Infrared studies of the conformation in salicylaldehyde, methylsalicylate and ethylsalicylate

Radhi, Muhammed Mizher; Bermani, M. F. El

doi:10.1016/0584-8539(93)80007-w

Cited by 15 publications

(6 citation statements)

References 19 publications

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“…Early ultrasonic relaxation data suggested that there is a second conformer in addition to the enol in the ground state, perhaps 2.3 kcal/mol higher in energy, but the authors were unable to identify its character. Later IR spectral measurements indicated that this second conformer may correspond to double rotamer d but was certainly less than definitive; the energy difference was estimated to be 2.8 kcal/mol.…”

Section: Discussionmentioning

confidence: 98%

Competition between Rotamerization and Proton Transfer in o-Hydroxybenzaldehyde

1998

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The proton transfer from one oxygen atom to the other within the intramolecular H-bond in a molecule like o-hydroxybenzaldehyde (oHBA) would be precluded by a prior rotational isomerism that breaks this H-bond. The likelihood of such rotamerization in the ground and several excited electronic states is investigated by ab initio calculations at the CIS and MP2 levels with a 6-31+G** basis set. In the ground state, the energetics of proton transfer and rotamerization are competitive with one another; both processes are endothermic and must surmount an energy barrier. Excitation to the singlet or triplet ππ* states presents a situation where tautomerization to the keto is exothermic, with a small barrier. In contrast, rotamerization is endothermic with high intervening barriers, so excited-state proton transfer is favored. The opposite situation is encountered in the nπ* states, where rotations of the hydroxyl and carbonyl groups are facile and lead energetically downhill, in contrast to the high barriers opposing endothermic tautomerization. The computations provide insights into the fundamental causes for the discrepancies between the behaviors of the ππ* and nπ* states.

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Section: Discussionmentioning

confidence: 98%

Competition between Rotamerization and Proton Transfer in o-Hydroxybenzaldehyde

1998

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“…The strength of this bond HB intra = (À6.5 AE 0.2) kJ mol À1 was determined from the temperature dependence of the OH-stretching vibration frequency shifts. 60 However, this result is markedly low compared to the HB intra E À30 kJ mol À1 derived with the gas-liquid chromatography (GLC) [61][62][63] and the HB intra = À51.0 kJ mol À1 calculated with the B3LYP/6-31G(d,p). 64 A compilation of the data available in the literature on the strength of the intra-molecular HB for methyl 2-hydroxybenzoate in the gas phase is given in Table 6.…”

Section: Strength Of Intra-molecular Hydrogen Bonding In Alkyl 2-hydr...mentioning

confidence: 85%

“…The gas-phase infrared (IR) spectral data 60 in the range 4000–200 cm −1 indicate the methyl 2-hydroxybenzoate exists as an equilibrium mixture of two conformers – a cis - and a trans - form (see Fig. 6).…”

Section: Strength Of Intra-molecular Hydrogen Bonding In Alkyl 2-hydr...mentioning

confidence: 99%

“…The definition of the intra-HB energy in the QC calculations is similar to that in the IR experiments - the intra-HB strength is defined as the energetic difference between the H-bonded specie ( cis -form) and the conformer without HB ( trans -form). 60 Using quantum chemistry, the structure of the cis -form (which is stabilised by the intra-H bond) is optimised in the first step and calculated using any QC method. From this structure, the trans -conformation is generated in the second step by rotating 180° around the C–O bond (see Fig.…”

Section: Strength Of Intra-molecular Hydrogen Bonding In Alkyl 2-hydr...mentioning

confidence: 99%

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Experimental and computational thermochemistry: how strong is the intramolecular hydrogen bond in alkyl 2-hydroxybenzoates (salicylates)

Verevkin¹,

Portnova²,

Emel´yanenko³

et al. 2023

Phys. Chem. Chem. Phys.

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“…The results of GC showed that the purities of salicylates were higher than 99% [10][11][12][13][14] . Preparation of ILs: ILs used were synthesized according to the previously published papers [4][5][6]15 .…”

Section: Brønsted Acidic Ionic Liquids (Ils) 1-butyl-3-methyl-imidazomentioning

confidence: 99%

The Synthesis of Salicylate Prompted by Br0nsted Acidic Ionic Liquids

Jiang

Liu

Wang

et al. 2009

J. Chil. Chem. Soc.

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Brønsted acidic ionic liquids based on imidazolium cation were employed as a series of efficient and environmentally benign catalysts and solvents for the synthesis of salicylate, the yields could reach 76%-96%. The optimal reaction conditions were determined. The results showed that Brønsted acidic ionic liquids were efficient catalysts and solvents which could be recycled easily without obvious decline in catalytic activities.

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Infrared studies of the conformation in salicylaldehyde, methylsalicylate and ethylsalicylate

Cited by 15 publications

References 19 publications

Competition between Rotamerization and Proton Transfer in o-Hydroxybenzaldehyde

Competition between Rotamerization and Proton Transfer in o-Hydroxybenzaldehyde

Experimental and computational thermochemistry: how strong is the intramolecular hydrogen bond in alkyl 2-hydroxybenzoates (salicylates)

The Synthesis of Salicylate Prompted by Br0nsted Acidic Ionic Liquids

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