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Thread: Chemistry of sugars

  1. #1 Chemistry of sugars 
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    Why does the 'D' carbon of glucose and fructose have to be involved in the reversible formation of pyranose in the former and furanose in the latter?

    Also, please let me know whether ribulose has a closed ring form in equilibrium to a open chain form. :x


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  3. #2  
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    To my knowledge there is no nomenclature which refers to the ā€˜Dā€™ carbon; you have D en L sugars (D-glucose being the mirror molecule of L-glucose). Normally you number the Carbons.

    The reason why glucose forms a pyranose (6 membered ring) and fructose forms a furanose (5 membered ring) is because glucose is a aldose (monosaccharide carrying his carbonyl group as an aldehyde) and fructose is a ketose (monosaccharide carrying his carbonyl group as a keton). Or better put this the main reason.


    The C forming the ring-structure for glucose is C1 (for fructose it is C2).


    The carbon that is always involved in forming the ring-structure is the C of the carbonyl function of the linear monosaccharide. If you think back to your organic chemistry, you will see that this is most electrophilic C plus it is able to loose its dubble binding.

    Just let me know if this helps you, otherwise I will look for links or figures were the reaction is schematized.


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    Maybe with D-carbon hes referring to the anomeric carbon atom.
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  5. #4  
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    Quote Originally Posted by Ultrashogun
    Maybe with D-carbon hes referring to the anomeric carbon atom.
    Okay then the reason why this carbon is involved in forming the ringstructure its just per definition.
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