Benzene In Acetonitrile Research Articles

Excess enthalpies of binary and ternary mixtures of acetonitrile with methanol, ethanol and benzene

Excess molar enthalpies are measured for the binary mixtures methanol—acetonitrile and ethanol—acetonitrile at 25 and 35°C and for the ternary mixtures methanol—acetonitrile—benzene and ethanol—acetonitrile—benzene at 25°C using an isothermal dilution calorimeter. The binary results are well reproduced with an association model which contains four equilibrium constants for the association of alcohol, two equilibrium constants for that of acetonitrile, and two solvation equilibrium constants between alcohol and acetonitrile molecules. The ternary results are compared with those calculated from the model with binary parameters.

Photochemical isomerizations of 2-phenyl-1,3-indanedione to E- and Z-benzalphthalide and of E-benzalphthalide to Z-benzalphthalide

The photochemical isomerizations have been studied of 2-phenyl-1,3-indanedione to mixture of E- and Z-benzalphthalide and of E-benzalphthalide to Z-benzalphthalide depending on the solvent used, concentration, and the light wavelength. The attempts at the reverse photochemical isomerization of E-benzalphthalide to 2-phenyl-1,3-indanedione have failed. Quantum yields of the isomerization of 2-phenyl-1,3-indanedione decrease in the following solvent series: cyclohexane acetonitrile benzene tetrachlormethane methanol. The isomerization quantum yield of 2-phenyl01,3-indanedione is inversely proportional to concentration of the starting substance, but the dependence of 1/φ on the concentration is not linear.

Titration of selected bases in benzene–acetonitrile binary solvent system

The benzene–acetonitrile binary solvent system was used in the determination of the half-neutralization potentials (hnp) of selected bases varying widely in basicity (pKb). The solvent mixtures had specific dielectric constants (Dm). The hnp values of the bases determined in a solvent of a specific Dm value were related to the corresponding pKb values. The slopes of these linear relationships were related to Dm values. A certain mixture of the binary solvent system was selected, and successful differentiating titration of various base mixtures was demonstrated in this medium. The Δhnp/ΔpK versus Dm data for acids were compared with those of bases in the benzene–acetonitrile binary solvent system. The resulting data on bases were compared with previously published data on acids, and the present report describes the behavior of acids and bases in the entire composition spectrum of the benzene–acetonitrile binary solvent system.

Electrochemical bromination of benzene, toluene and xylene in acetonitrile

A method for the preparation of bromo derivative compounds of aromatics is proposed and the electrodic process involved in the bromination on the third wave of the system Br−/aromatic substrate in acetonitrile is discussed.

Liquid phase PVT data, excess volume data, constant volume excess thermodynamic functions, and thermal pressures for ten binary mixtures

Liquid phase PVT data were obtained at 0°C, 45°C, and 90°C for pressures from 1–217.7 atm for various binary mixtures for the systems benzene—acetone, carbontetrachloride—acetone, acetonitrile—carbontetrachloride, toluene—acetonitrile, and ethanol—toluene. Excess volume data were obtained at 45°C for the same systems as well as for mixtures of toluene—nitroethane, toluene—acetone, acetonitrile—benzene, nitromethane—benzene, and ethanol—benzene Constant volume thermodynamic excess functions U E V , H E V , A E V , G E V , and TS E V were computed for each of the ten systems and are presented. It was found that mole fraction averages of each of these excess functions agree almost exactly with experimental values. Thermal pressures were also calculated for each of the ten systems and found to agree within 1–3% with mole fraction averages.

Electrochemical bromination of benzene, toluene and xylene in acetonitrile

A method for the preparation of bromo derivative compounds of aromatics is proposed and the electrodic process involved in the bromination on the third wave of the system Br −/aromatic substrate in acetonitrile is discussed.

Liquid phase PVT data for binary mixtures of toluene with nitroethane and acetone, and benzene with acetonitrile, nitromethane, and ethanol

Liquid phase PVT data were obtained at 0°C, 45°C, and 90°C for pressures up to 217.7 atm for various binary mixtures of toulene—nitroethane, toluene—acetone, acetonitrile—benzene, nitromethane—benzane, and ethanol—benzene. Such data are required for purposes of converting excess thermodynamic property data from a constant pressure basis to a constant volume basis. Data are presebt for each pure component and for three separate mole fractions for each binary pair. Because benzene solidifies at 5.5°C, data for pure benzene are reported at 12°C rather than 0°C.

