- Organic Reactions
Mr. Shields
Regents Chemistry
U17 L03
Organic Reaction Types
There are in fact so many types of organic rxn’s
It would be impossible to review them all.
Therefore we’re going to focus on just 7:
- Substitution
- Addition
- Fermentation
- Elimination
- Esterification
- Saponification
- Polymerization (Condensation & Addition)
Substitution Rxns
• 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)
• Need ultraviolet light to initiate the reaction
– Provides the energy of activation 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 are the products formed in the following rxn?
CH3CH3 + Br2 
CH3 CH2Br + HBr
sunlight
(What is the purpose of the sunlight?)
Let’s look at how this reaction occurs?
1. Br-Br  2Br
uv
2. R-H + Br  H-Br + R
A free radical
3. R
+ Br2  R-Br + Br
Substitution Rxns
Another example of a substitution reaction is
The replacement of a halogen with a hydroxyl group
CH3CH2CL + NaOH(aq)  CH3 CH2OH + NaCl
Or the replacement of a halogen with an amine group
CH3CH2CL + NH3 
CH3 CH2NH2 + HCl
Elimination Rxns
• Any reaction in which atoms are eliminated from
another molecule
• This can be done by
– Elimination of H2
– Elimination of HX
Elimination Rxns
-Loss of H2
- This process is often referred to as Dehydrogenation
HH
H-C-C-H
HH

H2C=CH2 + H2
Heat, catalyst
Elimination Rxns
-Loss of HX (X = a halogen)
-Also known as dehydrohalogenation
HH
H-C-C-H (g) + Heat
HX
 H2C=CH2 + HX (g)
Addition
• Takes place with unsaturated compounds which are usually
more reactive than saturated compounds
– Can take place with both Double and Triple bonds
– Two atoms are added across the electron rich double bond
• What are some examples of molecules that can be added?
–
–
–
–
X2
H2
HX
H 2O
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
H2C=CH2 + H2

Heat, catalyst
HH
H-C-C-H
HH
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

HH
H-C-C-H
HX
HX
HC=CH + HX  H-C-C-H + HX  H-C-C-H
HX
HX
Addition
• Addition of Water
- Water adds across a double bond to form an alcohol
- Water can add across a triple bond to form a diol
H2C=CH2 + H-OH

HH
H-C-C-H
H OH
HH
HC=CH + H-OH  H-C-C-H + HOH  H-C-C-H
H OH
HO OH
Esterification
• Alcohol + Organic Acid = Water + Ester
• Used to make perfumes, scents and flavors
• Combination rxn which involves dehydration (Loss of water).
• The alcohol becomes the alkyl group & the acid becomes -oate
alcohol
propyl ethanoate
acid
From the alcohol
From the acid
Aspirin – Made by Esterification
HO
C=O
OH
Salicylic Acid
(An alcohol and acid)
+ H-O-C-CH3 
O
Acetic acid
HO
C=O
O-C-CH3
O
Acetyl Salicylic Acid
(Common Name)
“Aspirin”
Name the Esterification Products
CH3CH2OH + HCOOH 
CH3CH2COOH + CH3CH2CH2OH 
Fermentation
• Fermentation is the process by which glucose is broken
down by an enzyme (a catalyst) in the absence of oxygen
into an alcohol and carbon dioxide
• One enzyme used is Zymase (Found in baker yeast)
– If Zymase is used the alcohol produced is ethanol
• The oldest chemical reaction practiced by man
– Dates back to at least 6000 B.C.
– In place of glucose, starches from grains can be used.
Hence the name grain alcohol
C6H12O6 
Zymase
Glucose
2C2H5OH + 2CO2
Ethanol
Carbon dioxide
Saponification
• Another very old chemical reaction practiced by man
• The hydrolysis of the ester bonds (back to acid + alcohol) in
triglycerides using an aqueous sol’n of a strong base to form
carboxylate salts and glycerol
• Triglycerides,from fats, and a strong base (KOH or NaOH)
– Products are soap and glycerol (a triol)
Carboxylate salt
An ester
O
CH2-0-C-(CH2)14CH3
|
O
CH2-O-C-(CH2)14CH3
|
O
CH2-0-C-(CH2)14CH3
A TRIGYCERIDE
+
1,2,3-propanetriol
O
CH2-0H
K+ -O-C-(CH2)14CH3
|
O
3KOH  CH -OH K+ -O-C-(CH ) CH
2
2 14
3
+
|
O
CH2-0H
K+ -O-C-(CH2)14CH3
GLYCEROL
3 SOAP MOLECULES
Polymers
The joining together of many smaller repeating
Units to form a very high MW molecule
- Polymers range from 10,000 amu to more
than 1,000,000 amu
The small repeating units used to build the polymer
are known as monomers
Monomers
Sometimes just one monomer is used to make the Polymer
(example: ethylene (a) to form polyethylene)
a
a
a
a
a
a
a
And sometimes two monomers alternate are used to form
an alternating polymer (ex: Nylon or Polyesters)
a
b
a
b
a
b
a
Natural polymers
Example of “natural” polymers in nature abound:
Some examples are:
Wool
Cotton
Starch
Protein
Cellulose
Polymerization
There are two methods we’ll look at for the
Production of Polymers:
- Addition polymerization
- Condensation polymerization
Addition Polymerization
-All the atoms present in the monomer are
retained in the polymer in Addition Polymerization
-This type of reaction involves monomers with
double or triple bonds
-An initiator is required to produce a free radical
-A very reactive substance having a free e-Peroxides are typically used to produce this free radical
Peroxide  Rad
Free radical induced addition polymerization of
Ethylene to form polyethylene
Rad
Rad
Free radical induced addition polymerization of
Styrene to form polystyrene
Monomer
Notice loss of electron pair to form
Connecting bonds in polymer
Addition Polymer
Condensation Polymerization
- Monomers that join together by the loss of water
- each monomer has two functional groups that are
the same
- monomer 1 and monomer have functional groups
that are different
- reaction occurs between the two pairs of
dissimilar functional groups
Let’s look at some examples …
One example of Condensation
Polymerization - Dacron
Di-Acid
Monomer A
Di-Alcohol
Monomer B
Formed by loss of water
A polyester
Condensation Polymerization Nylon
Formed by loss of water
An amide group
A Polyamide
I’m Done!
You’re Done!
WE Made it to the End!
Only the regents is left !!