14982-59-3Relevant academic research and scientific papers
Sulfonation and sulfation in reactions of C-methylated phenols and anisoles with sulfur trioxide. 4-Substituted phenyl hydrogen sulfates: effective reagents for transsulfonation
Goossens, Hans D.,Lambrechts, Hans J. A.,Cerfontain, Hans,Wit, Peter de
, p. 426 - 430 (1988)
The sulfation and sulfonation of the methyl- and dimethylphenols with 0.9 and 4.0 equiv. of SO3 in nitromethane at 0 deg C have been studied.On using 0.9 equiv. of SO3, the sulfonic acid product distributions are determined by the ortho- and para-directing effect of the activating hydroxy substituent.In the reactions with 4.0 equiv. of SO3, the sulfonic acid product distributions are affected by the predominant initial formation and the subsequent sulfonation of the corresponding phenyl hydrogen sulfates, of which the bulky OSO3H substituent is electronically deactivating and (mainly) para-directing.For comparison, the sulfonation of the methylanisoles, phenyl methanesulfonate and 2,3-dihydrobenzofuran was also studied.The sulfonation of 1,3-dimethoxybenzene in (2H8)dioxane at 17.0 deg C has been studied using 4-substituted phenyl hydrogen sulfates as transsulfonating agents.The transsulfonation was found to be first order with respect to the phenyl hydrogen sulfates and independent of the 1,3-dimethoxybenzene concentration.The reaction constant of the transsulfonation reaction was determined to be ρ=2.0+/-0.2.
Aromatic Sulphonation. Part 92. Sulphonation of the Three Methylphenols and the Six Dimethylphenols in Concentrated Aqueous Sulphuric Acid; and the Isomerization of Some of the Resulting Sulphonic Acids and of m-Xylene-2- and o-Xylene-3-sulphonic Acid
Lambrechts, Hans J. A.,Schaasberg-Nienhuis, Zwaan R. H.,Cerfontain, Hans
, p. 669 - 676 (2007/10/02)
The isomer distributions for the mono- and di-sulphonation of the three methylphenols in 81.6-90.0percent sulphuric acid and of the six dimethylphenols in 84.9percent sulphuric acid at 35 deg C have been determined by means of 1H n.m.r. spectroscopy.Products that would result from demethylation, disproportionation, or ipso-substitution have not been observed.The monosulphonation isomer distribution of each of the three methylphenols is independent of the sulphuric acid concentration. 2,4-Dimethylphenol in 84.9percent H2SO4 yields 19percent 5- and 79percent 6-sulphonic acid, and 2,6-dimethylphenol yields 28percent 3- and 72percent 4-sulphonic acid.With the phenols (2), (3), (5),and (7), which have positions both ortho and para to the -OH substituent available for sulphodeprotonation, the yield of ortho-substitution is relatively high, viz. 44, 45, 36, and 27percent, respectively.The mono- and di-sulphonic acids of which the sulpho group is between the -OH and an -Me group are unstable under the reaction conditions employed, with the exception of the 3,5-dimethylphenol-2-sulphonic acid.It is proposed that their isomerization proceeds by protiodesulphonation followed by resulphonation to yield the more stable sulphonic acid isomer(s).From a kinetic analysis of the calculated first-order rate coefficients for protiodesulphonation, it is concluded that the unprotonated substrate species is the entity undergoing the protiodesulphonation.
