Question

On the basis of which evidence D-glucose was assigned the following structure?

$\underset{C{H}_{2}OH}{\underset{|}{\underset{(CHOH{)}_4}{\underset{|}{CHO}}}}$

Answer 1

Evidences on the basis of which glucose was assigned the following structure are as follows
(i) Glucose on reaction with HI produces n hexane which indicates presence of six carbaon atom linked in a having straight chain.
$C_6{H}_{12}{O}_6\stackrel{HI}{\to }nhexane$
(ii) Glucose on reaction with acetic anhyride produces glucose penta acetate which indicates presencve of five OH groups.
$C_6{H}_{12}{O}_6\stackrel{A{C}_{2}O}{\to }$ Glucose pentaacetate
(iii) Glucose on oxidation with bromine water produces gluconic acid indicates presence of -CHO group.
$Glucose\stackrel{B{r}_2/H_{2}O}{\to }$ Gluconic acid
(iv) Glucose on reaction with $HN{O}_3$ produces saccharic acid which indicates presence of one primary OH group.