Substituent effects in alkynes and cyanides: a momentum density perspective

1985 ◽  
Vol 63 (7) ◽  
pp. 1412-1417 ◽  
Author(s):  
Alfredo M. Simas ◽  
Vedene H. Smith Jr ◽  
Ajit J. Thakkar
Keyword(s):  
Homologous Series ◽  
Three Dimensional ◽  
Substituent Effects ◽  
Momentum Density ◽  
Space Charge Density ◽  
Quantum Mechanical ◽  
Position Space ◽  
Partial Wave Decomposition ◽  
Substituent Constants ◽  
Wave Decomposition

Apriori quantum mechanical calculations are made for the alkynes XCCH (X = H, Li, F, Cl, and NC), and the cyanides XCN (X = H, F, Cl, O−, S−, and NC) in order to examine how substituent effects in these homologous series are reflected by changes in the three-dimensional one-electron momentum density. Our qualitative analysis is based on a partial wave decomposition of the momentum density, and is in harmony with analogous studies of the position space charge density. Our quantitative analysis is based on various properties of the isotropic momentum density and on the kinetic energy anisotropy. Values of the latter quantity relative to the parent unsubstituted molecule of the pertinent homologous series are found to correlate with the Taft resonance and Dewar–Grisdale mesomeric substituent constants.

scholarly journals THE PROTON-DEUTERON BREAK-UP PROCESS IN A THREE-DIMENSIONAL APPROACH

2003 ◽  
Vol 18 (02n06) ◽  
pp. 452-455 ◽  
Author(s):  
IMAM FACHRUDDIN ◽  
CHARLOTTE ELSTER ◽  
WALTER GLÖCKLE
Keyword(s):  
Partial Wave ◽  
Cross Section ◽  
Three Dimensional ◽  
Relativistic Effects ◽  
Peak Height ◽  
Partial Wave Decomposition ◽  
Leading Term ◽  
Break Up ◽  
The Cross ◽  
Wave Decomposition

The pd break-up amplitude in the Faddeev scheme is calculated by employing a three-dimensional method without partial wave decomposition (PWD). In the first step and in view of higher energies only the leading term is evaluated and this for the process d(p,n)pp. A comparison with the results based on PWD reveals discrepancies in the cross section around 200 MeV. This indicates the onset of a limitation of the partial wave scheme. Also around 200 MeV relativistic effects are clearly visible and the use of relativistic kinematics shifts the cross section peak to where the experimental peak is located. The theoretical peak height, however, is wrong and calls first of all for the inclusion of rescattering terms, which are shown to be important in a nonrelativistic full Faddeev calculation in PWD.

scholarly journals Relativistic nucleon–nucleon potentials in a spin-dependent three-dimensional approach

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. R. Hadizadeh ◽  
M. Radin ◽  
F. Nazari
Keyword(s):  
Cross Sections ◽  
Three Dimensional ◽  
Nucleon Nucleon ◽  
Triplet States ◽  
Partial Wave Decomposition ◽  
Proton Elastic Scattering ◽  
Spin Singlet ◽  
The Matrix ◽  
Single Integral ◽  
Wave Decomposition

AbstractThe matrix elements of relativistic nucleon–nucleon (NN) potentials are calculated directly from the nonrelativistic potentials as a function of relative NN momentum vectors, without a partial wave decomposition. To this aim, the quadratic operator relation between the relativistic and nonrelativistic NN potentials is formulated in momentum-helicity basis states. It leads to a single integral equation for the two-nucleon (2N) spin-singlet state, and four coupled integral equations for two-nucleon spin-triplet states, which are solved by an iterative method. Our numerical analysis indicates that the relativistic NN potential obtained using CD-Bonn potential reproduces the deuteron binding energy and neutron-proton elastic scattering differential and total cross-sections with high accuracy.

Substituent effects in 1,3-indanediones

1982 ◽  
Vol 47 (5) ◽  
pp. 1486-1493 ◽  
Author(s):  
Alexander Perjéssy
Keyword(s):  
Substituent Effects ◽  
Empirical Equations ◽  
Substituent Constants ◽  
Complex Structural

The carbonyl stretching frequencies correlate well with substituent constants in a series of 166 1,3-indanediones using improved and extended Seth-Paul-Van Duyse equation. Transmissive factors and group electronegativities have been used to find empirical equations for calculation of substituent constants of more complex structural fragments.

Kinetic Study of Hydrolysis of Benzoates. Part XXVI. Variation of the Substituent Effect with Solvent in Alkaline Hydrolysis of Substituted Alkyl Benzoates

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1557-1570 ◽  
Author(s):  
Vilve Nummert ◽  
Mare Piirsalu ◽  
Ilmar A. Koppel
Keyword(s):  
Kinetic Study ◽  
Alkaline Hydrolysis ◽  
Rate Constants ◽  
Substituent Effect ◽  
Substituent Effects ◽  
Alkyl Substituent ◽  
Solvent Parameters ◽  
Substituent Constants ◽  
Hydrolysis Of ◽  
Main Factor

