Showing papers on "Ether published in 1994"

Isolation of a bacterial culture that degrades methyl t-butyl ether

Abstract: We have isolated a mixed bacterial culture (BC-1) which is capable of degrading the gasoline oxygenate methyl t-butyl ether (MTBE). BC-1 was developed from seed microorganisms present in a chemical plant biotreater sludge. This enrichment culture has been maintained in continuous culture treating high concentrations of MTBE (120 to 200 mg/liter) as the sole carbon source in a simple feed containing NH4+, PO43-, Mg2+, and Ca2+ nutrients. The unit had a stable MTBE removal rate when maintained with a long cell retention time (ca. 80 to 90 days); however, when operated at a ≤50-day cell waste rate, loss of MTBE-degrading activity was observed. The following three noteworthy experimental data show that MTBE is biodegraded extensively by BC-1: (i) the continuous (oxygen-sparged) culture was able to sustain a population of autotrophic ammonia-oxidizing bacteria which could nitrify influent NH4+ concentrations at high rates and obtain CO2 (sole carbon source for growth) from the metabolism of the alkyl ether, (ii) BC-1 metabolized radiolabeled either (14CH3O-MTBE) to 14CO2 (40%) and 14C-labeled cells (40%), and (iii) cell suspensions of the culture were capable of degrading (substrate depletion experiments) MTBE to t-butyl alcohol, a primary metabolite of MTBE. BC-1 is a mixed culture containing several bacterial species and is the first culture of its kind which can completely degrade an alkyl ether.

Anaerobic Biodegradation of Gasoline Oxygenates: Extrapolation of Information to Multiple Sites and Redox Conditions

Abstract: A series of alcohol, ketone, ester, and ether oxygenates were tested for their susceptibility to anaerobic decay in samples from four chronically contaminated sedimentary environments. The effect of various electron acceptors on oxygenate biodegradation was also evaluated with a single inoculum source. In addition, two acetogenic bacteria were tested for their ability to metabolize selected oxygenate compounds. The susceptibility of the test oxygenates to anaerobic decay could be related to their chemical structure. That is, compounds other than the ethers that possessed primary or secondary substituted carbon atoms were readily degraded under all conditions tested while compounds that had tertiary substituted carbon atoms resisted biodegradation. The ether oxygenates were generally not degraded when incubated with various inocula, regardless of the electron acceptor status. The exceptions included methyl butyl ether, which was depleted in both sulfate-reducing and methanogenic incubations, and the partial transformation of methyl tert-butyl ether to tert-butanol after a 152-day acclimation period in a single replicate from a river sediment chronically contaminated with fuel. Heat-inactivated control incubations suggested that the latter transformation was biologically catalyzed. 47 refs., 1 fig., 3 tabs.

Degradation of 1,4-dioxane by an actinomycete in pure culture.

Abstract: An actinomycete capable of sustained aerobic growth on 1,4-dioxane was isolated from a dioxane-contaminated sludge samples. The actinomycete, CB1190, grows on 1,4-dioxane as the sole carbon and energy source with a generation time of approximately 30 h. CB1190 degrades 1,4-dioxane at a rate of 0.33 mg of dioxane min-1 mg of protein-1 and mineralizes 59.5% of the dioxane to CO2. CB1190 also grows with other cyclic and linear ethers as the sole carbon and energy sources, including 1,3-dioxane, 2-methyl-1,3-dioxolane, tetrahydrofuran, tetrahydropyran, diethyl ether, and butyl methyl ether. CB1190 is capable of aerobic autotrophic growth on H2 and CO2.

Structural Criteria for the Rational Design of Selective Ligands:Extension of the MM3 Force Field to Aliphatic Ether Complexes of the Alkali and Alkaline Earth Cations

Abstract: Structural requirements for strain-free metal ion complexation by an aliphatic ether group are investigated through the use of both ab initio molecular orbital and molecular mechanics calculations. Hartree-Fock calculations on simple models, M-O(Me)[sub 2] and M-O(Me)(Et), reveal a preference for trigonal planar geometry when aliphatic ether oxygens are coordinated to alkali and alkaline earth cations. This preference is found to be strongest in small, high-valent cations and weakest in large, low-valent cations. Results from the Hartree-Fock calculations are used to extend the MM3 force field for calculation on aliphatic ether complexes with the alkali (Li to Cs) and alkaline earth (Mg to Ba) cations. The resulting molecular model (i) reproduces the experimental crystal structures of 51 different complexes of multidentate ethers with alkali and alkaline earth cations, (ii) explains experimental trends in the structure of five-membered chelate rings of aliphatic ethers, (iii) reveals a fundamental difference between the metal ion size selectivity of five-membered chelate rings of ethers versus that of amines, and (iv) rationalizes trends in the stability of four potassium complexes with the diasteriomers of dicyclohexyl-18-crown-6. 40 refs., 9 figs., 5 tabs.

