Showing papers on "Hexane published in 1969"

Effect of Solvent Perturbation on the S3 → S1 Internal Conversion Efficiency of Benzene, Toluene, and p‐Xylene

Abstract: The S3 → S1 internal conversion efficiency of benzene is found to depend critically on the effectiveness of environmental perturbation in mixing the S3 and S1 states. Evidence for this derives from the experimental correlation of the conversion efficiency with the intensities of the 0–0 absorptive and emissive transitions in solutions with the solvents benzene, methanol, isopropyl alcohol, tetrahydrofuran, ethyl ether, acetonitrile, hexane, cyclohexane, methylcyclohexane, decalin, isooctane, and perfluorinated hexane. Additionally, the importance of S3 − S1 mixing is shown to explain the marked increase in the efficiency of internal conversion observed upon methyl substitution of benzene.

Photochemical Decomposition of DDT by a Free-Radical Mechanism

Abstract: Both as a pure solid and in hexane solution, DDT readily decomposed when irradiated with ultraviolet light (2537 angstroms). Principal products identified by gas-liquid and thin-layer chromatography from irradiations of the solid phase were 1,1-dichloro-2,2-bis (p-chlorophenyl) ethane, 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene, and 4,4'-dichlorobenzophenone. 1,1-Dichloro-2,2-bis(p-chlorophenyl) ethane and hydrochloric acid were identified from irradiated solutions of DDT in hexane. On the basis of products obtained, quantum yields, scavenger experiments, and other chemical tests, a nonchain, free-radical mode of degradation is proposed.

Inter‐ and Intramolecular Processes in Organic Solutions under Excitation in the Vacuum Ultraviolet

Abstract: The efficiency of energy transfer from solvent to solute is investigated as a function of solute concentration and excitation wavelength for solutions of diphenyloxazole in benzene, toluene, cyclohexane, and hexane. The results for benzene and toluene are similar but different from those for cyclohexane and hexane. For the first pair of solvents energy transfer takes place almost exclusively from the first excited level for all wavelengths of excitation; only for higher acceptor concentrations does the direct transfer from higher levels become noticeable. The transfer efficiency from the first excited level depends, however, strongly on the electronic level which has been initially excited. The effect of dilution of the transferring solvent is studied. For cyclohexane and hexane two or more transfer mechanisms or transferring species seem to be significantly involved even for low acceptor concentrations. The quenching effect of carbon tetrachloride and of chloroform is investigated for benzene and toluene...

A novel synthesis of neopentylbenzenes

Abstract: Benzyl chlorides react with t-butyl-lithium in a mixture of pentane and hexane to give neopentylbenzenes, XC6H4·CH2But. Yields were (X =) H, 75; o-Me, 25; m-Me, 55; p-Me, 62; m-F, 70; p-F, 70; m-Cl, 60; p-Cl, 69; p-Br, 60%.

The fluid hydrates of methylene chloride and chloroform: Their phase equilibria and behavior as influenced by hexane

Abstract: Thermodynamic properties pertaining to phase equilibria in the binary-fluid hydrate systems, methylene chloride-water and chloroform-water, and the ternary hydrate system, methylene chloride-chloroform-water, were measured. Total vapor pressure data were recorded as a function of temperature over a range of −3 to + 10°C. Quadruple locus measurements of the ternary four-phase equilibrium, L1-L2-H-G, and isobaric studies of the ternary system chloroform-methylene chloride-water, support the existence of a solid solution hydrate between methylene chloride and chloroform. The addition of the nonhydrate former, hexane, to the methylene chloride-water system lowered the isobaric critical decomposition temperature of the hydrate.

Abstraction of hydrogen atoms from bicyclo[2.1.1]hexane by methyl radicals and chlorine atoms: photochlorination of 1-methylbicyclo[2.1.1]hexane

Abstract: Photolysis of acetone has been used as a source of methyl radicals to study the abstraction of hydrogen atoms from bicyclo[2.1.1]hexane by methyl radicals. The reaction was found to have an activation energy of 10.3 kcal/mole and a pre-exponential factor that is typical of other abstraction reactions. The absolute rate of abstraction of hydrogen atoms from bicyclo[2.1.1]hexane by chlorine atoms at room temperature was measured to be 8.1 × 1010 l mole−1 s−1. The photochlorination of 1-methylbicyclo-[2.1.1]hexane in solution gave both the 1-chloromethyl and 2- or 3-chloro-1-methylbicyclohexanes. The relative rates of attack at the methyl and the 2- or 3- position were determined to be 1:2.1. It is pointed out that the rate parameters for the abstraction of an H atom from bicyclo[2.1.1]hexane by a methyl radical are slower than for cyclopentane, as would be expected for a highly strained hydrocarbon, whereas the abstraction by chlorine is slightly faster than the rate for cyclopentane.

Selective extraction of meta-chlorotoluene

Abstract: META-CHLOROTOLUENE IS SEPARATED FROM AMIXTURE CONTAINING THE THREE ISOMERS THEREOF BY CONTACTING THE MIXTURE WITH HYDROGEN FLUORIDE, BORON TRIFLUORIDE AND A LIGHT HYDROCARBON, SUCH AS HEXANE, AT A TEMPERATURE BELOW ABOUT 60*C.

Hydromethanisation of Several Paraffinic Hydrocarbons on Nickel Catalyst

Abstract: For the production of high calorific town gas from petroleum, the catalytic hydrogenolysis of several paraffinic hydrocarbons (propane, pentane, hexane and heptane) was studied in a flow system under atmospheric pressure.The activities of several catalysts for hydrogenolysis of hexane were examined in the temperature range of 200∼700°C. Nickel and cobalt catalysts proved to be the most active at 200∼500°C. Tke activity of the catalysts for hydromethanisation was found to be in the following sequence: Ni, Co>Fe>MoO3>MoS3, WO3, WS3, Cu.The hydrogenolysis of propane on a nickel catalyst was suppressed by hydrogen at temperatures less than 300°C, and the suppression effect of hydrogen decreased with the reaction temperature. Above 300°C, the reaction was found to be promoted by hydrogen when the amount of hydrogen present was less than 150% of the theoretical amount, and also to be independent of the partial pressure of hydrogen in the presence of excess hydrogen.Methane was formed as the predominant product, and the ratio of ethane or propane to methane in the product decreased with the reaction temperature. Methane was most likely formed directly from the feed hydrocarbons, and not via ethane or propane as the intermediate.The reactivity of hydrocarbons in the reaction with theoretical amounts of hydrogen was found to be in the following sequence: pentane>hexane>heptane. It was inferred that the reaction would likely be controlled by desorption of product methane.

UNTERSUCHUNGEN AN DIFFUSIONSFLAMMEN KONZENTRATIONSVERTEILUNG IN EINER HEXAN-DIFFUSIONSFLAMME (Investigation of the Distribution of Diffusion Flames in a Hexane Diffusion Flame),

Abstract: : In a hexane-airflame the temperature, emissivity, and concentration of N2, O2, CO, CO2, H2O, hexane, H2, methane, ethylene and ethane, propylene, acetylene, and benzene was quantitatively determined as was the abundance of the various organic groups in different regions of the flame. The formation of the final and intermediate products from different parts of the flame is discussed.