Hydrogen-bonding in non-cyclic vicinal diols and their mono-methyl ethers: an ftir study

Crystal structure of and conformational equilibria in 1,1′‐dihydroxybis(4H‐cyclopenta[def]phenanthrene) and related derivatives

“…12 This contrasting behavior between diols 1 and 2 and diol 3 in their conformational preferences is similar to that between 9, 9 0 -bifluorenyl (5) and 1,1,2,2-tetraphenylethane (6) in which the former exists as the gauche conformer and the latter as the anti conformer. 13 The explanation provided for the contrasting conformational preference in the hydrocarbons is the ability for the geminal phenyl substituents in 6 to adopt a twisted geometry enabling these to stack or nest by -interaction which would diminish geminal repulsion and result in a decrease in the valence angle.…”

“…5 Nevertheless vicinal diols contain the highest proportion of intramolecular H-bonded conformers. 6 This has been explained in terms of the magnitude of the entropy factor. 7 According to Buckley and Giguere,8 ethanediol is present in the gauche form only in the gas phase as well as in dilute solution.…”

1H NMR study of the hetero‐association of non‐symmetrical diols with pyridine; GIAO/DFT calculations on diols

“…In view of somewhat contradictory reports concerning the IR spectra of vicinal and other diols,7, 24, 32 spectra were recorded for some of the compounds in this study as very dilute solutions (<10 −4 M) in carbon tetrachloride (Supplementary Materials, Figs. S1–S6).…”

“…S1–S6). By resolution enhancement Singelenberg and van der Maas7 find for propan‐1,2‐diol, 1‐Me , four bands (3645, 3634, 3618, and 3593 cm −1 ) while Ma and Wang32 analyse their spectrum in terms of two Lorentzian functions, albeit with very poor fitting between the two maxima. Our own unenhanced spectrum shows a broad band at 3638 cm −1 of free OH, a band at 3599 cm −1 of associated OH and a small peak at 3615 cm −1 .…”

“…The hydrogen bonded to the acceptor oxygen is sometimes referred to as “pseudo‐free” 44, 45. For propan‐ and butan‐1,2‐diols, the peaks at higher frequency are composite,7 and the bands were assigned to primary and secondary free OH. An early microwave spectroscopic study, confirmed by 4–21G ab initio calculations, found that the primary OH in propan‐1,2‐diol is the main proton donor,4, 5 but a later study backed by calculations at the HF/6–31G level of theory found the tG'g conformer, in which the primary group is the acceptor, to be the lowest in energy 23.…”