Premium
The ephemeral dihydrate of sulfanilic acid
Author(s) -
Langenstück Stefanie,
Zhao Chenchen,
Englert Ulli
Publication year - 2018
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229617016886
Subject(s) - zwitterion , sulfanilic acid , hydrogen bond , crystallography , chemistry , molecule , orthorhombic crystal system , sulfonate , antiparallel (mathematics) , aqueous solution , crystal structure , organic chemistry , sodium , physics , quantum mechanics , magnetic field
Evaporation of an aqueous solution of sulfanilic acid (systematic name: 4‐aminobenzene‐1‐sulfonic acid) at 273 K affords a crystalline dihydrate, C 6 H 7 NO 3 S·2H 2 O. The organic molecule exists as a zwitterion; two zwitterions are aligned in an antiparallel fashion about a crystallographic centre of inversion. They interact directly via two N—H…O hydrogen bonds between the ammonium group of one zwitterion and the sulfonate group of its symmetry‐related counterpart, and their aromatic rings are π‐stacked, with an interplanar distance of 3.533 (3) Å. One of the cocrystallized water molecules connects the resulting pairs into layers and the second crosslinks the layers into a three‐dimensional network. All H atoms connected to N or O atoms find acceptors in suitable geometries. In the resulting crystal, polar and hydrogen‐bond‐dominated slabs alternate with stacks of organic arene rings. Although the new dihydrate shows efficient space filling, with a packing coefficient of 75.7%, it is unstable and undergoes fast desolvation at room temperature. In this process, the orthorhombic ansolvate forms as a pure phase.