Glycolaldehyde dimer in the stable crystal phase has axial OH groups: Raman, infrared and X-ray data analysis

Abstract

Mohaček-Grošev, V., Prugovečki, B., , ''Glycolaldehyde dimer in the stable crystal phase has axial OH groups: Raman, infrared and X-ray data analysis '', Journal of Molecular Structure, Vol. 1047, pp. 209-215. Glycolaldehyde dimer in the stable crystal phase has axial OH groups:Raman, infrared and X-ray data analysisGraphical abstract AbstractAlthough a small molecule and a simple 1,4-dioxane derivative, 2,5-dihydroxy-1,4-dioxane or glycolaldehyde dimer has a crystal structure that has eluded researchers so far, chief reason lying presumably in substance polymorphism. Here we report for the first time on the stable crystal structure of the glycolaldehyde dimer characterized by the X-ray powder diffraction method at room temperature. It crystallizes in the monoclinic system, space group P2 1 /c, with unit cell parameters a = 5.9473 (1) Mohaček-Grošev, V., Prugovečki, B., Prugovečki, S., Strukan, N. (2013), ''Glycolaldehyde dimer in the stable crystal phase has axial OH groups: Raman, infrared and X-ray data analysis '', Journal of Molecular Structure, Vol. 1047, pp. 209-215. Raman and infrared spectra were re-examined and assigned with the help of ab initio calculation followed by a normal modes analysis modes most sensitive to crystal packing were identified as the C-OH deformations which were assigned to the IR and Raman bands at 1239 and 1237 cm −1 , respectively; the two O-C-O deformation modes, both associated with the Raman and IR bands at 561 and 535 cm −1 and, the two OH torsion modes assigned to the IR bands at 630 and 604 cm −1 .

Understanding the Aldo‐Enediolate Tautomerism of Glycolaldehyde in Basic Aqueous Solutions

“…The dimer could be as ix-membered (1,4-dioxane-2,5-diol) or af ive-membered ring [2-(hydroxymethyl)-1,3-dioxan-4-ol],a lthough it is knownt hat the compound is ad ioxane. [11,14] Our experimental and computational resultsb ased on Ramans pectroscopy and an exhaustive ab initio conformational search reveal the existence of enediol species (in their enediolatef orms)i nb asic environment, and they correctm uch of the literature that provides erroneous results when an enediol structure is assigned in neutral medium.…”

“…With regardt ot he solidp hase, Mohaček-Grošev et al [11] reported on the stable crystal structure of the glycolaldehyde dimer characterizedb yX -ray powder diffractiona tr oom temperature. The glycolaldehyde dimer molecules are trans-isomers with the electronegative hydroxyl groupsi naxial dispositions.…”

On the Plausibility of Pseudosugar Formation in Cometary Ices and Oxygen-rich Tholins

“…This structure is closely related to that of glycolaldehyde dimer as inferred from X-ray studies too (Mohaček-Grošek et al 2013). As mentioned, the first chiral sugar, glyceraldehyde, may form a stable dimer in the solid state.…”

Structural Characterization of β-Glycolaldehyde Dimer

“…The asymmetric unit contains two halves of the symmetrically independent glycolaldehyde dimer molecules which lie on inversion centers. Analysis of the bond lengths revealed that the C−O bonds in one symmetrically independent glycolaldehyde dimer molecule in the β-form is lengthened in comparison to the previously reported α-glycolaldehide dimer [5] (Supporting Information, Table S1).…”

“…[3] Glycolaldehyde, CHOCHOH, is at room temperature a polycrystalline solid, existing in the form of 2,5-dihydroxy-1,4-dioxane or glycolaldehyde dimer, whose αand βpolymorphs were first distinguished by Kobayashi et al [4] The conformation of hydroxyl groups was assumed equatorial in the α-phase and axial in the β-phase. Recently, the crystal structure of the α-polymorph was solved by Mohaček-Grošev et al [5] and it was found that molecules crystallize with axially placed OH groups. On cooling, αphase transforms into the third γ-phase below 80 K. [6] Dissolving of glycolaldehyde is a complex, time dependent process.…”