scholarly journals Energetic and Structural Studies of Two Biomass-Derived Compounds: 6- and 7-hydroxy-1-indanones

2020 ◽  
Vol 10 (23) ◽  
pp. 8512
Author(s):  
Ana Luisa Ribeiro da Silva ◽  
Maria D. M. C. Ribeiro da Silva
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Intramolecular Proton Transfer ◽  
Molecular Structures ◽  
Experimental Techniques ◽  
Hydroxyl Group ◽  
Enthalpies Of Formation ◽  
Calvet Microcalorimetry ◽  
Computational Calculations ◽  
High Level

The energetic study of 6-hydroxy-1-indanone and 7-hydroxy-1-indanone was performed using experimental techniques and computational calculations. The enthalpies of combustion and sublimation of the two compounds were determined and allowed to derive the corresponding gas-phase standard molar enthalpies of formation. For this purpose, static-bomb combustion calorimetry and drop-method Calvet microcalorimetry were the experimental techniques used. Further, the enthalpy of fusion of each compound was obtained from scanning differential calorimetry measurements. Additionally, the gas-phase standard molar enthalpies of formation of these compounds were calculated through high-level ab initio calculations. The computational study of the molecular structures of the indanones was carried out and two possible conformers were observed for 6-hydroxy-1-indanone. Furthermore, the energetic effects associated with the presence of one hydroxyl group as a substituent on the benzenic ring of 1-indanone were also evaluated. Both experimental and theoretical methods show that 7-hydroxy-1-indanone is thermodynamically more stable than the 6-isomer in the gaseous phase and these results provide evidence for the existence of a strong intramolecular H-bond in 7-hydroxy-1-indanone. Finally, the intramolecular proton transfer in 7-hydroxy-1-indanone has been evaluated and as expected, it is not energetically favorable.

scholarly journals Experimental and Theoretical Investigation on the Thermochemistry of 3-Methyl-2-benzoxazolinone and 6-Nitro-2-benzoxazolinone

Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 24
Author(s):  
Ana L. R. Silva ◽  
Vânia M. S. Costa ◽  
Maria D. M. C. Ribeiro da Silva
Keyword(s):  
Gas Phase ◽  
Structural Characteristics ◽  
Enthalpies Of Formation ◽  
Calvet Microcalorimetry ◽  
Static Bomb ◽  
High Level ◽  
The Relationship ◽  
Related Compounds ◽  
Enthalpies Of Sublimation

The determination of the reliable thermodynamic properties of 2-benzoxazolinone derivatives is the main goal of this work. Some correlations are established between the energetic properties determined and the structural characteristics of the title compounds, and the reactivity of this class of compounds is also evaluated. Static-bomb combustion calorimetry and high-temperature Calvet microcalorimetry were used to determine, respectively, the standard molar enthalpies of formation in the solid state and the standard molar enthalpies of sublimation, both at T = 298.15 K. Using the results obtained for each compound, the respective gas-phase standard molar enthalpy of formation was derived. High-level quantum chemical calculations were performed to estimate the same property and the results evidence good accordance. Moreover, the gas-phase relative thermodynamic stability of 2-benzoxazolinone derivatives was also evaluated using the respective gas-phase standard molar Gibbs energy of formation. In addition, the relationship between the energetic and structural characteristics of the benzoxazolinones is presented, evidencing the enthalpic increments associated with the presence of a methyl and a nitro groups in the molecule, and this effect is compared with similar ones in other structurally related compounds.

scholarly journals Pathways to Detection of Strongly-Bound Inorganic Species: The Vibrational and Rotational Spectral Data of AlH2OH, HMgOH, AlH2NH2, and HMgNH2

2021 ◽  
Vol 8 ◽  
Author(s):  
Alexandria G. Watrous ◽  
Megan C. Davis ◽  
Ryan C. Fortenberry
Keyword(s):  
Small Molecules ◽  
Gas Phase ◽  
Spectral Data ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Hydroxyl Group ◽  
Phase Synthesis ◽  
Inorganic Species ◽  
Polycyclic Aromatic ◽  
High Level

