Electrophilic and nucleophilic substitution in the Benzene ring and the Hammett Equation

1956 ◽  
Vol 9 (1) ◽  
pp. 61 ◽  
Author(s):  
J Miller
Keyword(s):  
Large Deviations ◽  
Nucleophilic Substitution ◽  
Benzene Ring ◽  
Electrophilic Substitution ◽  
Substituent Effects ◽  
Hammett Equation ◽  
Wide Range ◽  
Good Agreement

The Hammett equation as applied to aromatic nuclear electrophilic and nucleophilic substitution is tested for a wide range of substituents. For nucleophilic substitution quite good agreement is obtained for electron-attracting substituents using σ* values, but large deviations occur with substituents releasing electrons by the conjugative mechanism. In electrophilic substitution, in so far as results are available, a fair measure of agreement obtains for electron-attracting substituents, but very large and to some extent irregular deviations occur for the conjugative electron- releasing substituents. The deviations occur whether σ or σ* values are used, and new sets of σN** and σE** values are defined and the values recorded. A comparison is made of substituent effects in nuclear electrophilic and nucleophilic substitution.

Substituent effects on the chemical shifts of the bridge protons of benzonorbornenes

1967 ◽  
Vol 45 (11) ◽  
pp. 1185-1193 ◽  
Author(s):  
Naoki Inamoto ◽  
Shozo Masuda ◽  
Kazuo Tori ◽  
Katsutoshi Aono ◽  
Hiroshi Tanida
Keyword(s):  
Benzene Ring ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Electron System ◽  
Electronic Interaction ◽  
Orbital System ◽  
Significant Difference ◽  
Bridge Carbon ◽  
Hammett Relationship ◽  
Good Agreement

The substituent effects on the chemical shifts of the C9 bridge protons in a series of 6-substituted benzonorbornenes and benzonorbornadienes, and on those of the C2 protons in 5-substituted 2-indanols, were investigated. They were linearly correlated with the modified Hammett relationship τR − τH = ρ (σm + σp)/2. The ρ values obtained from the anti-C9 protons in the bornenes and bornadienes were slightly but significantly larger than those from the corresponding syn protons, whereas no significant difference was observed between the ρ values obtained from syn-9-benzonorbornenols and the indanols. The larger ρanti values were explained in terms of a stereospecific electronic interaction between the π-electron system of the benzene ring and the orbital system of the bridge carbon. In addition, it was shown that the above modified Hammett relationship gives generally a good agreement with the substituent effects on the aliphatic constituents of benzocyclenes and analogous compounds.

The SN Mechanism in aromatic compounds. 25. Substituent effects of multiple-bond nitrogen.

1958 ◽  
Vol 11 (3) ◽  
pp. 302 ◽  
Author(s):  
J Miller ◽  
AJ Parker
Keyword(s):  
Double Bond ◽  
Nitrogen Atom ◽  
Nucleophilic Substitution ◽  
Benzene Ring ◽  
Aromatic Compounds ◽  
Halogen Atom ◽  
Multiple Bond ◽  
Substituent Effects ◽  
Aromatic Nucleophilic Substitution ◽  
Substituent Constants

The substituent effects in aromatic nucleophilic substitution of groups attached to the benzene ring by a multiple-bond nitrogen atom are considered. Attachment is para to a replaceable halogen atom, and generally as a 4-substituent to l-chloro-2-nitrobenzene. Comparisons with some other groups are shown. Reasons are given for the greater T effect of a triple than of a double bond. Hammett substituent constants (σ*) are computed. Those for the nitroso and diazonium groups .are the largest so far obtained for electrically neutral and cationic groups respectively. The activating power of four of the nitrogen groups in electrophilic as well as nucleophilic substitution is discussed briefly.

THE APPLICATION OF THE HAMMETT EQUATION TO ORTHO-SUBSTITUTED BENZENE REACTION SERIES

1960 ◽  
Vol 38 (12) ◽  
pp. 2493-2499 ◽  
Author(s):  
Marvin Charton
Keyword(s):  
Benzene Ring ◽  
Substituent Effects ◽  
Para Position ◽  
Steric Effects ◽  
Side Chain ◽  
Ortho Position ◽  
Reaction Site ◽  
Hammett Equation ◽  
Reaction Series ◽  
Electrical Effect

The Hammett equation is directly applicable to ortho-substituted benzene reaction series in which reaction site and benzene ring are separated by some group Z, apparently due to the absence of steric effects in these series. The σp values are used in the correlations. Fourteen ortho-substituted benzene reaction series have been correlated. The electrical effect of a substituent in the ortho position is found to be about 0.75 times its effect in the para position. The effect of the side-chain Z in the transmission of substituent effects is OCH2 > SCH2 > CH = CH > SeCH2 > CH2CH2.

