120161-24-2Relevant academic research and scientific papers
Sulfonation and sulfation in the reactions of the chloro- and dichlorophenols, 3-fluorophenol and (2,3-, 2,4- and 3,4-dichlorophenoxy)acetic acid with concentrated aqueous sulfuric acid and sulfur trioxide
Wit, Peter de,Cerfontain, Hans
, p. 121 - 124 (2007/10/02)
The chloro- and dichlorophenols have been sulfonated with sulfuric acid and with SO3 in aprotic solvents.In the sulfonations with concentrated aqueous sulfuric acid, the sulfonic acid isomer distribution is determined mainly by the ortho- and para-directing and activating effect of the hydroxy substituent; this is also the determining factor in the aprotic sulfonations using up to 1.0 equiv of SO3.Upon using larger amounts of SO3, the sulfonation isomer distribution is increasingly determined by additional sulfonation of the corresponding phenyl hydrogen sulfate, of which the -OSO3H substituent is deactivating and mainly para- (and further ortho-) directing.The sulfuric acid sulfonation of (2,3-, 2,4- and 3,4-dichlorophenoxy)acetic acid leads to the exclusive formation of the 4-, 6- and 6-sulfonic acid, respectively.
On the intermediacy of phenyl hydrogen sulfates in the sulfonation of phenols. Sulfonation of phenol, anisole, methyl phenyl sulfate, the 2-halogenophenols, a series of phenyl methanesulfonates together with 2,6-dimethylaniline and its N-methylsulfonyl derivative
de Wit, Peter,Woldhuis, Alex F.,Cerfontain, Hans
, p. 668 - 675 (2007/10/02)
The sulfonation of methyl phenyl sulfate (4) with concentrated aqueous sulfuric acid at 25 deg C yields the 4-sulfonic acid.This initial product then decomposes to give phenol-4-sulfonic acid, which is subsequently sulfonated to phenol-2,4-disulfonic acid.From the first-order-rate coefficients obtained for sulfonation of phenyl methanesulfonate (3) and (4) in 93,2percent H2SO4, for which acid concentration the sulfonating entity is H2S2O7, the ?p+ values of the OSO2Me and OSO2OMe substituents have been determined to be 0.40 and 0.46, respectively.The sulfonation of both 2-chlorophenyl (10) and 2-methylphenyl methanesulfonate (14) with 2.0 equiv of SO3 in nitromethane at 0.0 deg C yields the 4-sulfonic acid as the exclusive product, whereas 2-methoxyphenyl methanesulfonate (13), under the same conditions, forms exclusively the 5-sulfonic acid. 2-Chloro- (6), 2-bromo- (7) and 2-iodophenol (8) with 1.0 and 4.0 equiv of SO3 in nitromethane yield exclusively the 4-sulfonic acid, while 2-fluorophenol (5) with 2.0 and 5.0 equiv of SO3 yields in addition the 5-sulfonic acid to the extent of 4 and 30percent, respectively.In the reactions of 2,6-dimethylphenol (15) and 2,6-dimethylaniline (17) with at least 1 equiv of SO3 in nitromethane, the 3-SO3H/4-SO3H ratio was found to increase on increasing the relative amount of SO3.For both 15 and 17, the limiting 3-SO3H/4-SO3H ratio at high SO3/ArOH ratios is 86/14 and this value is considered to be the ratio for the sulfonation of both 2,6-dimethylphenyl hydrogen sulfate and 2,6-dimethylaniline-N-sulfonic acid.This assumption is supported by the observation that the sulfonation of 2,6-dimethylphenyl methanesulfonate (16) and N-(methylsulfonyl)-2,6-dimethylaniline (18) with SO3 leads to a similar 3-SO3H/4-SO3H ratio.
