Fischer → Haworth: Converting Open-Chain Sugars into Ring Forms (Hemiacetal Formation)

Learn how to convert Fischer projections to Haworth rings: hemiacetal formation, anomeric carbon, alpha vs beta, and quick exam rules.

• Reaction: Aldose open chain ⇌ cyclic hemiacetal
• What it does: Forms pyranose/furanose rings
• Typical conditions: Aqueous equilibrium; acid/base catalysis accelerates
• Key intermediate: Open-chain aldehyde + intramolecular nucleophilic addition
• Driving force: Formation of stable ring + hemiacetal
• Exam type: Stereochemistry
• Exam type: Projection conversion