Download Reactions of Hydrocarbons & their functional groups

CHAPTER 2:
REACTIONS OF
ORGANIC
COMPOUNDS
MAIN TYPES OF REACTIONS in
Organic Chem
She called it
a Blood Bath!
1)
2)
3)
4)
5)
6)
7)
8)
Addition
Substitution
Elimination
Oxidation
Reduction
Condensation
Hydrolysis
Combustion
Look! I think
she’s using it to
blow her nose
I wonder why
she wrote it in
Japanese
Types of Substitution
Reactions
Whew! That
was easy! 
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:
+
+
2) SUBSTITUTION REACTION
• A hydrogen atom or functional group is
replaced by a different atom or functional
group
• To recognize: two compounds react to form
two products.
2-bromobutane
2-butanamine
2) SUBSTITUTION REACTION
1) CH3CH2-OH + HI
ethanol
2)
3)
CH3CH2-I + H2O
iodoethane
SUBSTITUTION REACTION
Aromatics
• Aromatics can only undergo substitution
reactions
SUBSTITUTION REACTION
Alcohols
• Halogens in HCl, HBr or HI can substitute
the OH group of alcohol or the reverse.
• For Ex:
CH3-CH2-OH + HCl
CH3-CH2Cl + H2O
• The reverse reaction:
CH3-CH2Cl + OHCH3-CH2-OH + Cl(from water)
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 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
• If an asymmetrical molecule undergoes
an elimination reaction, constitutional
isomers can form  example #3
• General rule: H atom most likely to be
removed from C atom with most C-C
bonds
• “The poor get poorer!”
– opposite of Markovnikov’s Rule
– Called Zaitsev’s rule
Elimination
(major product)
(minor product)
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:
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/Pt where
Hydrogen [H] is added
5) REDUCTION:
Alkene
5) REDUCTION:
Aldehyde/Ketone
H
O
O
+
C
R1
Aldehyde or ketone
[H]
R1
C
R2
Reducing
agent
H
alcohol
R2
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
Condensation
O
R2
C
R1
O
+
H
carboxylic
water
acid
H
O
N
R2
C
R3
R1
amine
N
+
R3
amide
H
H
O
•
•
•
•
•
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
8) Combustion
• Type of reaction in which a compound reacts
with oxygen to produce the oxides of
elements that make up the compound
• 2 types:
1) Complete combustion: an excess of oxygen
reacts with a hydrocarbon and produces carbon
dioxide and water vapour, and releases energy
2) Incomplete combustion: reaction that occurs
when insufficient oxygen is present; all elements
in the fuel will not combine with oxygen to the
greatest extent possible
Combustion
• Example #1
CxHy + O2(g)  CO2(g) + H2O(g) +
energy
• Example #2
HC + O2(g)  C(s) + CO(g) + CO2(g) + H2O(g) + energy
POLYMERS
• very long molecules made by linking small molecules
called monomers
• Example:
-PET(Polyethylene terephthalate ) polymers
- Plastics are polymers that can be heated and moulded
into specific shapes and forms
-Polyethene is made from monomer of
POLYMERS
can be synthetic or natural
• Synthetic polymers
– man made polymer like plastics and polyester
• Natural polymers
– found in nature like glucose
and silk
ADDITION Polymerization
• Monomers added together through multiple
addition reactions
• Examples:
• Examples Pg 83: Table 2.1
CONDENSATION
Polymerization
• monomers are joined together by the formation of
ester or amide bond
• Water created as a side product
• Example:
• Polyesters contain many ester bonds
• Nylon (polyamide) contains many amide bonds