Small, inorganic hydrides are likely hiding in plain sight, waiting to be detected toward various astronomical objects. AlH2OH can form in the gas phase via a downhill pathway, and the present, high-level quantum chemical study shows that this molecule exhibits bright infrared features for anharmonic fundamentals in regions above and below that associated with polycyclic aromatic hydrocarbons. AlH2OH along with HMgOH, HMgNH2, and AlH2NH2 are also polar with AlH2OH having a 1.22 D dipole moment. AlH2OH and likely HMgOH have nearly unhindered motion of the hydroxyl group but are still strongly bonded. This could assist in gas phase synthesis, where aluminum oxide and magnesium oxide minerals likely begin their formation stages with AlH2OH and HMgOH. This work provides the spectral data necessary to classify these molecules such that observations as to the buildup of nanoclusters from small molecules can possibly be confirmed.

scholarly journals A Thermochemical Computational Study on Hydroxyquinolines and their Azulene Analogues

2018 ◽  
Author(s):  
Moyassar Meshhal ◽  
Safinaz El-Demerdash ◽  
Ahmed El-Nahas
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Enthalpies Of Formation ◽  
Mean Absolute Deviation ◽  
Electron Affinities ◽  
Absolute Deviation ◽  
The Mean ◽  
Experimental Values ◽  
Theory And Experiment ◽  
Good Agreement

Ab initio CBS-QB3 method has been used to determine gas-phase enthalpies of formation for 34 compounds including a number of hydroxyquinoline isomers, the corresponding azulene analogues and their parent systems. The mean absolute deviation of 4.43 kJ/mol reveals good agreement between our results and the available experimental data. Relative thermodynamic stabilities of hydroxyquinoline isomers and related analogues were discussed and several isomerization reactions enthalpies were derived. The same level of theory has also been utilized to calculate adiabatic ionization energies and electron affinities for the molecules with known experimental values and the agreement between theory and experiment was found to be within 8 kJ/mol.

A Thermochemical Computational Study on Hydroxyquinolines and their Azulene Analogues

2018 ◽  
Author(s):  
Moyassar Meshhal ◽  
Safinaz El-Demerdash ◽  
Ahmed El-Nahas
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Enthalpies Of Formation ◽  
Mean Absolute Deviation ◽  
Electron Affinities ◽  
Absolute Deviation ◽  
The Mean ◽  
Experimental Values ◽  
Theory And Experiment ◽  
Good Agreement

Ab initio CBS-QB3 method has been used to determine gas-phase enthalpies of formation for 34 compounds including a number of hydroxyquinoline isomers, the corresponding azulene analogues and their parent systems. The mean absolute deviation of 4.43 kJ/mol reveals good agreement between our results and the available experimental data. Relative thermodynamic stabilities of hydroxyquinoline isomers and related analogues were discussed and several isomerization reactions enthalpies were derived. The same level of theory has also been utilized to calculate adiabatic ionization energies and electron affinities for the molecules with known experimental values and the agreement between theory and experiment was found to be within 8 kJ/mol.

scholarly journals Hydrogen Storage: Thermodynamic Analysis of Alkyl-Quinolines and Alkyl-Pyridines as Potential Liquid Organic Hydrogen Carriers (LOHC)

2021 ◽  
Vol 11 (24) ◽  
pp. 11758
Author(s):  
Sergey P. Verevkin ◽  
Sergey P. Safronov ◽  
Artemiy A. Samarov ◽  
Sergey V. Vostrikov
Keyword(s):  
Liquid Phase ◽  
Gas Phase ◽  
Wood Preservation ◽  
Enthalpies Of Formation ◽  
Vapor Pressures ◽  
Liquid Phase Hydrogenation ◽  
Substituted Quinolines ◽  
Attractive Option ◽  
Substituted Pyridines ◽  
High Level

The liquid organic hydrogen carriers (LOHC) are aromatic molecules, which can be considered as an attractive option for the storage and transport of hydrogen. A considerable amount of hydrogen up to 7–8% wt. can be loaded and unloaded with a reversible chemical reaction. Substituted quinolines and pyridines are available from petroleum, coal processing, and wood preservation, or they can be synthesized from aniline. Quinolines and pyridines can be considered as potential LOHC systems, provided they have favorable thermodynamic properties, which were the focus of this current study. The absolute vapor pressures of methyl-quinolines were measured using the transpiration method. The standard molar enthalpies of vaporization of alkyl-substituted quinolines and pyridines were derived from the vapor pressure temperature dependencies. Thermodynamic data on vaporization and formation enthalpies available in the literature were collected, evaluated, and combined with our own experimental results. The theoretical standard molar gas-phase enthalpies of formation of quinolines and pyridines, calculated using the quantum-chemical G4 methods, agreed well with the evaluated experimental data. Reliable standard molar enthalpies of formation in the liquid phase were derived by combining high-level quantum chemistry values of gas-phase enthalpies of formation with experimentally determined enthalpies of vaporization. The liquid-phase hydrogenation/dehydrogenation reaction enthalpies of alkyl-substituted pyridines and quinolines were calculated and compared with the data for other potential liquid organic hydrogen carriers. The comparatively low enthalpies of reaction make these heteroaromatics a seminal LOHC system.

