Describe laboratory method for preparation of glucose . Write the reaction that indicates the presence of - CHO group in glucose .

Explanation

Laboratory method for the preperation of glucose :
Glucose can be prepared by boiling sucrose with dilute hydrchloric acid or dilute sulphuric acid for two hours . Sucrose gives glucose and fructose on hydrolysis .
`underset("Sucrose")(C_(12)H_(22)O_(11))+H_(2)O overset(H^(+))underset(("dil. HCl"))rarr underset("Glucose")(C_(6)H_(12)O_(6))+underset("Fructose")(C_(6)H_(12)O_(6))`
In order to separate glucose from fructose , alcohol during cooling .
Glucose crystallizes out first as it is insouble in alchol . While fructose is soluble in alcohol. while fructose is soluable , so it still rmaions in the solution then , the solution is fitered to obtain crystals of glucose . ,brgt action of bromine water on glucose : ,
The oxidation of glucose with bromine water forms gluconic acid . This indicatyes the presence of aldehyde group .