Comparison of Anion‐Anion Halogen Bonds with Neutral‐Anion Halogen Bonds in the Gas Phase and Polar Solvents

ChemPlusChem ◽  
2021 ◽  
Vol 86 (2) ◽  
pp. 232-240
Author(s):  
Ying Li ◽  
Lingpeng Meng ◽  
Yanli Zeng
Keyword(s):  
Gas Phase ◽  
Halogen Bonds ◽  
Polar Solvents

scholarly journals Efficient utilization of renewable feedstocks: the role of catalysis and process design

2017 ◽  
Vol 376 (2110) ◽  
pp. 20170064 ◽  
Author(s):  
Regina Palkovits ◽  
Irina Delidovich
Keyword(s):  
Elevated Temperature ◽  
Gas Phase ◽  
Process Design ◽  
Circular Economy ◽  
Paradigm Shift ◽  
Efficient Utilization ◽  
Polar Solvents ◽  
Platform Chemicals ◽  
Renewable Feedstocks

Renewable carbon feedstocks such as biomass and CO 2 present an important element of future circular economy. Especially biomass as highly functionalized feedstock provides manifold opportunities for the transformation into attractive platform chemicals. However, this change of the resources requires a paradigm shift in refinery design. Fossil feedstocks are processed in gas phase at elevated temperature. In contrast, biorefineries are based on processes in polar solvents at moderate conditions to selectively deoxygenate the polar, often thermally instable and high-boiling molecules. Here, challenges of catalytic deoxygenation, novel strategies for separation and opportunities provided at the interface to biotechnology are discussed in form of showcases. This article is part of a discussion meeting issue ‘Providing sustainable catalytic solutions for a rapidly changing world’.

Theoretical insight into the substituent effects on the antioxidant properties of 8-hydroxyquinoline derivatives in gas phase and in polar solvents

2018 ◽  
Vol 96 (5) ◽  
pp. 453-458
Author(s):  
Anes El-Hadj Saïd ◽  
Sidi Mohamed Mekelleche ◽  
Taki-Eddine Ahmed Ardjani
Keyword(s):  
Electron Transfer ◽  
Gas Phase ◽  
Antioxidant Properties ◽  
Substituent Effects ◽  
Hydrogen Atom Transfer ◽  
Polar Solvents ◽  
Antioxidant Power ◽  
Theoretical Insight ◽  
Insight Into

The objective of this work is to perform a theoretical analysis of the antioxidant properties of a series of 8-hydroxyquinolines (8-HQs) to rationalize the available experimental results and to design new potent 8-HQ derivatives. The study was carried out in gas phase and in methanol at the DFT/B3LYP/ 6-311++G(d,p) computational level. The formation of stable ArO• radicals is discussed on the basis of different mechanisms, namely, hydrogen atom transfer (HAT), single electron transfer followed by proton transfer (SET-PT), and single proton loss electron transfer (SPLET). The obtained results show that the HAT mechanism is, thermodynamically, more favoured in gas phase, whereas the SPLET pathway is more favoured in polar solvents. The calculated thermochemical descriptors allow classification of the antioxidant power of the studied compounds.

scholarly journals Effects of Solvent Polarity on Solvation Free Energy, Dipole Moment, Polarizability, Hyperpolarizability and Molecular Properties of Metronidazole

2016 ◽  
Vol 19 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Mohammad Firoz Khan ◽  
Ridwan Bin Rashid ◽  
Md Yeunus Mian ◽  
Mohammad S Rahman ◽  
Mohammad A Rashid
Keyword(s):  
Free Energy ◽  
Dipole Moment ◽  
Gas Phase ◽  
Chemical Potential ◽  
Solvent Polarity ◽  
Solvation Free Energy ◽  
Molecular Properties ◽  
Chemical Hardness ◽  
Electrophilicity Index ◽  
Polar Solvents

A computational study of medium effect on solvation free energy, dipole moment, polarizability, hyperpolarizability and different molecular properties like chemical hardness & softness, chemical potential, electronegativity and electrophilicity index of metronidazole have been reported in this paper. Becke, 3-parameter, Lee-Yang-Parr (B3LYP) level of theory with 6-31G (d,p) basis set was applied for gas phase and solution. The effect of solvent polarity on solvation free energy, dipole moment, polarizability, hyperpolarizability and molecular properties were calculated by employing Solvation Model on Density (SMD). The solvation free energies and dipole moment of metronidazole were found to be increased in nonpolar to polar solvents. The dipole moment of metronidazole was higher in different solvent than that of the gas phase. Moreover, from non-polar to polar solvents the chemical potential, electronegativity and electrophilicity index were increased. On the other hand, opposite relation was found in the case of chemical hardness and softness. The results obtained in this study may lead to understand the stability and reactivity of metronidazole and the results will be of assistance to use the title molecule as reaction intermediates and pharmaceuticals.Bangladesh Pharmaceutical Journal 19(1): 9-14, 2016

