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EEJ MAIN Chemistry QUESTION #5564
Question 1
Which of the following compounds will behave as a reducing sugar in an aqueous KOH solution? (A free hemiacetal/anomeric –OH is required for reducing sugar property)
  • The furanose with two free –OH groups on anomeric carbon✔️
  • The furanose with –OCH₃ at anomeric position
  • The furanose with –OCOCH₃ at anomeric position
  • The pyranose with –CH₂OCH₃ group
Correct Answer Explanation
A reducing sugar must have a free anomeric –OH (hemiacetal) that can open to give an aldehyde/ketone form. Option A shows a furanose ring with a free –OH at the anomeric carbon, which can open and reduce. Options B and C have the anomeric –OH blocked as an ether or ester (non-reducing). Option D also has a blocked anomeric position.