
water alcohol
phenol
5
Properties of Alcohols
• contain polar OH groups.
• form hydrogen bonds with
other alcohol molecules.
• Short alcohols (1-4 C
atoms) are soluble in
water
•
> 4 C atoms less soluble
• have much higher BPs
than alkanes of similar
mass.
6
Some Typical Alcohols (Know These)
OH
|
“rubbing alcohol” CH3—CH—CH3
2-propanol (isopropyl alcohol)
Could make you sick
antifreeze
HO—CH2—CH2—OH
1,2-ethanediol (ethylene glycol)
OH
Will kill you
|
glycerol
HO—CH2—CH—CH2—OH
1,2,3-propanetriol
Part of cooking oil
7
http://www.annals.org/cgi/content/full/122/6/456
The Elixir Sulfanilamide disaster of 1937
105 people died
1938 Federal Food, Drug and Cosmetic
Act, which required proof of safety before
the release of a new drug
In the 1980s similar incident happened in
Haiti killing dozens of Haitian infants
8
Properties of Phenol
• is soluble in water.
• has a hydroxyl group that ionizes slightly
(weak acid).
• is corrosive and irritating to skin.
OH
O-
+ H2O
+ H3O+
9
Derivatives of Phenol
Compounds of phenol are the active
ingredients in the essential oils of cloves,
vanilla, nutmeg, and mint.
10
Drawing structures revisited
Traditional drawing
OH
Abbreviated drawing
OH
CH3CH2CH2CHCH3
2-pentanol
H
C
HC
CH
HC
CH
C
H
Benzene
H
C
HC
CH
HC
CH
C
Phenol
OH
OH
11
Naming Alcohols
• IUPAC: Alcohols will be called somethingol
• If other functional groups present, the -OH group
will sometimes be named as a “hydroxyl” group
Formula
IUPAC
CH4
methane
CH3─OH
methanol
CH3─CH3
ethane
CH3─CH2─OH
ethanol
Common Name
methyl alcohol
ethyl alcohol
• Also know common names for propyl alcohol and
those mentioned earlier
12
Classification of Alcohols
• determined by the number of alkyl groups attached
to the carbon bonded to the hydroxyl.
• primary (1°), secondary (2°), or tertiary(3).
Primary (1º)
1 group
H
|
CH3—C—OH
|
H
Secondary (2º)
2 groups
CH3
|
CH3—C—OH
|
H
Tertiary (3º)
3 groups
CH3
|
CH3—C—OH
|
CH3
13
Reactions of Alcohols
14
Combustion of Alcohols
Alcohols undergo combustion with O2 to produce
CO2 and H2O.
2CH3OH + 3O2
2CO2 + 4H2O + Heat
15
Dehydration of Alcohols
• Alcohols dehydrate when heated with an acid
catalyst
• Lose —H and —OH from adjacent carbon
atoms
H OH
|
|
H—C—C—H
|
|
H H
alcohol
H+, heat
H—C=C—H + H2O
| |
H H
alkene
16
Learning Check
Write the equations for the reaction of 2propanol when it undergoes
1. combustion.
2. dehydration.
17
Solution
OH
│
CH3─CH─CH3 = 2-propanol = C3H8O
1. combustion
2C3H8O + 9O2
2. dehydration
OH
│
CH3─CH─CH3
6CO2 + 8H2O
Major Product: Alkene w/
more alkyl substiuents
H+
CH3─CH=CH2 + H2O
18
Oxidation of Primary (1) Alcohols
When a primary alcohol is oxidized, [O],
• one H is removed from the –OH.
• another H is removed from the C bonded to -OH.
• an aldehyde is produced.
This is a carbonyl
[O]
group…
Primary alcohol
Aldehyde
OH
O
|
[O]
||
CH3—C—H
CH3—C—H + H2O
|
H
Ethanol
Ethanal
(ethyl alcohol)
(acetaldehyde)
19
Oxidation of Secondary (2) Alcohols
When a secondary alcohol is oxidized, [O],
• one H is removed from the –OH.
• another H is removed from the C bonded to -OH.
• a ketone is produced.
ASK ME ABOUT “R”!!!
[O]
secondary alcohol
ketone
OH
O
│
[O]
║
CH3─C─CH3
CH3─C─CH3 + H2O
│
H
2-propanol (isopropyl alcohol)
(dimethyl ketone)
2-propanol
20
Oxidation of Tertiary ( 3)Alcohols
Tertiary 3 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
21
Oxidation of Ethanol in the Body
In the body,
• enzymes in the liver oxidize ethanol.
