Amount Of Cyclohexane Research Articles

Fabrication of Soft-Oxometalates {Mo132} Clusters With Novel Azobenzene Surfactants: Size Control by Micelles and Light.

Soft-oxometalates (SOMs) are colloid suspensions of superstructured assemblies of polyoxometalates (POMs) and are found to be very effective photo-catalysts in a number of chemical reactions. The stabilization of SOMs generally requires legends or stabilizers, e.g., polymers and surfactants. In this paper, a light responsive azobenzene surfactant, C10AZOC2N3, was developed and used to stable {Mo132} SOMs. Various techniques such as Dynamic light scattering, TEM, UV-Vis spectra and cyclic voltammetry were employed to characterize the experimental results. The outstanding structure-directing effect of surfactant self-assembly micelles in solution on inorganic counter-anions was demonstrated. Different amount of cyclohexane was solubilized into C10AZOC2N3 micelles to successfully control the size of {Mo132} SOMs cluster. Furthermore, the clusters exposed to UV light for a certain time can be served as a second trigger to control the size of SOMs due to the trans-cis conformation transition of surfactant molecules. The redox potentials of C10AZOC2N3-{Mo132} SOMs were investigated as the cluster size varied. Interestingly, the redox potential of {Mo132} was not affected by the cluster size, indicating that the presence of surfactant did not change the main function of {Mo132} as an electrochemical catalyst, but merely assisted in the size control of SOM aggregation.

Ways of controlling the selectivity of cyclohexane oxidation

Operation of an industrial installation for cyclohexane oxidation was analyzed, and causes of the low process selectivity (45–52%) were elucidated. The relationships of cyclohexane oxidation under laboratory conditions maximum similar to those of the industrial process were studied. Measures were suggested for optimizing the process so as to increase the yield of the target products by a factor of 1.2–1.6, decrease the amount of cyclohexane spent for the formation of by-products by a factor of 1.2–1.8, and increase the process selectivity to 68%.

Effect of Cyclohexane on the Phase Behavior of L64/1-Butyl-3-Methylimidazolium Tetrafluoroborate System

The triblock copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (L64, PEO13PPO30PEO13) in 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) can form lamellar liquid crystalline (Lα). The effect of apolar cyclohexane molecules on the Lα phase was investigated by using polarized optical microscopy (POM) and small-angle x-ray scattering (SAXS). The results of POM and SAXS show that a suitable amount of cyclohexane can contribute to the formation of lamellar liquid crystals, and the ordering of Lα phase is increased. For comparison, the effect of polar water on Lα phase was explored. After adding water, both EO groups and [BF4]– anion can form hydrogen bonds with water molecules, which weakens the electrostatic interactions between L64 and [Bmim][BF4] and therefore the ordering of lamellar structures is destroyed.

Selective Esterification of Ethylene Glycol Ethyl Ether over Silica-Cerous

With silica-cerous of high activity as catalyst, ethylene glycol ethyl ether acetate was synthesized from ethylene glycol ethyl ether and acetic acid. The proper conditions for the synthesis were obtained by a single factor experiment and orthogonal experiment. Based on 0.3 mol acetic acid, the optimum conditions were as follows: the mass ratio of silica-cerous (15% loaded sulfate cerous) / acetic acid being 0.056 : 1, the mol ratio of acetic acid / ethylene glycol ethyl ether being1 : 1.2, the amount of cyclohexane being 30 mL, reaction temperature being 90 °C, and reaction time being 2 h. Such optimal conditions give the highest yield of 99.53 % and selectivity of 100 % of ethylene glycol ethyl ether acetate. Its structure was confirmed by IR, and the catalyst still has high activity after being reused for five times.

