Transmission of Electronic Effects through the Vinyl Group. Reactives of the (E)-a-4-Substituted Phenyl-b-pyridineacrylic Acids

Heterocycles ◽  
1994 ◽  
Vol 37 (3) ◽  
pp. 1503 ◽  
Author(s):  
Milica Misic-Vukovic ◽  
Sasa Drmanic ◽  
Bratislav Jovanovic
Keyword(s):  
Electronic Effects ◽  
Vinyl Group

scholarly journals Effects of substituents on the 1H-NMR chemical shifts of 3-methylene-2-substituted-1, 4-pentadienes

2003 ◽  
Vol 68 (7) ◽  
pp. 525-534 ◽  
Author(s):  
Natasa Valentic ◽  
Gordana Uscumlic
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
Electronic Effects ◽  
Resonance Effects ◽  
Charge Densities ◽  
Linear Free Energy ◽  
Energy Relationships ◽  
Consistent Picture ◽  
Vinyl Group ◽  
Proton Chemical Shifts

The principle of linear free energy relationships was applied to the 1H chemical shifts of the ?-vinyl proton atoms of 3-methylene-2-substituted-1,4-pentadienes. The correlations of the proton chemical shifts with Swain and Lupton substituent parameters provide a mutually consistent picture of the electronic effects in these compounds. The overall pattern of proton chemical shifts can be largely accounted for by a model of substituent effects based on field, resonance and ? polarization effects. Owing to the particular geometric arrangement of the vinyl group in 3-methylene-2-substituted-1,4-pentadienes, the ?-vinyl protons HB and HC have different sensitivities to polar and resonance effects. The different sensitivities of the 1H chemical shifts to resonance effects reveals some effects not predicted by the model outlined above. Evidence is presented that demonstrates that both the 1H and 13C chemical shifts for these compounds reflect their ground-state charge densities.

Evolution thermique de N-oxydes de dimethylamino-5 alcanols-1 substitues en 5. Competition entre rearrangements de cope et de Meisenheimer

1985 ◽  
Vol 50 (4) ◽  
pp. 956-961
Author(s):  
Didier Barbry ◽  
Bruno Hasiak ◽  
Jean-Michel Augait ◽  
Daniel Couturier
Keyword(s):  
Hydrogen Atom ◽  
Statistical Distribution ◽  
Methyl Ethyl ◽  
Phenyl Substituent ◽  
Electronic Effects ◽  
Vinyl Group ◽  
Acidic Hydrogen

The effect of the substituent R in the position was studied in the decomposition of 1,5-aminoalcohol N-oxides: Meisenheimer rearrangement takes place when R is the vinyl group but is not observed with the phenyl substituent; elimination to alkenol only affects the more acidic hydrogen atom when R is the allyl or benzyl group; with substituents inducing less important electronic effects (methyl, ethyl), the reaction yields an alkenols mixture with statistical distribution.

Carbon-13 chemical shifts as a probe for conformational and electronic effects in alkyl vinyl ethers

1983 ◽  
Vol 61 (3) ◽  
pp. 488-493 ◽  
Author(s):  
John G. K. Webb ◽  
David K. Yung
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
Electronic Effects ◽  
Vinyl Ethers ◽  
Resonance Effects ◽  
Polarization Mechanism ◽  
Chemical Shift Data ◽  
Vinyl Group ◽  
The Relationship ◽  
Geminal Substituent

The principle of additivity of substituent chemical shifts (SCS) is applied to the carbon-13 chemical shifts of β carbons (δβ) in a number of 1,1-disubstituted ethylenes and propenes, which includes some α-substituted alkyl vinyl ethers. An additivity relationship is observed for 34 compounds that indicates an independent polarization mechanism across the double bond for each geminal substituent. Positive deviations from additivity are observed for compounds bearing bulky substituents. The magnitude of deviations is taken as an indication of the severity of steric interactions among substituents.Reductions in efficiency of transmission of substituent effects in ring substituted α-phenyl alkyl vinyl ethers, relative to para-substituted styrenes, are interpreted as the result of a variable dihedral angle between the ring and vinyl group. An explanation of the relationship between conformation and transmission of substituent effects is presented as an alternative to existing views. An angular dependence of π-polarization and resonance effects is consistent with the chemical shift data.

On the Crystal Chemistry of Inorganic Nitrides: Crystal-Chemical Parameters and Opportunities in the Exploration of Their Compositional Space

2020 ◽  
Author(s):  
Olivier Charles Gagné
Keyword(s):  
Functional Properties ◽  
A Priori ◽  
Lone Pair ◽  
Length Variation ◽  
Electronic Effects ◽  
Statistical Knowledge ◽  
Redox Active ◽  
Multiply Bonded ◽  
Jahn Teller ◽  
Compositional Space

