The Effects of Interactions of Dicarboxylic Acids on the Stability of the Caffeine Molecule: A Theoretical Study

2014 ◽  
Vol 87 (10) ◽  
pp. 1116-1123 ◽  
Author(s):  
Abolfazl Azizi ◽  
Ali Ebrahimi ◽  
Mostafa Habibi-Khorassani ◽  
Shiva Rezazadeh ◽  
Roya Behazin
Keyword(s):  
Theoretical Study ◽  
Dicarboxylic Acids ◽  
The Stability

A review of lignin hydrogen peroxide oxidation chemistry with emphasis on aromatic aldehydes and acids

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ajinkya More ◽  
Thomas Elder ◽  
Zhihua Jiang
Keyword(s):  
Hydrogen Peroxide ◽  
Oxidative Degradation ◽  
Reaction Medium ◽  
Dicarboxylic Acids ◽  
Aromatic Aldehydes ◽  
Product Distribution ◽  
Reaction Conditions ◽  
Alkaline Conditions ◽  
The Stability ◽  
Oxidation Chemistry

Abstract This review discusses the main factors that govern the oxidation processes of lignins into aromatic aldehydes and acids using hydrogen peroxide. Aromatic aldehydes and acids are produced in the oxidative degradation of lignin whereas mono and dicarboxylic acids are the main products. The stability of hydrogen peroxide under the reaction conditions is an important factor that needs to be addressed for selectively improving the yield of aromatic aldehydes. Hydrogen peroxide in the presence of heavy metal ions readily decomposes, leading to minor degradation of lignin. This degradation results in quinones which are highly reactive towards peroxide. Under these reaction conditions, the pH of the reaction medium defines the reaction mechanism and the product distribution. Under acidic conditions, hydrogen peroxide reacts electrophilically with electron rich aromatic and olefinic structures at comparatively higher temperatures. In contrast, under alkaline conditions it reacts nucleophilically with electron deficient carbonyl and conjugated carbonyl structures in lignin. The reaction pattern in the oxidation of lignin usually involves cleavage of the aromatic ring, the aliphatic side chain or other linkages which will be discussed in this review.

Theoretical Study on the Stability and Aromaticity of Metallasilapentalynes

2014 ◽  
Vol 33 (7) ◽  
pp. 1845-1850 ◽  
Author(s):  
Xuerui Wang ◽  
Congqing Zhu ◽  
Haiping Xia ◽  
Jun Zhu
Keyword(s):  
Theoretical Study ◽  
The Stability

Study of the Stability and Chemical Reactivity of a Series of Tetrazole Pyrimidine Hybrids by the Density Functional Theory Method (DFT)

2021 ◽  
Vol 37 (4) ◽  
pp. 805-812
Author(s):  
Ahissandonatien Ehouman ◽  
Adjoumanirodrigue Kouakou ◽  
Fatogoma Diarrassouba ◽  
Hakim Abdel Aziz Ouattara ◽  
Paulin Marius Niamien
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Molecular Descriptors ◽  
Chemical Reactivity ◽  
Density Functional Theory Method ◽  
Functional Theory ◽  
Reactivity Descriptors ◽  
The Density Functional Theory ◽  
The Stability ◽  
Global Reactivity Descriptors

Our theoretical study of stability and reactivity was carried out on six (06) molecules of a series of pyrimidine tetrazole hybrids (PTH) substituted with H, F, Cl, Br, OCH3 and CH3 atoms and groups of atoms using the density function theory (DFT). Analysis of the thermodynamic formation quantities confirmed the formation and existence of the series of molecules studied. Quantum chemical calculations at the B3LYP / 6-311G (d, p) level of theory determined molecular descriptors. Global reactivity descriptors were also determined and analyzed. Thus, the results showed that the compound PTH_1 is the most stable, and PTH_5 is the most reactive and nucleophilic. Similarly, the compound PTH_4 is the most electrophilic. The analysis of the local descriptors and the boundary molecular orbitals allowed us to identify the preferred atoms for electrophilic and nucleophilic attacks.

scholarly journals 3P141 Theoretical study on the stability of amphiphile aggregates: RISM approach

2005 ◽  
Vol 45 (supplement) ◽  
pp. S239
Author(s):  
T. Miyata ◽  
F. Hiratra
Keyword(s):  
Theoretical Study ◽  
The Stability

THEORETICAL STUDY OF SANDWICH COMPLEXES [Fe(η4 - E4)2]2- (E = N, P, As, Sb, AND Bi)

2007 ◽  
Vol 06 (02) ◽  
pp. 363-376 ◽  
Author(s):  
ZHIWEI LI ◽  
CUNYUAN ZHAO ◽  
LIUPING CHEN
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Sandwich Complexes ◽  
Functional Theory ◽  
Atomic Orbitals ◽  
Orbital Interactions ◽  
The Stability ◽  
Equilibrium Geometries ◽  
Orbital Analysis ◽  
Iron Center

The equilibrium geometries, energies, harmonic vibrational frequencies, stability, and aromaticities for the [Formula: see text], E 4 Fe , and [ Fe (η4 - E 4)2]2- ( E = N, P, As, Sb, and Bi ) species are studied using density functional theory (DFT). The ground states of the E 4 Fe and [ Fe (η4 - E 4)2]2- systems are predicted to be Cs and D4d structures, respectively. Orbital analysis indicates that the orbital interactions between the π orbitals of the ligands and the atomic orbitals of the d 6 iron center are the main bonding scheme for these [ Fe (η4 - E 4)2]2- (D4d) complexes. The stability of the [ Fe (η4 - E 4)2]2- complexes exhibits the order P > As > Sb > Bi > N for E. On the basis of comparison with the known ferrocene, the NICS analysis confirms that the [ Fe (η4 - E 4)2]2- (D4d) as well as ferrocene are aromatic. The dissected NICS reveals that the aromaticities of the [ Fe (η4 - E 4)2]2- (D4d) are primarily attributed to the effects of their E–E π bonds and Fe lone pairs.

Halogen⋯halogen interactions in decahalo-closo-carboranes: CSD analysis and theoretical study

2020 ◽  
Vol 22 (11) ◽  
pp. 6122-6130 ◽  
Author(s):  
Maria de las Nieves Piña ◽  
Antonio Bauzá ◽  
Antonio Frontera
Keyword(s):  
Theoretical Study ◽  
The Stability

We theoretically (PBE0-D3/def2TZVP) and experimentally (CSD analysis) demonstrate the importance of “like–like” halogen interactions for the stability of several decahalo-closo-carborane dimers.

Theoretical study of the stability and NMR spectroscopic properties of vanadium(V) complexes

2019 ◽  
Vol 138 (11) ◽  
Author(s):  
Lisset Noriega ◽  
María Eugenia Castro ◽  
Jose Manuel Perez-Aguilar ◽  
Norma A. Caballero ◽  
Thomas Scior ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Spectroscopic Properties ◽  
The Stability
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