Question

A chalcone was synthesized by reacting 101 mg of acetaphenone with 122 mg of p-anisaldehyde and 2.0 mL of 10 M NaOH. The resulting aldol product underwent dehdration under the reaction conditions to produce 173 mg of chalcone.

Find the limiting reagent, theoretical yield, actual yield and percent yield.

Answer 1

moles of acetophenone = 101 mg /120.15 = 0.841 millimoles

moles of anisaldehyde = 122 mg /136.15 = 0.896 millimoles

moles of NaOH =2 x 2.13 /39.99 = 0.106 mole

One mole of both acetophenone and p- anisaldehyde must react to form the chalcone but here the moles of acetophenone are less so it is the limiting reagent.

theoretical yield :-

as one mole of both reactabts react to form one mole of chalcone .But here the limiting reagent is acetophenone

so the theoretical tield must be = 0.841 millimol x 238.28 gmol^-1 = 200.39 mg

Actual yield = 173 mg

Percent yield = 173 x 100 / 200.39 = 86.33 %