Alkanes of Pharmaceutical Importance
Session 8: Alkanes of Pharmaceutical Importance.
Total Session Time: 120 minutes
Prerequisites
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 |10 minutes |Brainstorming |Definition of Alkanes |
| | |Presentation | |
|3 |15 minutes |Buzzing |Alkanes and their Isomers |
| | |Presentation | |
|4 |15 minutes |Presentation |Nomenclature of Alkanes |
|5 |15 minutes |Presentation |Chemical Structure of Alkanes |
|6 |10 minutes |Brainstorming |Chemical Properties of Alkanes |
| | |Presentation | |
|7 |30 minutes |Group |Chemical Reactions and Uses of |
| | |discussion |Alkanes |
| | |Presentation | |
|8 |10 minutes |Presentation |Key Points |
|9 |10 minutes |Presentation |Evaluation |
SESSION 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 Alkanes (10 minutes).
|Activity: Brainstorming (5 minutes) |
| |
|Ask students to brainstorm on the following question: |
| |
|What is Alkane? |
| |
|ALLOW few students to respond. |
| |
|WRITE their responses on the flip chart/ board. |
| |
|CLARIFY and SUMMARISE by using the content below; |
carbons and hydrogen atoms and contain carbon-carbon single bonds.
Homologous series (homo is Greek for “the same as”) is a family of
compounds in which each member differs from the next by one methylene
group (CH2).
integer.
o Methane CH4
o Ethane C2H6
o Propane C3H8
o Butane C4H10
o Pentane C5H12
o Hexane C6H14
o Heptane C7H16
o Octane C8H18
o Nonane C9H20
o Decane C10H22
o Undecane C11H24 etc
if it has two carbon atoms, it must have six hydrogen.
NOTE; Only one possible structure for an alkane with molecular formula CH4
(methane) and molecular formula C2H6 (ethane)
branched structure.
four bonds and each hydrogen forms only one bond.
STEP 3: Alkanes and their Isomers (15 minutes).
|Activity: Buzzing (5minutes) |
| |
|ASK students to pair up and buzz on the following question for 5 |
|minutes. |
| |
|What is an isomer? |
|What is isomerism? |
|ALLOW pairs to respond on the question. |
| |
|WRITE their response on the flip chart/board. |
| |
|CLARIFY and SUMMARIZE by using the content below |
but different structural formula (have different arrangements of atoms in
space).
rise to a linear chain.
formed.
Example.1; C6H14 has 5 isomers as follows:
o Hexane
o 2-Methylpentane
o 3-Methylpentane
o 2,2-Dimethylbutane
o 2,3-Dimethylbutane
Example.2; C7H16 has 9 isomers as follows:
o Heptane
o 2-Methylhexane
o 3-Methylhexane
o 2,2-Dimethylpentane
o 2,3-Dimethylpentane
o 2,4-Dimethylpentane
o 3,3-Dimethylpentane
o 3-Ethylpentane
o 2,2,3-Trimethylbutane
Example 3; C5H12 has 3 isomers which are:
o Pentane
o 2-Methylbutane
o 2,2-Dimethylpropane
Example 4; C4H10 has 2 isomers which are;
o Butane
o 2-Methylpropane
STEP 4: Nomenclature of Alkanes (15 Minutes).
o This chain is called the parent hydrocarbon.
Carbon to which the alkyl group is attached.
in the use of the lowest numbers; thus, II is called 2–‐ methylpentane
rather than 4–‐ methylpentane.
indicate this by the prefix di-, tri-, tetra- etc., to show how many of
these alkyl groups are there and indicate by various numbers the position
of each group, as in 2,2,4‐trimethyl-pentane.
[pic]
parent chain, name them in alphabetical order, as in 3,3‐diethyl-5-
isopropyl-4-methyloctane
[pic]
STEP 5: Chemical Structure of Alkanes (15 minutes).
molecular formula CnH2n+2, where n is the number of carbon atoms in
the chain.
and n-alkanes (n stands for normal)
[pic]
STEP 6: Chemical Properties of Alkanes (10 minutes).
|Activity: Brainstorming (5minutes) |
| |
|ASK students to pair up and brainstorm on the following question for 5 |
|minutes. |
| |
|What are the chemical properties of Alkanes? |
| |
|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 |
o Complete combustion (Under sufficient amount of oxygen (Air)) any
hydrocarbon produces carbon dioxide and water.
o Also, can react with very strong oxidizing agents like Potassium
permanganate, potassium dichromate, Manganese oxide, to produce carbon
dioxide and water.
o Halogenation is the replacement of one or more hydrogen atoms in an
organic compound by a halogen (Fluorine, Chlorine Bromine or Iodine).
o Under ultra violet light or temperature that makes up the free radical
chain for halogenation reaction to proceed and that is the first step.
o Cracking is the breakdown of large alkanes under high temperature and
pressure into smaller, more useful alkenes.
o Cracking of alkanes produce a mixture of alkenes and alkanes, cracking
is an example of thermal decomposition reaction.
o Conditions are Temperature of about 500°C and moderately low
pressures.
STEP 7: Chemical Reactions and Uses of Alkanes (30 minutes).
|Activity: Small Group Discussion (15 minutes) |
| |
|DIVIDE students into small groups |
| |
|ASK students to discuss in groups on the following questions |
|What are the reactions involving Alkanes? |
| |
|[pic]REFER Students to Book |
| |
|ALLOW students to discuss for 15 minutes |
| |
|ALLOW each group to present for 5 minutes |
| |
|CLARIFY and SUMMARIZE by using the contents below |
o Complete combustion (Under sufficient amount of oxygen (Air)) any
hydrocarbon produces carbon dioxide and water.
o Example; [pic]
o Halogenation is the replacement of one or more hydrogen atoms in an
organic compound by a halogen (Fluorine, Chlorine Bromine or
Iodine).
o Example;
[pic]
o Cracking is the breakdown of a large alkanes under high temperature
and pressure into smaller, more useful alkenes.
o Product of cracking of alkanes are alkenes and alkanes.
o Cracking is an example of thermal decomposition reaction at
temperature of about 500°C and moderately low pressures.
o Example;
[pic]
Uses of alkanes
o Alkane is a compound of halothane which is a general anesthetic agent.
diesel, furnace oil and wax which are used as fuels.
useful organic compounds.
o For example, methane on chlorinate on gives chloromethane,
dichloromethane, trichloromethane (chloroform) and tetrachloromethane.
STEP 8: Key Points (10 minutes).
carbons and hydrogen atoms and contain carbon-carbon single bonds.
structure.
have no isomers because there is only one way in arranging the molecule
in 3D structures but the rest of the alkane’s series might have an
isomer, which is called structure isomers.
names also called general or primary names or the un-systematic name and
The IUPAC name, or the systematic name.
cracking.
which is a general anaesthetic.
STEP 9: 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 Rao Nadendla (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.). California, 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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