Densities, refractive indices, speeds of sound, and shear viscosities of diethylene glycol dimethyl ether with ethyl acetate, methyl benzoate, ethyl benzoate, and diethyl succinate in the temperature range from 298.15 to 318.15 K

Abstract: Densities, refractive indices, speeds of sound, and shear viscosities for the mixtures of diethylene glycol dimethyl ether with ethyl acetate, methyl benzoate, ethyl benzoate, or diethyl succinate are measured as a function of mole fraction at temperatures of 298.15, 303.15, 308.15, 313.15, and 318.15 K. The values of these properties are fitted to a power series equation involving both temperature and the mole fraction of the mixture. The experimental values of the mixtures and pure liquids are also used to calculate excess molar volume V E , changes in isentropic compressibility Δβ, changes in refractivity ΔR, and changes in viscosity Δη for the mixing process

Photodecomposition of several compounds commonly used as sunscreen agents

Abstract: The photolysis reactions of three compounds commonly used as a sunscreen agents, Parsol 1789 (1-[4-(1,1-dimethylethyl)phenyl]-3-(4-methoxyphenyl)-1,3- propanedione), Oxybenzone ((2-hydroxy-4-methoxyphenyl)phenyl-methanone) and Padimate O (2-ethylhexyl-4-(dimethylamino)benzoate), were investigated to provide a chemical background to aid in the understanding of the photosensitization of the sunscreen agents. Photolysis was carried out in cyclohexane for 70–140 h using a mercury vapor lamp (450W) without excluding oxygen. Irradation of Parsol 1789 in cyclohexane yielded tert -butylbenzene, p - tert -butylbenzoic acid and p -methoxybenzoic acid; products obtained from the combination of the sunscreen with the solvent included the cyclohexyl esters of p -methoxybenzoic acid, p - tert -butylbenzoic acid and methanoic acid; products obtained from the solvent included cyclohexanol, cyclohexanone and dicyclohexyl ether. Irradiation of Oxybenzone in the cyclohexane for 100 h produced no detectable products by either gas or liquid chromatographic analysis. Oxybenzone was recovered unchanged and no products were observed from the photoinitiated reaction of oxygen with the solvent. Irradiation of Padimate O in cyclohexane yielded the ethylhexyl esters of p -aminobenzoic acid, p -monomethylaminobenzoic acid and p -dimethylamino ( o/m )-methylbenzoic acid, as well as products from the photoinitiated reaction of oxygen with the solvent.

Flexible poly(amino ethers) for barrier packaging

Abstract: Polyaminoethers prepared by reacting (1) a primary amine or bis(secondary) diamine with (2) a diglyeidyl ether and (3) an amine- or epoxy-functionalized poly(alkylene oxide) exhibit a combination of low glass transition temperature (Tg of 14° C. to 73° C.) and low oxygen transmission rate (OTR of 0.53 to 19.0 cc-mil/100-in2 -atm-day).

Photopolymerizable composition and production of light control board

Abstract: PURPOSE:To obtain a photopolymerizable composition for use in producing a light control board which selectively scatters light rays incident thereon at angles in a specific range by using a combination of a radical-polymerizable compound and a cationically polymerizable compound having a vinyl ether structure as a functional group. CONSTITUTION:The composition comprises a combination of at least two polymerizable compounds having different refractive indexes, the compounds being a radical-polymerizable compound (a) and a cationically polymerizable compound (b) having a vinyl ether structure as a functional group. Examples of the compound (a) include tetrahydrofurfuryl acrylate, ethyl carbitol acrylate, and N-vinylpyrrolidone. Examples of the compound (b) include methyl vinyl ether, propyl vinyl ether, and vinyl cyclohexyl ether.

Mechanism of Polymer Stabilization by Hindered-Amine Light Stabilizers (HALS). Model Investigations of the Interaction of Peroxy Radicals with HALS Amines and Amino Ethers

Abstract: Peroxy radicals, when generated in the presence of hindered-amine light stabilizers (HALS), oxidized HALS to produce nitroxides. This reaction, in addition to the scavenging of alkyl radicals by nitroxides, forms a cycle describing HALS as a class of excellent polymer stabilizers. As model systems for the mechanism of the oxidation of HALS, both alkyl peroxy and acyl peroxy radicals were produced by photolyzing the photoinitiators, ketones 2,4-diphenylpentan-3-one and 1-benzoyl-1-hydroxycyclohexane, in oxygen-saturated hexane in the presence of HALS amine I and amino ethers 11-V. Significant yields of the nitroxide VI were observed in these reactions. Product analysis shows that the chemical yields of nitroxide VI are dependent on the HALS structure and on the electronic properties of peroxy radicals, being substantially higher for acylperoxy radicals than for alkyl peroxy radicals. ESR analysis shows that the oxidation of HALS amine I to VI was much less temperature dependent than the oxidation of the HALS amino ether 111. A mechanism for the efficient production of VI from HALS with peroxy radicals is proposed.

