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

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 crystallo­graphic m symmetry. 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 notation C₂²(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 notation C(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.

Antidiarrhetic loperamide hydro­chloride

Single crystals of the anhydrous form of the title compound {systematic name: 1-[3-(dimethyl­carbamo­yl)-3,3-diphenyl­prop­yl]-4-hy­droxy-4-(4-chloro­phen­yl)piperidin-1-ium chlor­ide}, C₂₉H₃₄ClN₂O₂⁺·Cl⁻, were obtained by diffusion of acetone into a solution in 2-propanol. In the structure, N—H...Cl⁻ and O—H...Cl⁻ hydrogen bonds connect neighbouring mol­ecules and chloride anions to form chains along the c-axis direction. Neighbouring chains along the b-axis direction are connected by inter­molecular C—H...Cl⁻ con­tacts, defining layers parallel to the (100) planes. The layers are connected by weak inter­molecular C—H...Cl inter­actions only, which may account for the plate-like shape of the crystals.