14503-46-9

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The sulfonation of amines of the benzene series with sulfur trioxide in dichloroethane is described by a third-order kinetic equation for an irreversible process, and first order is observed with respect to the compound being sulfonated and second with respect to the sulfur trioxide.The unprotonated molecules of the amines undergo sulfonation, and this leads to the production of the para-aminosulfonic acids with small amounts of the ortho isomers.The reaction mechanism involves electrophilic reaction of the unprotonated amine molecule with the sulfur trioxide dimer S2O6 and subsequent dissociation of the obtained pyrosulfonate with the production of the amino sulfonic acid and sulfur trioxide.

The kinetics of the sulfonation of amines of the benzene series by an equimolar amount of chlorosulfonic acid in o-dichlorobenzene were studied.It was shown that the sulfonation of aniline and N-alkylanilines is described by a second-order kinetic equation for irreversible reactions.The sulfonation of N,N-dialkylanilines by chlorosulfonic acid is described by a first-order kinetic equation for irreversible reactions.The observed relationships are explained by different mechanism for the sulfonation of amines of the benzene series by chlorosulfonic acid.The sulfonation of aniline and N-alkalynilines takes place by direct reaction between the unprotonated molecules of the amines and the HSO3(1+) ion, whereas in the reaction of chlorosulfonic acid with N,N-dialkylanilines complexes of the N,N-dialkylanilines with sulfur trioxide (dialkylanilinesulfotrioxides) are formed initially and then rearrange to the corresponding para-aminosulfonic acids.

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The kinetics of the rearrangement of phenyl- and N-alkylphenylammonium hydrogen sulfates in halogen-containing organic solvents were investigated in closed systems and with the removal of the water produced in the reaction.The isomeric composition of the obtained aminobenzenesulfonic acids was also studied.The rearrangement is described by a second-order kinetic equation.The reaction mechanism involves thermal dissociation of the phenyl- and N-alkylphenylammonium hydrogen sulfates at high temperatures to amines (bases) and sulfuric acid, followed by direct sulfonation of the amines (bases) by the sulfuric acid with the formation mostly of para-aminosulfonic acids of the benzene series.

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The kinetics of the sulfonation of primary, secondary, and tertiary amines of the benzene series with 80-99.7percent sulfuric acid were investigated.It was shown that the unprotonated and protonated forms of the amines, which are present in equilibrium, undergo sulfonation.The effective reaction rate constants and the activation energies for the sulfonation of the unprotonated and protonated molecules of the amines were calculated.The reaction mechanism and the structure of the transition state are discussed.

The kinetics of the rearrangement of unsubstituted and N-substituted phenylammonium hydrogen sulfates to the corresponding aminosulfonic acids of the benzene series were studied.The isomeric composition of the reaction products formed during the sulfonation of amines of the benzene series by various amounts of 100percent H2SO4 was also studied.The rearrangement is described by a second-order kinetic equation.Its effective rate constant at various temperatures and the activation energies were calculated.It is suggested that the sulfonation of aromatic amines by an equimolar amount of sulfuric acid at high temperatures takes place through the dissociation of the arylammonium hydrogen sulfates with the formation of arylamines and sulfuric acid and subsequent direct sulfonation of the arylamines by the sulfuric acid.

Sulfonated mixtures with increased contents of the meta isomers are formed during the sulfonation of amine sulfates of the benzene series with oleum containing mercuric sulfate.The following mechanism is proposed for the sulfonation of the amines by oleum in the presence of mercuric sulfate.Two fast reactions take place initially, i.e., sulfonation of the unprotonated molecules of the amines of the benzene series and electrophilic mercuration of the protonated molecules of the amines with the formation of the meta-mercurio derivatives.Electrophilic substitution of the mercury by the sulfo group with formation of the meta-mercuric derivatives then occurs under the influence of the oleum.

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The isomerization of aminosulfonic acids of the benzene series was investigated in 85, 90, and 95percent sulfuric acid at 180, 190, and 200 deg C.It was established that the transformation of the ortho and para isomers into the meta isomers takes place almost irreversibly.The effective rate constants for the isomerisation of the aminosulfonic acids and the activation energies of the reactions were calculated.It was shown that in 85-95percent sulfuric acid the protonated molecules of the aminosulfonic acids undergo hydrolysis in addition to the unprotonated molecules.