Regioselective nitration of aromatics under phase-transfer catalysis conditions

Mononitration of aromatics was performed in a two-phase system using phase-transfer catalyst. The most advantageous conditions for the nitration were determined (temperature, reaction time, the type and amount of phase transfer catalyst, nitrification strength of the nitro-sulfuric acid). From the results, a significant improvement in the selectivity and conversion of the nitration of xylene was observed: the ratio of 4-nitro-m-xylene to 2-nitro-m-xylene was unprecedented increased up to 91.3%:7.7%, the ratio of 4-nitro-o-xylene to 3-nitro-o-xylene was also increased to 71.1%:27.2%; both the conversions were over 96%.

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► Unreported high regioselectivity of disubstituted aromatics was obtained with PTC.
► Mixed acid was significantly reduced and valuable for industry application.
► Quantitative calculation of C atoms' net charge on substituted benzenes was carried.