Acyl Chlorides of Pharmaceutical Importance
Session 14: Acyl Chlorides 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 acyl chlorides |
| | |Presentation | |
|3 |15 minutes |Presentation |Nomenclature of acyl chlorides |
|4 |15 minutes |Presentation |Physical Properties of Acyl |
| | | |Chlorides |
|5 |20 minutes |Buzzing |Preparation of Acyl Chlorides |
| | |Presentation | |
|6 |40 minutes |Group |Chemical Reactions involving acyl |
| | |discussion |chlorides |
| | |Presentation | |
|7 |05 minutes |Presentation |Key Points |
|8 |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 Acyl Chlorides (10 minutes).
|Activity: Brainstorming (5 minutes) |
| |
|Ask students to brainstorm on the following question: |
|What are acyl chlorides? |
| |
|ALLOW few students to respond. |
| |
|WRITE their responses on the flip chart/ board. |
| |
|CLARIFY and SUMMARISE by using the content below |
[pic]
acid is replaced by something else.
acid derivative.
[pic]
STEP 3: Nomenclature of Acyl Chlorides (15 minutes).
with the corresponding.
|carboxylic acid |acyl chloride |acyl chloride |
|name |name |formula |
|ethanoic acid |ethanoyl |CH3COCl |
| |chloride | |
|propanoic acid |propanoyl |CH3CH2COCl |
| |chloride | |
|butanoic acid |butanoyl |CH3CH2CH2COCl |
| |chloride | |
replacing -oic acid by -ly.
in the -COCl group counts as the number 1 carbon.
[pic]
from methanoic acid.
carbon monoxide and HCl.
STEP 4: Physical properties of acyl chlorides (15 minutes).
o An acyl chloride like ethanoyl chloride is a colourless fuming liquid.
o The strong smell of ethanoyl chloride is a mixture of the smell of
vinegar (ethanoic acid) and the acrid smell of hydrogen chloride gas.
o The smell and the fumes are because ethanoyl chloride reacts with
water vapour in the air.
o Acyl chlorides can't be said to dissolve in water because they react
(often violently) with it.
o The strong reaction means that it is impossible to get a simple
aqueous solution of an acyl chloride.
o Taking ethanoyl chloride as typical:
o Ethanoyl chloride boils at 51°C.
o It is a polar molecule, and so has dipole-dipole attractions between
its molecules as well as van der Waals dispersion forces.
o However, it doesn't form hydrogen bonds.
o Its boiling point is therefore higher than, say, an alkane of similar
size (which has no permanent dipoles), but not as high as a similarly
sized alcohol (which forms hydrogen bonds in addition to everything
else.)
STEP 5: Preparation of Acyl Chlorides (20 minutes).
|Activity: Buzzing (5minutes) |
| |
|ASK students to pair up and buzz on the following question for 5 |
|minutes. |
|How are acyl chlorides prepared? |
| |
|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 |
thionyl (SOCl2).
[pic]
[pic]
STEP 6: Chemical Reactions involving acyl chlorides (40 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 chemical reactions involving Esters? |
|[pic]REFER Students to Book |
|ALLOW students to discuss for 10 minutes |
| |
|ALLOW each group to present for 5 minutes |
| |
|CLARIFY and SUMMARIZE by using the contents below |
o Acyl chlorides are extremely reactive, and in their reactions the
chlorine atom is replaced by other groups.
o In each case, in the first instance, hydrogen chloride gas is produced
as steamy acidic fumes.
o However, in some cases the hydrogen chloride goes on to react with one
of the substances in the reaction mixture.
o Taking ethanoyl chloride as typical, the initial reaction is of this
kind:
[pic][pic]
o The reactions involve compounds like water, alcohols and phenols, or
ammonia and amines.
o All of these particular cases contain a very electronegative element
with an active lone pair of electrons – either oxygen or nitrogen.
STEP 8: Key Points (05 minutes).
which at least one –OH (hydroxyl) group is replaced by a halogen
chlorine.
thionyl.
chlorine atom is replaced by other groups
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 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.). 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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