Organic Chemistry: Addition Reactions

Overview

• Addition Reaction: Involves adding atoms to a double-bonded compound, turning it into a single-bonded compound.
• Typically involves alkenes (compounds with double bonds) forming alkanes (compounds with single bonds).
• Key types of addition reactions: Hydrogenation, Halogenation, Hydrohalogenation, and Hydration.

Types of Addition Reactions

Hydrogenation

• Definition: Adding hydrogen (H2) to alkenes.
• Example:
  • Compound: But-1-ene
  • Reacts with: H2
  • Product: Butane (single-bonded compound)
• Catalyst: Often uses platinum as a catalyst.

Halogenation

• Definition: Adding halogen molecules (XX) such as Cl2, Br2, I2, or F2 to alkenes.
• Example:
  • Adding Cl2 to hex-1-ene
  • Product: 1,2-dichlorohexane (haloalkane)
• Reaction Conditions: Occurs at room temperature, no water or heat required.

Hydrohalogenation

• Definition: Adding a hydrogen atom and a halogen atom (e.g., HCl, HBr) to alkenes.
• Example:
  • Compound: But-1-ene
  • Reacts with: HBr
  • Product: Haloalkane
• Reaction Conditions: No water present; follows Markovnikov's rule.
• Markovnikov's Rule:
  • Hydrogen adds to the carbon with the most hydrogen atoms already.
  • Determines the major (most common) product.

Hydration

• Definition: Adding water (H2O) to alkenes.
• Example:
  • Compound: But-1-ene
  • Reacts with: H2O
  • Product: Butan-2-ol (alcohol)
• Reaction Conditions: Requires a strong acid catalyst (e.g., sulfuric or phosphoric acid), water in excess.
• Markovnikov's Rule:
  • Hydrogen from water adds to the carbon with the most hydrogens.

Reaction Conditions and Catalysts

• Each reaction type has specific conditions and catalysts that must be met for the reaction to occur.
• Examples:
  • Hydrogenation often uses platinum.
  • Halogenation occurs at room temperature.
  • Hydration requires strong acid catalysts and excess water.

Conclusion

• Addition reactions are characterized by the conversion of double bonds to single bonds.
• Understanding the type of addition reaction and its specific conditions is crucial.
• Markovnikov's rule is essential for predicting major products in hydrohalogenation and hydration.
• Next topics: Elimination and substitution reactions.

Note: For further details on major vs minor products and Markovnikov's rule, refer to additional resources or videos provided by the instructor.