SCH 4U Day 7
Aldehydes and Ketones
Assignment:
Page 51 # 1-3
52 # 4,5
56 # 6-8
Learning Check Ox-Red 1
Classify the following as 1º, 2º, or 3º alcohols:
OH
A. CH3CH 2CH 2OH
C.
OH
B. CH3-CH-CH 2CH3
D.
OH
CH 3-C-CH 2CH 3
CH 3
Solution Ox-Red 1
Classify the following as 1º, 2º, or 3º alcohols:
OH
A. CH3CH3CH2OH 1º
B. CH3-CH-CH2CH3 2º
OH
C.
2º
D.
OH
3º
CH 3-C-CH 2CH 3
CH 3
Learning Check Ox-Red 4
Write the structure of the following:
A. 3-pentanol
B. Dimethyl ether
C. 3-methylcyclobutanol
Solution Ox-Red 4
Write the structure of the following:
OH
|
A. 3-pentanol
CH 3CH 2CHCH 2 CH3
B. Dimethyl ether
CH 3-O-CH3
CH 3
C. 3-methylcyclobutanol
OH
Carbonyl Compounds
Aldehydes and Ketones
l In an aldehyde, an H atom is attached to a
carbonyl group
O
carbonyl group
;
CH3-C-H
l In a ketone, two carbon groups are attached to
a carbonyl group
O
;
CH3-C-CH 3
carbonyl group
IUPAC Names
for Ketones
• Replace -e with -one. Indicate the
position of the carbonyl with a number.
• Number the chain so that carbonyl
carbon has the lowest number.
• For cyclic ketones the carbonyl carbon
is assigned the number 1.
Examples
O
O
CH3
C
CH CH3
CH3
Br
3-methyl-2-butanone
3-bromocyclohexanone
O
CH3
C
CH CH2OH
CH3
4-hydroxy-3-methyl-2-butanone
Naming Aldehydes
l IUPAC Replace the -e in the alkane name -al
l Common Add aldehyde to the prefixes form
(1C), acet (2C), propion(3), and butry(4C)
O
O
O
;
;
;
H-C-H
CH3-C-H
CH3CH2C-H
methanal
ethanal
propanal
(formaldehyde) (acetaldehyde) (propionaldehyde)
Naming Aldehydes
• IUPAC: Replace -e with -al.
• The aldehyde carbon is number 1.
• If -CHO is attached to a ring, use the
suffix -carbaldehyde.
Examples
CH3
CH2
CH3
O
CH CH2
C H
3-methylpentanal
CHO
2-cyclopentenecarbaldehyde
Name as Substituent
• On a molecule with a higher priority
functional group, C=O is oxo- and -CHO
is formyl.
• Aldehyde priority is higher than ketone.
COOH
CH3
O
CH3
O
C
CH CH2
C
H
3-methyl-4-oxopentanal
CHO
3-formylbenzoic acid
Aldehydes as Flavorings
O
O
CH
CH
O
CH=CH CH
HO
OCH3
Benzaldehyde
(almonds)
Vanillin
(vanilla beans)
Cinnamaldehyde
(cinnamon)
Glucose is an aldehyde
O
H
C
H C OH
HO C H
H C OH
H C OH
CH2OH
glucose
Naming Ketones
l In the IUPAC name, the -e in the alkane name is
replaced with -one
l In the common name, add the word ketone
after naming the alkyl groups attached to the
O
carbonyl group
O
O
;
CH3 -C-CH3
Propanone
;
CH3-C-CH2-CH3
2-Butanone
Cyclohexanone
(Dimethyl ketone) (Ethyl methyl ketone)
Historical Common
Names
O
C
O
CH3
C
CH3
CH3
acetophenone
acetone
O
C
benzophenone
Ketones
OO
; ;
Butter flavor
CH3-C-C-CH 3
O
butanedione
;
Clove flavor
CH3-C-CH2CH 2CH 2CH2CH3
2-heptanone
Fructose is a Ketone
C H 2OH
C
O
HO
C
H
H
C
OH
H
C
OH
CH 2OH
D-Fructose
Ketones as Hormones
CH 2OH
O
CH 3
O
OH
CH 3
O
Cortisone
Aldehyde Common
Names
• Use the common name of the acid.
• Drop -ic acid and add -aldehyde.
% 1 C: formic acid (ants), formaldehyde
% 2 C’s: acetic acid (sour), acetaldehyde
% 3 C’s: propionic acid (first fat),
propionaldehyde
% 4 C’s: butyric acid (butter), butyraldehyde.
