1966 年 15 巻 6 号 p. 262-267
In the preceeding paper the authors reported a pronounced selectivity owing to the steric hindrance of the alkyl chain in the sulfonation of higher mono-alkylbenzenes with 20% oleum at 18.
The present paper deals determination of the correlation between concentration of sulfonatiog agent and the structure of dodecylbenzenes in the selectivity of the sulfonation.
The effect of dilution of sulfonating agent is increased as the position of aromatic nucleus locates toward the center of the alkylchain. When the nucleus moves from the second position to the center in the chain, the relative sulf onation rate by 95.5% sulfuric acid decreases from 10% to 25% in comparison with those by sulfur trioxide.
Distribution of ortho and para isomers was also determined by infrared spectrography. The distribution in n-alkylbenzenesulf onic acid, sulfonated with 3.2 moles of 20% oleum at low temperature, was about 25% ortho and 75%, para. And in the sulfonation at 50°C it was about 21% ortho and 79%, para.