Saturated Hydrocarbon Solvents Research Articles

Observation of transient cyclohexene and 1,4-cyclohexadiene radical cations. Time-resolved fluorescence-detected magnetic resonance

Transient radical cations of cyclohexene and 1,4-cyclohexadiene are characterized in pulse radiolysis in liquid hydrocarbons. Time-resolved fluorescence-detected magnetic resonance allows observation and EPR spectral assignment of these very short-lived radical cations. The olefin radical cations are created by charge transfer from saturated hydrocarbon solvent cations to the solute olefins.

Contact charge—transfer interaction of iodine with saturated hydrocarbons

With the help of the thermodynamic quantities just reported, the spectrophotometric properties of the contact charge-transfer complexes of iodine with saturated hydrocarbon solvents such as cyclohexane, methylcyclohexane and heptane have been calculated from the u.v. spectra of iodine in these solvents. Both the thermodynamic and spectrophotometric properties of these complexes are free from the interaction of other solvents.

Picosecond pulse radiolysis studies on the formation of excited singlet states of solute molecules in several saturated hydrocarbon and ethanol solvents

Two kinds of the formation components of excited singlet states of solute molecules have been observed in the picosecond time region in methylcyclohexane, 3-methylpentane, and iso-octane as well as in cyclohexane, as reported previously. The ratios of two components are significantly dependent on solute concentrations and kinds of solvents. A fairly large amount of the slower formation component has been observed in cyclohexane and methylcyclohexane, little in iso-octane, and none in ethanol. The slower component is mainly due to the solute geminate ion recombination and partly due to the energy transfer from the excited singlet states of solvent molecules. The faster component has not been made clear, but could be due to Čerenkov light. The life-time of the excited singlet state of cyclohexane was directly measured to be 1.1 ± 0.1 ns.

A novel means of investigating the polarity gradient in the micelle sodium lauryl sulphate using a series of n-(9-anthroyloxy) fatty acids as fluorescent probes

The fluorescence behaviour of a series of n-(9-anthroyloxy) fatty acids has been studied in saturated hydrocarbon solvents of increasing viscosity and solvents of increasing polarity. Fluorescence quenching experiments in these solvents and in micelles of sodium lauryl sulphate show that the probes locate at a graded series of depths in the micelle. The spectral characteristics of emission from the probes indicate an increasing polarity gradient from the core to the surface of the micelle.

ChemInform Abstract: NUCLEAR MAGNETIC RELAXATION AND MOLECULAR REORIENTATION OF DICYANOACETYLENE IN HYDROCARBON SOLUTIONS

14N linewidths and 13C spin lattice relaxation rates have been measured for dicyanoacetylene, neat and in several hydrocarbon solutions. The correlation between molecular reorientation rates and solvent viscosity is found to break down in the sense that the reorientation rates of dicyanoacetylene in aromatic solvents are significantly slower than in saturated hydrocarbon solvents. Without making reference to specific solute–solvent interactions this behavior may be rationalized by taking into account the isothermal compressibility of the various solvents.

Nuclear magnetic relaxation and molecular reorientation of dicyanoacetylene in hydrocarbon solutions

14N linewidths and 13C spin lattice relaxation rates have been measured for dicyanoacetylene, neat and in several hydrocarbon solutions. The correlation between molecular reorientation rates and solvent viscosity is found to break down in the sense that the reorientation rates of dicyanoacetylene in aromatic solvents are significantly slower than in saturated hydrocarbon solvents. Without making reference to specific solute–solvent interactions this behavior may be rationalized by taking into account the isothermal compressibility of the various solvents.

Adsorbent deactivation in high-performance liquid chromatography

Water is often added to the eluent in high-performance adsorption chromatography to improve isotherm linearity and therefore increase the amount of sample which can be separated without affecting retention or plate height. Water is especially inconvenient as a deactivating agent in saturated hydrocarbon solvents because of its low solubility. First, it is difficult to prepare eluents with reproducible water content. Secondly, humidified solvents must be freshly prepared because the water content changes rapidly due to equilibration with the walls of the container. Thirdly, large volumes of eluent must be passed through the column to establish equilibrium. In order to circumvent these problems, the use of acetonitrile and methylene chloride as substitutes for water has been studied. The maximum sample capacity, θ .1, defined as the largest sample size (g sample/g adsorbent) which can be separated while maintaining k′ to within 90% of that for a very small sample, is compared at several concentrations of each deactivating agent. Similarly, the maximum sample capacity is compared in terms of plate height. It is shown that acetonitrile is equal to or better than water with respect to sample capacity, plate height, convenience, and equilibration time. Sample selectivity with acetonitrile is not identical to sample selectivity with water as deactivating agent. Methylene chloride is significantly less effective with respect to sample capacity.

