O-キシレン-3-および4-スルホン酸の合成ならびに平衡について

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o-Xylene-4-sulfonic acid prepared by sulfonation of o-Xylene at 100°C was purified.3-Sulfonic acid was synthesized by reduction, Gattermann reaction, chlorination and hydrolysis from 3-nitro-o-Xylene. The melting points of 3-and 4-sulfonic acid-S-benzyl-thiuronium salts prepared by usual method, were 147°C and 210.5°C, respectively. The melting points of their mixture in various proportion were determined. The eutectic point was 137.6°C and eutectic mixture was consisted of about 10% of 3-acid and 902/s of 4-acid. The ratios on the yields of 3- and 4-acids obtained by sulfonation of o-Xylene with conc.sulfuricacid were determined by use of melting point curve. The yield of 3-acid depended on the temp.and was not accelerated by catalyser.I studied on the equilibrium of 3-acid k1⇔k2 4-acid, as 3-acid can be transformed by heating in the mixture of sulfuricacid and a small amount of water. When barium 3-sulfonate (0.001 mol) in 3 cc.of sulfuricacid (d: 1.656) was heatedbetween 80 and 100°C, a reversible first order reaction kt=t (k1+k2) =lnXe/(Xe-X) was done and the following results were obtained: The activation energies of k1 and k2 were 30 kcal/mol., respectively.Log k was proportional to the acidity function (Ho) and the tangent was about 0.68, wbe the same reaction was done at 100° by change of sulfuricacid concentration.
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