Question

phenyl acetic acid from diethylmelonate?​

Answer 1

• Phenylacetic acid from mandelic acid [4]

• 15 grams mandelic acid (0.1 mol) [5], 2.07g KI (6.25% of theory), and 6g Red Phosphorous is dissolved in a solution of 70ml phosphoric acid and 10 ml of water, and this solution is refluxed for six hours (bp of soln 144°C).

• After the reaction mixture has cooled down, a little water is added to dissolve precipitated inorganic salts.

• The solution is extracted with ether, and the pooled extracts washed with a little dilute NaHSO3, followed by water, and is then dried over Na2SO4. The ether is removed under diminished pressure and the residue is distilled (bp 138-139 @13mmHg).

• The yield is 12.5 grams (90%) of phenylacetic acid melting at 76°C. 3.2 grams of phosphorous could be recovered from the aqueous solution.