Review

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Chemistry 203
Review Organic Chemistry
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Bonding
Noble gases (Stable)
Goal of atoms
Filled valence level

• Ionic bonds
• 2. Covalent bonds

3
Bonding
Ionic bonds result from the transfer of
electrons from one element to another.
Cation (Y)
Metals lose 1, 2 or 3 e-
Ions
Nonmetals gain 1, 2 or 3 e-
Anion (X-)
Cation (Y) Na Li Ca2 Al3 Anion (X-)
Cl- F- O2-
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Bonding
Ionic bonds
Metal-Nonmetal
Cl 1s2 2s2 2p6 3s2 3p5
Na 1s2 2s2 2p6 3s1
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Bonding
Covalent bonds result from the sharing of
electrons between two atoms.
Nonmetal-Nonmetal Metalloid-Nonmetal
Sharing of valence electrons
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Lewis Dot Structure
He
Li
Al
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Intermolecular Forces
London dispersion forces
Intermolecular Forces
lt
Dipole-dipole interaction
Ionic bonds Covalent bonds
Intramolecular (Bonding) Forces
Hydrogen bonding
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London dispersion forces
Attractive forces between all molecules
Only forces between nonpolar covalent molecules
He
He
He
He
d-
d
_
_
_

_
_
_
_
2
2
_
2
2
Original Temporary Dipole
No Polarity
He
He
d-
d
d-
d
_
_
2
_
2
_
Original Temporary Dipole
Induced Temporary Dipole
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London dispersion forces
He T -240C (1 atm) ? liquid
Kinetic energy ? Move slower
Attractive forces become more important
T ?
liquid
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Dipole-Dipole Interactions
Attractive forces between two polar molecules
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Hydrogen bonding
Between H bonded to O, N, or F (high
electronegativity) ? d and a nearby O, N, or F ?
d-
H2O
Stronger than dipole-dipole interactions London
dispersion forces
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Hydrogen bonding
d
CH3COOH Acetic acid
d-
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H-bonding in our body
Protein (a-helix)
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Intermolecular Forces
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Solubility
polar dissolves polar Nonpolar dissolves nonpolar
like dissolves like
octane CCl4
octane
CCl4
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Organic Compounds
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Hydrocarbons
Large family of organic compounds Composed of
only carbon and hydrogen
Saturated hydrocarbons Alkanes
Unsaturated hydrocarbons Alkenes, Alkynes
Aromatics
C C
C C
C - C
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Alkanes
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Chemical reactions of Alkanes
Low reactivity
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Chemical reactions of Alkanes
Low reactivity
2- Halogenation Alkanes react with
Halogens. CH4 Cl2 CH3Cl HCl
Chloromethane
Heat or light
Dichloromethane
CH3Cl Cl2 CH2Cl2 HCl
Heat or light
CH2Cl2 Cl2 CHCl3 HCl
Trichloromethane
Heat or light
CHCl3 Cl2 CCl4 HCl
Tetrachloromethane
Heat or light
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Alkenes Alkyens
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Chemical properties of Alkenes Alkynes
More reactive than Alkanes
Addition of Hydrogen (Hydrogenation-Reduction)
Addition of Hydrogen Halides (Hydrohalogenation)
Addition of water (Hydration)
Addition of Bromine Chlorine (Halogenation)
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Chemical properties of Alkenes Alkynes
Addition reactions
Exothermic reactions
Products are more stable (have the lower energy).
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Chemical properties of Alkenes Alkynes

• A hydrogen atom adds to each carbon atom of a
  double bond.
• A catalyst such as platinum or palladium is used
  (Transition metals).
• H H H H
• Pt
• HCCH H2 H C C H
• H H
• Ethene
  Ethane

More reactive than Alkanes
1. Hydrogenation (Reduction)
Pt
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Chemical properties of Alkenes Alkynes

• A hydrogen halide (HCl, HBr, or HI) adds to
  alkene to
• give haloalkane.
• H H H H
• HCCH HCl H C C H
• H Cl
• Ethene
  Chloroethane

More reactive than Alkanes
2. Hydrohalogenation
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Chemical properties of Alkenes Alkynes
2. Hydrohalogenation

• reaction is regioselective.
• Markovnikovs rule H adds to double bonded
  carbon that
• has the greater number of H and halogen adds to
  the other carbon.

The rich get richer!
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Chemical properties of Alkenes Alkynes

• Water adds to CC to give an alcohol.
• Acid catalyst (concentrated sulfuric acid).
• A regioselective reaction (Markovnikovs rule).

3. Hydration (addition of water)
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Chemical properties of Alkenes Alkynes

• A halogen atom adds to each carbon atom of a
  double bond.
• Usually by using an inert solvent like CH2Cl2.
• H H H H
• CH3CCCH3 Cl2 CH3 C C CH3
• Cl Cl
• 2-Butene
  2,3-dichlorobutane

More reactives than Alkanes
4. Halogenation
CH2Cl2
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Aromatic Hydrocarbons
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Chemical properties of aromatics
No addition reactions (almost unreactive)
Aromatic substitution One of the H atoms is
repalecd by some groups.
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Chemical properties of benzene
1. Halogenation
Cl and Br react rapidly with benzene in the
presence of an iron catalyst.
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Chemical properties of benzene
2. Nitration
In presence of concentrated nitric acid and
sulfuric acid, one of the H atoms is replaced by
a nitro (-NO2) group.
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Chemical properties of benzene
3. Sulfonation
In presence of concentrated sulfuric acid and
heat, one of the H atoms is replaced by sufonic
acid (-SO3H) group.
Heat
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Alcohols
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Chemical Properties of Alcohols
1. Acidity of Alcohols
2. Acid-Catalyzed Dehydration
H2SO4
CH3CH2OH
CH2 CH2 H2O
180C
Dehydration
C C H20
- C C -
Hydration
H
OH
3. Oxidation of Alcohols
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Acid-Catalyzed Dehydration

• Alkene having the greater number of alkyl groups
  on the double bond
• generally predominates.

