Sulfonation and Isomerization of some Halogenobenzenesulfonic Acids

Abstract

The behavior of the isomeric halogenobenzenesulfonic acids (halogen = F, CI, and Br) in sulfuric acid was studied. In 115% H2S04 at 25" only sulfonation takes place. Both the ortho-and para-isomers yield the l-halogenobenzene-2.4-disulfonic acid, whereas the meta-isomers yield a mixture of mainly 3,4-and 3 3 -with some 2,5-disulfonic acid.In 98.1% H2S04 at 150-17O0, both sulfonation and isomerization occur. The ortho-isomers are sulfonated to the 2,4-disulfonic acid and isomerized to the para-isomer in competing reactions. The para-isomers are sulfonated to the 2,4-disulfonic acids much more slowly than the ortho-isomers. The least reactive are the metaisomers which in competing reactions are sulfonated to a mixture of mainly 2,5-and 3,5-disulfonic acids, and isomerized to the para-isomers which eventually yield the 2.4-disulfonic acids.It is suggested that the formatcon of the 3,4-disulfonic acids from the meta-isomers in 115% H2S04 proceeds by an intramolecular rearrangement of the initially formed arenepyrosulfonic acids.Le comportement des acides halogenobenzenesulfoniques isomeres (halogene = F, CI, Br) dans l'acide sulfurique a ete ttudie. A 25' dansl'acide sulfurique a 115%, seule la sulfonation a lieu. Les isomeres ortho et para donnent tous deux I'acide halogCno-1 benzene disulfonique-2,4 tandis que les isomeres mtta conduisent A un melange constitue principalement des acides disulfoniques-3,4 et -3 3 et un peu de -2.4.Dans I'acide sulfurique a 98.1% a 150-170". la sulfonation et I'isomerisation ont lieu toutes les deux. Les isomeres ortho sont sulfonCs en acide disulfonique-2,4 et isomerists en para dans des reactions competitives. Les isomeres para donnent les acides disulfoniques-2,4 beaucoup plus lentement que pour les analogues ortho. Les moins rtactifs sont les isomtres meta qui, dans des reactions competitives, sont sulfonts en un melange d'acides disulfoniques-2.5 et -3,5 surtout et isomerisks en para pour donner eventuellement les acides disulfoniques-2,4.On pense que la formation des acides disulfoniques-3,4 a partir des isomtres meta dans H'SO, 1 I5%, se fait selon un rearrangement intramoltculaire des acides artnepyrosulfoniques initialement formts.

Quantitave nuclear magnetic resonance analysis of mixtures of isomeric arenesulfonic acids in sulfonation mixtures

“…The applicability of the PMR analysis of a sulfonation mixture both in fuming and concentrated aqueous sulfuric acid is illustrated for the disulfonic mixtures formed on sulfonation of three m-halogenobenzenesulfonic acids in 115% H2SO4. From the PMR spectrum of the to 98% H2SO4 diluted reaction mixture, a complete analysis in terms of the l-halogeno-2,5-, -3,4-, and -3,5-benzenedisulfonic acids was obtained only for the fluorine and chlorine derivatives, whereas for the bromo compound only the relative amount of the 3,5-disulfonic acid was obtained (6). However, from the PMR spectra in 115% H2S04 a complete analysis was obtained for all three halogen compounds (Table III).…”

“…We recently obtained a satisfactory quantitative analysis of a large number of mixtures of isomeric arenesulfonic acids by PMR spectrometric analysis without requiring the constituents themselves as reference compounds (6)(7)(8)(9)(10)(11)(12). The isomeric composition of mixtures obtained on sulfonation of disubstituted (6,(9)(10)(11) and trisubstituted (11) benzene derivatives was determined on the basis of the aromatic hydrogen pattern, in conjunction with the absorption pattern of the benzyl hydrogens, if present. With a sulfonation mixture of a monosubstituted benzene derivative, the relative abundance of at least one of the three isomers can often be determined (13,14).…”

“…A further requisite for a quantitative analysis is that the spectra of the components of the mixture are predictable. This requirement is met for arenesulfonic acids, as the chemical shift of the substituents, such as H, F, CH3, and CF3, in a benzene derivative can be calculated by comparison with a suitable reference compound on the basis of additivity of substituent shielding parameters (6,17). A tabulation of shielding parameters on aromatic hydrogen has recently been published (18).…”

“…It is strictly additive in the case of p-and m-benzenedisulfonic acid, but with the ortho isomer, deviations from additivity are observed. For concentrated sulfuric acid up to 98% H2SO4, the shielding parameters for 85% H2SO4 can be applied satisfactorily (6). 'fot h/ka «0,5…”