Transcript Chapter 25 - Organic Reactions

Electrophiles and Nucleophiles
An electrophile is a molecule that is attracted to electrons in
another molecule and will accept electron pairs
A nucleophile is a molecule donates an electron pair to an
electrophile, forming a chemical bond
Cl
electrophile
H
H
H
nucleophile
H
C
C
H
© Tom Selegue Pima Community College 2008
Reactions of alkanes
One of the most common reactions of alkanes is combustion
CH3CH2CH3 + 5 O2 → 4 CO2 + 6 H2O
If the reaction takes place in an environment with
insufficient oxygen, CO will be made as well
CH3CH2CH3 + 4 O2 → CO2 + 2CO + 4 H2O
Alkanes can also undergo halogenation reactions
43%
H3 C
H3C
CH2 CH2
Cl + HCl
CH2 CH3 + Cl2
57%
Cl
H3C
C
CH3 + HCl
H
© Tom Selegue Pima Community College 2008
Other hydrocarbons can give even more different products
CH3
CH3
Cl
C
H3C
CH2 CH3
H
27%
14%
CH2 Cl
H
CH3
+ HCl
H3 C
36%
C
+ HCl
CH2 CH3
H
+ Cl2
23%
CH3
CH3 H
H3 C
C
C
C
H
Cl
CH3
H3C
C
CH2 CH3
Cl
+ HCl
+ HCl
© Tom Selegue Pima Community College 2008
Reactions of alkenes
Alkenes commonly undergo electrophilic addition reactions
electrophile
Cl
Cl -
H
CH3
H3C
C
C
H3C
H
H3C
H
+
C
C
H3C
H
nucleophile
The electrophile adds across the double bond
Aromatic compounds can undergo electrophilic
substitution as well
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CH3
CH3
C
H
C
C
C
C
H
C
H
HNO3
H2SO4
heat
H
H
CH3
O
C
N
C
C
C
C
H
C
2-Nitrotoluene
Toluene
H2SO4
HNO3
O
CH3
O
N
C
N
C
C
C
C
H
C
H
O
H
HNO3
H2SO4
HEAT!!
N
O
H
H
H
O
O
O
2,4,6-Trinitrotoluene
Heat!
CH3
O
C
N
C
C
C
C
H
C
O
H
N
O
O
2,4-Dinitrotoluene
© Tom Selegue Pima Community College 2008
We can add organic groups to the aromatic ring by
Friedel Crafts alkylation
H
H
H
C
C
C
C
H
H
+ H3 C
C
C
H
H
CH2 Br
C
C
C
C
C
H
C
CH2
CH3
H
+ HBr
H
H
Adding different organic groups to the ring of different aromatic
molecules can lead to a series of multifunctional compounds
© Tom Selegue Pima Community College 2008
Reactions of alcohols
Alcohols can undergo condensation reactions to form ethers
H3C CH2 OH
H+
+
H3C CH2 O CH2 CH3
heat
H3C CH2 OH
H+
H3C
CH2
O
H
H
O
© Tom Selegue Pima Community College 2008
CH2
CH3
Alcohols can be oxidized to carboxylic acids
H3C CH2 OH
Ethanol
H2CrO4
O
H3 C C H
+ H2O
Acetaldehyde
H2CrO4
O
H3 C C
OH
Acetic acid
The process can be stopped at the aldehyde and
the acetaldehyde can be isolated
© Tom Selegue Pima Community College 2008
Reactions of carboxylic acids
Carboxylic acids can condense with alcohols to form esters
O
H3C C
O H
+ H3C CH2
Acetic acid
O H
Ethanol
O
H3 C C
O CH2 CH3
Ethyl acetate
© Tom Selegue Pima Community College 2008
+ H2O
Synthesis of acetylsalicylic acid
H
O
C
O
H
H
C
C
C
C
C
C
OH
+
H
O H
H O
H C C O C C H
H
H
Acetic Anhydride
H
Salicylic Acid
O
H3 C C
O
H
C
H
C
C
C
O
C
C
C
OH
H
H
Acetylsalicylic Acid
H O
+
H
C C O H
H
Acetic Acid
© Tom Selegue Pima Community College 2008