In: Chemistry
Show an extraction scheme in how to purify the benzaldehyde. Draw the mechanism for each of the four products that can be formed in the first part of the reaction.
Benzaldehyde is commonly contaminated with benzoic acid. It is purified in the following way. Benzoic acid is poorly soluble in water but it is soluble in Na2CO3. So, a sample of benzaldehyde is washed with 10% sodium carbonate and then with water. It is then dried over 5–10 g. of anhydrous magnesium sulfate. A few small crystals of hydroquinone are added with the drying agent. Hydroquinone reacts with O2 more quickly than of benzaldehyde, thus protecting benzaldehyde from oxidation. The dry benzaldehyde is decanted through a cotton plug into a flask and is distilled under reduced pressure.
An extraction scheme to purify the benzaldehyde