English

A Gram-positive bacterium, Bacillus lentus LP32, originally isolated on the basis of its ability to utilise pyrene as sole source of carbon was found to be able to grow luxuriantly on alicyclic compounds as sole substrates. It showed poor growth on anthracene, naphthalene, 1-naphthol and phenanthrene. Growth rate on cyclohexane was 1.32 d-1, while doubling time was 0.76 d. The corresponding values for growth on cyclohexanone were 0.77 d-1 and 1.29 d, respectively. Within 10 days, the amount of cyclohexane in culture reduced from 317.62 to 102.55 mgl-1, then to 23.04 mgl-1 on day 18. On cyclohexanone, substrate concentration decreased from 287.56 mgl-1 to 101.66 mgl-1 in 10 days before declining to 24.21 mgl-1 on day 18. The rate of degradation when growing on cyclohexane was 23.50 mgl-1d-1 in the first 10 days and 9.93 mgl-1d-1 between day 10 and day 18, with 67.71% degradation in 10 days and overall percentage degradation of 92.43%. On cyclohexanone, the corresponding values were 18.59 and 9.68 mg l-1d-1 as well as 64.65 and 91.58%, respectively. This organism is a potential candidate for bioremediation purpose.   Keywords: Degradation, cyclohexane, cyclohexanone, alicyclic compounds.

Micromeritics and release behaviours of cellulose acetate butyrate microspheres containing theophylline prepared by emulsion solvent evaporation and emulsion non-solvent addition method

The present research work compares the effect of microsphere preparation technique on micromeritics and release behaviors of theophylline microspheres. Microspheres were prepared by oil-in oil (O(1)/O(2)) emulsion solvent evaporation method (ESE) using different ratios of anhydrous theophylline to cellulose acetate butyrate (CAB). Cyclohexane was used as non-solvent to modify the ESE technique (MESE method) and the effect of non-solvent volume on properties of microspheres was investigated. The obtained microspheres were analyzed in terms of drug content, particle size and encapsulation efficiency. The morphology of microsphere was studied using scanning electron microscope. The solid state of microspheres, theophylline and CAB were investigated using X-ray, FT-IR and DSC. The drug content of microspheres prepared by MESE method was significantly lower (15.54% +/- 0.46) than microspheres prepared by ESE method (41.08 +/- 0.40%). The results showed that as the amount of cyclohexane was increased from 2 mL to 6 mL the drug content of microspheres was increased from 15.54% to 28.71%. Higher encapsulation efficiencies were obtained for microspheres prepared by ESE method (95.87%) in comparison with MESE method (64.71%). Mean particle size of microsphere prepared by ESE method was not remarkably affected by drug to polymer ratio, whereas in MSES method when the volume of cyclohexane was increased the mean particle size of microsphere was significantly decreased. The ratio of drug to polymer significantly changed the rate of drug release from microspheres and the highest drug release was obtained for the microsphere with high drug to polymer ratio. The amount of cyclohexane did not significantly change the drug release. Although, x-ray showed a small change in crystallinity of theophylline in microspheres, DSC results proved that theophylline in microspheres is in amorphous state. No major chemical interaction between the drug and polymer was reported during the encapsulation process.

Synthesis of butyl propionate using novel aluminophosphate molecular sieve as catalyst

The esterification of propionic acid with n-butanol at 126–133°C in the presence of catalytic quantities of novel aluminophosphate molecular sieve AP-9 gives the corresponding esterified product in a high yield. The effects of the amount of catalyst used, reaction time, the molar ratio of alcohol to acid, the amount of cyclohexane used, reaction temperature, the kinds of catalyst, and the methods of preparing the catalysts, on the synthesis of butyl propionate have been investigated. The yield of butyl propionate obtained was 85.3% when the reaction conditions employed were as follows: catalyst: propionic acid: n-butanol: cyclohexane=1.0 g: 1 mol: 1.2 mol: 5.0 ml, at 126–133°C for 5 h. The aluminophosphate molecular sieve AP-9 can be recovered and reused to give almost the same yield as that given by a fresh aluminophosphate molecular sieve.

The phase of condensate coexisting with the solid phase of nitrogen on Grafoil, studied by volumetric adsorption measurements of nitrogen

Volumetric adsorption isotherms of nitrogen at 77 K have been measured on Grafoil (compressed exfoliated graphite) preadsorbed with various amounts of cyclohexane or n-hexane. For cyclohexane preadsorption, the fluid-solid phase transition of post-adsorbed nitrogen is observed as a step on the isotherm until cyclohexane completes its monolayer, indicating that post-adsorbed nitrogen compresses cyclohexane to convert its submonolayer phases into the monolayer phase. On the other hand, n-hexane preadsorbed at submonolayer coverage is found, just like CCl 4 studied previously, to prevent nitrogen from undergoing the fluid-solid phase transition. It is argued that n-hexane islands coexisting with pure nitrogen domains are in the higher-order commensurate submonolayer phase with nitrogen involved along its domain walls.

