Nitration of Toluene with Nitric Acid in the Mixture of Aromatic Sulfonic Acids and Phosphoric Acid

Abstract

Mononitration of toluene with nitric acid in the mixture of aromatic sulfonic acids and phosphoric acid in place of sulfuric acid on the usual nitration method with mixed acid (nitric acid and sulfuric acid) was studied. The distribution of mononitro-isomer was examined by means of GLC. It was found that the yield of mononitrated products was favorable and the content of p-isomer wes higher than that on the usual method.
Thus, the liquid mixture (water content 1.0-1.5%) of m-benzenedisulfonic acid-H₃PO₄ (1: 3 weight ratio), toluene-2, 4-disulfonic acid-H₃PO₄(1: 3) or nitrobenzene sulfonic acids (nitrated products of benzenesulfonic acid)-H₃PO₄(1: 2) and toluene (CH, C, FISHNO, : 1.5 (mole ratio)) was violently stirred and 98% nitric acid (HNOSaeid mixture: 1/20-1/30 (weight ratio)) was added dropwise at 0-2°C. The yield and pi° ratio in the mononitrotoluene mixtures was 94-97% and 1.5-1.6, respectively.