2,5-Dihydroxybenzaldehyde

Abstract

The title compound, C7H6O3, features a planar molecule (r.m.s. deviation for all non‐H atoms = 0.019 Å). Geometric parameters are in the usual ranges. Whereas one hydroxyl group forms an intramolecular hydrogen bond with the carbonyl group, the other forms an intermolecular hydrogen bond with the carbonyl group of a symmetry‐equivalent molecule. The molecules crystallize in planes parallel to the bc plane.

Hydrogen Bonding as a Modulator of Aromaticity and Electronic Structure of Selectedortho-Hydroxybenzaldehyde Derivatives

“…Unfortunately, the chemical nature of some of the studied compounds makes them difficult to obtain in a monocrystalline form, leaving us unable to make a comparison of calculated parameters with experimental metric parameters. This was possible only for compounds III and V. As a reference, using the X-ray data for these compounds 71,72 we can conclude that the applied level of theory was able to reproduce correctly their molecular structure. Next, to get a more general picture of the bridged (H15) proton dynamics on the basis of DFT, potential energy profiles were calculated for all of the investigated compounds, and they are presented in the upper panel of Figure 2.…”

“…This was possible only for compounds III and V . As a reference, using the X-ray data for these compounds , we can conclude that the applied level of theory was able to reproduce correctly their molecular structure. Next, to get a more general picture of the bridged (H15) proton dynamics on the basis of DFT, potential energy profiles were calculated for all of the investigated compounds, and they are presented in the upper panel of Figure .…”

“…The deviations can be explained by (a) different equilibrium value of the O–H bond length in the DFT framework, (b) intramolecular character of the investigated hydrogen bond, which puts additional constraints on the molecular structure. The last remark is also valid for the experimental data on ortho -hydroxybenzaldehydes, , included in the Figure , and another factor leading to deviations is the use of X-ray crystallography in these two studiesthis has influence on the positions of the located protons.…”

2,3,4-Trihydroxybenzaldehyde

“…On the other hand, the antipyrine derivative has the expected neutral structure (Sun et al, 2007). Although there are several structural studies on hydroxysubstituted benzaldehydes (Kretz et al, 2007;Ng, 2005), the structure of 2,3,4-trihydroxybenzaldehyde has not been reported.…”

“…For some references on hydroxy-substituted benzaldehydes, see: Kretz et al (2007); Ng (2005). For the crystal structures of Schiff base derivatives of 2,3,4-trihydroxysalicylaldehyde, see: Petek et al (2006); Sun et al (2007).…”