Carbohydrates: glucose, fructose — structure, tests (Tollens, Fehling)
Biomolecules · Chemistry
Study notes
Distinguish glucose from fructose using bromine water. Step 1: Both reduce Tollens'/Fehling's (fructose via enediol rearrangement in base). Step 2: Bromine water (mild oxidant): oxidizes glucose's aldehyde → gluconic acid (decolourises Br₂). Step 3: Fructose (ketose): no oxidation → brown colour stays. Step 4: Bromine water distinguishes where Fehling's can't — oxidant strength matters!