JEE PYQ: Biomolecules And Polymers Question 18
Question 18 - 2020 (02 Sep Shift 1)
Consider the following reactions:
(i) Glucose + ROH $\xrightarrow{\text{dry HCl}}$ Acetal $\xrightarrow{x \text{ eq. of } (\text{CH}_3\text{CO})_2\text{O}}$ acetyl derivative (ii) Glucose $\xrightarrow{\text{Ni/H}_2}$ A $\xrightarrow{y \text{ eq. of } (\text{CH}_3\text{CO})_2\text{O}}$ acetyl derivative (iii) Glucose $\xrightarrow{z \text{ eq. of } (\text{CH}_3\text{CO})_2\text{O}}$ acetyl derivative
‘x’, ‘y’ and ‘z’ in these reactions are respectively.
(1) 5, 4 & 5
(2) 4, 6 & 5
(3) 4, 5 & 5
(4) 5, 6 & 5
Show Answer
Answer: (2)
Solution
(i) Glucose + ROH $\xrightarrow{\text{dry HCl}}$ Acetal (glucoside with OR, 4 free OH) $\xrightarrow{4 \text{ eq. } \text{Ac}_2\text{O}}$ acetyl derivative. (ii) Glucose $\xrightarrow{\text{Ni/H}_2}$ Sorbitol (6 OH groups) $\xrightarrow{6 \text{ eq. } \text{Ac}_2\text{O}}$ acetyl derivative. (iii) Glucose $\xrightarrow{5 \text{ eq. } \text{Ac}_2\text{O}}$ pentaacetate. Thus $x = 4$, $y = 6$ and $z = 5$.
BETA
