Regioselective Synthesis Of Dinitronaphthalene

The regioselective synthesis of dinitronaphthalene was studied in this paper.The nitration of naphthalene or1-nitronaphthalane with nitrogen dioxide or nitricacid in organic solvent over zeolite was researched. Meanwhile, the mono-nitrationof naphthalene with nitric acid also was evaluated. It was found that whennaphthalene or α-nitronaphthalane was nitrated with nitric acid in the presence ofzeolite, the regioselection of nitration can be comparatively improved. Naphthalene,HBEA-25and nitric acid were stirred for12h at refluxing, the1,5-:1,8-dinitronaphthalene isomer ratio was1.92. When naphthalene was mononitratedwith zeolite, the selectivity of the β-nitronaphthalene can be remarkably improved.Naphthalene, HBEA-25and nitric acid were stirred for0.4h at refluxing, the α-:β-nitronaphthalene isomer ratio is2.37.In the presence of an appropriate catalyst, nitrogen dioxide is activated to reactwith a wide variety of nonactivated and moderately activated aromatic substratesand the reaction can afford the corresponding nitro compounds in good yield.Efficient methods of nitration of naphthalene with nitrogen dioxide in organicsolvent over zeolite were investigated, where the regioselection of nitration can beimproved and in certain cases the isomer ratio of nitration products can be reversed.When naphthalene, HBEA-500and NO2were stirred for12h at room temperature,the1,5-:1,8-dinitronaphthalene isomer ratio was2.83. The recovered zeolite wasreused three times without appreciable loss of catalytic activity. The posttreatmentof mononitration product can give α-nitronaphthalene of purity of99.12%.Meanwhile, the separation of dinitration product can give1,5-dinitronaphthaleneof purity of98.65%and1,8-dinitronaphthalene of purity of98.86%. The structureof the target products are characterized by1H-NMR and IR.