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Oxidation of 1 Alcohols
In the oxidation O of a primary alcohol 1?, one
H is removed from the OH group and another H
from the C bonded to the OH.
primary alcohol aldehyde
OH O

CH3-C-H CH3-C-H H2O
H ethanol
ethanal (ethyl alcohol)
(acetaldehyde)
O
K2Cr2O7
H2SO4
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Oxidation of 2 Alcohols
The oxidation of 2? alcohols is similar to 1,
except that a ketone is formed.
secondary
alcohol ketone OH O
CH3-C-CH3
CH3-C-CH3 H2O
H 2-propanol
2-propanone
O
K2Cr2O7
H2SO4
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Oxidation of 3 Alcohols
Tertiary 3? alcohols cannot be oxidized.
Tertiary alcohol no reaction
OH
CH3-C-CH3 no product

CH3 no H on the C-OH to
oxidize 2-methyl-2-propanol
O
K2Cr2O7
H2SO4
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Thiols
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Chemical Properties of Thiols
1. Thiols are weak acids (react with strong
bases).
H2O
CH3CH2SH NaOH CH3CH2S-Na H2O
Sodium ethanethiolate
2. Oxidation to disulfides -S-S- disulfide
Oxidation
2HOCH3CH2SH O2 HOCH2CH2S-SCH2CH2OH
Reduction
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Amines
NH2
CH3-NH2 CH3-NH-CH3
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Chemical properties of Amines
They are weak bases (like ammonia) react with
acids.
(to form water-soluble salts)
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Aldehydes Ketones
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Chemical properties of Aldehydes and Ketones
1. Oxidation only for aldehydes (not for
ketones).
O
K2Cr2O7

CH3-CH2-CH2-CH2-C-OH
H2SO4
Pentanoic acid
K2Cr2O7 Oxidizing agent
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Chemical properties of Aldehydes and Ketones
2. Reduction

• Like reducing the alkene (C C) to alkane (C
  C)
• Reduction of an aldehyde gives a primary alcohol
  (-CH2OH).
• Reduction of a ketone gives a secondary alcohol
  (-CHOH-).

O


CH3-CH2-CH2-CH2-C- H
CH3-CH2-CH2-CH2-CH2- OH
Pentanal
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Chemical properties of Aldehydes and Ketones
3. Addition of alcohols (hemiacetals)
H of the alcohol adds to the carbonyl oxygen and
OR adds to the carbonyl carbon.
unstable
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Chemical properties of Aldehydes and Ketones
3. Addition of alcohols (Acetals)
Acid
C
H

C
H2O

H
H
An Acetal
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Chemical properties of Aldehydes and Ketones
3. Addition of alcohols (hemiacetals)
If OH is part of the same molecule that contains
CO.
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Carboxylic Acids
carbonyl group O ?? CH3
COH hydroxyl Carboxyl group
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Chemical properties of Carboxylic Acids
1- Reaction with bases
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Chemical properties of Carboxylic Acids
2- Reduction
Resistant to reduction
Using a powerful reducing agent LiAlH4 (Lithium
aluminum hydride).
1 alcohol
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Chemical properties of Carboxylic Acids
3- Fischer Esterification - A carboxylic acid
reacts with an alcohols to form an ester. -
Using an acid catalyst such as concentrated
sulfuric acid.
The best way to prepare an ester.
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Chemical properties of Carboxylic Acids
4- Decarboxylation
Loss of CO2 from a carboxyl group.
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Esters Amides
O
CH3 C NH2
Amide group
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Formation of Esters
O

A carboxylic acid
Fischer Esterification
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Chemical Reactions of Esters
1. Hydrolysis reaction with water.
(breaking a bond and adding the elements of
water)
Heat
Acid
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Chemical Reactions of Esters
2. Saponification (Hydrolysis) an ester reacts
with a hot aqueous base.
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Chemical Reactions of Esters

• 3. Esters react with ammonia and with 1 and 2
  amines to form amides.
• Thus, an amide can be prepared from a
  carboxylic acid by first converting the
  carboxylic acid to an ester by Fischer
  esterification and then reaction of the ester
  with an amine.

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Formation of Amides
O

A carboxylic acid
O
O
H
HN
C
H
C
H
C
H
C
-
O
H

C
H
C
-
N
H
C
H
C
H

3
3
2
3
2
3
Ethanamine
N-ethylethanamide
Acetic acid
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Chemical Reactions of Amides
Such as esters Hydrolysis in hot aqueous acid
or base.
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Chemical Reactions of Amides
Amides do not react with ammonia or with amines.