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Reducing Sugars quiz #1 Flashcards

Reducing Sugars quiz #1
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  • What structural feature must a sugar possess to be classified as a reducing sugar?
    A reducing sugar must have a free aldehyde group or be able to generate one, typically indicated by the presence of a free hemiacetal or hemiketal group.
  • Why are hemiacetals and hemiketals considered important in identifying reducing sugars?
    Hemiacetals and hemiketals are important because their instability allows them to equilibrate with the linear form of the sugar, which can expose a free aldehyde group, making the sugar reducing.
  • How do non-reducing sugars differ from reducing sugars in terms of their chemical structure?
    Non-reducing sugars have full acetal or ketal groups at their anomeric carbons, which prevents them from being oxidized and thus they cannot act as reducing agents.
  • Can ketoses be considered reducing sugars? Explain your answer.
    Yes, ketoses can be considered reducing sugars because they can rearrange to form aldoses, which have free aldehyde groups capable of being oxidized.
  • What structural feature must a sugar possess to be classified as a reducing sugar?
    A reducing sugar must have a free aldehyde group or be able to generate one, usually indicated by the presence of a free hemiacetal or hemiketal group.
  • Why are hemiacetals and hemiketals considered important in identifying reducing sugars?
    Hemiacetals and hemiketals are important because their instability allows them to equilibrate with the linear form of the sugar, exposing a free aldehyde group and making the sugar reducing.
  • How do non-reducing sugars differ from reducing sugars in terms of their chemical structure?
    Non-reducing sugars have full acetal or ketal groups at their anomeric carbons, which prevents them from being oxidized and thus they cannot act as reducing agents.
  • Can ketoses be considered reducing sugars? Explain your answer.
    Yes, ketoses can be considered reducing sugars because they can rearrange to form aldoses, which have free aldehyde groups capable of being oxidized.
  • What is the significance of the anomeric carbon in determining whether a cyclic sugar is reducing or non-reducing?
    The anomeric carbon must be part of a free hemiacetal or hemiketal group for the cyclic sugar to be reducing; if it is part of a full acetal or ketal, the sugar is non-reducing.
  • Why are acetal and ketal groups more stable than hemiacetal and hemiketal groups in sugars?
    Acetal and ketal groups are more stable because they have two OR groups branching off the anomeric carbon, making them less reactive and less likely to revert to the linear form.