The scarcity of nitrogen in Earth’s crust, combined with challenging synthesis, have made inorganic nitrides a relatively-unexplored class of compounds compared to their naturally-abundant oxide counterparts. To facilitate exploration of their compositional space via <i>a priori</i> modeling, and to help <i>a posteriori</i> structure verification not limited to inferring the oxidation state of redox-active cations, we derive a suite of bond-valence parameters and Lewis-acid strength values for 76 cations observed bonding to N<sup>3-</sup>, and further outline a baseline statistical knowledge of bond lengths for these compounds. We examine structural and electronic effects responsible for the functional properties and anomalous bonding behavior of inorganic nitrides, and identify promising venues for exploring uncharted compositional spaces beyond the reach of high-throughput computational methods. We find that many mechanisms of bond-length variation ubiquitous to oxide and oxysalt compounds (e.g., lone-pair stereoactivity, the Jahn-Teller and pseudo Jahn-Teller effects) are similarly pervasive in inorganic nitrides, and are occasionally observed to result in greater distortion magnitude than their oxide counterparts. We identify inorganic nitrides with multiply-bonded metal ions as a promising venue in heterogeneous catalysis, e.g. in the development of a post-Haber-Bosch process proceeding at milder reaction conditions, thus representing further opportunity in the thriving exploration of the functional properties of this emerging class of materials.<br>

scholarly journals Substituent Effects on EI-MS Fragmentation Patterns of 5-Allyloxy-1-aryl-tetrazoles and 4-Allyl-1-aryl-tetrazole-5-ones; Correlation with UV-Induced Fragmentation Channels

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3282
Author(s):  
Alina Secrieru ◽  
Rabah Oumeddour ◽  
Maria L. S. Cristiano
Keyword(s):  
Theoretical Calculations ◽  
Substituent Effects ◽  
Radical Cations ◽  
Electronic Effects ◽  
Diverse Range ◽  
The Matrix ◽  
Electron Impact Mass ◽  
Fragmentation Patterns ◽  
Tetrazole Derivatives ◽  
Impact Mass

1,4- and 1,5-disubstituted tetrazoles possess enriched structures and versatile chemistry, representing a challenge for chemists. In the present work, we unravel the fragmentation patterns of a chemically diverse range of 5-allyloxy-1-aryl-tetrazoles and 4-allyl-1-aryl-tetrazolole-5-ones when subjected to electron impact mass spectrometry (EI-MS) and investigate the correlation with the UV-induced fragmentation channels of the matrix-isolated tetrazole derivatives. Our results indicate that the fragmentation pathways of the selected tetrazoles in EI-MS are highly influenced by the electronic effects induced by substitution. Multiple pathways can be envisaged to explain the mechanisms of fragmentation, frequently awarding common final species, namely arylisocyanate, arylazide, arylnitrene, isocyanic acid and hydrogen azide radical cations, as well as allyl/aryl cations. The identified fragments are consistent with those found in previous investigations concerning the photochemical stability of the same class of molecules. This parallelism showcases a similarity in the behaviour of tetrazoles under EI-MS and UV-irradiation in the inert environment of cryogenic matrices of noble gases, providing efficient tools for reactivity predictions, whether for analytical ends or more in-depth studies. Theoretical calculations provide complementary information to articulate predictions of resulting products.

Steric and Electronic Effects on the Interaction of Xe and Kr with Functionalized Zirconia Metal–Organic Frameworks

2021 ◽  
pp. 504-510
Author(s):  
David C. Fairchild ◽  
Mohammad I. Hossain ◽  
Jesus Cordova ◽  
T. Grant Glover ◽  
Fernando J. Uribe-Romo
Keyword(s):  
Metal Organic Frameworks ◽  
Electronic Effects ◽  
Metal Organic

scholarly journals An Electrochemical Evaluation of Novel Ferrocene Derivatives for Glutamate and Liver Biomarker Biosensing

Biosensors ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 254
Author(s):  
Geok Hong Soon ◽  
Mary Deasy ◽  
Eithne Dempsey
Keyword(s):  
Film Studies ◽  
Redox Potentials ◽  
Signal Loss ◽  
Electronic Effects ◽  
Ferrocene Derivatives ◽  
Electroactive Films ◽  
Glutamate Oxidase ◽  
Electronic Effects Of Substituents ◽  
Glutamyl Transpeptidase

Here, we present an evaluation of two new monosubstituted ferrocene (Fc) derivatives, 3-(1H-pyrrol-1-yl)propanamidoferrocene and 1-hydroxy-2-[2-(thiophen-3-yl)-ethylamino]ethylferrocene, as glutamate oxidase mediators, together with their preparation and characterisation. Taking into consideration the influence of the electronic effects of substituents on the redox potentials of the Fc species, two candidates with pyrrole or thiophene moieties were proposed for investigation. Film studies involved potential sweeping in the presence of pyrrole or 3,4-ethylenedioxythiophene monomers resulting in stable electroactive films with % signal loss upon cycling ranging from 1 to 7.82% and surface coverage (Γ) 0.47–1.15 × 10−9 mol/cm2 for films formed under optimal conditions. Construction of a glutamate oxidase modified electrode resulted in second-generation biosensing with the aid of both cyclic voltammetry and hydrodynamic amperometry, resulting in glutamate sensitivity of 0.86–1.28 μA/mM and Km (app) values over the range 3.67–5.01 mM. A follow-up enzyme assay for liver biomarker γ-glutamyl transpeptidase realised unmediated and mediated measurement establishing reaction and incubation time investigations and a realising response over <100 U/L γ-glutamyl transpeptidase with a sensitivity of 5 nA/UL−1.

scholarly journals Element-resolved local lattice distortion in complex concentrated alloys: An observable signature of electronic effects

2021 ◽  
pp. 117135
Author(s):  
Hyun Seok Oh ◽  
Khorgolkhuu Odbadrakh ◽  
Yuji Ikeda ◽  
Sai Mu ◽  
Fritz Körmann ◽  
...  
Keyword(s):  
Lattice Distortion ◽  
Electronic Effects ◽  
Local Lattice Distortion ◽  
Local Lattice
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