Question

Explain the preparation of glucose from the cane sugar.

Answer 1

Hint: Cane sugar (sucrose) is boiled with dilute HCl or ${H_2}S{O_4}$. Hydrolysis gives an equimolar mixture of glucose and fructose. The mixture is then cooled and alcohol added. Insoluble glucose crystallizes out first on cooling and is separated by filtration.

Complete step by step answer:
Glucose can be prepared in the laboratory by boiling sucrose (cane sugar) with dilute hydrochloric acid or sulphuric acid for about two hours. This hydrolyses sucrose to glucose and fructose. In order to separate glucose from fructose, alcohol is added during cooling. Glucose is almost insoluble in alcohol.it crystallizes out first, while fructose is more soluble. It remains in the solution. The solution is filtered to obtain the crystals of glucose.

By boiling sucrose with dilute HCL or ${H_2}S{O_4}$ in alcoholic solution
${C_{12}}{H_{22}}{O_{11}} + {H_2}O\xrightarrow{{{H^ + }}}{C_6}{H_{12}}{O_6} + {C_6}{H_{12}}{O_6}$

By boiling starch with dilute ${H_2}S{O_4}$, at $393{\text{ }}K$,under pressure
${({H_2}S{O_4})_n} + n{H_2}O\xrightarrow[{393k,2 - 3{\text{ }}atoms}]{{{H^ + }}}n{C_6}{H_{12}}{O_6}$


Note:
Sugar, any of numerous sweet, colourless, water-soluble compounds present in the sap of seed plants and the milk of mammals and making up the simplest group of carbohydrates. (See also carbohydrates.) The most common sugar is sucrose, a crystalline tabletop and industrial sweetener used in foods and beverages.
As a chemical term, “sugar” usually refers to all carbohydrates of the general formula ${C_n}{({H_2}O)_{n - 1}}$. Sucrose is a disaccharide, or double sugar, being composed of one molecule of glucose linked to one molecule of fructose. Because one molecule of water $({H_2}O)$ is lost in the condensation reaction linking glucose to fructose, sucrose is represented by the formula ${C_{12}}{H_{22}}{O_{11}}$ (following the general formula ${C_n}{({H_2}O)_{n - 1}}$.