Aromatic sulphonation IV Kinetics and mechanism of the sulphonation of benzene in aqueous sulphuric acid

Abstract

The kinetics of the sulphonation of benzene have been measured at 5.0", 25.0" and 45.0" in aqueous sulphuric acid solutions, varying from 77.6 to 99.2 wt-% HzS04. In addition, sulphonation rate measurements have been made at 5.0" in 98.8 wt-% HzS04 containing various concentrations of sodium bisulphate. All reactions were found to be first order with respect to benzene. The kinetics are discussed in terms of the mechanism:It is suggested that sulphur trioxide or, though less probable, the sulphuric acid solvate of sulphur trioxide S03(H2S04) or disulphuric acid (H&07), is the sulphonating entity X and that kl < k2 1 B / + k3. No kinetic distinction can be made between the deprotonation by reaction [2] and the less probable intramolecular proton shift (reaction [3]).A comparison between the mechanisms of sulphonation in aqueous and fuming sulphuric acid furnishes additional evidence that so3, instead of S03(HzS04) or HzSz07, should be regarded as the sulphonating entity.

Diatom type material in permanent slides does not need to be permanently unavailable for electron microscopy examination

“…Sulfonation (Kaandorp et al. 1962) was therefore applied to remove the solvent. Benzene‐suspended diatom material and concentrated sulfuric acid (98%) were poured into a glass beaker at 1:5 ratio and heated for ca.…”