D and L sugars

Discussion in 'DAT Discussions' started by rockets32, Jul 26, 2006.

  1. rockets32

    rockets32 Junior Member

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    Anyone know how to tell the difference? These questions always seem to get me and I think the answer has something to do with the location of an OH group.

    Thanks
     
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  3. dat_student

    dat_student Junior Member

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    L sugars have the hydroxyl group at the lowest stereogenic center pointing to the left in Fischer projection (Remember: L >> Left)

    D sugars have the hydroxyl group at the lowest stereogenic center pointing to the right in Fischer projection. Most naturally occuring sugars are D sugars.

    The ring forms are usually represented using the Haworth projections. -OH on the right in a Fischer projection is up in a Haworth projection. -OH on the left in a Fischer projection is down in a Haworth projection. For D sugars the terminal -CH2OH group is always up in Haworth projections whereas for L sugars the -CH2OH group is down.
     

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