Lecture 66 Organic Chemistry II

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Lecture 66 - Organic Chemistry II
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Lecture 65 - Organic Chemistry II

• Assignment 17 from chapter 23

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Organic Compounds

• alkanes, alkenes, alkynes
• aromatics
• alcohols, ethers
• aldehydes, ketones
• carboxylic acids, esters
• amines, amides
• polymers

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Reactions of Alkanes

• C - C and C - H bonds are strong!
• 1. Reaction with oxygen
• C8H18 17 O2 8 CO2 9 H2O heat

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Reactions of Alkanes

• 2. Reaction with chlorine
• CH4 Cl2 CH3Cl HCl (methylchlorid
  e)
• CH3Cl Cl2 CH2Cl2 HCl
• (methylene chloride)
• CH2Cl2 Cl2 CHCl3 HCl
• (chloroform)
• CHCl3 Cl2 CCl4 HCl
• (carbon tetrachloride)

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Reactions of Alkanes

• 3. Dehydrogenation

Cr2O3
CH2CH2 H2
CH3CH3
500oC
ethene
ethane
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Alkenes

• general formula CnH2n
• alkenes are unsaturated
• (contain at least one CC double bond)

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Naming Alkenes

• C2H4 ethene (ethylene)
• C3H6 propene (propylene)
• C4H8 butene

2
1
C-CC-C
CC-C-C
1-butene
2-butene
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other examples...

• styrene
• polypropylene
• b-carotene

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cis-trans isomerism
s-bond
C
C
twisting requires energy!
p-bond
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cis-trans isomerism
H3C
CH3
CC
cis-2-butene
H
H
CH3
H
trans-2-butene
CC
H3C
H
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Reactions of Alkenes

• Addition reactions take place at the double bond!

X Y
CC
XY ?
- C - C -
XY H2 (hydrogenation)
Cl2 (chlorination)
H2O (hydration)
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for example...
Pd or Pt
CH2CHCH3 H2
CH3CH2CH3
Pd or Pt
H2
H2SO4
CH3-CH2OH
CH2CH2 HOH
OH
H2SO4
H2O
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Alkynes

• general formula CnH2n-2
• alkynes are unsaturated
• (contain at least one triple bond)

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Naming Alkynes

• C2H2 ethyne (acetylene)
• C3H4 propyne
• C4H6 butyne

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Aromatic Compounds

• originally meant odourous
• now means contains the benzene ring

or
or
CH2 at each corner!
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Naming Benzene Compounds
1,2 Cs are ortho
1,3 Cs are meta
I
Cl
Cl
1
1
2
2
3
I
meta-diiodobenzene
ortho-dichlorobenzene
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Naming Benzene Compounds
1,4 Cs are para
NO2
1
2
para-dinitrobenzene
3
4
NO2
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As a group, benzene phenyl

CH3
methylbenzene
toluene
or
phenylmethane
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Reactions of Benzene

• benzene undergoes substitution reactions (H is
  replaced by another atom)

Cl
FeCl3
HCl
Cl2
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Reactions of Benzene

• benzene undergoes substitution reactions (H is
  replaced by another atom)

CH3
AlCl3
HCl
CH3Cl