REACTIONS
OF
ORGANIC COMPOUNDS
MAIN TYPES OF REACTIONS in
Organic Chem
1)
2)
3)
4)
5)
6)
7)
8)
Addition
Substitution
Elimination
Oxidation
Reduction
Condensation
Hydrolysis
Combustion
Types of Substitution
Reactions
1) ADDITION REACTION
•Atoms added to a double or triple bond
•Alkene or Alkyne undergoes addition reaction
to break a double or triple bond
•Example:
Reactant XY added to alkene makes alkane
To recognize: Two reactants make 1 product
1) ADDITION REACTIONS
Common atoms that can be added to
an alkene or alkyne
•H and OH (from H2O )
•H and X (from H-X) where X= Cl , Br, or I
•X and X from (X2) where X= Cl , Br, or I
•H and H (from H2)
EXAMPLES: Addition Reactions
1)
2)
ADDITION REACTIONS:
ALKENES
• Symmetrical molecule reacts
with asymmetrical molecule to
give one product.
Symmetrical
Asymmetrical
RULES FOR ADDITION
• Two asymmetrical molecules react to
give two products.
Example:
+
Asymmetrical
or
Asymmetrical
Which product is favoured ?
“MARKOVNIKOV’S” Rule
• "the rich get richer"
• The carbon atom with the largest number of
carbon atoms gets the X (halogen) or OH bind to
it
• Therefore 2- bromobutane is favoured
+
2-bromobutane
Major product
1-bromobutane
Minor Product
ADDITION REACTIONS:
ALKYNES
• Also follow Markovnikov’s rule when
asymmetrical
Asymmetrical
1,1,2,2-tetrabromopropane
ADDITION REACTIONS:
ALKYNES
• May occur as two addition reactions:
+
+
Addition
• Takes place with unsaturated compounds which are
usually more reactive that saturated compounds
– Takes place with both Double and Triple bonds
– Two atoms are added across the electron rich bond
• What can be added?
–
–
–
–
X2
H2
H2O
HX
Addition
• Addition of halogen
– Normally occurs dissolved in a solvent such as CCl4
– Alkenes form dihaloalkanes
– Alkynes produce dihaloalkenes or tetrahaloalkanes
H
H
H
H
C
H
C
H
+
Cl2
C
H
C
Cl
Cl
H
1,2-dichloroethane
Addition
• Addition of Hydrogen
– Catalysts normally used such at Pt, Pd or Ni
• Known as Hydrogenation
– Alkene becomes an alkane
– Alkyne becomes and alkene or alkane
H2C=CH2 + H2
HH
H-C-C-H
HH

Heat, catalyst
Addition
• Addition of Hydrogen Halides (HX)
– HX = HCl, HBr, HI (Not HF)
– Alkene becomes an alkyl Halide
– Alkynes form Monohalo alkenes or dihaloalkanes
with
the halogens on the same carbon
H2C=CH2 + HX
HC=CH + HX 
HH
H-C-C-H
HX

H-C-C-H
HX
+ HX 
HX
H-C-C-H
HX
2) SUBSTITUTION REACTION
• A hydrogen atom or functional group is
replaced by a different functional group
• To recognize: two compounds react to form
two products.
2-bromobutane
butan-2-amine
Substitution Reactions
• Any reaction in which one atom is replaced by another
• Used to place a halogen onto an alkane
• The products always are a halocarbon and the acid of
the halogen (ex: hydrobromic acid)
• Needs ultraviolet light to initiate the reaction
– Provides the high energy needed to form the excited state
H
H
H
C
H
H
C
H
H
H
hv
+
Cl2
C
H
Cl
C
H
H
+ HCl
Substitution Rxns
What is the products formed in the following rxn?
CH3CH3 + Br2 
CH3 CH2Br + HBr
sunlight
(Why sunlight?)
SUBSTITUTION REACTION
Aromatics
• Aromatics can only undergo substitution
reactions
3) ELIMINATION REACTION
• atoms are removed form a molecule to form
double bonds.
• Reverse of addition
• To recognize: One reactant breaks into two
products
ELIMINATION REACTION:
Alcohol
• undergo elimination dehydration when heated
in presence of strong acids, for example:
H2SO4
Example:
ELIMINATION REACTION:
Alkyl Halides
• Undergo elimination to produce alkenes
Bromoethane
ethene
hydrobromic acid
Elimination Rxns
• Any reaction in which atoms are eliminated
from another molecule
• This can be done by
– Elimination of H2
– Elimination of HX
– Elimination of H20
Elimination Reactions
-Loss of H2
- This process is often referred to as Dehydrogenation
HH
H-C-C-H
HH

