A and B are two funtional isomers of compound C_(3)H_(6)O. On heating with NaOH and I_(2), isomer B forms yellow precipitate of iodoform whereas isomer A does not form any precipitate. Write the structures of A and B.

A and B are two funtional isomers of compound C_(3)H_(6)O. On heating

1.	A and B are two funtional isomers of compound C_(3)H_(6)O. On heating with NaOH and I_(2), isomer B forms yellow precipitate of iodoform whereas isomer A does not form any precipitate. Write the structures of A and B.
Answer» Solution :Two possible functional isomes having the M.F. `C_(3)H_(6)O` are: `underset("Propanal (A)")(CH_(3)CH_(2)CHO)""underset("Acetone (B)")(CH_(3)COCH_(3))` Since isomer B on HEATING with NaOH and `I_(2)` forms YELLOW ppt. of `CHI_(3)`, therefore, it MUST be a methyl ketone, i.e., isomer B is acetone `underset("Acetone (B)")(CH_(3)COCH_(3)) underset(("Iodoform reaction")) overset(I_(2)//NaOH,Delta)to underset("Sod. acetate")(CH_(3)COONa)+ underset("Iodoform (yellow ppt.)")(CHI_(3))` In other words, isomer A which does not give any ppt. with `NaOH//I_(2)` must be propanal `underset("Propanal (A)")(CH_(3)CH_(2)CHO) underset(Delta)overset(I_(2)//NaOH)to ` No ppt. of `CHI_(3)`.