The phase of condensate coexisting with the solid phase of nitrogen on Grafoil, studied by volumetric adsorption measurements of nitrogen

Volumetric adsorption isotherms of nitrogen at 77 K have been measured on Grafoil (compressed exfoliated graphite) preadsorbed with various amounts of cyclohexane or n-hexane. For cyclohexane preadsorption, the fluid-solid phase transition of post-adsorbed nitrogen is observed as a step on the isotherm until cyclohexane completes its monolayer, indicating that post-adsorbed nitrogen compresses cyclohexane to convert its submonolayer phases into the monolayer phase. On the other hand, n-hexane preadsorbed at submonolayer coverage is found, just like CCl 4 studied previously, to prevent nitrogen from undergoing the fluid-solid phase transition. It is argued that n-hexane islands coexisting with pure nitrogen domains are in the higher-order commensurate submonolayer phase with nitrogen involved along its domain walls.

Studies in the synthesis of ZSM-5 zeolites

ZSM-5 zeolites have been synthesized using tri-ethyl-n-propylammonium (TEPA) cations as the source of the organic base. X-ray diffraction, framework i.r. spectroscopy, scanning electron microscopy, adsorption of n-heptane and cyclohexane and product distribution in the conversion of methanol to hydrocarbons have been utilized in characterizing the synthesized zeolite. The rates of both nucleation and growth of ZSM-5 crystals are lower when TEPA rather than tetrapropylammonium (TPA) cation is used. The amount of cyclohexane (but not n-heptane) adsorbed on the ZSM-5 zeolite (prepared by the TEPA route) decreases at increased SiO 2 /Al 2 O 3 ratios. Under certain conditions, the ZSM-5 zeolite (in both the TPA and TEPA systems) undergoes transformation into α -quartz.

Study of the isotopic exchange of deuterium with hydrogen in benzene under conditions of its hydrogenation on nickel

1. The curves of the temperature dependence of the degree of exchange and hydrogenation of benzene during the simultaneous occurrence of these reactions on a nickel catalyst are of different types. 2. The introduction of a substantial amount of cyclohexane into the initial mixture has no effect upon the degree of hydrogenation of benzene, but it appreciably lowers the degree of exchange at temperatures above 150°. 3. The curves of the isotopic distribution of cyclohexane, formed during the process of hydrogenation (deuteration) of benzene, differ from the curves of the isotopic distribution of the products of exchange both of benzene and of cyclohexane, introduced separately. 4. The observed experimental facts can be explained on the assumption that the reactions of deuterohydrogen exchange and hydrogenation of benzene proceed through different intermediate surface compounds.

Phase titrations—VI: New applications and the phase titration of homologous alcohols

Results are given for the phase titration of 11 new systems, all containing pyridine as the water-miscible component. Binary solutions of methanol in n-propanol, ethanol in n-propanol, and methanol in ethanol have been analysed by adding a constant amount of cyclohexane and titrating with water to the appearance of turbidity. Results are satisfactory for solutions containing propanol (average error: 0.8% absolute) but are not satisfactory for solutions of methanol in ethanol.

Motions of Molecules in Condensed Systems III. The Infra-Red Spectra for Cyclohexane Solid II, Solid I, Liquid and Vapor in the Range from 3 to 15μ

Infra-red spectra are compared throughout the interval from 650 to 3300 wave numbers for the same amount of cyclohexane when it exists separately as vapor at 20°, liquid at 10°, and solid I at 3°C, likewise in the intervals from 700 to 1600 and 2500 to 3300 wave numbers when it exists as solid I at −75° and solid II at −100°C. The four spectra obtained with the condensed phases are quite similar and differ only slightly from the one for the vapor. These results contrast sharply with ones reported previously for a similar study of benzene and indicate that there is a greater semblance of order in liquid cyclohexane than in liquid benzene. The spectra are consistent with, but yield no constructive evidence to confirm or deny the notion that molecules of cyclohexane are able to rotate freely in solid I. Developments attributable to intermolecular forces, although not spectacular, contain new information about the numbers and positions of bands which may prove useful toward assigning frequencies to normal modes of vibration in the isolated molecule of cyclohexane. The results of this study do not contradict any of the principles set forth in the first paper of this series.