H2C=CH2 + H2
Heat, catalyst
This type of rxn takes place in industry in what
is know as a catalytic cracking unit
Elimination Rxns
-Loss of HX
-Alkyl halides can also undergo elimination. This is as
known as dehydrohalogenation
HH
H-C-C-H
HX

H2C=CH2 + HX
Base (ex KOH)
The base extract a proton (H+) and X- leaves
Elimination Rxns
-Loss of H2O
-Alcohols can undergo elimination via the loss of water.
This is known as dehydration
HH
H-C-C-H
H OH

H2C=CH2 + H2O
Acid, heat
a) The acid protonates the –OH group, water leaves
Positive carbon remains behind
b) An adjacent proton (H+) leaves next leaving the
electron pair to form the double bond
4) OXIDATION &
5) REDUCTION REACTIONS
• Change in the number of H or O atoms
bonded to C
• Always occur together
• One reactant is oxidized while the
other is reduced
• For now, lets focus on reactant only…
4) OXIDATION
• Carbon atom forces
more bonds to Oxygen
or less to Hydrogen
• For example: formation
of C=O bond
• Occurs in presence of
oxidizing agents [O]
such as KMnO4, K2Cr2O7,
and O3
• For now, focus on
organic reactant only
4) OXIDATION:
Alcohol
• Alcohol oxidation can form an aldehyde or
ketone
Primary Alcohol
Secondary Alcohol
Tertiary Alcohols do not oxidize
4) OXIDATION:
Aldehyde
• Aldehydes undergo oxidation to produce
carboxylic acid
Example:
IV- Oxidation/Reduction
• Oxidation: the loss of electrons
– alternatively, the loss of H, the gain of O,
or both
• Reduction: the gain of electrons
– alternatively, the gain of H, the loss of O,
or both
5) REDUCTION REACTION
• Carbon atom forms fewer bonds to
Oxygen or more bonds to Hydrogen
• Aldehydes, ketones and carboxyliic
acids can be “reduced” to alcohols
• Alkenes and alkynes can be reduced to
become alkanes
• Occurs in the presence of reducing
agents such as LiAlH4, and H2 where
Hydrogen [H] is added
5) REDUCTION:
Alkene
5) REDUCTION:
Aldehyde/Ketone
6) CONDENSATION
• two molecules combine to form a single, bigger
molecule.
• Water is usually produced in this reaction
• A carboxylic acid and alcohol can condense to form an
ester
– called “ esterification”
• A carboxylic acid and amine can condense to form an
amide
Esterification
• Alcohol + Organic Acid = Water + Ester
• Used to make perfumes, scents and flavors
• Combination reaction which involves
dehydration.
• The alcohol becomes the alkyl group and the
acid becomes -oate
Methyl propanoate
Aspirin – Made by
Esterification
HO
C=O + H-O-C-CH3
OH
Salicylic Acid
(An alcohol and acid)

O
Acetic acid
HO
C=O
O-C-CH3
O
Acetyl Salicylic Acid
(Common Name)
“Aspirin”
•
•
•
•
•
7) HYDROLYSIS
water adds to a bond splitting it into two
Reverse of a condensation reaction
Water can add to an ester or amide bond
Ester + water makes a carboxylic acid and alcohol
Amide + water makes a carboxylic acid and amine
1-propanol