Erythro and Threo Nomenclature

erythro2

source : oc hempal.org

Erythro and Threo Nomenclature-

 

This nomenclature is based on four carbon aldose sugars ; erythrose & threose.

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Erythrose                                  Threose

Compounds having two different chiral or assymetric carbon atoms are named by using prefix- erythro or threo. When two same groups are on the same side of chiral carbon atom in fischer Projection formula then it is ‘ erythrose ‘. When two identical groups are on the opposite side of chiral carbon atom in Fischer Projection formula then it is ‘threose’

Ex.

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(Erythrose)                            (Threose)