glucose ring opening question

[theonlytycrane]

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What would be the best way to describe glucose ring opening? KA says hydration, but I don't think water is being added? I just think of deprotonation of the hydroxyl O-H, the electrons reforming the carbonyl group, and the -O picking up a proton.

 

[rdub]

You can also protonate the oxygen in the ring, and then have the hydroxyl kick electrons down to open the ring up.

 

[BerkReviewTeach]

View attachment 203391

What would be the best way to describe glucose ring opening? KA says hydration, but I don't think water is being added? I just think of deprotonation of the hydroxyl O-H, the electrons reforming the carbonyl group, and the -O picking up a proton.

I assume they may have mistakenly been thinking about cleaving linkages as opposed to ring opening and closing (mutarotation). The answer choices describe reactions (as opposed to mechanisms), so use this question as a trigger to review the above mechanism, but you probably shouldn't worry too much about any of the answer choices.

 

[7331poas]

Actually the correct answer would be elimination. An alpha elimination to be precise.