Alkylene Oxide Research Articles

The Combination of Accurate Fragment Mass and A New Database Search Algorithm for the Identification of Unexpected Modifications

One of the primary difficulties with protein identification using database search algorithms is the determination of post-translational modifications. When the appropriate modification isn't chosen in the initial search, the modification may not only be missed but this spectrum can be assigned to the wrong peptide producing a false positive. Sample handling alone can produce several different peptide modifications, most notably deamidation, oxidation, carbamylation, and improper alkylation. This work examines a new search mode designed to identify peptides with unexpected modifications. A trypsin digest of a HeLa cell protein lysate was fractionated by pI then analyzed using microfluidic-based nano-LC coupled to a Q-TOF mass spectrometer. Database searches were performed against the human IPI database and the initial database search was performed looking for only unmodified matches. Unexpected modifications were subsequently identified using an unassigned single mass gap mode which identifies any potential peptide modification by the mass of the modification. To determine the impact of MS/MS mass accuracy, searches were performed using the unassigned single mass gap homology search mode holding the precursor mass accuracy at 10 ppm while varying the fragment mass tolerances from 40 ppm to 1000 ppm. Results demonstrate that the combination of high mass accuracy for both precursor and product ion spectra and a new database search mode where modifications are not known beforehand, confident identification can be made for peptides that would previously have been missed.

Imprinted Nanoporous Organosilicas for Selective Adsorption of Nitroenergetic Targets

Periodic mesoporous organosilicas incorporating diethylbenzene bridges in their pore walls were applied for the adsorption of nitroenegetic targets from aqueous solution. The materials were synthesized by co-condensing 1,4-bis(trimethoxysilylethyl)benzene (DEB) with 1,2-bis(trimethoxysilyl)ethane to improve structural characteristics. Molecular imprinting of the pore surfaces was employed through the use of a novel target-like surfactant to further enhance selectivity for targets of interest (tri- and dinitrotoluenes) over targets of similar structure ( p-cresol and p-nitrophenol). The headgroup of the commonly used alkylene oxide surfactant Brij76 was modified by esterification with 3,5-dinitrobenzoyl chloride. This provided a target analogue which was readily miscible with the Brij76 surfactant micelles used to direct material mesopore structures. The impact of variations in precursor ratios and amounts of imprint molecule was evaluated. The use of 12.5% of the modified Brij surfactant with a co-condensate employing 30% DEB was found to provide the best compromise between total capacity and selectivity for nitroenergetic targets.

Synthesis of functionalized 2‐trimethylsiloxy‐substituted O‐trimethylsilyl alkylphosphonites, their analogues, and derivatives

AbstractNucleophilic addition of trimethylsilyl esters of tricoordinate organophosphorus acids to several functionalized alkylene oxides is proposed as convenient methods for the synthesis of new 2‐trimethylsiloxysubstituted alkylphosphonites, their analogues, and derivatives. Also the new functionalized derivatives of these phosphonites, including amino, carboxy, or sulfo groups as well as certain properties of these compounds, which may be the important precursors of new functionalized 2‐hydroxyalkylorganophosphorus acids, are presented. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:450–454, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20453

Electronic Effect of Substituent of Quinones on their Catalytic Performance in Hydrocarbons Oxidation

Quinones with electron-withdrawing F, Cl or Br groups and N-hydroxyphthalimide (NHPI) were used as catalysts in selective oxidation of hydrocarbons with molecular oxygen as oxidant. The catalytic activity in the selective oxidation of ethylbenzene to oxygenation products was in the following order: p-benzoquinone < tetrafluoro-p-benzoquinone ≈ tetrachloro-p-benzoquinone < tetrabromo-p-benzoquinone (p-TBBQ). Moderate electron-withdrawing power of substituent was suitable for quinone abstracting hydrogen from NHPI to generate reactive phthalimido-N-oxyl (PINO). The catalytic activity of p-TBBQ/NHPI, the best catalyst in our study, was also tested in the selective oxidation of alkylarenes, alkenes and alkanes.

Ionic liquid promoted selective oxidation of organic compounds with NaBrO3

1-Butyl-3-methylimidazolium bromide ([bmim]Br) as an ionic liquid promoted selectively the oxidation of alkyl arenes and alcohols to the corresponding carbonyl compounds with NaBrO3 in excellent yields under neutral conditions at the 70°C. Among the various ionic liquids examined, the [bmim]Br exhibited the best performances with NaBrO3. The ionic liquid can be recycled and reused for several runs without any significant loss of activity.

New Recoverable Organoselenium Catalyst for Hydroperoxide Oxidation of Organic Substrates

New benzisoselenazol-3(2H)-one covalently bounded to a silica support was synthesized and characterized. It was used as an effective, selective, and easy-to-regenerate catalyst for t-BuOOH and H2O2 oxidation of alkyl arenes to alkyl aryl ketones, aromatic aldehydes to arene carboxylic acids, and sulfoxides and/or sulfones.

