Place about 2.3 mL benzyl chloride into a 250 mL round bottomed flask equipped with a reflux condenser  and wash the flask with 50 mL distilled water. Then add 2 g sodium carbonate (Na2CO3) , 4.5 g potassium permanganate, 50mL distilled water and a few excess boiling chips to it. Boil the mixture gently unitl no oily drops appear along the condenser of the percolation liquid mixture (i.e 2 hours). Allow to cool, acidify with conc. Hydrochloric acid (about 20mL ) and add 20% aqueous solution of sodium sulfite (Na2SO3. 7H2O) with shaking to dissolve MnO2 completely and make sure the complete precipitation of benzoic acid. Filter the precipitation and wash it with cold water (10 mL).  Recrystallize the crued product from boiling water, cool and filter it. Dry the crystallized product which is benzoic acid.