Question

Which of the following is not true about acetal?

a) pH control between 3-4 is necessary as it can induce hydrolysis of acetal outside of this pH window

b) Two equivalents of alcohol is needed to protect aldehyde

c) Alcohol can be protected in the form of acetal

d) Azeotrope is involved in dehydration step when toluene is used as solvents.

e) none of A-D

Answer 1

a) Acetals are stable in basic conditions, means they are stable in high pH but not in an acidic pH range. Thus the statement "a" is not true.

b) To form acetal and protect aldehyde we always need two equivalents of alcohol (in case of od diol we need it one equivalent!). So the statement "b" is true.

c) alcohols can be protected as an acetal.

d) toluene and water form an azeotropic mixture, hence in the dehydration step azeotrope is involved. Thus statement "d" is true.

The answer is option "a".