Aromatic sulphonation. Part XXII. Kinetic isotope effects in the reaction of [1,3,5-2H3]benzene with sulphur trioxide: competitive sulphonation of benzene and toluene

Abstract

The kinetic isotope effect of hydrogen in the sulphonation of [I ,3,5-2H3] benzene in trichlorofluoromethane has been determined askH/kD = 1.23 f 0.08 at -35"; with nitromethane as solvent kH/kD = 1.34 f 0.08 at 20'. The kinetic isotope effect for the accompanying sulphonylation in trichlorofluoromethane w a s found to be kH/kD = 1-1 f 0.1 at -35".These results are discussed in terms of the recently established mechanism for aromatic sulphonation with sulphur trioxide in aprotic solvents. It has been determined, by competitive experiments, that the sulphonation rate ratio of toluene to benzene and the degree of para-substitution in toluene are greater with nitromethane than with trichlorofluoromethane as solvent. The apparent greater selectivity in the case of the former solvent is explained in terms of complex formation between sulphur trioxide and nitromethane.

Aromatic sulfonation with sulfur trioxide: mechanism and kinetic model

“…No reaction is observed until a barrier height Δ F ‡ ≅ 244 kJ mol –1 is reached, which is incompatible with the fast experimental reaction kinetics. 15 In conclusion, the MTD simulations suggest that sulfonation of benzene with a single SO 3 is not a viable pathway, and can be discarded in the kinetic analysis.…”

"Chemometrics" applied to the optimization of the preparation of hydrotopes for detergents starting from BTX fraction of natural gas

“…Some of these variables were previously found [6][7][8][9][10][11][12][14][15][16][17][18][27][28][29] to have a significant effect on the sulfonation of toluene alone or benzene alone.…”

“…The competitive sulfonation of toluene and benzene has been studied by Cerfontain et al [11,12] and El Homsi et al [17,18] using SO 3 as sulfonating agent. These studies were undertaken at low temperatures (-20, +20°C) in order to find the most selective solvents, as regards the isomer distribution and the relative reactivity of toluene and benzene.…”

“…The work of Cerfontain et al [6][7][8][9][10][11][12] carried out over many years on sulfonation kinetic and isomer distribution, is still the major reference on this subject. A large body of literature about the methods and processes for the manufacture of aromatic sulfonic acids can be found in the patent literature [4,[13][14][15][16].…”

Synthesis of Aromatic Disulfonic Acids for Water-Soluble Dibenzo­thiophene Derivatives

“…[6][7][8][9][10][11][12][13] Arylsulfonic acids are typically prepared via sulfonation. 8 A series of over ninety articles on aromatic sulfonation reactions were published last century, [14][15][16][17][18][19][20][21][22][23][24][25][26] and, yet, there are still no reports that specifically address the issues associated with the synthesis and subsequent purification of multifunctional aryldisulfonic acids such as those in Figure 1. 27 Sulfonation reactions can be severely restrictive to the design of multistep syntheses due to harsh reaction conditions (i.e., low pH, high temperatures) and a regioselectivity similar to other electrophilic aromatic substitution reactions.…”