Aromatic sulfonation XIV orientation in the homogeneous sulfonation of t ‐butylbenzene in sulfuric acid

1967

The degree of ortho-substitution in the sulfonation of toluene, ethylbenzene and isopropylbenzene with sulfuric acid varying in concentration from 80.6 to 98.5% HzS04 at 25" was determined. For a given sulfuric acid concentration the ratio of ortho-to (para-+ meta-) substitution decreases with increasing size of the alkyl group, whereas for a given alkyl group this ratio decreases with decreasing sulfuric acid concentration.Partial rate factors for the homogeneous sulfonation of toluene, ethylbenzene, isopropylbenzene and t-butylbenzene in 86.3% sulfuric acid at 25" were calculated. The partial rate factors for ortho-substitution decrease with increasing size of the alkyl group, while those for para-substitution follow the BakerNaihan order.Introduction of a sulfonic acid group ortho to the alkyl group of an alkylbenzene can be effected with weak oleurn (-16%) as reagent under conditions of disulfonation with toluene, ethylbenzene and isopropylbenzene, but not with t-butylbenzene. IntroductionThe overall rate constant for sulfonation of toluene, ethylbenzene, isopropylbenzene 1 and t-butylbenzene 2 in concentrated aqueous sulfuric acid decreases in the order given 2 . It was suggested 192 that this rate order arises predominantly from a decrease in ortho-substitution with increasing size of the alkyl substituent as the result of an increase in steric hindrance for that type of substitution. With toluene there is, in fact, a substantial

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Aromatic sulfonation. Part XVIII: Ortho‐substitution in the sulfonation of monoalkylbenzenes with sulfuric acid

Vries

1967

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Aromatic sulfonation. Part 33: Effects of sulfonic acid addenda upon the isomer distribution in the sulfonation of toluene with sulfuric acid

Ris

1972

The isomer distribution in the sulfonation of toluene with 95.8% H,S04 at 25" in the presence of some sulfonic acids and other addenda was determined. All the addenda studied effect a decrease in the degree of orrho-substitution. Most effective are p-t-butylbenzenesulfonic acid, methyl trimethylphenylammonium sulfate and nitrobenzene. The effect of methanesulfonic acid is very small, that of water and of sodium bisulfate almost negligible. The degree of meta-substitution is small and is unarfected by the addenda.The variations in the isomer distribution are discussed in terms of changes in the solvation of the reactants and of the transition states.

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Sulfur trioxide sulfonation of aromatic hydrocarbons

1985