Substituent Effects on the Thermal Decomposition of Phosphate Esters on Ferrous Surfaces

2019 ◽  
Author(s):  
James Ewen ◽  
Carlos Ayestaran Latorre ◽  
Arash Khajeh ◽  
Joshua Moore ◽  
Joseph Remias ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Film Formation ◽  
Substituent Effects ◽  
Vapour Phase ◽  
Industrial Applications ◽  
Phosphate Esters ◽  
Antiwear Additives ◽  
Formation Mechanisms ◽  
Phosphate Ester ◽  
Wide Range

<p>Phosphate esters have a wide range of industrial applications, for example in tribology where they are used as vapour phase lubricants and antiwear additives. To rationally design phosphate esters with improved tribological performance, an atomic-level understanding of their film formation mechanisms is required. One important aspect is the thermal decomposition of phosphate esters on steel surfaces, since this initiates film formation. In this study, ReaxFF molecular dynamics simulations are used to study the thermal decomposition of phosphate esters with different substituents on several ferrous surfaces. On Fe<sub>3</sub>O<sub>4</sub>(001) and α-Fe(110), chemisorption interactions between the phosphate esters and the surfaces occur even at room temperature, and the number of molecule-surface bonds increases as the temperature is increased from 300 to 1000 K. Conversely, on hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>, most of the molecules are physisorbed, even at high temperature. Thermal decomposition rates were much higher on Fe<sub>3</sub>O<sub>4</sub>(001) and particularly α-Fe(110) compared to hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>. This suggests that water passivates ferrous surfaces and inhibits phosphate ester chemisorption, decomposition, and ultimately film formation. On Fe<sub>3</sub>O<sub>4</sub>(001), thermal decomposition proceeds mainly through C-O cleavage (to form surface alkyl and aryl groups) and C-H cleavage (to form surface hydroxyls). The onset temperature for C-O cleavage on Fe<sub>3</sub>O<sub>4</sub>(001) increases in the order: tertiary alkyl < secondary alkyl < primary linear alkyl ≈ primary branched alkyl < aryl. This order is in agreement with experimental observations for the thermal stability of antiwear additives with similar substituents. The results highlight surface and substituent effects on the thermal decomposition of phosphate esters which should be helpful for the design of new molecules with improved performance.</p>

Pharmacologically potentials of different substituted coumarin derivatives

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Benzene Ring ◽  
Bioactive Compounds ◽  
Biological Activities ◽  
Pharmacological Properties ◽  
Coumarin Derivatives ◽  
Wide Range ◽  
Anti Oxidant ◽  
Anti Inflammatory ◽  
Coumarin Compounds

Coumarin and its derivatives are widely spread in nature. Coumarin goes to agroup as benzopyrones, which consists of a benzene ring connected to a pyronemoiety. Coumarins displayed a broad range of pharmacologically useful profile.Coumarins are considered as a promising group of bioactive compounds thatexhibited a wide range of biological activities like anti-microbial, anti-viral,antiparasitic, anti-helmintic, analgesic, anti-inflammatory, anti-diabetic, anticancer,anti-oxidant, anti-proliferative, anti-convulsant, and antihypertensiveactivities etc. The coumarin compounds have immense interest due to theirdiverse pharmacological properties. In particular, these biological activities makecoumarin compounds more attractive and testing as novel therapeuticcompounds.

scholarly journals Separate Universe calibration of the dependence of halo bias on cosmic web anisotropy

2020 ◽  
Vol 499 (3) ◽  
pp. 4418-4431 ◽  
Author(s):  
Sujatha Ramakrishnan ◽  
Aseem Paranjape
Keyword(s):  
Dark Matter ◽  
High Precision ◽  
Gaussian Distribution ◽  
Initial Perturbation ◽  
Analytical Framework ◽  
Web Environment ◽  
Wide Range ◽  
Galaxy Assembly ◽  
Very High ◽  
Good Agreement

ABSTRACT We use the Separate Universe technique to calibrate the dependence of linear and quadratic halo bias b1 and b2 on the local cosmic web environment of dark matter haloes. We do this by measuring the response of halo abundances at fixed mass and cosmic web tidal anisotropy α to an infinite wavelength initial perturbation. We augment our measurements with an analytical framework developed in earlier work that exploits the near-lognormal shape of the distribution of α and results in very high precision calibrations. We present convenient fitting functions for the dependence of b1 and b2 on α over a wide range of halo mass for redshifts 0 ≤ z ≤ 1. Our calibration of b2(α) is the first demonstration to date of the dependence of non-linear bias on the local web environment. Motivated by previous results that showed that α is the primary indicator of halo assembly bias for a number of halo properties beyond halo mass, we then extend our analytical framework to accommodate the dependence of b1 and b2 on any such secondary property that has, or can be monotonically transformed to have, a Gaussian distribution. We demonstrate this technique for the specific case of halo concentration, finding good agreement with previous results. Our calibrations will be useful for a variety of halo model analyses focusing on galaxy assembly bias, as well as analytical forecasts of the potential for using α as a segregating variable in multitracer analyses.