ChemInform Abstract: Copper‐Triethanolamine Complex as Efficient and Active Catalyst for Selective Oxidation of Alkylarenes to Phenyl Ketones by tert‐Butylhydroperoxide.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Copper Catalyzed Oxidative Alkylation of sp3 C—H Bond Adjacent to a Nitrogen Atom Using Molecular Oxygen in Water.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Aerobic oxidation of alkyl arenes using a combination of N-hydroxy phthalimide and recyclable cobalt(II) tetrasulfophthalocyanine supported on silica

Abstract Aerobic oxidation of alkyl arenes to the corresponding carbonyl compounds was developed using a combined catalytic system consisting of N -hydroxy phthalimide and silica supported cobalt(II) tetrasulfophthalocyanine at 80 °C. The supported Na 4 [CoTSPc] can be recycled and reused for five runs without any significant loss of catalytic activity.

Aerobic oxidation of alkyl arenes and alcohols using cobalt(II) phthalocyanine as a catalyst in 1-butyl-3-methyl-imidazolium bromide

Abstract The aerobic oxidation of alkyl arenes and alcohols to the corresponding carbonyl compounds has been achieved using a catalyst and oxygen (0.1 atm) in an ionic liquid. Excellent yields were obtained under mild, easily obtainable conditions. Among the various metallophthalocyanine catalysts and ionic liquids examined, the best results were obtained with cobalt(II) phthalocyanine in 1-butyl-3-methylimidazolium bromide ([bmim]Br). These materials can be recycled and reused for several times without any significant loss of catalytic activity.

Polymer-supported Zinc Tetrahalide Catalysts for the Coupling Reactions of CO2and Epoxides

Homogeneous zinc tetrahalide complexes, highly active catalysts for the coupling reactions of alkylene oxide and CO 2 produce alkylene carbonates, were heterogenized due to their tendency to decompose produced alkylene carbonates during the distillation process. Heterogenization of homogeneous zinc tetrahalide complexes was achieved by polymerizing 1-alkyl-3-vinylimidazolium zinc tetrahalides. These polymerized zinc tetrahalide catalysts displayed similar activities to their corresponding monomeric analogues for the coupling reactions of carbon dioxide with ethylene oxide (EO) or propylene oxide (PO) to produce ethylene carbonate (EC) or propylene carbonate (PC). TGA studies showed that the polymer-supported zinc tetrahalide catalysts are thermally stable up to 320 °C. The catalyst recycle test showed that the supported catalysts could be reused over six times. After removal of the polymer-supported catalyst through a simple filtration, EC was able to be isolated without decomposition.

Copper-triethanolamine complex as efficient and active catalyst for selective oxidation of alkylarenes to phenyl ketones by tert-butylhydroperoxide

Several types of alkylarenes were selectively oxidized to the corresponding α-phenyl ketones in moderate to good selectivities and conversions using tert-butylhydroperoxide in the presence of a tetranuclear copper-triethanolamine complex under mild reaction conditions.

Various nano-size iron oxide polymorphs on mesoporous supports I: New mesoporous catalyst supports synthesized in acidic and alkaline media

A fairly large number (altogether 12) of new mesoporous silica catalyst supports have been synthesized mainly in alkaline media using ionic (CTAB) and non-ionic Aldrich-type triblock poly(alkylene oxide) copolymers and polyglycol mixtures. Preference was given to water–glass as the silicon source. This study was aiming at setting up an own catalyst carrier repertory to be able to select supports with “good” characteristics for the investigation of deconvoluted Mössbauer and EPR spectra. This task could not be carried out on compact oxides. The physical characterization (N 2 adsorption, XRD, SEM, HRTEM, SAED, Mössbauer, EPR and 29Si-NMR spectroscopy) was supplemented by activity testing, as well, in the N 2O-mediated selective oxidation of benzene and synthesis of (carbon) nanotubes at very high temperature. The first part of the planned two publications deals with the description of various synthesis recipes of silica carriers and a few novel observations obtained during their characterization. It seems to be important to know that the so called amorphous silicas are not always and never fully amorphous. Their structure consists of crystalline SiO 2 polymorph grains (β-tridymite or quartz) embedded and randomly oriented in the agglomeration of amorphous silica particles of similar (15–20 nm) size. This final state of genesis is preceded during the synthesis by the separation of viscous, tacky liquid droplets from the aqueous phase when the “surfactant + silicate” complex becomes insoluble in the slurry. Later on the droplets solidify as such or experience a slight deformation if the ordering continues even after their separation. The amorphous silica grains have no hexagonal pore structure, thus, pore walls either. Their extreme heat– and hydrothermal stability is due to this fact. They can be synthesized from water–glass in a wide range of specific surface areas and pore diameters, and in the possession of activity testing data and information obtained from the respective deconvoluted EPR and Mössbauer spectra, the selection of a “good” carrier from the literature or rather from an own carrier repertory seems to be a promising perspective.