ANTIOXIDANT ACTIVITY OF AMINOTHIAZOL HYDROXYCOUMARIN DERIVATIVES

2013 ◽  
Vol 12 (06) ◽  
pp. 1350058 ◽  
Author(s):  
DAVOOD FARMANZADEH ◽  
MEYSAM NAJAFI
Keyword(s):  
Antioxidant Activity ◽  
Gas Phase ◽  
Antioxidant Activities ◽  
Antioxidant Properties ◽  
Experimental Studies ◽  
Structure Parameters ◽  
Coumarin Derivatives ◽  
Polar Solvents ◽  
B3lyp Method ◽  
High Antioxidant Activity

In this work, the antioxidant properties of the series of 10 aminothiazol hydroxyl coumarin derivatives have been investigated with DFT/B3LYP method. For these antioxidants all reaction enthalpies related to HAT, SPLET, SET-PT mechanisms were calculated in the gas phase and polar solvents. Based on calculated reaction enthalpies (BDE, IP and PA values) the derivations 2, 3 and 4 have the highest antioxidant activity among the studied compounds. Calculated results show that derivations 7, 5 and 6 have the lowest antioxidant activity. The observed theoretical trends for antioxidant activities of studied compounds were similar to trends of previous experimental studies that OH50, TAC50, IC50, CE50 values have been used as a benchmark for measuring the antioxidant properties of these compounds. These results can be useful in synthesis of novel aminothiazol hydroxycoumarin derivatives with high antioxidant activity. Calculated results show that BDE, PA and IP values of studied derivations have linear dependence with structure parameters such as R( O – H ), q( O ) and E HOMO . These observed linear dependences can be useful in synthesis of novel aminothiazol hydroxyl coumarin derivatives with high antioxidant activity. For studied compounds, results indicated that the SPLET and HAT mechanisms represent the thermodynamically preferred mechanism both, in solvent and the gas phase.

scholarly journals The Thermal Degradation of Tobacco: VI. Influence of Extraction on the Formation of Some Major Gas Phase Constituents

1975 ◽  
Vol 8 (4) ◽  
Author(s):  
H.R. Burton ◽  
G. Childs
Keyword(s):  
Thermal Decomposition ◽  
Thermal Degradation ◽  
Gas Phase ◽  
Inert Atmosphere ◽  
Polar Solvents ◽  
Volatile Constituents

AbstractFormation profiles have been determined for the major gas phase constituents formed in an inert atmosphere during the dynamic thermal decomposition of tobaccos extracted with hexane, chloroform, acetone, acetonitrile, and methanol. The profiles include methane, ethane, ethene, propane, propene, isoprene, formaldehyde, acetaldehyde, acetone, 2-butanone, acetonitrile, benzene, and toluene. Except for propene and propane, extraction of tobacco does not dramatically influence either the temperatures for maximum formation or the level of hydrocarbons formed during thermal decomposition of the tobaccos. This suggests that the majority of the gas phase hydrocarbons are formed from the insoluble leaf constituents. Isoprene has formation maxima at 375°C and 450°C, and extraction of tobacco with non-polar solvents removes leaf precursors responsible for the formation maxima at 375°C. Polar solvents remove the major isoprene precursors which are responsible for the maxima at 375° and 450°C. Extraction effects an increase of both formaldehyde and acetaldehyde formation but has little influence on the formation of either acetone or 2-butanone. The formation profile for acetonitrile has been established and shows that it has maximum formation at 410° and 500°C. Extraction has no influence either on the formation of benzene or toluene. Data from the profiles of these volatile constituents generally agree with smoke data from extracted tobacco which indicates that this method is useful for studying factors that influence the formation of the gas phase constituents

scholarly journals Unveiling the regioselective synthesis of antiviral 5-isoxazol-5-yl-2'deoxyuridines with a molecular electron density theory perspective

2021 ◽  
pp. 106-106
Author(s):  
Nivedita Acharjee ◽  
Haydar Mohammad-Salim ◽  
Mrinmoy Chakraborty
Keyword(s):  
Gas Phase ◽  
Electron Density ◽  
Activation Enthalpy ◽  
Regioselective Synthesis ◽  
Polar Solvents ◽  
Aim Analysis ◽  
Covalent Bonds ◽  
Molecular Electron ◽  
Molecular Electron Density Theory ◽  
Density Transfer

