Question

What happens when glycerol is heated with $KHS{{O}_{4}}$?

Answer 1

Hint: Glycerol is a type of poly hydroxyl molecule called as a triol that has 3 alcohol functional groups with a formula, ${{C}_{3}}{{H}_{8}}{{O}_{3}}$. Potassium hydrogen sulphate is $KHS{{O}_{4}}$ that is used as an acid based catalyst for organic reactions. The heating of glycerol with potassium bisulphate can result in a dehydration reaction.

Complete answer:
A glycerol is a poly hydroxyl organic compound that has 3 alcoholic groups (OH groups) also called a triol. Glycerol is heated in the presence of potassium bisulphate that results in an acid catalyzed dehydration reaction, as potassium bisulphate acts as an acid in organic reactions. This acid catalyzed dehydration results in the removal of two units of water molecules from the glycerol that forms a compound having an unsaturated group and an aldehyde group that is $\alpha ,\beta $- unsaturated aldehyde also called as acryl aldehyde.
The reaction is as follows:

Hence, when glycerol is heated with $KHS{{O}_{4}}$ then a dehydration reaction occurs by the removal of water that results in the formation of an $\alpha ,\beta $- unsaturated aldehyde also called as acryl aldehyde.

Note:
Glycerol is a polyol compound that is a common by-product in the soap industry. Glycerol has moisturizing properties and is used in skin softening. On treating it with potassium bisulphate, acrolein is formed that is $\alpha ,\beta $- unsaturated aldehyde. Acrolein is used in synthesis of acrylic acid. Also acrolein is formed when any oil or fat is subjected to heat.