scholarly journals 3,3-Bis(2-hydroxyethyl)-1-(4-nitrobenzoyl)thiourea: crystal structure, Hirshfeld surface analysis and computational study

2020 ◽  
Vol 76 (2) ◽  
pp. 155-161 ◽  
Author(s):  
Sang Loon Tan ◽  
Mukesh M. Jotani ◽  
Edward R. T. Tiekink
Keyword(s):  
Hydrogen Bonds ◽  
Gas Phase ◽  
Computational Study ◽  
Three Dimensional ◽  
Molecular Structures ◽  
Close Match ◽  
Covalent Interaction ◽  
Compound C ◽  
Hirshfeld Surfaces ◽  
Type C

In the title compound, C12H15N3O5S, a trisubstituted thiourea derivative, the central CN2S chromophore is almost planar (r.m.s. deviation = 0.018 Å) and the pendant hydroxyethyl groups lie to either side of this plane. While to a first approximation the thione-S and carbonyl-O atoms lie to the same side of the molecule, the S—C—N—C torsion angle of −47.8 (2)° indicates a considerable twist. As one of the hydroxyethyl groups is orientated towards the thioamide residue, an intramolecular N—H...O hydrogen bond is formed which leads to an S(7) loop. A further twist in the molecule is indicated by the dihedral angle of 65.87 (7)° between the planes through the CN2S chromophore and the 4-nitrobenzene ring. There is a close match between the experimental and gas-phase, geometry-optimized (DFT) molecular structures. In the crystal, O—H...O and O—H...S hydrogen bonds give rise to supramolecular layers propagating in the ab plane. The connections between layers to consolidate the three-dimensional architecture are of the type C—H...O, C—H...S and nitro-O...π. The nature of the supramolecular association has been further analysed by a study of the calculated Hirshfeld surfaces, non-covalent interaction plots and computational chemistry, all of which point to the significant influence and energy of stabilization provided by the conventional hydrogen bonds.

scholarly journals Structural and Energetic Insights on Two Dye Compounds: 1-Acetyl-2-Naphthol and 2-Acetyl-1-Naphthol

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3827
Author(s):  
Vera L. S. Freitas ◽  
Maria D. M. C. Ribeiro da Silva
Keyword(s):  
Gas Phase ◽  
Enthalpy Of Formation ◽  
Computational Study ◽  
Structural Rearrangement ◽  
Enthalpies Of Formation ◽  
Naphthalene Ring ◽  
Gaseous State ◽  
Knudsen Effusion ◽  
Intramolecular Hydrogen ◽  
Good Agreement

The energy involved in the structural switching of acyl and hydroxyl substituents in the title compounds was evaluated combining experimental and computational studies. Combustion calorimetry and Knudsen effusion techniques were used to determine the enthalpies of formation, in the crystalline state, and of sublimation, respectively. The gas-phase enthalpy of formation of both isomers was derived combining these two experimental data. Concerning the computational study, the G3(MP2)//B3LYP composite method was used to optimize and determine the energy of the isomers in the gaseous state. From a set of hypothetical reactions it has been possible to estimate the gas-phase enthalpy of formation of the title compounds. The good agreement between the experimental and computational gas-phase enthalpies of formation of the 1-acetyl-2-naphthol and 2-acetyl-1-naphthol isomers, provided the confidence for extending the computational study to the 2-acetyl-3-naphthol isomer. The structural rearrangement of the substituents in position 1 and 2 in the naphthalene ring and the energy of the intramolecular hydrogen bond are the factors responsible for the energetic differences exhibited by the isomers. The gas phase tautomeric keto ↔ enol equilibria of the o-acetylnaphthol isomers were analyzed using the Boltzmann’s distribution.

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