CH2(OH)-CH(OH)-CH2(OH) + KHSO4 ={dehydration}.
CH2=CH-CHO + 2H2O
Glycerol on heating potassium hydrogen sulphate undergoes dehydration with removal of two water molecule from the glycerol molecule, resulting in formation of unsaturated aldehyde that is acrylic aldehyde ( acrolein).
3steps are 1st dehydration than tautomerization & 2nd dehydration.

Acrolein Formation from Glycerol

Introduction:
Acrolein is an unsaturated aldehyde with the chemical formula CH2=CH-CHO. It is an important industrial chemical used in the production of plastics, dyes, and pharmaceuticals. Acrolein can be formed by the heating of glycerol (a trihydroxy alcohol) in the presence of certain reagents. Let's explore the options given and determine which reagent is responsible for the formation of acrolein.

Options:
a) Acidified KMnO4
b) Bromine water
c) KHSO4
d) HNO3

Explanation:

a) Acidified KMnO4:
When glycerol is heated with acidified KMnO4, it undergoes oxidation to form glyceric acid. This reaction does not result in the formation of acrolein.

b) Bromine water:
Bromine water can react with glycerol to form 3-bromo-1,2-propanediol. This reaction does not involve the formation of acrolein.

c) KHSO4:
When glycerol is heated with KHSO4, it undergoes dehydration to form acrolein. KHSO4 acts as a catalyst in this reaction by removing water molecules from glycerol, leading to the formation of acrolein.

d) HNO3:
Heating glycerol with HNO3 results in the formation of glycerol trinitrate (nitroglycerin). This reaction does not involve the formation of acrolein.

Conclusion:
From the given options, the correct answer is option c) KHSO4. When glycerol is heated with KHSO4, it undergoes dehydration to form acrolein. It is important to note that the formation of acrolein from glycerol requires the presence of a suitable catalyst, such as KHSO4.