Volume of mixing effect on solvent shifts in fluorine magnetic resonance spectra

Fluorine chemical shifts have been determined for dilute solutions of 1,1,1,10,10,10-hexafluorodecane in twenty saturated hydrocarbon solvents. The van der Waals contribution to the solvents shifts was found to depend on the cohesive energy density of the solvent in an unexpected way. After correcting for bulk magnetic susceptibility effects, the shifts are fairly well correlated by an equation of the form δ s = A + B(1 − 2 ζ)( n 2 − 1)/( n 2 + 2), where A and B are empirical constants, n is the solvent refractive index, and ζ is a function of the cohesive energy density closely related to that used to predict volume changes on mixing for dilute solutions of fluorocarbons in hydrocarbon solvents.

Mechanism of Dissolution III: Relationship between Solid-Liquid Interfacial Energies and Dissolution Rates in Organic Solvents

The interfacial energies between m-acetotoluide and four saturated hydrocarbon solvents, n-hexane, n-heptane, cyclohexane, and decahydronaphthalene, were determined using the Ostwald-Fruendlich equation. Dissolution rates were determined in a descending direction to obtain interfacial control. The dissolution rates were found to decrease as the interfacial energy increased. The dissolution rates were also found to decrease as the saturation solubility of m-acetotoluide in the four solvents increased. An interfacial dissolution model, in which the interfacial region is associated with the solid phase rather than the liquid phase, is postulated.

The effect of temperature on the solubilities of testosterone propionate in low polarity solvents.

Abstract The solubilities of testosterone propionate have been determined between 25 and 100° in 15 solvents and compared with theoretical values obtained from regular solution theory. Entropy considerations show that solvent-solute interactions occur in some solvents, increasing the solubility and resulting in deviations from regular solution behaviour. “Regular solutions” are obtained only in saturated hydrocarbon solvents, and the solubility is more accurately predicted as the temperature approaches the melting point, and as the molar volumes of solvent approach that of the solute.

Association constants of the hexamethylbenzene‐1,3,5‐trinitrobenzene complex in various saturated hydrocarbon solvents

AbstractFrom NMR chemical shift measurements, it is shown that the degree of association for the interaction between hexamethylbenzene and 1,3,5‐trinitro benzene in various saturated hydrocarbon solvents is dependent on the particular solvent, irrespective of the particular concentration scale used.

Structures of some derivatives of bis-π-cyclopentadienyltetracarbonyl-di-iron

The i.r. spectra of a number of [(π-dienyl)Fe(CO)2]2 and [(π-dienyl)(π-C5H5)Fe2(CO)4] complexes [dienyl = CH3C5H4 and C9H7(indenyl)] have been investigated between 400 and 700, and 1700 and 2100 cm.–1. They are solvent-dependent, and it is proposed that these compounds, like [(π-C5H5)Fe(CO)2]2, exist as their trans-bridged isomers in the solid state, but as a mixture of cis- and trans-bridged forms, together with small amounts of non-bridged species, in solution. The spectra of solutions of [(π-C9H7)Fe(CO)2]2 in saturated hydrocarbon solvents show two well-resolved bands of comparable intensities at ca. 1790 cm.–1, thereby confirming that two bridged isomers of this compound exist in solution.

Theoretical treatment of solvent effects on the electronic spectra of polar organic dye molecules

The dye molecule in a saturated hydrocarbon solvent (instead of the vacuum) is taken as reference state; the σ-electrons of solute and solvent are treated as a continuous medium of dielectric constant ϵ o = 2. The π-electrons of the solute are assumed to be immersed in this medium. Solvent shifts of absorption and fluorescence are calculated from known ground and excited state dipole moments and polarizabilities of solute and dielectric constant and refractive index of solvent.