Global ETD Search
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Showing 1 to 20 of 31 for “"Aromatization"”.
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Aromatization over platinum/zeolite L catalysts : the effect of oxygenates
… had exceptionally high selectivity for the aromatization of n-hexane to benzene. The selectivity was ca. 95 at 99 conversion of n-hexane. This Pt/KL catalyst has been extensively studied to determine the reasons for the exceptional stability and benzene yields relative to platinum supported …
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Aromatization of alkenes by gallium/H-ZSM-5 zeolite catalysts
… have been extensively researched for the aromatization of liquified petroleum gas (LPG). In 1989 BP and UOP collaborated to commission a pilot plant in Grangemouth, Scotland, for the aromatization of propane and butane. This plant, based on a technology called the Cyclar process, used …
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Aromatization of light olefins and paraffins on pure and hybrid ZSM-5 catalysts
… evaluation of a novel class of catalysts used in aromatization of short chain hydrocarbons. It was found that when an acidic H-ZSM-5 zeolite with Si/Al atomic ratio equal to about 40, was mixed with a ZnO based co-catalyst, aromatization selectivity followed the principles of synergy. For a feed …
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Androgen aromatization and cytosol estradiol-receptors in the mediation of masculine sexual behavior in Japanese quail
… (LM) line quail to compare (1) the in vivo aromatization of ³H-testosterone and (2) cytosolic estradiol-binding by in vitro saturation analyses. After in vivo incubation with ³H-testosterone, all radioactivity recovered in brain tissues was in the form of testosterone, dihydrotestosterone, …
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Aromatization of n-hexane by platinum containing molecular sieves and distribution and motion of organic guest molecules in zeolites
… sieves were tested as catalysts for the aromatization of n-hexane at 460 - 510°C and atmospheric total pressure in order to study the influence of Pt cluster size and support acidity/basicity, microstructure and chemical composition on activity and selectivity. High selectivity to benzene …
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I. Dissociation and aromatization of a semibenzene. Reactions of triphenylmethyl and methyl isobutyryl radicals. II. The chemistry of alpha- and beta- azo radicals
… oligomeric radicals. From the measured heat of aromatization, the C-C bond dissociation enthalpy of 1 and its analog lacking the side chain ("p-isotriphenylmethane") is calculated to be the lowest value known for any closed shell neutral hydrocarbon. Exposure of 1 to the atmosphere causes rapid …
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Catalytic Light Hydrocarbon Upgrading under Methane Environment
… to terminal silanol hydroxyl groups. The co-aromatization of methane and olefins is also investigated using Ag-Ga/HZSM-5 catalyst and verified using isotope labelling and GC-MS analysis as well as monitoring the reaction heat effect. The co-aromatization reaction between olefins and methane …
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Development of Nickel and Zirconium Mediated Cycloadditions for the Synthesis of Substituted Pentacene
… silyl alkynes to bromo alkynes allowed Bergman aromatization of the naphthalenes to occur. The substituted anthracenes formed could then be treated with bis(triphenylphosphine)dichloro-nickel(II) and sodium amalgam to produce a nickelaryne. Application of the [2+2+2] cycloaddition methodology to …
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The Osteogenic Effects of 12 Weeks of Oral Supplementation of Androstenedione in Middle-Aged Men.
… plasma estrogens in males result from peripheral aromatization of plasma androgens. Thus, it was hypothesized that dietary supplementation with an aromatizable androgen (androstenedione) may stimulate increases in BMD.</p><p>BMD (measured by dual energy x-ray absorptiometry) and biochemical …
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Spectroscopic characterization of iron-oxygen intermediates in human aromatase (CYP19A1)
… which involves a carbon-carbon bond scission and aromatization. The catalytic mechanism of P450s has been long studied and it is well known that an oxo-ferryl π-cation radical, known as “Compound 1” in P450 chemistry is the reactive intermediate that catalyzes most of the reactions of P450s. The …
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Post-translational modifications catalyzed by RiPP and RiPP-adjacent enzymes
… heterocycle dehydration and subsequent pyridine aromatization. Despite in vitro reconstitution of an early example of this class (TbtD), mutagenic scanning, binding data, X-ray crystallographic data, and more, it remained unclear how exactly this enzyme performs its role in thiopeptide …
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Caratterizzazione ed isolamento di intermedi delle reazioni di sostituzione elettrofila e nucleofila in serie aromatica
… makes slow the proton elimination in the re-aromatization process. In presence of a carbon super electrophile reagent as 4,6-dinitrobenzofuroxan or 4,6-dinitrotetrazolepiridine, 1,3,5–tris(N,N-dialkylamino)benzene derivatives afford C–C coupling products which are “double σ complexes”, …
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The synthesis of some new aromatic polycyclic hydrocarbons
… hthyl)-5,6,8,9-tetrahydrobenz[a]anthracene and on aromatization yielded 11-(1-naphthyl)benz[a]-anthracene. When 1-naphthyl magnesium bromide was allowed to react with the 11-keto-8,9,10,11-tetrahydrobenz[a]anthracene, 11-(1-naphthyl)-8,9~dihydrobenz[a]anthracene was obtained when distilled under …
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Enediynylacridans: design and synthesis of oxidase triggered diyl progenitors
In 1972, Bergman reported cycloaromatization via 1,4- benzenoid diradicals of enediyne systems. Since 1985, five enediyne fungal products with anticancer antibiotic activity have been structurally elucidated, namely, neocarzinostatin chromophore, the calicheamicins, the esperamicins, the …
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Studies in Selective C-C Bond Formation via Borylation and Dehydrogenation
… We demonstrate this strategy is successful for aromatization of a number of unactivated alkenes in up to 96% yield.
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In vitro progesterone and estrone synthesis by the porcine placenta and endometrium at 30, 60 and 90 days of gestation
… were detected in either study, suggesting rapid aromatization of C₁₉ steroids to estrogens.
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Developing green processes for the conversion of biobased materials into pyrones
… could be transformed into 5-hydroxychomones by aromatization in good yields.</p> <p>In the third chapter, we found new applications for citric and malic acid mixtures (similar to those found in fruit) by converting them into plasticizers. Citric and malic acid could be reacted together to form …
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I. Radical Cyclizations Mediated by Transition Metal Hydrides II. Study toward the Total Synthesis of Pluraflavin A III. Cytoprotective Polyacetylenes Inspired by Panaxytriol
… by a key [3+2] cycloaddition and a Diels-Alder-aromatization sequence. A derivative of the des-carbohydrate bearing a bromine atom enabled the attachment of the C-glycosidic residue by Stille coupling. Subsequent stereoselective glycosylation reactions appended the O-glycosidic residues. The …
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Total syntheses of (±)-dracephalone A and (±)-dracocequinones A and B, progress towards a total synthesis of cassiabudanols A and B, and synthetic studies towards total synthesis of N-oxy-diketopiperazine containing natural products.
… from known materials. Brønsted acid-promoted aromatization of a late-stage intermediate, followed by careful oxidations, allowed for the rearrangement to the [2.2.2] oxabicyclic core poised for conversion to (±)-dracocequinones A and B in 13 and 15 steps, respectively, from known materials. An …
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Exploring Prokaryotic Thiamin Biosynthesis: Mechanistic Studies On Thiamin Thiazole Synthase And Pyrimidine Synthase
… able to assign function to a gene involved in aromatization of the unstable thiazole tautomer phosphate to the thiazole carboxylate phosphate. We also knew that a single gene product ThiC converts amino-imidazole ribonucleotide, an intermediate in the purine nucleotide biosynthesis, to HMP, …
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