Organic Reactions

Salman Bin Abdulaziz University
College of Applied Medical Science,
Medical lab science Department
Organic Chemistry: CHEM-106,
Second level.
Organic Reactions
Organic Reactions
 Organic chemistry is the chemistry of Carbon and its compounds.
 Organic molecules constitute the essence of life (fats, sugars,
proteins, DNA), and also permeate our everyday lives (cotton, polyester,
toothpaste, plastics, etc).
 Chemistry’s top two commercial fields are organic dominated: Pharmaceuticals
and Polymers.
 Basic Organic Chemistry.
 Organic Chemistry is very simple / logical.
 Organic Chemistry is totally dominated by electrons.
 Electrons control bonding, molecular shapes, reactivity.
 Chemical reactions are just movement of electrons.
 Organic Molecules consist of atoms bound together by a covalent bond.
 A covalent bond is the sharing of two valence electrons between two atoms.
Organic reactions are of following four types:



Addition reactions – two molecules combine.
Elimination reactions – one molecule splits into two.
Substitution – parts from two molecules exchange.
Polymerization reactions – Many monomers molecules undergo chemical
reaction to give one large molecule called polymer.
Addition Reactions
Definition:
 In an addition reaction, two molecules add together.
 Addition reactions are typical of unsaturated compounds.
The most common reactants added to organic compounds are:
 hydrogen
 halogens
 hydrohalogens
 water
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Dr. Kakul Husain Firoz
Organic Reactions
The examples are:-
Addition Reactions: Markovnikov‛s rule


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If an alkene is not symmetrical about its double bond, two different products
could result.
The product that is predominant can be predicted by Markovnikov‛s rule: “the
dominant product is the one that has the hydrogen atom attached to the carbon
atom that had more hydrogen atoms at the start”
Dr. Kakul Husain Firoz
Organic Reactions
Elimination Reactions: An elimination reaction is a type of organic reaction in which two substituents are
removed from a molecule. WRITE
Zaitsev's rule

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Zaitsev's rule is a rule that states that if more than one alkene can be formed by an
elimination reaction, the compound that has a more highly substituted C=C
double bond is preferred.
Dr. Kakul Husain Firoz
Organic Reactions
Substitution Reactions
 In a substitution reaction an atom or group (X) in a molecule is replaced by
another (Y).
 Substitution reactions are typical of saturated compounds.
Oxidation of organic molecules
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Dr. Kakul Husain Firoz
Organic Reactions
 Oxidation in organic chemistry is often carried out using potassium dichromate in
acidic solution as the oxidant.
 In the case of ethanol, during the first stage, hydrogen is removed from the
molecule; during the second stage oxygen is added to the molecule.
 Secondary alcohols are oxidized to ketones.
 Ketones resist further oxidation.
Reduction of organic molecules: Compounds with carbon-carbon double bonds are reduced by catalytic
hydrogenation.
 Sodium tetrahydroborate and lithium tetrahydroaluminate are commonly
used for reducing carbonyl compounds.
Polymerisation Reaction
In polymer chemistry, polymerization is a process of
reacting monomer molecules together in a chemical reaction to form three-dimensional
networks or polymer chains. WRITE


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Polymer: large molecules made up of many monomers
Monomer: simpler substance of which polymer is made
Dr. Kakul Husain Firoz
Organic Reactions

Addition Polymerization: monomers' double-bonds open up to form
continuous chain

*Condensation Polymerization: elimination of smaller molecule when
functional groups react
Addition Polymerization
Addition polymers form:


when unsaturated carbon (organic) molecules react to form a long chain polymer
molecule
and no small molecules or atoms are eliminated during the reaction
The general reaction can be represented as:
n R-C=C-R'
R R'
catalyst
| |
→
-(- C - C -) n-
where R and R' can represent hydrogen atoms, halogen atoms, alkyl or other carboncontaining side chains.
Monomer Name
Monomer Structure
Polymer Name
Polymer Structure
Polymer Uses
ethene (ethylene)
CH2=CH2
polyethene (polythene or
polyethylene)
-[-CH2-CH2-]n-
LDPE for sandwich wrap,
cling wrap
HDPE for water pipes, wire
insulation
propene (propylene)
CH2=CHCH3
polypropene (polypropylene)
-[-CH2-CHCH3-]n-
electrical appliances,
automotive applications,
ropes, carpets, films
chloroethane (vinyl
chloride)
CH2=CHCl
polyvinyl chloride (PVC)
-[-CH2-CHCl-]n-
indoor electrical conduit,
underground water pipes
tetrafluoroethene
(tetrafluoroethylene)
CF2=CF2
polytetrafluorethene
(polytetrafluoroethylene, teflon)
-[-CF2-CF2-]n-
Insulation for wires, motors,
generators, etc.
Anti-stick applications in
cookware, bearings.
styrene (vinyl benzene)
CH2=CH
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Polystyrene
heat and electrical insulation,
pipes
Dr. Kakul Husain Firoz
Organic Reactions
H
|
[C|
H
H
|
C|
]n-
Condensation Polymerization
Condensation polymers form:


when bifunctional monomers react to form a long chain polymer molecule
small molecules, such as water, are eliminated during the reaction
Polyesters, polyamides, proteins and polysaccharides such as cellulose, are all examples
of condensation polymers.
Polyesters
 Polyesters form when the -OH functional group of one monomer reacts with the COOH functional group of another monomer.
 An ester link (-COO-) is formed between monomers during the reaction.
 H2O is eliminated in the reaction.
 General reaction between a dicarboxylic acid and a diol:
HO
|
C -R||
O
OH
|
C + HO- R'-OH
||
O
Example:
terephthalic acid + ethylene glycol
nHOOC
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→
OH
|
C -R- C -O-R'-OH + H2O
||
||
O
O
→ polyethyleneterephthalate (terylene or dacron)
COOH + nHO-(CH2)2-OH → -(-OC
COO-(CH2)2-O-)n- + nH2O
Dr. Kakul Husain Firoz
Organic Reactions
Polyamides
 Polyamides form when the -COOH functional group of one monomer reacts with
the -NH2 functional group of another monomer.
 An amide link or peptide bond (-CO-NH-) forms between monomers during the
reaction.
 H2O is eliminated in the reaction.
 Proteins are naturally occurring polyamides.
 General reaction between a dicarboxylic acid and a diamine:
HOOC-R-COOH + H2N-R'-NH2
→
HOOC-R-CONH-R'-NH2 + H2O
Example:
hexanedioc acid + 1,6-hexanediamine
→
nylon-6,6 + water
nHOOC-(CH2)4-COOH + nH2N-(CH2)6-NH2 → -(-OC-(CH2)4-CONH-(CH2)6-NH-)n+ nH2O
 Carboxylic acids are weak organic acids which contain the carboxyl group
(RCO2H).
 The simplest acid is formic acid.
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Organic Reactions
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Dr. Kakul Husain Firoz

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