On the Structure of Liquid Methyl Salicylate: the Role of Intramolecular Hydrogen Bonding

Abstract

A study on the structure of methyl salicylate is reported using quantum mechanical calculations, molecular dynamics simulations, vibrational spectroscopy and microwave dielectric relaxation spectroscopy tools. The reported results show that a strong intramolecular hydrogen bonding is developed between the hydroxyl hydrogen and carbonyl oxygen. This intramolecular interaction is maintained in gas and liquid phases and even when diluted in inert solvents. Interaction between neighbour molecules is developed through dipolar interactions, and thus, intermolecular hydrogen bonding should be discarded for pure liquid methyl salicylate. The interaction between neighbour methyl salicylate molecules do not lead to remarkable changes in the intramolecular hydrogen bonding. SalicylateHydrogen bonding DFT-Molecular dynamics Vibrational spectroscopy Relaxation spectroscopy

Multimode Vibrational Strong Coupling of Methyl Salicylate to a Fabry–Pérot Microcavity

“…The vibrational frequency of free aromatic CO ester resides usually between 1735 and 1750 cm –1 . In MS hydrogen bonding leads to a red shift of the CO stretching frequency, which is consistent with values reported in the literature. , The bands observed at 1585 and 1616 cm –1 in the FTIR spectrum of MS arise from CC vibrational stretching modes of the phenyl moiety …”

“…52 In MS hydrogen bonding leads to a red shift of the CO stretching frequency, which is consistent with values reported in the literature. 53,54 The bands observed at 1585 and 1616 cm −1 in the FTIR spectrum of MS arise from CC vibrational stretching modes of the phenyl moiety. 55 In order to create the vibrational polaritonic states in MS, the cavity was tuned toward the CO vibrational band.…”

Sodium Salicylate: An In‐Depth Thermal and Photophysical Study

“…4) The band at 345 nm is caused by proton transfer species, previously shown to exist in the case of similar species such as methyl salicylate . Here, the phenolic proton hops to the carboxylate group effectively creating a co‐existing phenolate species.…”

“…[10] 4) The band at 345 nm is caused by proton transfer species, previously shown to exist in the case of similar species such as methyl salicylate. [19,21] Here, the phenolic proton hops to the carboxylate group effectively creatingaco-existing phenolate species.T he equilibrium would depend upon the relative stabilitieso ft he two speciesi nt he selected medium as well as the temperature.…”

“…Equally important for an API, [18] detailed studies on its dissolution and behaviour in solution are also lacking. In addition, unlikei ts methyl ester counterpart, [19][20][21] no literature can be found that thoroughly explains its photophysical behaviour in terms of molecular orbital structure. Even the reported thermal data have been observed to be contradictory.…”