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Preparative Scale (preparative + scale)
Selected AbstractsCHROMATOGRAPHIC SEPARATION AT A PREPARATIVE SCALE OF EGG WHITE OVALBUMIN AND ITS APPLICATION IN THE ELABORATION OF YOGURT MOUSSEJOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2006B. PAREDES ABSTRACT Egg white contains high-quality proteins. Some processes using eggs produce egg white as by-product. These egg white proteins may be recovered for use as additive in food products. In the first part of this study, a new polymeric material was developed and used in the chromatographic separation of ovalbumin at preparative scale. Ovalbumin is the major component of egg white and thus, it has the greatest weight in terms of its functional effects. An application of the purified ovalbumin was subsequently studied in the elaboration of yogurt mousse. The results obtained showed that the poly(glycidil methacrylate-co-ethylene dimethacrylate) resin that was manufactured enabled the separation of ovalbumin with good efficiency. This study also showed that the formulation obtained from the yogurt mousse with ovalbumin had a greater yield in volume than the commercial product used as a benchmark, improving the majority of its organoleptic qualities without appreciably affecting its stability and organoleptic properties. [source] Electrocarboxylation of Benzyl Halides through Redox Catalysis on the Preparative ScaleCHEMISTRY - A EUROPEAN JOURNAL, Issue 28 2006Onofrio Scialdone Dr. Abstract The electrocarboxylation of benzyl halides to the corresponding carboxylic acids through homogeneous charge-transfer catalysis was investigated both theoretically and experimentally to determine the influence of the operative parameters on the yield of the process and on the catalyst consumption. Theoretical considerations, based on fast kinetics of redox catalysis, were confirmed by the electrocarboxylation of 1-phenyl-1-chloroethane catalyzed by 1,3-benzenedicarboxylic acid dimethyl ester performed at a carbon cathode under different operative conditions. We obtained high yields of the target carboxylic acid and experienced a low catalyst consumption by operating with optimized [RX]bulk/[CO2]bulk and [RX]bulk/[catalyst] ratios. [source] Lanthanide Formamidinates as Improved Catalysts for the Tishchenko ReactionEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2008Agustino Zuyls Abstract The tris(formamidinato)lanthanum(III) complexes [La(o -TolForm)3(thf)2] [1; o -TolForm = N,N, -bis(o -tolyl)formamidinate], [La(XylForm)3(thf)] [2; XylForm = N,N, -bis(2,6-dimethylphenyl)formamidinate], and [La(EtForm)3] [3, EtForm = N,N, -bis(2,6-diethylphenyl)formamidinate] are a new class of precatalysts for the Tishchenko reaction. Their catalytic activity is a result of their high Lewis acidity and the ease with which the ligand spheres can be interchanged. For the dimerization of benzaldehyde to give benzyl benzoate, which is a benchmark reaction, compound 1 is, to the best of our knowledge, the most active catalyst ever reported. On a preparative scale, the reaction can be performed in the absence of solvent. A range of aromatic, heteroaromatic, and aliphatic aldehydes was rapidly converted into the corresponding esters by using catalysts 1,3.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Towards a Selective Functionalization of Amino-Terminated DendrimersEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2004Fritz Vögtle Abstract Selective functionalization of the periphery of commercial polypropyleneamine (POPAM) and polyamidoamine (PAMAM) dendrimers has been investigated in preparative scale. The first generation (G1) POPAM dendrimer was for the first time selectively N,N -bis(sulfonylated) with tosyl chloride and the corresponding mono-, di-, tri-, and tetra- N -tosylsulfonamides were isolated and fully characterized. Unexpectedly, similar persulfonylation of G2 POPAM results in splitting of a central C,N bond and only fully and partially sulfonylated halves of the initial dendrimer could be isolated. Higher generations of POPAM are also split during the persulfonylation yielding complex mixtures of persulfonylated dendritic fragments which could hardly be identified. A plausible mechanism of the POPAM decomposition on the basis of the reaction product analysis is proposed. N -Sulfonylation of a peripheral octasulfonamide of G2 POPAM with tosyl chloride also leads to the destruction of the dendrimer, while its N -alkylation with benzyl bromide proved to be not selective yielding a completely alkylated derivative. Unlike POPAM dendrimers, PAMAM dendrimers were shown to be more stable during their sulfonylation and no decomposition of the dendritic backbone was detected. In contrast to the POPAM dendrimers, PAMAM dendrimers were shown to be rather inert with respect to the formation of N -tosylsulfonamides since they could only be N -monosulfonylated at all peripheral amino groups. The combination of MALDI-TOF and ESI-FT-ICR tandem mass spectrometry has been shown to be an effective method for structure assignment and purity check of selectively or fully persulfonylated dendritic oligoamines. