2-Ammonio-5-chloro-4-methylbenzenesulfonate, its 1-methyl-2-pyrrolidone and dimethyl sulfoxide monosolvates and a corrected structure of 2,2′-(1,4-phenylene)di(4,5-dihydroimidazolium) bis(4-aminobenzenesulfonate) dihydrate

Abstract

2-Ammonio-5-chloro-4-methylbenzenesulfonate, C7H8ClNO3S, (Ia), is an intermediate in the synthesis of lake red azo pigments. The present structure determination from single-crystal data confirms the results of a previous powder diffraction determination [Bekö, Thoms, Brüning, Alig, van de Streek, Lakatos, Glaubitz & Schmidt (2010).Z. Kristallogr.225, 382–387]. The zwitterionic tautomeric form is confirmed. During a polymorph screening, two additional pseudopolymorphs were obtained,viz.2-ammonio-5-chloro-4-methylbenzenesulfonate 1-methyl-2-pyrrolidone monosolvate, C7H8ClNO3S·C5H9NO, (Ib), and 2-ammonio-5-chloro-4-methylbenzenesulfonate dimethyl sulfoxide monosolvate, C7H8ClNO3S·C2H6OS, (Ic). The molecules of (Ib) have crystallographicmsymmetry. The 1-methyl-2-pyrrolidone solvent molecule has an envelope conformation and is disordered around the mirror plane. The structure shows hydrogen-bonded ladders of molecules [graph-set notationC22(6)R22(12)] in the [010] direction. The benzene groups of adjacent ladders are also stacked in this direction. A different type of hydrogen-bonded ladder [graph-set notationC(6)R22(4)R44(12)] occurs in (Ic). In (Ia), (Ib) and (Ic), the molecules correspond to the zwitterionic tautomer. The structure of the cocrystal of 4-aminobenzenesulfonic acid with 1,4-bis(4,5-dihydroimidazol-2-yl)benzene [Shang, Ren, Wang, Lu & Yang (2009).Acta Cryst.E65, o2221–o2222] is corrected; it actually contains 4-aminobenzenesulfonate anions and 2,2′-(1,4-phenylene)di(dihydroimidazolium) dications,i.e.2,2′-(1,4-phenylene)di(4,5-dihydroimidazolium) bis(4-aminobenzenesulfonate) dihydrate, C12H16N42+·2C6H6NO3S−·2H2O. Hence, all known structures of aminobenzenesulfonic acid complexes contain ionic or zwitterionic molecules; there is no known structure with a neutral aminobenzenesulfonic acid molecule.