The second-order rate constants k2 (dm3 mol-1 s-1) for the alkaline hydrolysis of substituted alkyl benzoates C6H5CO2R have been measured spectrophotometrically in aqueous 0.5 M Bu4NBr at 50 and 25 °C (R = CH3, CH2Cl, CH2CN, CH2C≡CH, CH2C6H5, CH2CH2Cl, CH2CH2OCH3, CH2CH3) and in aqueous 5.3 M NaClO4 at 25 °C (R = CH3, CH2Cl, CH2CN, CH2C≡CH). The dependence of the alkyl substituent effects on different solvent parameters was studied using the following equations:      ∆ log k = c0 + c1σI + c2EsB + c3∆E + c4∆Y + c5∆P + c6∆EσI + c7∆YσI + c8∆PσI     ∆ log k = c0 + c1σ* + c2EsB + c3∆E + c4∆Y + c5∆P + c6∆Eσ* + c7∆Yσ* + c8∆Pσ* .  ∆ log k = log kR - log kCH3. σI and σ* are the Taft inductive and polar substituent constants. E, Y and P are the solvent electrophilicity, polarity and polarizability parameters, respectively. In the data treatment ∆E = ES - EH2O , ∆Y = YS - YH2O , ∆P = PS - PH2O were used. The solvent electrophilicity, E, was found to be the main factor responsible for changes in alkyl substituent effects with medium. When σI constants were used, variation of the polar term of alkyl substituents with the solvent electrophilicity E was found to be similar to that observed earlier for meta and para substituents, but twice less when σ* constants were used. The steric term for alkyl substituents was approximately independent of the solvent parameters.

Effects of Medium and Substituents on Dissociationof 4,4'-Disubstituted Bis(benzenesulfon)imides

1996 ◽  
Vol 61 (8) ◽  
pp. 1205-1214 ◽  
Author(s):  
Miroslav Ludwig ◽  
Pavel Štverka
Keyword(s):  
Latent Variables ◽  
Dissociation Constants ◽  
Substituent Effects ◽  
Principal Component ◽  
H Nmr ◽  
Base Process ◽  
Elemental Analyses ◽  
Substituent Constants ◽  
Model Substances ◽  
Strong Acids

Ten 4,4'-disubstituted bis(arenesulfon)imides of the general formula XC6H4SO2NHSO2C6H4X have been synthesized and their structures confirmed by their 1H NMR spectra. Elemental analyses are presented for the compounds not yet described. The dissociation constants of these model substances have been measured potentiometrically in pyridine, dimethylformamide, methanol, ethanol, propylene carbonate, acetone, acetonitrile, 1,2-dichloroethane and tetramethylene sulfone. The pKHA values obtained have been correlated with three sets of the Hammett substituent constants and the results have been used to discuss the solvent and substituent effects on the dissociation of the compounds studied. Sulfonimides with electron-acceptor substituents behave as rather strong acids in some solvents (pyridine, dimethylformamide, methanol and ethanol), whereas normal substituent dependences are found in other solvents. The experimental data have also been interpreted with the help of the statistical methods based on latent variables. From the calculations it follows that only the first principal component, which correlates well with the substituent constant sets adopted, is statistically significant in describing the substituent effect on the acid-base process studied.

Infrared spectra of aqueous sodium benzoates and salicylates in the carboxyl-stretching region: chelation in aqueous sodium salicylates

1969 ◽  
Vol 47 (24) ◽  
pp. 4577-4588 ◽  
Author(s):  
G. E. Dunn ◽  
R. S. McDonald
Keyword(s):  
Salicylic Acid ◽  
Carbon Tetrachloride ◽  
Infrared Spectra ◽  
Aromatic Compounds ◽  
Deuterium Oxide ◽  
Substituent Effects ◽  
Good Evidence ◽  
Frequency Region ◽  
Aqueous Sodium ◽  
Substituent Constants

Infrared spectra in the frequency region 1300–1760 cm−1 are reported for 41 substituted sodium benzoates and 10 substituted sodium salicylates in deuterium oxide solution, and for 9 substituted salicylic acids in chloroform and carbon tetrachloride solutions. Carboxylate stretching frequencies of benzoates and salicylates correlate poorly with substituent constants, but the asymmetric frequencies of benzoates and salicylates correlate well with each other, and the asymmetric frequencies of benzoates correlate well with the asymmetric frequencies of the corresponding nitrobenzenes. It is suggested that, among substituted aromatic compounds, group vibrations which couple with the ring vibrations may correlate well with similar vibrations of other groups, but not with coupled vibrations of different symmetry, uncoupled vibrations, or substituent constants. Chelation in chloroform solutions of salicylic acid dimers can be detected by its influence on substituent effects, but infrared spectra provide no good evidence for chelation in aqueous sodium salicylates.

Quantum information entropy and squeezing of 𝒫𝒯-symmetric potential

2021 ◽  
Vol 36 (10) ◽  
pp. 2150065
Author(s):  
Aarti Sharma ◽  
Pooja Thakur ◽  
Girish Kumar ◽  
Anil Kumar
Keyword(s):  
Phase Transition ◽  
Quantum Information ◽  
Information Entropy ◽  
Momentum Space ◽  
Quantum Mechanical ◽  
Position Space ◽  
Entropy Squeezing ◽  
Information Theoretic ◽  
Symmetric Potential ◽  
Quantum Mechanical Systems

The information theoretic concepts are crucial to study the quantum mechanical systems. In this paper, the information densities of [Formula: see text]-symmetric potential have been demonstrated and their properties deeply analyzed. The position space and momentum space information entropy is obtained and Bialynicki-Birula–Mycielski inequality is saturated for different parameters of the potential. Some interesting features of information entropy have been discussed. The variation in these entropies is described which gets saturated for specific values of the parameter. These have also been analyzed for the [Formula: see text]-symmetry breaking case. Further, the entropy squeezing phenomenon has been investigated in position space as well as momentum space. Interestingly, [Formula: see text] phase transition conjectures the entropy squeezing in position space and momentum space.

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