Question

Acid or enzyme hydrolysis of sucrose to give an equimolar mixture of glucose and fructose is called:

• A. Esterification
• B. Inversion
• C. Saponification
• D. Insertion

Answer 1

The correct option is B Inversion

$\underset{Sucrose}{C_{12}{H}_{22}{O}_{11}}+H_{2}O\stackrel{H^{+}}{\to }\underset{D-glucose}{C_6{H}_{12}{O}_6}+\underset{D-fructose}{C_6{H}_{12}{O}_6}$

$[\alpha {]}_D=+{66.5}^o$ $[\alpha {]}_D={52.5}^o[\alpha {]}_D=-{92.4}^o$

Acid or enzyme hydrolysis of sucrose to give an equimolar mixture of glucose and fructose is called inversion.

Sucrose is dextrorotatory but after hydrolysis gives dextrorotary glucose and laevorotatory fructose. Since the laevorotation of fructose (-92.4 ) is more than dextrotation of glucose (+52.5) the mixture is laevorotatory.

Thus hydrolysis of sucrose brings a change in the sign of rotation from dextro(+) is laevo(-) and is known as inversion and the mixture is known as invert sugar.

Sucrose solution is fermented by yeast when the enzyme invertase hydrolyses sucrose to glucose and fructose.

Option B is correct.