1. Tardigrade
  2. Question
  3. Chemistry
  4. A carbohydrate X having molecular weight 180 g mol-1 has one primary alcoholic group and four secondary alcoholic groups. It reacts with acetic anhydride to form pentaacetate. The molecular weight of pentaacetate formed is

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Q. A carbohydrate X having molecular weight $180\, g\, mol^{-1}$ has one primary alcoholic group and four secondary alcoholic groups. It reacts with acetic anhydride to form pentaacetate. The molecular weight of pentaacetate formed is

Biomolecules

Solution:

The possible structure of X and reaction with
Molecular weight of $CH3CO-$ group = 43, since ‘H’ is replaced by $-COCH_3$, therefore, increase in weight per $COCH_3$ is 42.
Molecular weight of glucose pentaacetate $= 180 + 5 × 42 = 180 + 210 = 390 g \,mol^{-1}$

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