A Novel Kinetic Method for the Determination of Cobalt(Ⅱ) in Vitamin Bl2

Cobalt(Ⅱ) in NaOH(a.q.) can catalyze the decolorizing reaction resulting from the oxidation of dibromohydoxylphenylfluorone(DBH-PF) by H₂O₂(a.q.). A new catalytic spectrophotometry for determining trace Cobalt(Ⅱ) was obtained. The method has been used to determine trace Cobalt(Ⅱ) in Vitamin B₁₂ samples. The sensitivity of this method is higher than the references, and the selectivity of the method is better than the references too.     

A Novel Approach for the Surface Modification of Polymeric Membrane with Phospholipid Polymer

A new economic and convenient method to modify the surface of microporous polypropylene (PP) membranes with phospholipid polymer was given. The process included the photo-irradiated graft polymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA) and the ring-opening reaction of the grafted polyDMAEMA with 2-alkyloxy-2-oxide-1,3,2-dioxo-phospholanes (AOP). Four AOPs, whose alkyloxy groups consisted of dodecyl, tetradecyl,hexadecyl and octadecyl moieties, were used to convert the grafted polyDMAEMA to phospholipidpolymers. FT-IR spectra confirmed the chemical change of membrane surface. Platelets adhesion experiment indicated that PP membrane with excellent blood compatible surface could be fabricated by this method.     

A Novel Approach to Improve the Detectability of CO2 by GC Analysis

A novel stochastic resonance algorithm was employed to enhance the signal-to-noise ratio (SNR) of signals of analytical chemistry.By using a gas chromatographic data set,it was proven that the SNR was greatly improved and the quantitative relationship between concentrations and chromatographic responses remined simultancously.The linear range was extended beyond the instrumental detection limit.     

A New Synthesis of 5,8‐Dimethyl‐2‐tetralone—A Potential Intermediate for the Synthesis of Ring‐A Aromatic Sesquiterpenes. Novel Transformation During Acetoxylation of 5,8‐Dimethyldihydronapthalene

Abstract

An efficient synthesis of 5,8‐dimethyl‐2‐tetralone 4 starting from 5,8‐dimethyl‐1‐tetralone 2 is described. It was converted into the unsaturated derivative 3, which on epoxidation followed by acid hydrolysis yielded tetralone 4. Acetoxylation of 3 with manganese(III) acetate and potassium bromide afforded dimethylnaphthalene 8 and derivative 9.     

A Novel Approach for Determining the Orientation of 3-Hydroxyl Group of Some Steroids by CIMS

Stereochemicalanalysisisanimportantsubjectinorganicstructureelucidation,andmassspectrometryprovestobeapromisingtoolforthisproposeduetoitshighsensitivity(thelimitofdetectionisabout10-14mole),rapidity,etcl.Inourpreviouswork,aseriesofstudiesonthestereochemicaleffectsinmassspectrometryhavebeendiscussed2-6.Inthiscommunicationwereportanovelapproachfordeterminationtheeoraorientationof3hydroxylgroupofsomesteroidsdirectlybychemicalionizationmassspectrometryusingtrimethylchlorosilaneasastereoselectivere…     

Novel Method for the Synthesis of 6,12‐Dihydro‐2‐Methylindolo[2,3‐ b]Carbazol‐6‐Ones

A novel method for the synthesis of 6,12‐dihydro‐2‐methylindolo[2,3‐b]carbazol‐6‐ones was developed from 1‐oxo‐2,3,4,9‐tetrahydro‐1H‐carbazol‐1‐one through methyl 6‐methyl‐2‐(1‐oxo‐2,3,4,9‐tetrahydro‐1H‐carbazol‐2‐yl)oxoacetate in good yields. This method provides an alternative path for the synthesis of this product using 2‐hydroxy methylene‐2,3,4,9‐tetrahydro‐1H‐carbazol‐1‐one.     

Reconstructed Mass Spectra,A Novel Approach for the Utilization of Gas Chromatograph—Mass Spectrometer Data

Abstract

Peak profile analysis of each of the few hundred mass chromatograms generated during a complete GC-MS experiment identifies all m/e values which maximize at any of the few hundred consecutive mass spectra recorded during the gas chromatogram. The resulting sets of data correspond to the mass spectrum of each eluting component (even very minor ones) practically free of the contributions of unresolved companion substances, tailing fractions, column bleed, etc. These “reconstructed mass spectra” are therefore more easily interpreted or automatically identified than the mass spectra originally recorded. A plot of the summed abundance of the ions that maximize at a given spectrum index number (“mass resolved gas chromatogram”) results in a gas chromatogram of dramatically improved apparent resolution.     

Stereoselective Reactions of δ2-Isoxazoline Exo-azaenolates. A Model for Construction of the C-Ring of Sesbanimide A

A Stereoselective aldol reaction between bis(tert-butyldimethylsilyloxy) acetone and an isoxazoline-derived azaenolate is a key step in the construction of a C-ring model of sesbanimide A.     

L‐Proline–H2O2: A New Chemoselective Approach for Oxidation of Sulfides to Sulfoxides

A facile and selective oxidation of sulfides to sulfoxides using an L‐proline–H₂O₂ system for structurally divergent sulfide substrates with excellent yields at ambient conditions is reported.     