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] 1,3,6-Azadiphosphacycloheptanes: A novel type of heterocyclic diphosphinesHETEROATOM CHEMISTRY, Issue 2 2008Andrey A. Karasik The novel type of seven-membered cyclic diphosphines, namely 1,3,6-azadiphosphacycloheptanes, has been synthesized by condensation of 1,2-bis(phenylphosphino)ethane, formaldehyde, and primary amines (aniline, p -toluidine, benzylamine, and 5-aminoisophthalic acid) as a mixture of rac- and meso-stereoisomers. The structures of rac-stereoisomers of N -tolyl and N -(3,,5,-dicarboxyphenyl)-substituted diphosphines were investigated by X-ray crystal structure analyses. The stereoisomers of N -(3,,5,-dicarboxyphenyl)-substituted compound were separated at a preparative scale, and their platinum(II) dichloride complexes were obtained. The corresponding meso-isomer readily forms P,P -chelate complex with [PtCl2(cod)], whereas the rac-stereoisomer forms oligomeric complex. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:125,132, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20397 [source] Preparative Enzymatic Synthesis of the Acylglucuronide of Mycophenolic AcidADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6-7 2003Matthias Kittelmann Abstract The acylglucuronide (3) of mycophenolic acid (1) was enzymatically synthesised on a preparative scale (450,mg substrate) under optimised reaction conditions with 51% conversion. By screening 9 liver homogenates from 8 vertebrate species, it was shown that only with liver homogenate from horse as the catalyst were the acyl- (3) and the O -glucuronide (2) were formed in a ca. 1,:,1 ratio. With homogenates from other sources, the O -glucuronide (2) was produced in high excess. By optimising the concentration of the co-substrate UDP-glucuronic acid and the reaction temperature, the conversion to the acylglucuronide (3) was increased from initially 34 to 55% and the ratio of acyl- (3) to O -glucuronide (2) from 1.5,:,1 to 3.9,:,1. The reaction was also performed continuously in an enzyme membrane reactor, however, with lower conversion yield and therefore, higher specific UDP-glucuronic acid consumption. [source] CHROMATOGRAPHIC SEPARATION AT A PREPARATIVE SCALE OF EGG WHITE OVALBUMIN AND ITS APPLICATION IN THE ELABORATION OF YOGURT MOUSSEJOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2006B. PAREDES ABSTRACT Egg white contains high-quality proteins. Some processes using eggs produce egg white as by-product. These egg white proteins may be recovered for use as additive in food products. In the first part of this study, a new polymeric material was developed and used in the chromatographic separation of ovalbumin at preparative scale. Ovalbumin is the major component of egg white and thus, it has the greatest weight in terms of its functional effects. An application of the purified ovalbumin was subsequently studied in the elaboration of yogurt mousse. The results obtained showed that the poly(glycidil methacrylate-co-ethylene dimethacrylate) resin that was manufactured enabled the separation of ovalbumin with good efficiency. This study also showed that the formulation obtained from the yogurt mousse with ovalbumin had a greater yield in volume than the commercial product used as a benchmark, improving the majority of its organoleptic qualities without appreciably affecting its stability and organoleptic properties. [source] Easy preparative scale syntheses of labelled xanthines: caffeine, theophylline and theobromineJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 1 2007Frédéric Balssa Abstract Several easy preparative scale (0.5,1.5 g) syntheses of deuterium labelled caffeine, theophylline and theobromine are described. Some new selective syntheses of theophylline and theobromine have been developed. Labelled xanthines are of great interest in