Organic Chemistry Reaction Pathways

Alkenes are your starting point for many important reactions. When you treat an alkene with a hydrogen halide at room temperature, you'll get a haloalkane - this is a straightforward addition reaction that's dead useful for creating new functional groups.

From haloalkanes, you've got loads of options. Mix with NaCN in ethanol and you'll form a nitrile. Use NH₃ in ethanol instead and you'll create an amine. Want an alcohol? NaOH in aqueous solution under reflux does the trick perfectly.

Primary alcohols are proper versatile. You can dehydrate them using concentrated H₂SO₄ under reflux to get back to alkenes. Alternatively, use H₃PO₄ with water for hydration reactions going the opposite direction.

The esterification process is crucial for A-levels. Combine a carboxylic acid with H₂SO₄ under reflux to form an ester. You can reverse this through hydrolysis using either dilute acid under reflux or NaOH under reflux for alkaline hydrolysis, which gives you the sodium salt of the carboxylic acid plus an alcohol.

Top Tip: Reflux conditions mean heating with a condenser attached - this lets you heat reactions without losing volatile substances through evaporation.

Oxidation and reduction reactions complete the picture. Use K₂Cr₂O₇ with H₂SO₄ under distillation to oxidise primary alcohols to aldehydes, or under reflux to push further to carboxylic acids. For reduction, NaBH₄ in water will convert aldehydes back to primary alcohols, whilst H₂ with Ni catalyst reduces many functional groups.