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Showing 1 to 20 of 59 for “"isomerisation"”.
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Synthesis and kinetics of isomerisation of 2',6'-dihydroxychalcones
… constant, kₒbₛ, for the chalcone - flavanone isomerisation has been determined over the pH range 0-14 in water (μ = 1.0 mol 1⁻¹ with KC1) at 30°C for the following 2' ,6'-dihydroxychalcones: 2' ,6'-dihydroxychalcone (34); 2' ,6'-dihydroxy-4-methoxychalcone (38); 2' …
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Isomerisation of cresols over zeolites HZSM5, HBeta and HMordenite
… importance to natural cresol producers. The isomerisation of one cresol isomer into one or more of the others would enable a producer to swing (to a limited extent) the distribution of isomers to suite the demand of customers. For this study, the isomerisation and disproportionation of the …
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Reactions of a super-electron donor with diarylcyclopropanes and epoxides
… epoxides with electron donor 1.57. The geometric isomerisation of diarylcyclopropanes was also achieved by DMAP-derived electron donor 1.57. Both geometric isomers of 1,2-bis(4-fluorophenyl)cyclopropane and 1,2- diphenylcyclopropane were isomerised when submitted to 1.57 (Scheme 2). However, no …
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Analytical Studies Concerning the Stability of Betamethasone Valerate and Fusidic acid Hemihydrate in Topical Pharmaceutical Preparations
… factors affecting the intra-molecular isomerisation of betamethasone 17-valerate to 21-valerate in a developmental topical cream for treatment of atopic dermatitis and psoriasis. Appropriate analytical tools for the simultaneous analysis of both drug substances have been developed and …
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Synthetic Investigations towards the Total Synthesis of Neuroprotective Natural Products
… of a unique ring closing metathesis (RCM)/olefin isomerisation methodology that installed the key tertiary enamide functionality. With the successful completion of the synthesis of palmyrolide A (13f) an analogous RCM/olefin isomerisation strategy was used to effect the synthesis of the related …
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Synthesis and Biological Investigation into the Metabolism of Retinoids
… However, natural retinoids readily undergo photo-isomerisation in the presence of natural light and / or in physiological conditions. This propensity for isomerisation is believed to be the cause of many unwanted problems / side effects. Synthetic retinoids have been made by replacing key …
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Growth of unsaturated, cyclic, and polycyclic aromatic hydrocarbons: Reactions under the conditions of the interstellar medium
… thermal equilibrium constants, and microcanonic isomerisation and radiative deactivation rate coefficients. In order to cope with the variety of reaction parameters, a hierarchic workflow scheme was set up. First, the reaction potential energy surface was sampled by molecular dynamics …
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The optimization of the ZSM-5 catalyst activity with respect to crystallinity
… and highly crystalline materials using isomerisation of para-xylene as the probe reaction.
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Improvement of propylene yield via butene metathesis
… which describes a one-step process where isomerisation of 1-butene to 2-butene followed by cross-metathesis taking place. Products of the cross metathesis are propene and 2-pentene. In addition ethene and 3-hexene are expected as products of 1-butene metathesis.
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The synthesis of derivatives of naturally occurring naphthalenes
… The key step in the third approach involved the isomerisation of a dioxolane substituted naphthalene by an intramolecular version of the Mukaiyama reaction. Treatment of a C-8 brominated dioxolanyl naphthalene with titanium tetrachloride resulted in the formation of two angular …
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Conversion of n-pentenes over H-ZSM-5
The skeletal isomerisation of I-pentene provides the feed stock 2-methyl-2-butene and 2-methyl-I-butene for the production of tertiary amyl methyl ether (TAME), an octane booster for petrol. Benzene, toluene, xylenes and ethylbenzene (BTX+EB) are good or even better octane boosters, although the …
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Azobenzenes for the development of therapeutics
… for their ability to undergo light-mediated isomerisation. This unique property enables them to modulate biological systems upon their incorporation. Chapter 1 explores the utilisation of azobenzenes for peptide stapling, that has gained notable interest for therapeutic applications. However, …
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Spectroscopic studies of Metal(II) complexes and application of the Ni(II) complexes to olefin oligomerisation catalysis
… and the presence of phosphine ligands on the isomerisation, as well as the activity and selectivity of the oligomerisation reaction, are discussed. Two polymer-supported catalyst complexes have been prepared; the first,: by polymerisation of a nickel β-ketoenolate complex monomer and th, …
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Synthesis of gemcitabine and it's tetrafluorinated analogues
… media was not very high. Anomerisation and ring isomerisation studies have been conducted
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CRYSTAL ENGINEERING STUDIES ON THE MOLECULAR SALTS AND SILVER(I) COORDINATION COMPOUNDS FOR [2+2] CYCLOADDITION REACTION IN THE SOLID STATE
… before photodimerization and the acid catalysed isomerisation of the cyclobutane derivatives have been explored. It also has been shown how the cooperation of various supramolecular interactions with argentophilic interaction resulted in parallel alignment of linear olefins in various silver(I) …
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Evaluation of three heterologous xylose isomerase genes for the fermentation of plant biomass to bioethanol in Saccharomyces cerevisiae
… production, growth differences and xylose isomerisation but no introduced characteristics were detected. RT-PCR suggested transcription occurred for all the genes tested but no recombinant protein nor any xylose isomerase activity was detected. An in silico bioinformatic analysis showed a …
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Migration of potassium in an iron-based Fischer-Tropsch/zeolite composite catalyst
… and aromatic products formed from skeleton isomerisation and aromatisation reaction over acid zeolites have a high octane number. Thus an alternative process proposed for the production of high quality gasoline from synthesis gas utilises a composite catalyst comprising of an alkali promoted …
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Zeolite deactivation during hydrocarbon reactions: characterisation of coke precursors and acidity, product distribution
… initial stage which deactivated rapidly allowing isomerisation to become the main reaction afterwards. Deactivation studies showed that coke formation was very strong initially which is in good correlation with the initial rapid deactivation. The hydrogen freed during this initial time from the …
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Spectroscopic studies of some heterocyclic hydrazones and their metal complexes
… molecules. The chemical shift changes on isomerisation of the E to Z-isomer have been measured and those for the aldehyde ring are consistent with the withdrawal of charge from this ring via the nitrogen atom. Metal complexes of the two isomers of PAPHY have been prepared and their PMR …
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Ligand-bridged dinuclear carbonyl compounds of rutheniun and osmium
… were tested as homogeneous catalysts for the isomerisation of terminal alkenes. Complex 4 was inactive while the complex 118 gave a 100 % conversion. It is proposed that the catalysis proceeded via the displacement of one acetonitrile ligand from the metal centre providing a vacant site onto …
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