Boiling Points
• More polar than comparable alkane or
ether, so higher boiling point.
• Cannot H-bond to each other, so lower
boiling point than comparable alcohol.
Chapter 18
Solubility
• Good solvent for alcohols.
• Lone pair of electrons on oxygen of
carbonyl can accept a hydrogen bond
from O-H or N-H.
• Acetone and acetaldehyde are miscible
in water.
Industrial Importance
• Acetone and methyl ethyl ketone are
important solvents.
• Formaldehyde used in polymers like
Bakelite .
• Flavorings and additives like vanilla,
cinnamon, artificial butter.
Oxidation
vIs a gain of oxygen (O)
or
vA loss of hydrogen (H)
Alcohols
1Ealcohols are oxidized to
aldehydes and 2E alcohols
are oxidized to ketones
Alcohols
1E
2E
aldehydes ketones
Oxidation of Alcohols
[O]
Primary alcohol
aldehyde
OH
O
[O]
CH 3-C-H
;
CH3-C-H
H
Ethanol
(ethyl alcohol)
Ethanal
(acetaldehyde)
Oxidation of Alcohols
[O]
Secondary alcohol
OH
ketone
O
[O]
CH3-C-CH 3
2-Propanol
(isopropyl alcohol)
;
CH 3-C-CH 3
2-propanone
(dimethyl ketone,
“acetone”)
Oxidation of Alcohols
[O]
Tertiary alcohols
OH
no reaction
[O]
CH3-C-CH 3
CH3
no product
no H on the C-OH to oxidize
2-Methyl-2-propanol
Oxidation of Ethanol in the
Body
l Enzymes in the liver oxidize ethanol
l Aldehyde product impairs coordination
l Blood alcohol over 0.4% can be fatal.
O
O
;
CH3CH2OH
ethyl alcohol
;
CH3CH
CH3COH
2CO2 + H2O
acetaldhyde acetic acid
Reduction
vIs a loss of oxygen (O)
or
vgain of hydrogen (H)
Reduction
Aldehydes are reduced to 1E
alcohols and ketones are
reduced to 2E alcohols
Alcohols
1E
aldehydes
2E
ketones
Addition of Water
O
H
C
HO
+ H2O
H
O
CH3
C
CH3
C
H
HO
+ H2O
OH
CH3
H
Many products form
OH
C
CH3
Few products form
Learning Check AK 1
Classify each as an aldehyde (1), ketone (2)
or neither(3).
O
;
A. CH 3CH 2CCH 3
CH 3
O
;
C. CH3-C-CH2CH
CH 3
B. CH3-O-CH3
O
D.
Solution AK 1
Classify each as an aldehyde (1), ketone (2)
or neither(3).
O
;
A. CH 3CH 2CCH 3
CH 3
2
O
;
C. CH3-C-CH2CH 1
CH 3
B. CH3-O-CH3 3
O
D.
2
Learning Check AK 2
Name the following
O
O
;
A. CH3CH2CCH 3
CH3
O
;
C. CH 3-C-CH 2CH
CH 3
B.
Solution AK 2
O
;
A. CH 3CH2CCH 3
B.
O
2-butanone (ethyl methyl ketone)
CH3
O
;
C. CH3-C-CH 2CH
CH3
2,2-dimethylbutanal
cyclohexanone
Learning Check AK 3
Draw the structural formulas for each:
A. 3-Methylpentanal
B. 2,3-Dibromopropanal
C. 3-Methyl-2-butanone
Solution AK 3
Draw the structural formulas for each:
CH 3
A. 3-Methylpentanal
O
;
CH3CHCHCH 2CH
Br O
B. 2,3-Dibromopropanal
;
Br-CH2 CHCH
O
;
C. 3-Methyl-2-butanone
CH 3CHCCH 3
CH3
Learning Check Ox-Red 3
Select the product for the reaction of
CH3CH2CH2OH in the following conditions:
O
;
1) CH3CH=CH 2
2) CO2 + H2O 3) CH 3CH2CH
A. H+, heat
_________
B.
[O]
_________
C. O2, heat
_________
Solution Ox-Red 3
Select the product for the reaction of
CH3CH2CH2OH in the following conditions:
A. H+, heat
1) CH3 CH=CH2
O
;
B.
[O]
C. O2, heat
3) CH3CH2CH
2) CO2 + H2 O