Test for Unsaturation Lecture Notes

Introduction to Saturation and Unsaturation

• Saturated Molecules:
  • Contain only carbon-to-carbon single bonds.
  • Examples: Alkanes, Cycloalkanes.
• Unsaturated Molecules:
  • Contain carbon-to-carbon multiple bonds.
  • Example: Alkenes (with carbon-to-carbon double bonds).

Testing for Unsaturation

• Bromine Water Test:
  • Used to differentiate between saturated and unsaturated molecules.
  • Unsaturated Compounds:
    • Rapidly decolourise bromine water.
    • Reaction involves opening of the carbon-to-carbon double bond.
    • Bromine (Br₂, brown) adds across the double bond causing the brown color to disappear.
  • Saturated Compounds:
    • Bromine is not decolourised as there are no double bonds to react with.

Examples

• Methane:
  • Does not show a positive test for unsaturation.
• Propene:
  • Contains a carbon-to-carbon double bond.
  • Shows a positive test with bromine water.
• Cyclopropane:
  • Contains only single carbon-to-carbon bonds.
  • Does not show a positive test for unsaturation.
• 2-Methylbutene:
  • An alkene with a double bond.
  • Shows a positive result with bromine water.

Conclusion

• Bromine water test is an effective method for identifying unsaturation in organic molecules.

Additional Information

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