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Improved Yield (improved + yield)
Selected AbstractsImproved synthesis of [18F]fluoromethyl tosylate, a convenient reagent for radiofluoromethylationsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 8 2005Timothy R. Neal Abstract The utility of [18F]fluoromethyl tosylate as an [18F]fluoromethylation reagent has been reexamined. The preparation of this potentially useful compound from the reaction of bis(tosyloxy) methane with 18F- was reported several years ago, but it had not found use as a labeling reagent. When the reported reaction of bis(tosyloxy) methane with 18F- was carried out, [18F]fluoromethyl tosylate was formed along with [18F]tosyl fluoride. The product ratio depended upon reaction conditions, with the yield of [18F]fluoromethyl tosylate usually in the range of 25,40%. Addition of a small amount of water to the reaction mixture resulted in a significant increase in the yield of [18F]fluoromethyl tosylate. Reaction conditions were defined that produced a yield of 71±6% of [18F]fluoromethyl tosylate (decay corrected). The product was conveniently purified by alumina chromatography. Reaction of [18F]fluoromethyl tosylate with the (des-fluoromethyl) fluticasone propionate thioacid precursor produced [18F]fluticasone propionate in improved yield (16%, from fluoride in production-scale runs) over other synthesis methods. Similarly, formation of [18F]choline, [18F]fluoromethionine and N- ([18F]fluoromethyl)spiperone from the reaction of [18F]fluoromethyl tosylate with corresponding precursors was examined. Copyright © 2005 John Wiley & Sons, Ltd. [source] Intraspecific olive diversity assessed with AFLPPLANT BREEDING, Issue 2 2003F. Sanz-Cortés Abstract Amplified fragment length polymorphism (AFLP) was used to study diversity within and among Spanish olive varieties. A high degree of diversity was found among the varieties present in each growing region. Olive oil production and quality relies on appropriate cultivar selection as well as good orchard management. Production based only on a few superior cultivars would result in improved yield, oil quality, and production management. Amplified fragment length polymorphism were evaluated as a tool to identify the intraspecific and intravarietal diversity of olive. Amplified fragment length polymorphism analysis of 38 accessions belonging to 10 cultivars using six primer combinations produced 106 polymorphic bands. Results were analyzed for similarity among accessions via unweighted pair-group means cluster analysis, resulting in 10 clusters corresponding to named variety designations. Similarity among varieties ranged from 0.60 to 0.72. Diversity within varieties was identified. Similarity within named varieties (accessions with the same varietal name) ranged from 0.75 to 0.96. Differences in several markers were found among 34 accessions. Intravarietal diversity was shown to exist within the Spanish olive varieties grown in the region surrounding Valencia. [source] Intramolecular phenylborane complexes with monobasic bidentate Schiff basesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 2 2007Shweta Gaur Abstract A series of intramolecular complexes with Schiff base ligands having N,S and N,O donor systems were synthesized in an open vessel under microwave irradiation (MWI) using a domestic microwave oven. The reaction time has been brought down from hours to seconds with improved yield as compared with the conventional heating. The complexes have been characterized on the basis of elemental analysis, conductance measurements and spectroscopic analysis. Based on the IR, 1H NMR, 11B NMR and 13C NMR spectroscopic studies, a tetrahedral geometry has been proposed for the resulting complexes. The compounds have been screened in vitro against bacteria and fungi to test their antimicrobial property and in vivo in male albino rats to test their antifertility property. The testicular sperm density, motility and density of cauda epididymal spermatozoa along with biochemical parameters of reproductive organs have been examined and discussed. Copyright © 2007 John Wiley & Sons, Ltd. [source] 1,3-Dipolar Cycloaddition Reactions of Organic Azides with Morpholinobuta-1,3-dienes and with an , -Ethynyl-enamineHELVETICA CHIMICA ACTA, Issue 7 2005Martina Brunner The cycloaddition of organic azides with some conjugated enamines of the 2-amino-1,3-diene, 1-amino-1,3-diene, and 2-aminobut-1-en-3-yne type is investigated. The 2-morpholinobuta-1,3-diene 1 undergoes regioselective [3+2] cycloaddition with several electrophilic azides RN32 (a, R=4-nitrophenyl; b, R=ethoxycarbonyl; c, R=tosyl; d, R=phenyl) to form 5-alkenyl-4,5-dihydro-5-morpholino-1H -1,2,3-triazoles 3 which are transformed into 1,5-disubstituted 1H -triazoles 4a,d or ,,, -unsaturated carboximidamide 5 (Scheme,1). The cycloaddition reaction of 4-[(1E,3Z)-3-morpholino-4-phenylbuta-1,3-dienyl]morpholine (7) with azide 2a occurs at the less-substituted enamine function and yields the 4-(1-morpholino-2-phenylethenyl)-1H -1,2,3-triazole 8 (Scheme,2). The 1,3-dipolar cycloaddition reaction of azides 2a,d with 4-(1-methylene-3-phenylprop-2-ynyl)morpholine (9) is accelerated at high pressure (ca. 7,10,kbar) and gives 1,5-disubstituted dihydro-1H -triazoles 10a,b and 1-phenyl-5-(phenylethynyl)-1H -1,2,3-triazole (11d) in significantly improved yields (Schemes,3 and 4). The formation of 11d is also facilitated in the presence of an equimolar quantity of tBuOH. The three-component reaction between enamine 9, phenyl azide, and phenol affords the 5-(2-phenoxy-2-phenylethenyl)-1H -1,2,3-triazole 14d. [source] Fuel Cells, Advanced Reactors and Smart Catalysis: The Exploitation of Ceramic Ion-Conducting MembranesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 8 2003I.S. Metcalfe Abstract Membrane reactors are of great interest in the chemical industries because they offer the possibility of improved yields, improved selectivities and more compact plant. However, a significant barrier to their uptake is the unavailability of membrane systems having the required performance at an acceptable cost. In this paper we will explore the use of one class of membrane that has the potential to deliver high performance at reasonable cost. Ion-conducting ceramic membranes can be used in a wide range of high temperature applications including fuel cells, advanced reactors and even smart catalytic systems. [source] | ||||||||||