Abstract
Optimum reaction conditions for preparing potassium 5, 8-diisopropyl-2-naphthalenesulfonate (KDNS) were investigated. When naphthalene was β-sulfonated with concentrated sulfuric acid for 13h at 160°C and then alkylated with 2-propanol (molar ratio to naphthalene=2 : 1) for 2h at 80°C, KDNS was recovered in a maximum yield (ca. 30%) by neutralizing the sulfonated product with a potassium hydroxide solution. A highly purified KDNS (purity : >99%) was obtained only by recrystallizing the raw KDNS four times from water. On the contrary, the preparation of potassium dibutylnaphthalenesulfonate applying the previous reaction conditions was very difficult. Moreover, the quantitative preparating procedures of 5, 8-diisopropyl-2-naphthalenesulfonyl chloride and methyl 5, 8-diisopropyl-2-naphthalenesulfonate as easily soluble and volatile derivatives of KDNS, were found for determining the purity of KDNS by means of instrumental analyses in approximately 100% yields and conversion ratios.
