Question

Oxidation of Methoxyacetophenone to Anisic Acid

1. Why did you lower the pH of the reaction mixture to 2, rather than to some higher pH?

4. Why did we use bleach as our source of chlorine, rather than chlorine itself?

5. Iodine could have been used instead of chlorine. How much iodine would have been required to do the reaction is we use 1 gram?

Answer 1

1. The oxidation reaction of methoxyacetophenone (C₉H₁₁O₂) to anisic acid (C₈H₈O₂₃) can be written as follows.

CH₃O-C₆H₄-COCH₃ + 4NaOCl + H₂O CH₃O-C₆H₄-COOH + CHCl₃ + 3NaOH + NaCl

In the above reaction, a ketone is oxidized to acid, which requires a decrease in pH due to the generation of acid (anisic acid).

4. Chlorine is a toxic gas, which is difficult to handle, but bleach is a harmless solid which can be handled with ease. This is the reason why you use bleach as a source of chlorine, rather than chlorine itself.

5. The oxidation of methoxyacetophenone (C₉H₁₁O₂) to anisic acid (C₈H₈O₂₃) can also be performed as follows.

CH₃O-C₆H₄-COCH₃ + 4NaOH + 3I₂ CH₃O-C₆H₄-COONa + CHI₃ + 3NaI + 3H₂O

The amount of I₂ required is 3 equivalents with respect to methoxyacetophenone.

i.e. For 1 mmol of methoxyacetophenone, 3 mmol of I₂ is required = 3*10^-3 mol * 253.809 g/mol = 0.761 g