Study On Synthesis Of Sodium1-Amino-4-Naphthalene Sulfonate By Solvent Method

Sodium1-amino-4-naphthalene sulfonate is an important intermediate and it canalso be as a key antidote of nitrite as well as iodine. The complex of sodium1-amino-4-naphthalene sulfonate can be studied as chemoreceptor, absorber andmedical. Present production method of sodium1-amino-4-naphthalene sulfonate is theprocess of traditional baking sulfonation of1-naphthylamine. However, thisconventional process is associated with various problems, e.g., poor work condition,high energy consumption and low yield. Liquid sulfonation with solvent was used inplace of solid baking sulfonation in this paper. o-Dichlorobenzene, durene, mesityleneand S-150have been studied as the solvent. And we also discuss the effect of thesulfonate time, additives, amount of sulfuric acid and mother liquid recycle.The highest yield of sodium1-amino-4-naphthalene sulfonate witho-dichlorobenzene as the solvent comes out at5h-6h, and then down with time extend.Addition of some additives could improve the color and increase the yield of product.The optimum conditions were found as follows:80%sulfuric acid, excess5%anddropped in the solvent as1mL/min. The yield can be highly raised when recycle useof organic phase and aqueous mother liquid after handled. We found that there wereunsatisfactory sulfonation results under high pressure.The temperature of sulfonation is197℃when durene as the solvent. Theproduct purity was good(76.6%), but yield was low (62.6%) for sulfonating1.5h, andthe yield further lower as time extend.When S-150as the solvent, the color of product was white when reaction time6h,and the purity was higher. But the yield was lower than that when o-dichlorobenzeneas solvent. The yield was raised to80.4%after recycling the treated organic phase.Liquid sulfonation in mixed solvent can rise reaction temperature and overcomethe shortcoming of single solvent. Durene-o-dichlorobenzene as the mixed solventcan make the reaction temperature rise to188℃. The product color was white and thepurity is77.8%after sulfonating6h. The yield can be raised to93.2%after recyclingthe managed organic phase and mother liquid. However, there was a drawback thatdurene would precipitate out when distilling solvent.The sulfonation results were better when S-150and o-dichlorobenzene as themixed solvent. Addition of1.5g sodium hydrogen sulfite can restrain the oxidationside reaction after ammonium salifying. The product color was white with higher purity and yield was satisfied after reacting6h at188℃. The mixed solvent andaqueous mother liquid can be recycled.The product color and purity always become unsatisfied after aqueous motherliquid was recycled some times. We inspected the refine effect of some solvents(e.g.absolute ethyl alcohol, methanol, o-dichlorobenzene etc.). The best refine effect wascome out when absolute ethyl alcohol as the solvent, but the cost was higher.Generally considering,80%alcohol as the refine solvent was the best choice, and theproduct color was white and the purity was increased by6%.