Kinetics of the Liquid-Phase Synthesis of Ethyl tert-Butyl Ether (ETBE)

Abstract: The liquid-phase addition of ethanol to isobutene to give ethyl tert-butyl ether (ETBE) on the ion exchange resin Lewatit K2631 has been studied. Rate data were obtained free of mass transfer influence in a continuous differential reactor operated at 1.6 MPa and 40--90 C, measuring steady-state conversions <10% for ethanol-isobutene and ethanol-isobutene-ETBE feeds. The reaction is highly temperature-sensitive. Isobutene has an enhancing effect on the rate whereas ethanol has an inhibitor one. Besides, low ETBE concentrations enhance the reaction but as chemical equilibrium is approached the ether shows an inhibitor effect, as expected. As alcohol-olefin-ether mixtures behave nonideally, kinetic analysis has been performed by using the UNIFAC liquid-phase activities of isobutene, ethanol, and ETBE. The best kinetic model stems from an Eley-Rideal mechanism in which the ethanol, adsorbed on one center, reacts with the isobutene from solution to give the ether adsorbed on one center. Surface reaction is the rate-limiting step. Two additional centers take part in this step.

Direct Nitrosation of Aromatic Hydrocarbons and Ethers with the Electrophilic Nitrosonium Cation

Abstract: Various polymethylbenzenes and anisoles are selectively nitrosated with the electrophilic nitrosonium salt NO+BF 4 - in good conversions and yields under mild conditions in which the conventional procedure (based on nitrite neutralization with strong acid) is ineffective. The reactivity patterns in acetonitrile deduced from the various time/conversions in Tables 2 and 3 indicate that aromatic nitrosation is distinctly different from those previously established for electrophilic aromatic nitration. The contrasting behavior of NO + in aromatic nitrosation is ascribed to a rate-limiting deprotonation of the reversibly formed Wheland intermediate, which in the case of aromatic nitration with NO 2 + occurs with no deuteric kinetic isotope effect. Aromatic nitroso derivatives (unlike the nitro counterpart) are excellent electron donors that are subject to a reversible one-electron oxidation at positive potentials significantly less than that of the parent polymethylbenzene or anisole. As a result, the series of nitrosobenzenes are also much better BrOnsted bases than the corresponding nitro derivatives, and this marked distinction, therfore, accounts for the large differentiation in the deprotonation rates of their respective conjugate acids (i.e. Wheland intermediates)

Vapor Pressures of Methyl tert-Butyl Ether, Ethyl tert-Butyl Ether, Isopropyl tert-Butyl Ether, tert-Amyl Methyl Ether, and tert-Amyl Ethyl Ether

Abstract: The vapor pressures of methyl tert-butyl ether, ethyl tert-butyl ether, isopropyl tert-butyl ether, tert-amyl methyl ether, and tert-amyl ethyl ether were measured by ebulliometry or the static method in the pressure ranges 14--102 and 3--835 kPa (methyl tert-butyl ether), respectively. The data were correlated using the Antoine and Wagner equations. The experimental data of methyl tert-butyl ether and ethyl tert-butyl ether were compared with data available in the literature.

Reaction of C60 with Benzocyclobutenol: Expeditious Route to Fullerene Adducts

Abstract: Reaction of C 60 with benzocyclobutenol (2a) and its methoxy ether (2b) in refluxing toluene gave 1,9-dihydrofullerene cycloadducts (3a) and (3b) in 59% and 50% yields, respectively. The alcohol was converted to pyranyl ether (4), acrylate (5), p-vinylbenzoate (6) and acid succinate esters (7) in good yields under very mild conditions. The adducts exist as two interconverting boat conformers. Acrylate (5) and p-vinylbenzoate (6) should be used for polymerization studies. Acid (7) shows enhanced solubility in polar solvents

H2O2 recycling during oxidation of the arylglycerol beta-aryl ether lignin structure by lignin peroxidase and glyoxal oxidase.

Abstract: Oxidative C alpha-C beta cleavage of the arylglycerol beta-aryl ether lignin model 1-(3,4-dimethoxy-phenyl)-2-phenoxypropane-1,3-diol (I) by Phanerochaete chrysosporium lignin peroxidase in the presence of limiting H2O2 was enhanced 4-5-fold by glyoxal oxidase from the same fungus. Further investigation showed that each C alpha-C beta cleavage reaction released 0.8-0.9 equiv of glycolaldehyde, a glyoxal oxidase substrate. The identification of glycolaldehyde was based on 13C NMR spectrometry of reaction product obtained from beta-, gamma-, and beta,gamma-13C-substituted I, and quantitation was based on an enzymatic NADH-linked assay. The oxidation of glycolaldehyde by glyoxal oxidase yielded 0.9 oxalate and 2.8 H2O2 per reaction, as shown by quantitation of oxalate as 2,3-dihydroxyquinoxaline after derivatization with 1,2-diaminobenzene and by quantitation of H2O2 in coupled spectrophotometric assays with veratryl alcohol and lignin peroxidase. These results suggest that the C alpha-C beta cleavage of I by lignin peroxidase in the presence of glyoxal oxidase should regenerate as many as 3 H2O2. Calculations based on the observed enhancement of LiP-catalyzed C alpha-C beta cleavage by glyoxal oxidase showed that approximately 2 H2O2 were actually regenerated per cleavage of I when both enzymes were present. The cleavage of arylglycerol beta-aryl ether structures by ligninolytic enzymes thus recycles H2O2 to support subsequent cleavage reactions.