Evaluation of Trinder's Glucose Oxidase Method for Measuring Glucose in Serum and Urine

1975 ◽  
Vol 21 (12) ◽  
pp. 1754-1760 ◽  
Author(s):  
John A Lott ◽  
Kathie Turner
Keyword(s):  
Glucose Oxidase ◽  
Oxidase Activity ◽  
Color Reaction ◽  
Critical Variable ◽  
Wide Range ◽  
Serum And Urine ◽  
Good Agreement

Abstract Trinder's method for glucose has nearly all the attributes of an ideal automated colorimetric glucose oxidase procedure. The chemicals used in the color reaction with peroxidase are readily available, the solutions are stable and can be prepared by the user, the method is highly specific and largely free of interferences, the sensitivity can be adjusted by the user to cover a wide range of glucose concentrations, and the reagents are not hazardous. We found very good agreement between results by this method and by the hexokinase and Beckman Glucose Analyzer methods. The method has been modified and adapted to the AutoAnalyzer I and SMA 6/60 (Technicon) with manifolds that give very little interaction between specimens. A study of the method by the simplex technique revealed that the glucose oxidase activity in the reagent is the most critical variable.

Estimation of the Thermodynamic Properties of Branched Hydrocarbons

2000 ◽  
Vol 122 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Hui He ◽  
Mohamad Metghalchi ◽  
James C. Keck
Keyword(s):  
Thermodynamic Properties ◽  
Degrees Of Freedom ◽  
Statistical Thermodynamic ◽  
Motion Modes ◽  
Branched Alkanes ◽  
Branched Hydrocarbons ◽  
Wide Range ◽  
On Line ◽  
Kinetic Calculations ◽  
Good Agreement

A simple model has been developed to estimate the sensible thermodynamic properties such as Gibbs free energy, enthalpy, heat capacity, and entropy of hydrocarbons over a wide range of temperatures with special attention to the branched molecules. The model is based on statistical thermodynamic expressions incorporating translational, rotational and vibrational motions of the atoms. A method to determine the number of degrees of freedom for different motion modes (bending and torsion) has been established. Branched rotational groups, such as CH3 and OH, have been considered. A modification of the characteristic temperatures for different motion mode has been made which improves the agreement with the exact values for simple cases. The properties of branched alkanes up to 2,3,4,-trimthylpentane have been calculated and the results are in good agreement with the experimental data. A relatively small number of parameters are needed in this model to estimate the sensible thermodynamic properties of a wide range of species. The model may also be used to estimate the properties of molecules and their isomers, which have not been measured, and is simple enough to be easily programmed as a subroutine for on-line kinetic calculations. [S0195-0738(00)00902-X]

Substituent effects on the thermodynamic functions of ionization of metasubstituted anilinium ions

1968 ◽  
Vol 21 (4) ◽  
pp. 939 ◽  
Author(s):  
PD Bolton ◽  
FM Hall
Keyword(s):  
Linear Function ◽  
Thermodynamic Functions ◽  
Substituent Effects ◽  
Negative Slope ◽  
Hammett Equation ◽  
Reaction Parameter ◽  
Reaction Series ◽  
Acidity Constants ◽  
Temperature Range ◽  
Relationship Of

Thermodynamic acidity constants of the meta-methoxyanilinium, meta- chloroanilinium, meta-bromoanilinium, and meta-iodoanilinium ions have been measured spectrophotometrically over the temperature range 5-50� and those of the meta-nitroanilinium ion over the temperature range 5-60�. The thermodynamic functions of ionization, ΔG25, ΔH25, ΔS25, and ΔCp,25, have also been calculated for each ion. For a series of seven meta-substituted anilinium ions the acidity constants show close obedience to the Hammett equation over the temperature range 10-50� with the reaction parameter p being a precise linear function of 1/T. The same reaction series also shows a well-defined isoequilibrium relationship of negative slope.

scholarly journals Rate Equation Modelling of Nonlinear Dynamics in Directly Modulated Multiple Quantum Well Laser Diodes

VLSI Design ◽  
1998 ◽  
Vol 8 (1-4) ◽  
pp. 355-360 ◽  
Author(s):  
Stephen Bennett ◽  
Christopher M. Snowden ◽  
Stavros Iezekiel
Keyword(s):  
Nonlinear Dynamics ◽  
Quantum Well ◽  
Multiple Quantum Well ◽  
Period Doubling ◽  
Rate Equations ◽  
Multiple Quantum ◽  
Quantum Well Laser ◽  
Wide Range ◽  
Multiple Quantum Well Laser ◽  
Good Agreement

A theoretical (using rate equations) and experimental study of the nonlinear dynamics of a distributed feedback multiple quantum well laser diode is presented. The analysis is performed under direct modulation. Period doubling and period tripling are identified in both the measurements and simulations. Period doubling is found over a wide range of modulation frequencies in the laser. Computational results using rate equations show good agreement with the experimental results.

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