• aldehyde product impairs coordination.
• blood alcohol over 0.4% can be fatal.
O
O
║
║
CH3CH2OH
CH3CH
CH3COH
2CO2 + H2O
ethanol
acetaldehyde
acetic acid
22
Ethanol CH3CH2OH
• 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.
23
Effect of Alcohol on the Body
24
Alcohol Contents in Common Products
% Ethanol
50%
40%
15-25%
12%
3-9%
Product
Whiskey, rum, brandy
Flavoring extracts
Listerine, Nyquil, Scope
Wine, Dristan, Cepacol
Beer, Lavoris
25
Ethers
• contains an ─O─ between two carbon
groups (R-O-R’).
• has a common name that gives the alkyl
names of the attached groups followed
by ether.
CH3─O─CH3 CH3─CH2─O─CH3
26
Boiling Points of Ethers
Ethers
• are only modestly
polar.
• have an O atom,
but there is no H
attached.
• cannot form
hydrogen bonds
between ether
molecules.
27
Solubility of Alcohols & Ethers in Water
Alcohols and ethers
• are more soluble in water than alkanes because
the oxygen atom can hydrogen bond with water.
• with 1-4 C atoms are soluble, but not with 5 or
more C atoms.
28
Comparing Solubility & Boiling Points
Molar
Compound
Mass
Alkane CH3─CH2─CH3 44
Ether
CH3─O─CH3
Alcohol CH3─CH2─OH
Boiling
Point (°C)
-42
Soluble
in Water?
No
46
-23
Yes
46
78
Yes
29
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 1960’s 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
30
MTBE
Methyl tert-butyl ether
CH3
│
CH3─O─C─CH3
│
CH3
• is second in production of organic chemicals.
• is an additive used to improve gasoline
performance.
• use is questioned since the discovery that MTBE
has contaminated water supplies.
31
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.
• the -SH group may
also be called a
“mercapto” group
32
Thiols
Thiols
• often have
strong odors.
• are used to
detect gas
leaks.
• are found in
onions,
oysters, and
garlic.
33
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
34
Aldehydes and Ketones
An aldehyde contains a
carbonyl group (C=O),
which is a carbon atom
with a double bond to an
oxygen atom.
In a ketone, the carbon of
the carbonyl group is
attached to two other
carbon atoms.
35
Naming Aldehydes
36
Aldehydes in Flavorings
Several naturally occurring aldehydes are
used as flavorings for foods and fragrances.
O
C
H
Benzaldehyde (almonds)
O
CH=CH C
H
Cinnamaldehyde (cinnamon)
37
Naming Ketones
• as IUPAC, 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
O
║
║
CH3 ─C─CH3
CH3─C─CH2─CH3
propanone
(dimethyl ketone)
2-butanone
(ethyl methyl ketone)
38
Ketones in Common Use
Nail polish remover,
solvent
Butter flavoring
Propanone,
Dimethylketone, Acetone
39
Learning Check
Classify each as 1) aldehyde or 2) ketone.
O
O
||
||
A. CH3—CH2—C—CH3
B. CH3—C—H
CH3
O
|
||
C. CH3—C—CH2—C—H
|
CH3
O
D.
40
Properties of Aldehydes & Ketones
• The polar carbonyl group provides dipole-dipole
interactions.
+ -
C=O
+ -
C=O
• Without an H on the oxygen, aldehydes and
ketones cannot form hydrogen bonds to each
other.
41
Boiling Points
Aldehydes and ketones have
• polar carbonyl groups (C=O).
+ -
C=O
• attractions between polar groups.
+ -
+ -
C=O
C=O
• higher bp’s than alkanes and ethers of similar
mass.
• lower bp’s than alcohols of similar mass.
42
Comparison of Boiling Points
43
Solubility in Water
The electronegative O atom of the carbonyl
group of aldehydes and ketones forms
hydrogen bonds with water.
44
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.
45
Benedict’s Test
• Benedict’s reagent,
which contains Cu2+,
reacts with aldehydes
that have an adjacent
OH group.
• An aldehyde is
oxidized to a
carboxylic acid, while
Cu2+ is reduced to
give red Cu2O(s).
46