3.10.2

Elimination Reactions

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Elimination Reactions

When a halogenoalkane is reacted with hydroxide ions, you can get an alcohol via substitution. But there is another reaction that can happen - elimination - which produces an alkene.

Elimination mechanism

Elimination mechanism

  • The image shows the mechanism for the elimination reaction of a halogenoalkane to form an alkene.
    • All the steps happen at the same time - it is a one step process.
Elimination

Elimination

  • Hydroxide ions are nucleophiles, but they are also bases.
  • They can take a proton off of a halogenoalkane if the next-door carbons have protons on them.
    • This results in formation of an alkene.
Diagram
Which reaction?

Which reaction?

  • Hydroxide reacting with a halogenoalkane can either eliminate to produce an alkene or substitute to produce an alcohol.
    • Both are very possible.
  • To promote the elimination reaction, we can:
    • Use ethanol as the solvent rather than water.
    • Heat the reaction under reflux conditions.
      • Reflux involves using a reflux condenser to condense gases back into the reaction flask.
Jump to other topics
1

Structure - Models of the Particulate of Matter

2

Structure - Models of Bonding & Structure

3

Structure - Classification of Matter

3.1

The Periodic Table: Classification of Elements

3.2

Periodic Trends

3.3

Group 1 Alkali Metals

3.4

Halogens

3.5

Noble gases, group 18

3.6

Functional Groups: Classification of Organic

3.7

Functional Group Chemistry

3.8

Alkanes

3.9

Alcohols

3.10

Halogenoalkanes

4

Reactivity - What Drives Chemical Reaction?

5

Reactivity - How Much, How Fast & How Far?

6

Reactivity - The Mechanisms of Chemical Change

7

Measurement, Data Processing & Analysis

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