qualitative or quantitative isotope dilution-mass spectrometry, coupled with gas or liquid chromatography, currently performed in anti-doping and forensic laboratories. Copyright © 2007 John Wiley & Sons, Ltd. [source] Rapid identification and preparative isolation of antioxidant components in licoriceJOURNAL OF SEPARATION SCIENCE, JSS, Issue 4-5 2010Yeon Sil Lee Abstract This study employed the online HPLC-2,2,-azinobis-(3-ethylbenzothiazoline-6-sulfonate radical cation (ABTS+·) bioassay to rapidly determine antioxidant compounds occurring in the licorice extract of Glycyrrhiza uralensis. The negative peaks of the ABTS+· radical scavenging detection system, which indicated the presence of antioxidant activity, were monitored by measuring the decrease in absorbance at 734,nm. The ABTS+ -based antioxidant activity profile showed that three peaks exhibited antioxidant activity, and then the high-speed counter-current chromatography technique of preparative scale was successfully applied to separate the three peaks I-III in one step from the licorice extract. The high-speed counter-current chromatography was performed using a two-phase solvent system composed of n -hexane,ethyl acetate,methanol,water (6.5:5.5:6:4, v/v). Yields of the three peaks, dehydroglyasperin C (I, 95.1% purity), dehydroglyasperin D (II, 96.2% purity), and isoangustone A (III, 99.5% purity), obtained were 10.33, 10.43, and 6.7% respectively. Chemical structures of the purified dehydroglyasperin C (I), dehydroglyasperin D (II), and isoangustone A (III) were identified by ESI-MS and 1H- and 13C-NMR analysis. [source] Structural investigations of isomeric oxidised forms of hyperforin by HPLC-NMR and HPLC-MSnPHYTOCHEMICAL ANALYSIS, Issue 5 2003J.-L. Wolfender Abstract The prenylated phloroglucinol hyperforin, thought to be an essential component for the anti-depressant activity of St. John's Wort (Hypericum perforatum), is unstable. The facile oxidative degradation of hyperforin poses serious problems for standardisation, and may also dramatically affect the pharmacological activity of the extracts. Hyperforin was dissolved in hexane and stored at room temperature for 3 days and yielded various closely related degradation products which, although dif,cult to isolate on the preparative scale, have been analysed by on-,ow and stop-,ow HPLC-NMR and HPLC-MS/MS. From on-line spectroscopic data, and with the aid of complementary in-mixture standard NMR two-dimensional correlation experiments, the different oxidised forms of hyperforin were found to be phloroglucinol derivatives in which a hydroxy-dihydrofuran ring is formed involving the enol OH at C-7 or C-9 (tautomeric form) and the prenyl chain at C-8 of the core nucleus of hyperforin. The strategy followed for the on-line identi,cation of these constituents is discussed. Copyright © 2003 John Wiley & Sons, Ltd. [source] Direct measurement of the kinetics of CBM9 fusion-tag bioprocessing using luminescence resonance energy transferBIOTECHNOLOGY PROGRESS, Issue 3 2009Mojgan Kavoosi Abstract The economics of affinity-tagging technologies, particularly at preparative scales, depends in part on the cost and efficiency of the bioprocessing step used to remove the affinity tag and obtain the final purified product (Lowe et al., J Biochem Biophys Methods. 2001;49:561,574). When CBM9, the family 9 cellulose binding module from Thermotoga maritima, serves as the affinity tag, the overall efficiency of tag removal is a function of the choice of processing enzyme and the local structure of the cleavage site, most notably the linker sequence flanking the bioprocessing recognition site on the tag side. A novel spectroscopic method is reported and used to rapidly and accurately measure CBM9 fusion-tag bioprocessing kinetics and their dependence on the choice of linker sequence. The assay monitors energy transfer between a lanthanide-based donor bound to the CBM9 tag and an acceptor fluorophore presented on the target protein or peptide. Enzyme-catalyzed cleavage of the fusion tag terminates this resonance energy transfer, resulting in a change in fluorescence intensity that can be monitored to quantify substrate concentration over time. The assay is simple, fast and accurate, providing kcat/KM values that contain standard errors of less than 3%. As a result, both substantial and subtle differences in bioprocessing kinetics can be measured and used to guide bioproduct design. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] | ||||||||||