The regioselective synthesis of a potent antiviral sugar nucleoside isoxazole analogue from the [3+2] cycloaddition (32CA) reaction of aceto-nitrile-N-oxide (ANO) and acetyl-protected 5-ethynyl-2?-deoxyuridine (EDU) has been studied at MPWB1K/6-311G(d,p) level within the molecular electron density theory (MEDT) perspective. ANO is classified as a zwitterionic species devoid of any pseudoradical or carbenoid center from the electron localization function (ELF) analysis. The ortho regioisomer is energetically preferred over the meta one by the activation enthalpy of 21.7-24.3 kJ mol-1, suggesting complete regioselectivity in agreement with the experiment. The activation enthalpy increases from 53.9 kJ mol-1 in gas phase to 71.5 kJ mol-1 in water suggesting more facile reaction in low polar solvents. The minimal global electron density transfer (GEDT) at the TSs suggests non-polar character and the formation of new covalent bonds has not been started at the located TSs showing non-covalent intermolecular interactions from Atoms-in-Molecules (AIM) study and in the Independent Gradient Model (IGM) isosurfaces. The AIM analysis shows more accumulation of electron density at the C-C interacting region relative to the C-O one, and earlier C-C bond formation is predicted from the bonding evolution theory (BET) study.

Structures of Energetic Acetylene Derivatives HC≡CCH2ONO2, (NO2)3CCH2C≡CCH2C(NO2)3 and Trinitroethane, (NO2)3CCH3

2013 ◽  
Vol 68 (5-6) ◽  
pp. 719-731 ◽  
Author(s):  
Thomas M. Klapötke ◽  
Burkhard Krumm ◽  
Richard Moll ◽  
Alexander Penger ◽  
Stefan M. Sproll ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Room Temperature ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
Polar Solvents ◽  
X Ray ◽  
Nmr Study ◽  
Acetylene Derivatives

The molecular structures and relative ratios of the two conformers (anti and gauche) of HCCCH2ONO2 detected in the gas phase at room temperature have been determined by electron diffraction. The results are discussed on the basis of quantum chemical calculations. The molecular structures of (NO2)3CCH2C≡CCH2C(NO2)3 and (NO2)3CCH3 have been determined by X-ray diffraction. A109Ag NMR study was performed for silver trinitromethanide Ag[C(NO2)3] in various polar solvents.

A THEORETICAL STUDY OF THE INTERACTIONS OF IODO-PERFLUOROCARBON AND IODO-HYDROCARBON WITH HALOID ANIONS

2006 ◽  
Vol 05 (04) ◽  
pp. 719-732 ◽  
Author(s):  
YANHUA WANG ◽  
JIANWEI ZOU ◽  
YUNXIANG LU ◽  
QINGSEN YU
Keyword(s):  
Carbon Atom ◽  
Gas Phase ◽  
Theoretical Study ◽  
Halogen Bonds ◽  
Interatomic Distances ◽  
Geometrical Data ◽  
Opposite Order ◽  
Anion Complexes ◽  
Insight Into ◽  
Fluorine Anion

Ab initio calculations have been performed on a series of complexes formed between iodo-perfluorocarbons(PFCs) and iodo-hydrocarbons(HCs) and haloid anions to gain a deeper insight into the nature of halogen bonds. It appears that halogen bonds in these complexes are much stronger than neutral halogen bonds. Calculations also show that the strength of halogen bonds in iodo-PFC⋯ haloid anion dimers are greater than those in iodo-HC⋯ haloid anion dimers. A comparison of the two complex series reveals that the hybridization state of the carbon atom bonded to iodine has a less pronounced effect on the interatomic distances I⋯X in the iodo-PFC series in relation to the iodo-HC series. PCM calculations used to investigate the solvent effect on halogen bonds unveil that, in the gas phase, fluorine anion prefers to form halogen-bonded complexes with respect to chloride, bromide, and iodine anions; however, the preference is not obvious, and even an opposite order is observed in solutions. It is worth mentioning that the iodo-PFC⋯ fluorine anion complexes present a special structure, i.e. the interatomic I⋯F distances in these complexes are relatively short and the corresponding C–I bonds tend to be further broken. These features, in combination with the geometrical data, indicate that ate-complexes are formed between iodo-PFC and fluorine anions.

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