TBR carb. question

[nickelbackfan]

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Are all cyclic sugars hemiactyl or hemiketal? IE is it possible to have a cyclic monosacharide that is acetal or ketal.

 

[Hanguk]

I would think so....all you're doing is changing an OH to an OR to go from hemiacetal to acetal

 

[CodeRedDew]

It is possible, but the monosaccharide would have to react with something else (doesnt have to be another sugar) so that the OH can be transformed into an OR group. So as far as I know, just a monosaccharide by itself is not sufficient enough to produce a ketal/acetal (unless it dimerizes with itself).


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[sciencebooks]

It is possible, but the monosaccharide would have to react with something else (doesnt have to be another sugar) so that the OH can be transformed into an OR group. So as far as I know, just a monosaccharide by itself is not sufficient enough to produce a ketal/acetal (unless it dimerizes with itself).


Sent from my iPhone

That's what I would think. Because if you think about it, in the monomer, there's an always alcohol on the anomeric carbon. Then when it dimerizes, the second part adds there. But at least one of the sugars (at the end) will always have a hemi- configuration, wouldn't it? Because at least one (at the end of the chain) will always have that alcohol at the anomeric position?

 

[CodeRedDew]

That's what I would think. Because if you think about it, in the monomer, there's an always alcohol on the anomeric carbon. Then when it dimerizes, the second part adds there. But at least one of the sugars (at the end) will always have a hemi- configuration, wouldn't it? Because at least one (at the end of the chain) will always have that alcohol at the anomeric position?

Not necessarily because you can have a disaccharide where the two anomeric carbons are joined together. If my biochem memory serves me correctly, we refer fo those as non-reducing sugars.


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[sciencebooks]

Not necessarily because you can have a disaccharide where the two anomeric carbons are joined together. If my biochem memory serves me correctly, we refer fo those as non-reducing sugars.


Sent from my iPhone

Oh, okay, that would make sense. I don't know why I assumed it never went that way.