Download Organic Part 2

Organic Part 2
Hydrocarbons
1. Alkanes:
all single bonds
2. Alkenes:
C=C
saturated v. unsaturated
structural isomers
geometric isomers
3. Alkynes:
C≡C
4. Aromatic hydrocarbons
Reactivity of hydrocarbons
•  addition reactions
•  combustion reactions
Petroleum
Mary J. Bojan
Chem 110
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Hydrocarbons
This is the structure of
4-ethyl-2,3,3-trimethylnonane
What is the molecular formula of this compound?
How many ⎯CH3 groups are there on this compound?
Mary J. Bojan
Chem 110
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HYDROCARBONS
Simplest organic compounds
Contain only C and H
Alkanes
Alkenes
Alkynes
Aromatic
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saturated
have the maximum number of H
attached to the C skeleton.
unsaturated
have double or
triple bonds
Chem 110
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ALKENES
Contain one or more double bonds
C
CnH2n
C
The C=C⎯H or C=C⎯C angle is 120°
H
H
C
H
H
H
C
C
H
H
ethene
(ethylene)
C
CH 3
propene
Rotation about double bond is restricted
Mary J. Bojan
Chem 110
4
Butene
C 4H 8
There are several possible structures for a chain of
4 carbons with one double bond.
1-butene
2-methylpropene
2-butene
cis-2-butene
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trans-2-butene
Chem 110
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Structural vs. Geometric
Structural isomers:
same molecular formula: different structure
1-butene
2-methylpropene
2-butene
Geometric isomers
same molecular formula: different geometry
cis-2-butene
trans-2-butene
cis-isomer:
trans-isomer:
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same side
opposite side (across)
Chem 110
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ALKYNES: CnH2n-2
Contain ⎯C≡C⎯
H⎯C≡C⎯H
ethyne
(acetylene)
CH3⎯C≡C⎯H
propyne
bond angle is 180°
H
H
H
C
C
H
H
H
C
C
H
H
C
H
C
C
H
1-butyne
C
H
H
2-butyne
structural isomers
no geometric isomers are possible
Mary J. Bojan
Chem 110
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Reactions of Alkenes and Alkynes
Addition reaction
–  Double and triple bonds are reactive: addition reactions
typically occur at room temperature.
For Alkenes
or
CH3⎯CH=CH2 + Br2 →
CH3⎯CH=CH⎯CH3 + HX →
where X = Cl, Br, I, OH, etc.
For Alkynes
CH3 ⎯C≡CH + 2Br2 →
CH3-C ≡C -CH3 + 2HCl →
Mary J. Bojan
Chem 110
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Aromatic Hydrocarbons
Contain alternating single and double C-C Bonds
Benzene is prototypical molecule
H
H
H
C
C
C
C
H
C
C
H
H
H
H
H
C
C
C
C
C
C
H
H
H
Usually written:
Aromatic hydrocarbons are less reactive than alkenes:
Special kind of bonding
Have “delocalized” π electrons
Results in added stability
Mary J. Bojan
Chem 110
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Reactivity of Hydrocarbons
Same reaction:
hydrocarbon +
Colorless
Br2
red
ALKANE
Heptane + Br2 ⎯→
ALKENE (and ALKYNES)
2-pentene + Br2 ⎯→
AROMATIC
toluene + Br2 ⎯→
CH3
Mary J. Bojan
Chem 110
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Functional Group classes
Contain a representative group of elements in a fixed pattern
Have similarities in structure and function (reactivity).
Seemingly small changes in structure can have big affect on
molecular properties
Example: adding
an oxygen
changes a
hydrocarbon
into an alcohol
or an ether…
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Functional Group Type
hydrocarbon
CH3⎯CH2⎯H
ethane
gas
bp –89°C
Chem 110
alcohol
ether
CH3⎯CH2⎯O H CH3⎯O⎯CH3
ethanol
di-methyl ethe r
liquid
gas
bp 78°C
bp –24 °C
water soluble
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Functional Group Classes
Contain a representative group of elements in a fixed pattern:
Each class has similarities in structure and function (reactivity).
Alcohols
R-OH
R≠H
Groups which have
a carbonyl
R = alkyl group
Ethers R-O-R’
R,R’≠H
Aldehydes
Amines
H N H
H N R'
R N R'
R
R
R"
C
Ketones
O
O
C
C
H
R
R
Carboxylic
Acid
(R,R’≠H)
R'
Ester
Amide
O
O
O
C
C
C
R
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O
Chem 110
OH
R
OR'
R
NHR'
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Functional Groups with O and N
Alcohols
R⎯OH
hydroxyl group
hydrocarbon (alkyl) group
Ether
R⎯O⎯R’
Amines
H N H
H N R'
R N R'
R
R
R"
Mary J. Bojan
Chem 110
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Functional Groups
Containing the carbonyl group
C O
O
Aldehyde
C
R
H
O
Ketone
C
R
R'
O
Carboxylic Acids
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⎯COOH
Chem 110
C
R
OH
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Organic Acids and Bases
AMINES
weak bases, organic bases (like NH3)
(CH3)3N(aq) + H+(aq)
(CH3)3NH+(aq)
CARBOXYLIC ACIDS
weak acids, organic acids
R
R
C O (aq)
HO
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C O (aq) + H+(aq)
-O
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Questions
Which of the following hydrocarbon classes does NOT have a
double or triple bond?
1
2
3
4
alkane
alkene
alkyne
aromatic
Which one of the following functional group
classes does not have a double bond?
1
2 
3 
5 
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aldehyde
Ketone
amine
ester
Chem 110
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The presence and properties of functional groups are
responsible for the action of drugs.
What functional groups are present in these molecules?
O
C
H
OH
O
C
HO
C
CH 3
O
CH3
O
Acetaminophen
Acetyl salicylic acid
H3C
Ibuprofen
N
O
CH3
OH
CH3
Mary J. Bojan
Chem 110
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What’s Next?
•  Formulas tell us how atoms are connected to
each other
•  Lewis structures tell us where the electrons
are.
QUESTIONS
•  What are the shapes of these molecules?
•  Can we use information about bonding,
connectivity of atoms, molecular formulas, etc.
to predict the shapes (and properties) of
molecules?
Mary J. Bojan
Chem 110
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