Kinetics of the copolymerization of alkylene oxides with glycidyl methacrylate

AbstractIn the present study, the kinetics of copolymerization reaction of propylene oxide (PO) and butylene oxide (BO) with glycidyl methacrylate (GMA) in the presence of BF3·O(C2H5)2 catalyst were investigated. The kinetic parameters and activation energy of the copolymerization reaction were calculated. The amounts of reacting PO, BO, and GMA during copolymerization were determined by chromatographic method, because the same copolymerization conditions were carried out for them. It was determined that the copolymerization rate of PO (r0) and BO (r0) was higher than that of GMA, but activation energy (E) of GMA was higher than that of PO and BO. The rate of reaction, the rate constant, and activation energy were calculated from the amount of copolymer obtained with respect to time. The structures of synthesized copolymers were determined by the spectral and chemical analysis methods. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Intermolecular interactions governing solubilization in micelles of poly(alkylene oxide) surfactants

Partition coefficients for 39 low-molecular-mass compounds between water and micelles of an ethylene oxide-propylene oxide block copolymer (Pluronic P85) and the monolauryl ether of poly(ethylene oxide) (Brij 35) have been measured by the methods of fluorescence spectroscopy, fluorescence anisotropy, and dialysis kinetics. The tested compounds include aromatic hydrocarbons, phenols, naphthols, xanthene dyes, anthracycline antibiotics, and porphyrins. The multifactor analysis of the partition coefficients in terms of the linear free-energy relationships has been performed. It has been shown that the H-donating ability of compounds facilitates their solubilization in Pluronic micelles and has no effect on solubilization in micelles of monolauryl ether of poly(ethylene oxide). This difference indicates that, when solubilization occurs in Pluronic micelles, the compounds under study appear in a hydrophobic core composed of poly(propylene oxide) blocks.

Radiation degradation of blends polypropylene/poly(ethylene- co-vinyl acetate)

Physicochemical and mechanical characteristics of irradiated electron beam polypropylene/ethylene-vinyl acetate (PP/EVA) blends and individual components were investigated. Although oxidation of alkyl radicals in the blends proceeds slower than in PP, the total oxidation effect monitored by content of oxygen-containing groups shows opposite tendency. Blending with EVA does not affect degree of PP crystallinity. The enthalpy of melting and crystallization of the blends reveal phase separation between dispersed copolymer and PP matrix. In all studied blends, degradation prevails over tendency of EVA to cross-linking.

A simple synthetic protocol for oxidation of alkyl-arenes into ketones using a combination of HBr–H 2O 2

A wide variety of alkyl- and cycloalkyl-arenes undergo benzylic C–H oxidation by employing a combination of 48% hydrogen bromide and 30% hydrogen peroxide in dichloromethane at room temperature. In addition, a chemoselective oxidation at the benzylic position is feasible by deactivating the aromatic ring using the same combination.

Effect of Water Content and Surfactant Type on Viscosity and Stability of Emulsified Heavy Mukhaizna Crude Oil

Heavy crude oil from the Mukhaizna oil field in Oman was emulsified with water in an attempt to decrease its viscosity. The oil has a kinematic viscosity of 7160 mm2/s at 30 °C, density of 0.9571 g/cm3 at 15 °C, and asphaltene content of 4.7 wt %. The effects of changes in water content (20−30 wt %), type and concentration of surfactant, addition of a water-soluble polymer, and agitation temperatures (25 and 42 °C) were studied in order to identify the optimum viscosity and stability for transporting the oil. The stability was measured by the water separation rate from the emulsion. For the Mukhaizna heavy crude oil, 21−22 wt % of water content and 0.4 wt % of nonylphenol ether type or higher alcohol alkylene oxide type surfactant were found to be optimum for a stable emulsion with a concomitant significant decrease in viscosity to about 1/3−1/4 that of the original crude oil. This improves the transportability of the heavy crude oil and makes it suitable for use as a power generation fuel.

Synthesis of Hydrophobic Poly(alkylene oxide)s and Amphiphilic Poly(alkylene oxide) Block Copolymers

The anionic ring-opening polymerization of alkylene oxides, except ethylene oxide, is accompanied by strong side reactions, leading to high molecular weight and low molecular weight byproducts. In this work we investigated the anionic polymerization of hydrophobic alkylene oxides at different temperatures, solvents, and initiating systems. For polymers synthesized in the temperature range between 40 and 80 °C and employing potassium and cesium alcoholate initiators significant amounts of byproducts were found. With the help of crown ethers the temperature could be reduced to −23 °C without extending polymerization times too much. This measure allowed eliminating byproducts almost completely. The best results were obtained with potassium alcoholates and 18-crown-6 in toluene at −10 to −23 °C. Poly(1,2-butylene oxide), poly(1,2-hexylene oxide), and poly(1,2-octylene oxide) homopolymers were synthesized up to molecular weights in the range of 50 000−100 000 and Mw/Mn < 1.1. Furthermore, the method was employ...

Copper catalyzed oxidative alkylation of sp3 C–H bond adjacent to a nitrogen atom using molecular oxygen in water

A simple and highly efficient C–C bond formation was developed by the activation of two sp3 C–H bonds.