For synthesis of n,n-diethyl-m-tolamide,why is final reaction mixture extracted with 55 sodium hydroxide?

from m-tolualdehyde,we react with KMnO4,NaOH,HCl to get m-toluic acid. then we react with dry ether, diethylamine,anhydrous ether to get maybe m-tolunyl chloride which is then reacted with this 5% sodium hydroxide....why???