Biomolecules



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    Is it possible that a carbohydrate is reduced either only by Fehling solution or by tollen's reagent? If yes,then will it be a reducing sugar or non reducing?



  • @100-miles
    Both are necessary
    We GENERALLY say the ones which are reduced by Fehling's are also reduced by tollen's so then you can see acc to fehlings



  • @100-miles Tollens' reagent : It is an alkaline solution of ammoniacal silver nitrate and is used to test for aldehydes. Silver ions in the presence of hydroxide ions come out of solution as a brown precipitate of silver(I) oxide, Ag2O(s). This precipitate dissolves in aqueous ammonia, forming the diamminesilver(I) ion, [Ag(NH3)2]+.

    Fehling's reagent : It is a blue colored basic solution of bistartratocuprate(II) complex. It is used as a chemical test used to differentiate between water-soluble aldehyde and ketone functional groups, and as a test for monosaccharides.

    I think it is not possible. If it is reduced by fehling's solution then it will also get reduced by tollen's reagent and hence they will be called as reducing sugar and if they can't reduce then they will be called as non reducing sugar. (This is the case in carbohydrate/sugar.)

    Remarks: Benzaldehyde gives tollen's as well as Schiff's test but not fehling's test because benzaldehyde does not contain Alpha hydrogen and hence cannot form intermediate to undergo further reaction with fehling's solution.



  • @100-miles
    Practise Questions of biomolecules on dubbtr.com available both in practice mode and as time-based test
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