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Systematic approach to the determination of cephalosporins in biological fluids by reversed-phase liquid chromatography 总被引:1,自引:0,他引:1
The chromatographic behaviour of some cephalosporins as a function of pH and ionic strength of the mobile phase was studied on 10-microns LiChrosorb RP-18. Acidic cephalosporins were retained longest in their neutral form with an acidic eluent. Amphoteric cephalosporins were retained longest in their protonated form with an acidic eluent of low ionic strength. Cefotiam was retained longer with an alkaline mobile phase. LiChrosorb RP-18, Nucleosil C18 and muBondapak C18 gave rise to different selectivities when an acidic eluent, methanol-water (25:75) containing 0.2% of 1.8 M H2SO4 was used. This may be related to interactions with residual silanol groups. The studied cephalosporins (with the exception of cefotiam and cefsulodin) were separated from compounds present in biological fluids on 5-microns LiChrosorb RP-18 using the mobile phase 0.2% of 1.8 M H2SO4 in a mixture of methanol and water with various methanol contents. The determination of cefotiam in biological fluids was performed with an alkaline mobile phase. The preparation of the sample was simple and rapid: precipitation of plasma proteins or dilution of urine. The method was applied to the determination of ceftizoxime in human plasma and urine. Concentrations down to 0.2 micrograms/ml of plasma and 25 micrograms/ml of urine could be determined with good reproducibility and accuracy. 相似文献
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[reaction: see text] Reductive cleavage of the carbon-sulfur bond present in S-alkyl-thionocarbonates (xanthates) was achieved by high-yielding, tin-free radical reactions based on phosphorus reagents. The combination hypophosphorous acid/triethylamine/AIBN led to fast, efficient, and smooth formation of the alkane. Reduction with diethyl phosphite was sufficiently slow to permit sequential intermolecular addition of a 2-oxoalkyl xanthate onto an olefin followed by cleavage of the newly formed carbon-sulfur bond. 相似文献
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J. P. Genet J. Uziel Y. Janin A. M. Touzin S. Juge 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract (1-aminoalkyl)phosphonic acids are important amino acids with interesting biological properties (1). They are available by various procedures (2). However, a potentially efficient and direct route not very well documented is the use of schiff bases derived from diethyl-aminomethylphosphonate. These substrates have been used to prepare a-alkylated phosphonic aminoacids using strong bases under anhydrous conditions (3). We report here a simple method using solid-liquid phase transfer catalysis (PTC) as wel1 as solid-liquid PTC without solvent: 相似文献
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S. Achi J. P. Genet S. Juge Ph. Potin 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract The asymmetric synthesis of phosphinous compounds from diheterophosphacycloal kane-1,3,2 was investigated in a transition metal complex series. Complexes 1 and 2 were prepared from diaminophosphine, (?)-ephedrine and W (CO)5 THP (1: δ31 P=+147,6 ppm; JPW=313 Hz M.+=595;2 δ3 p=+156 ppm JPW=304 Hz M.+=533; 90%dp) in two steps. Methyl lithium reacted with 1 to give stereospecific 3 (83%Yield) by P-O linkage (3 δ31 P=+64 ppm; JPW =261 Hz; M.+ ? 28=583). The aminophosphine complex 3 was stereochemically stable and was used for studies of synthetic applications. HCL gas reacted with 3 in CH2Cl2 to give the non optically active chlorophosphine complex 4 (δ31 P=+103,6 ppm; JPW=290 Hz; M.+ =482). This compound immediately gave salt 6 (δ31 P=+66,7 ppm; JPW =240 Hz) by reaction with (?)-menthol and triethylamine. The acid methanolysis of 3 gave a mixture of 5 and 6 and the unchanged (?)-ephedrine salt [5:30% yield; δ31 P=+114 ppm; Jpw=280 Hz; [α]D=+1,2° (CH2Cl2); M.+=478; 6 : 60% yield; δ31p=+102,9 ppm; JPW=264 Hz; [α]D =+16,9° (CH2Cl2); M.+=464]. Compound 6 was thus obtained with a 80% yield and a specific rotation of + 20,2° (CH2Cl2) in isopropanol/H2SO4 5M medium. The enantiomeric excess of 6 was determined by RMN31P. Acid hydrolysis of 3 or the reaction with CH3SO3H, gave phosphinous acid complex 6 with an optical rotation of + 4,8° or ?1,8° respectively. These results provide precious informations about the stereochemistry and reactivity of the P-N linkage in this aminophosphine transition metal series, which differs notably from that of the corresponding (PO) N bond. 相似文献
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(R)(?)-N-(3,5-dinitrobenzoyl)-α-phenylethylamine is a good chiral shift reagent for sulfoxides such as Ar-(SO)-CH3 (Ar=substituted phenyl, naphthyl) or R-(SO)-CH3 (R=t-Bu,Cyclohexyl, n-Octyl). 1-Naphthyl propyl sulfoxide was also successfully resolved. The sharpness of the signals allows to measure e.e. 's in the range of 90%. Twenty-five examples are given. 相似文献
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J. P. Genet J. Uziel S. Juge 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract Aminoalkyl phosphonic compounds have many interesting biological properties: they are used as herbicides, antibiotics and enzyme inhibitors. Several approaches to the preparation of α-aminophosphonic acids have been reported. One efficient method using the schiff base of diethyl amino methylphosphonate 1 has been developped, allowing alkylation at the α carbon after deprotonation using strong bases such as LDA. In our continuing program dealing with the synthesis of unusual α-aminoacids which relies on C-C bond formation by transition metal catalyzed reactions (l), we report here a method based on the palladium-promoted alkylation of diethyl aminophosphonate schiff bases 2 and 3 with n3-allyl species 5 generated in situ from the allylic derivative 4: 相似文献
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