Crystal structure of ammonium isosaccharate and aqueous solubility of ammonium and sodium isosaccharates Original Research Article

Ammonium isosaccharate, C6H15NO6·H2O (NH4-ISA), has been synthesized and its crystal structure solved by single-crystal X-ray diffraction methods. NH4-ISA crystallizes in the monoclinic space group P21 (#4) with cell parameters a = 8.6470(12) Å, b = 5.0207(7) Å, c = 9.8193(14) Å, β = 91.643(3)°, V = 426.12(10) Å3, Z = 2. The structure was refined by full-matrix least-squares on F2 yielding final R-values (all data) R1 = 0.0485 and Rw2 = 0.1104. The structure consists of alternating (NH4)+ and (C6H11O6)− layers parallel to the ab plane. An extended network of O–H⋯O intermolecular (ISA)⋯(ISA) hydrogen bonds links the (ISA)− anions within the ab plane, while the 3-D connectivity along the c-axis is provided only by (ISA−)⋯image⋯(ISA−) hydrogen bonds. The aqueous solubility (Si, [M L−1]) of NH4- and Na-ISA has been shown to be pH independent at ambient conditions within the range 4.5 < pH < 10 with image and SNa-ISA = 1.731, respectively, which values are about two orders of magnitude higher than that of the Ca-ISA analogue.