Photolysis of 5-iodopyrimidines in benzene or heteroarenes; a convenient route to 5-phenyl- and 5-heteroaryl-pyrimidines

Photolysis of 5-iodo-, 2-chloro-5-iodo-, and 2,4-dichloro-5-iodo-pyrimidine in solutions of heteroarenes (furan, thiophen, pyrrole, and 1-methylpyrrole) or benzene in acetonitrile affords conveniently and in high yield the corresponding 5-(2-heteroaryl)- and 5-(phenyl)-pyrimidines (1)–(3)(X = O, S, NH, NMe, or CHCH). Only for those photolyses carried out in thiophen are small amounts of the 3-heteroaryl isomers formed. In contrast, photolysis of the relatively unstable 4-chloro-5-iodopyrimidine in solutions of the above heteroarenes or benzene in acetonitrile gives only low yields of the 4-chloro-5-substituted pyrimidines.

Temperature and solvent effects on the fluorescence of some simple aromatic molecules

The fluorescence yields and lifetimes of α-methylnaphthalene, o-xylene and tetralin in ethanol and methylcyclohexane, toluene in methylcyclohexane, benzene in cyclohexane, methylcyclohexane and ethanol have been measured as a function of temperature, and also for benzene in methanol and acetonitrile at room temperature. In every case, the measured fluorescence yield and lifetime decrease with temperature and are dependent on the solvent used. Expressing the radiative lifetime, τr, as τr=τ°r/n2, where n is the refractive index of the medium, it has been found that τ°r is constant with temperature for α-methylnaphthalene, o-xylene, tetralin, and toluene. It decreases slightly with increasing temperature for benzene. In every compound the value for τ°r, at room temperature, is independent of the solvent used. Possible reasons for the variation of the fluorescence yields with solvent and temperature are discussed. In benzene, solvent perturbations can increase non-radiative disappearance of the S1 state.

Halochromism of thiophene-containing analogs of chalcones and their derivatives

The formation of hydroxy-, acyloxy-, chloro-, and tetrachlorophosphoroxycarbonium ions was established on the basis of the electronic absorption spectra of thiophene-containing analogs of chalcones and their derivatives in concentrated sulfuric acid, in dilute solutions of sulfuric acid in acetic and trichloroacetic anhydrides, and in acetonitrile benzene, dichloroethane, and nitromethane in the presence of phosphorous pentachloride.

The kinetics and mechanism of the reaction of triarylphosphines with 7,7,8,8-tetracyanoquinodimethane and tetracyanoethylene

Triarylphosphines react with 7,7,8,8-tetracyanoquinodimethane (TCNQ) in chloroform, acetonitrile or acetonitrile–benzene in the presence of water and catalytic quantities of hydrochloric acid to give quantitative yields of 1,4-bis-(dicyanomethyl)benzene and triarylphosphine oxide. Similarly, in acetonitrile in the presence of aqueous acid, tetracyanoethylene (TCNE) and triarylphosphine give tetracyanoethane and the phosphine oxide. Using an optically active phosphine, the oxide recovered from both reactions is completely racemic. Kinetic data on the reaction of TCNQ with triarylphosphines are reported and by consideration of the order, deuterium isotope effect and activation parameters coupled with the stereochemical evidence it is proposed that the reaction proceeds through a phosphinium radical cation intermediate. A Hammett correlation of rate with σ-substituent parameters of the substituted phosphines gives a ρ value of –3·2. The reactions of triarylphosphines with TCNQ and TCNE in absolute aprotic media are also discussed.

The kinetics and mechanism of the reaction of cyclopentadienylidenetriarylphosphoranes with cyano-olefins. Part III. Elimination of hydrogen cyanide from 2-(1-phenyl-1,2,2-tricyanoethyl)cyclopentadienylidenetriphenylphosphorane; an E1CB reaction via an ion-pair

Kinetic data on the base-catalysed elimination of hydrogen cyanide from 2-(1-phenyl-1,2,2-tricyanoethyl)-cyclopentadienylidenetriphenylphosphorane in benzene, benzene–acetonitrile, or acetonitrile solvent are reported. The elimination is of the first order in substrate and base (tertiary amine) and the second-order rate constants (k2) increase with increasing polarity of the medium. The deuterium isotope effect (k2H/k2D) is ca. 1·0 in each solvent system and a linear Bronsted plot is observed with a number of tertiary amines over a range of five pKa units. Activation parameters are reported for the reaction with triethylamine and the kinetic results are interpreted in terms of a E1CB reaction involving fast proton loss to form an ion-pair, followed by rate-determining elimination of cyanide ion from the ion-pair intermediate.

Solvent systems for the identification of opiates in narcotic seizures by thin-layer chromatography

Eight solvent systems are described which make it possible to separate and identify twenty-six compounds, found in narcotic seizures, by thin-layer chromatography. The separation and identification of five opium alkaloids is best achieved in the solvent systems ethyl acetate—benzene—acetonitrile—ammonium hydroxide (50:30:15:5) and acetonitrile—benzene—ethyl acetate—ammonium hydroxide (40:30:25:5). These solvent systems offer a procedure that is convenient, rapid, and highly selective for the systematic separation and identification of opiates found in narcotic seizures.