Starch, when boiled with dilute sulphuric acid under high pressure, gives compound $A$. On prolonged heating…

Starch, when boiled with dilute sulphuric acid under high pressure, gives compound $A$. On prolonged heating with hydroiodic acid, $A$ gives compound $B$. What is the compound $B$ ?
  1. $\mathrm{CH}_3-\left(\mathrm{CH}_2ight)_4-\mathrm{CH}_3$
  2. $\mathrm{HO}-\mathrm{CH}_2-(\mathrm{CHOH})_4-\mathrm{CHO}$
  3. $\mathrm{HOOC}-(\mathrm{CHOH})_4-\mathrm{COOH}$
  4. $\mathrm{HO}-\mathrm{CH}_2-(\mathrm{CHOH})_4-\mathrm{COOH}$

Solution

Starch is a polysaccharide with formula $\left(\mathrm{C}_6 \mathrm{H}_{10} \mathrm{O}_5ight)_2$, when starch is boiled with dil. $\mathrm{H}_2 \mathrm{SO}_4$ under high pressure, it hydrolysed to give glucose.
Which one pronged heating with $\mathrm{HI}$ gives $\mathrm{C}_6 \mathrm{H}_{14}$ i.c. $\mathrm{CH}_3-\left(\mathrm{CH}_2ight)_4 \cdot \mathrm{CH}_3$. The reaction occurs as follows,
Hence, option (a) is the correct answer. undefined

Asked in: JEE-TOPICTESTS-CHEMISTRY

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