Chemical Reactions
Chapter Name : Haloalkanes And Haloarenes |
Sub Topic Code : 102_12_10_06_02 |
Topic Name : Chemical Reactions |
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Sub Topic Name : Nucleophilic Substitution Reactions |
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Introduction
• In this reaction, a nucleophile reacts with haloalkane (the substrate) having a partial positive charge on the carbon atom bonded to halogen. • A substitution reaction takes place and halogen atom, called leaving group departs as halide ion. Since the substitution reaction is initiated by a nucleophile, it is called nucleophilic substitution reaction. • This reaction takes place in two different ways: • Substitution nucleophilic bimolecular (SN2) • Substitution nucleophilic unimolecular (SN1) • A SN2 reaction proceeds with complete stereochemical inversion. • a SN1 reaction proceeds with racemisation.
Pre-Requisites:
Elements, bond, halides
Activity:
• Synthetic halogen compounds, viz. • chloroquine is used for the treatment of malaria; • Halothane is used as an anaesthetic during surgery.
Real Life Question:
What are haloarenes and haloalkane?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| - Haloalkanes - Haloarenes | • Haloalkanes contain halogen atom(s) attached to the sp3 hybridised carbon atom of an alkyl group. • Haloarenes contain halogen atom(s) attached to sp2 hybridised carbon atom(s) of an aryl group. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| • Chlorine containing antibiotic, chloramphenicol, produced by soil microorganisms is very effective for the treatment of typhoid fever. |
Real life uses :
• Synthetic halogen compounds, viz. ? chloroquine is used for the treatment of malaria; ? Halothane is used as an anesthetic during surgery..
Places to visit :
Pharmacy.
Practical examples around us
| Examples | Explainations |
|---|---|
| • Synthetic halogen compounds, viz. ? chloroquine is used for the treatment of malaria; ? Halothane is used as an anesthetic during surgery. |
What you learn in Theory:
• In this reaction, a nucleophile reacts with haloalkane (the substrate) having a partial positive charge on the carbon atom bonded to halogen. • A substitution reaction takes place and halogen atom, called leaving group departs as halide ion. Since the substitution reaction is initiated by a nucleophile, it is called nucleophilic substitution reaction. • This reaction takes place in two different ways: • Substitution nucleophilic bimolecular (SN2) • Substitution nucleophilic unimolecular (SN1) • A SN2 reaction proceeds with complete stereochemical inversion. • a SN1 reaction proceeds with racemisation.
What you learn in Practice:
• Haloalkanes and Haloarenes are classified based on the number of halogen compounds contained in them.