Question

A compound with molecular formula C₄H₁₀O₃ is converted by the action of acetyl chloride to a compound with molecular weight 190°. The original compound has 

(a) 1-OH group 

(b) 2-OH groups 

(e) 3-OH groups 

(d) no-OH group

Answer 1

(b) 2-OH groups 

Molecular wt. of the compound = 48 + 10 + 48 = 106

Change in molecular weight = 190 - 106 = 84 

Since the reaction involves the use of acetyl chloride, -COCH₃ group(s) must have be introduced during the reaction. Introduction of one -COCH₃ group (molecular weight e increases the molecular weight by 42 (43 - 1 for the 1 H atom removed); the compound have 2-OH groups.