Chemical Reaction in Organic Compounds
Session 6: Chemical Reaction in Organic Compounds.
Total Session Time: 60 minutes
Prerequisites
Students Learning Tasks
By the end of this session students are expected to be able to:
Resources Needed:
SESSION OVERVIEW
|Step |Time |Activity/ |Content |
| | |Method | |
|1 |05 minutes |Presentation |Introduction, Learning Tasks |
|2 |15 minutes |Presentation |Definition of the term chemical |
| | |Buzzing |reaction |
|3 | |Group |Types of chemical reactions |
| |30 minutes |discussion |involving organic compounds |
| | |Presentation | |
|4 |05 minutes |Presentation |Key Points |
|5 | | Presentation |Evaluation |
| |05 minutes | | |
CONTENTS
STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)
READ or ASK students to read the learning tasks and clarify.
ASK students if they have any questions before continuing.
STEP 2: Definition of Chemical Reaction (15 minutes)
|Activity: Buzzing (10minutes) |
| |
|ASK students to pair up and buzz on the following question for 5 |
|minutes |
| |
|What is chemical reaction? |
| |
|ALLOW pairs to respond on the question |
| |
|WRITE their response on the flip chart/board |
| |
|CLARIFY and SUMMARIZE by using the content in the table 1 below |
Definition
new substance through chemical change, OR
reactants, are converted to one or more different substances, the
products, substances are either chemical elements or compounds.
create different substances as products.
STEP 3: Types of Chemical Reactions Involving Organic Compounds (30
minutes).
|Activity: Small Group Discussion (20 minutes) |
| |
|DIVIDE students into small manageable groups. |
|ASK students to discuss on the following question. |
| |
|What are the types of chemical reactions involving organic compounds? |
| |
|ALLOW students to discuss for 15 minutes |
|ALLOW few groups to present for 5 minutes and the rest to add points |
|not mentioned. |
| |
|CLARIFY and SUMMARIZE by using the contents below |
There are five main types of organic reactions that can take place. They
are as follows:
Let us study each of these reactions in detail, to understand more about
them.
[pic]
o In a substitution reaction, one atom or a group of atoms take place of
another atom or a group of atoms which leads to the formation of an
altogether new substance.
o We can take an example of C – Cl bond, in which the carbon atom
usually has a partial positive charge due to the presence of highly
electronegative chlorine atoms.
o In a nucleophilic substitution reaction, it is important that the
nucleophile must have a pair of electrons and it also should have a
high affinity for the electropositive species in comparison to the
substituent which was originally present in the element.
o In order for the substitution reaction to occur, there are certain
conditions that have to be present such as maintaining low
temperatures same as room temperature.
o These are reactions which involve the elimination and removal of the
adjacent atoms.
o After these multiple bonds are simultaneously formed and there is a
release of small molecules as product.
o One of the examples of a typical elimination reaction is the
conversion of ethyl chloride to ethylene.
o In the above reaction, the eliminated molecule is HCl, which can form
out of the combination of H+ from the carbon atom which is on the left
side and Cl– from the carbon atom which is on the right side.
o An addition reaction is simply just the opposite of an elimination
reaction.
o In an addition reaction, the components or molecules of A and B are
added to the carbon-carbon multiple bonds and this is called an
addition reaction.
o In the reaction given below when HCl is added to ethylene, it will
give us ethylene chloride.
o Most of the organic reactions involve radicals and their movement.
o Addition of a halogen to a typically saturated hydrocarbon involves
free radical mechanism.
o There are usually three stages involved in a radical reaction which
are;
o Initially when the weak bond is broken initiation of the reaction
takes place with the formation of free radicals.
o After that when the halogen is added to the hydrocarbon a radical is
produced and finally, it gives alkyl halide.
o Electrons in an organic redox reaction often are transferred in the
form of a hydride ion – a proton and two electrons.
o Because they occur in conjunction with the transfer of a proton, these
are commonly referred to
as hydrogenation and dehydrogenation reactions: a hydride plus a
proton adds up to a hydrogen (H2) molecule.
o When a carbon atom in an organic compound loses a bond to hydrogen and
gains a new bond to a heteroatom (or to another carbon), this means
the compound has been dehydrogenated, or oxidized.
o A very common biochemical example is the oxidation of an alcohol to a
ketone or aldehyde:
[pic]
o Conversely, when a carbon atom in an organic compound gains a bond to
hydrogen and loses a bond to a heteroatom (or to another carbon atom),
it means the compound has been hydrogenated, or reduced.
o The hydrogenation of a ketone to an alcohol, for example, is overall
the reverse of the alcohol dehydrogenation shown above.
o Illustrated below is another common possibility, the hydrogenation
(reduction) of an alkene to an alkane
[pic]
STEP 4: Key Points (5 minutes)
reactants, are converted to one or more different substances, the
products, substances are either chemical elements or compounds.
reactions, addition reactions, radical reactions and Oxidation-Reduction
Reactions.
STEP 5: Evaluation (10 minutes).
References
States: W.B. Saunders Co.
Morrison R.T and Boyd R N (1997). Organic Chemistry (6th Ed.). New Delhi,
India: Prentice Hall of India
Graham Solomon et al (2014). Organic Chemistry (11th Ed.). New Jeysey,
United States: John Willey and Sons.
Rama R. N. (2005). Principles of Pharmaceutical Organic Chemistry. New
Delhi, India: MacMillan Publishers
Bruice Y (2013). Organic Chemistry (7th ed.). New York, United States:
Prentice Hall Pearson.
Delgado J. N. Et al (1998). Wilson and Gisvold's Textbook of Organic
Medicinal and Pharmaceutical Chemistry (10th Ed.). Calfornia, United
States: Lippincott Williams
Bhassin S.K, Gupta R.(2013). Pharmaceutical organic chemistry (E-book
Kindle edition). New Delhi, India: Elsevier Publishing Services
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