Organic Chemistry Fifth Edition

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Organic Chemistry II (Chem 234)Professor Duncan
J. Wardrop
Spring 2004
University of Illinois at Chicago
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16.14Epoxides in Biological Processes
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16.15Preparation of Sulfides
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Preparation of RSR'

• prepared by nucleophilic substitution (SN2)

S
R
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16.16Oxidation of SulfidesSulfoxides and
Sulfones
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Oxidation of RSR'
sulfide
sulfoxide

• either the sulfoxide or the sulfone can be
  isolated depending on the oxidizing agent and
  reactionconditions

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Example
water
(91)

• Sodium metaperiodate oxidizes sulfides to
  sulfoxides and no further.

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Example

• 1 equiv of H2O2 or a peroxy acid gives a
  sulfoxide, 2 equiv give a sulfone

H2O2
(2 equiv)
(74-78)
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16.17Alkylation of SulfidesSulfonium Salts
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Sulfides can act as nucleophiles




R"
R
X
R"
S
R
S
X

R'
R'

• product is a sulfonium salt

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Example

CH3I
CH3(CH2)10CH2SCH3
CH3(CH2)10CH2SCH3
I
CH3
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Chapter 17Aldehydes and Ketones.Nucleophilic
Additionto theCarbonyl Group
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17.1Nomenclature
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IUPAC Nomenclature of Aldehydes
Base the name on the chain that contains the
carbonyl group and replace the -e ending of the
hydrocarbon by -al.
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IUPAC Nomenclature of Aldehydes
4,4-dimethylpentanal
5-hexenal
2-phenylpropanedial(keep the -e endingbefore
-dial)
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IUPAC Nomenclature of Aldehydes
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Substitutive IUPAC Nomenclature of Ketones
Base the name on the chain that contains the
carbonyl group and replace -e by -one. Number
the chain in the direction that gives the lowest
number to the carbonyl carbon.
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Substitutive IUPAC Nomenclature of Ketones
3-hexanone
4-methyl-2-pentanone
4-methylcyclohexanone
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Functional Class IUPAC Nomenclature of Ketones
List the groups attached to the carbonyl
separately in alphabetical order, and add the
word ketone.
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Functional Class IUPAC Nomenclature of Ketones
ethyl propyl ketone
benzyl ethyl ketone
divinyl ketone
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17.2Structure and BondingThe Carbonyl Group
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Structure of Formaldehyde

• planar
• bond angles close to 120
• CO bond distance 122 pm

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The Carbonyl Group
O
1-butene
propanal
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Carbonyl group of a ketone is morestable than
that of an aldehyde
heat of combustion
2475 kJ/mol
2442 kJ/mol

• Alkyl groups stabilize carbonyl groups the
  sameway they stabilize carbon-carbon double
  bonds,carbocations, and free radicals.

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Spread is greater foraldehydes andketones than
for alkenes

• Heats of combustion ofC4H8 isomeric alkenes
• CH3CH2CHCH2 2717 kJ/mol
• cis-CH3CHCHCH3 2710 kJ/mol
• trans-CH3CHCHCH3 2707 kJ/mol
• (CH3)2CCH2 2700 kJ/mol

2475 kJ/mol
2442 kJ/mol
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Resonance Description ofCarbonyl Group

• nucleophiles attack carbon electrophiles
  attack oxygen

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Bonding in Formaldehyde
Carbon and oxygen are sp2 hybridized
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Bonding in Formaldehyde
The half-filledp orbitals oncarbon andoxygen
overlapto form a ? bond
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17.3Physical Properties
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Aldehydes and ketones have higher boilingthan
alkenes, but lower boiling points than alcohols.
boiling point
6C

• More polar than alkenes, but cannot form
  intermolecular hydrogen bonds to other carbonyl
  groups

49C
97C
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17.4Sources of Aldehydes and Ketones
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Many aldehydes and ketones occur naturally

2-heptanone(component of alarm pheromone of bees)
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Many aldehydes and ketones occur naturally
O
H
trans-2-hexenal (alarm pheromone of myrmicine
ant)
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Many aldehydes and ketones occur naturally
O
H
citral (from lemon grass oil)
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Synthesis of Aldehydes and Ketones

• from alkenes
• ozonolysis
• from alkynes
• hydration (via enol)
• from arenes
• Friedel-Crafts acylation
• from alcohols
• oxidation

A number of reactions alreadystudied
provideefficient syntheticroutes to aldehydes
and ketones.
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What about..?

• aldehydes from carboxylic acids

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Example

• benzaldehyde from benzoic acid

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What about..?

• ketones from aldehydes

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Example

• 3-heptanone from propanal

O
C
CH3CH2
H
(57)