2‐Hydroxy‐1,2,3,6‐tetrahydro‐azulen‐6‐carboxylic Acid Ethyl Ester—A Novel Precursor for a New Class of Liquid Crystalline Materials

A novel approach for the syntheses of carbene adduct 4 is reported. A ring-enlargement strategy was employed for the synthesis of precursors 5 and 6 and established the mechanism of the formation of azulene derivative 6. Synthesis of target precursor 13, a novel precursor for the synthesis of new mesogenic materials, and its various halogenated derivatives (14–16) was carried out.     

In－situ Thin Layer Spectroelectrochemical Study of the Redox Mechanism add Intermediate for Vitamin B_2 in Aqueous Solution

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A Solid‐phase Spectrophotofluorimetry for the Determination of Trace Amount of Nitrite in Food Samples with Rhodamine B

Abstract

A simple and sensitive solid‐phase fluorescence quenching method for the determination of trace amounts of nitrite in food samples has been developed. The method is based on that rhodamine B (RhB) which is used as an emission reagent and is included by β‐cyclodextrin polymer(β‐CDP), reacts with nitrite in the presence of iodide to form a nonfluorescence compound in acidic medium. The fluorescence intensity of the RhB‐included β‐CDP was measured in solid phase with excitation and emission wavelengths of 353 and 592 nm, respectively. The fluorescence quenching degree is good linear with the concentration of nitrite over the ranges of 1.0–3.0 µg with a detection limit of 0.04 µg and RSD is 1.2%. The general coexisting ions do not interfere to the reaction of RhB with nitrite. The proposed method has been applied to the determination of trace amount of nitrite in food samples with the recoveries of 102.8% (ham) and 99.0% (sausage), respectively.     

A Novel Method for the Synthesis of 2(3H)‐Benzimidazolones, 2(3H)‐Benzoxazolone,and 2(3H)‐Benzothiazolone via In Situ Generated Ortho Substituted Benzoic Acid Azides: Application of Ammonium Azide and Vilsmeier Complex for Acid Azide Generation

Abstract

An easy and generalized route to 2(3H)‐benzimidazolones, 2(3H)‐benzoxazolone and 2(3H)‐benzothiazolone is attempted. A novel one‐pot method for the in situ generation and cyclisation of ortho substituted benzoic acid azides is reported via the application of ammonium azide and Vilsmeier complex.     

Unambiguous Assignment of the Stereochemistry at the Anomeric Carbon in Methyl‐α‐D‐C‐Aryl‐glucopyranoside Derivative: A Representative of Products from our New Strategy for 2‐Deoxy‐C‐aryl‐glucopyranosides

The X‐ray study firmly establishes the stereochemistry at the anomeric carbon in methyl‐α‐D‐C‐aryl‐glucopyranoside derivative.     

Novel Synthesis of (3R,4R)‐4‐Acetoxy‐3‐[1′(R)‐tert‐butyldimethylsilyloxyethyl] Azetidin‐2‐one: A Key Intermediate for Penem and Carbapenem Synthesis

Diastereoselective synthesis of (3R,4R)‐4‐acetoxy‐3‐[1′(R)‐tert‐butyldimethylsilyloxyethyl] azetidin‐2‐one (AOSA) using (‐)‐D‐2,10‐camphorsultam as a key and recyclable chiral auxiliary is described.     

A New Model for Correlating the Solubility of Solids in SupercriticalCo_2 and Study on Some Systems (I): The New Model

Manyresearchershavesuggestedthatthereexistsolvent-soluteclustersinsupercriticalfluid(SCF)-solutesystems.'-'TocorrelatethephaseequilibriaofSCF-solidbinarysystems,weproposeamodelwhichisbasedonthefoIlowingfactsandassumptions.l.TheSCFphaseconsistsofsolventmolecules,freesolutemolecuIes,andthesolvent-soluteclusterswithonesolutemoleculeandanumberofthesolventmolecules.2.Thenumberofthesolventmoleculesineachclusterisassumedtobeindependentofpressure.ThisassumptionisthesameasthatusedbyChrastillinhism…     

Reaction of Imidazo[1,2‐a]pyridines with Aliphatic Aldehydes: A Simple and Efficient Method for the Preparation of Novel C‐3 Vinylic Derivativesof Imidazo[1,2‐a]pyridines

A simple and efficient method for the preparation of novel C‐3 vinylic derivatives of imidazo[1,2‐a]pyridines has been developed by the reaction of imidazo [1,2‐a]pyridines with appropriate aliphatic aldehydes in acetic acid in a sealed tube.     

A Novel Method for the Synthesis of High Hindered Iminoesters by the Reaction of Decomposition of Phenyldiazoacetate in the Presence of Rh2(OAc)4 with Arylamines and DEAD

It is well known that iminoesters were condensed by ketoesters with amines, but the procedure to ketoesters require harsh reaction conditions and multi steps. Herein we report a mild and practical one-step approach for the synthesis of iminoesters, especially for the high steric hindered iminoesters. Decomposition of phenyl diazoacetate catalyzed by rhodium acetate with amines to give N-H insertion product has been reported.     

Novel Pyridazine Fused Heterocyclic System: A New Route for the Synthesis of 2‐Alkyl/Aryl[1,3,4]Thiadiazole[2′,3′:2,3] Imidazo[4,5‐d]Pyridazin‐8(7H)‐One

A series of novel imidazo[2,1‐b][1,3,4]thiadiazole fused pyridazinones have been synthesized in moderate yields by the reaction of 2‐alkyl/arylimidazo[2,1‐b] [1,3,4]thiadiazole‐6‐carbohydrazides under Vilsmeier–Haack reaction conditions. This simple methodology has utility for the synthesis of various fused heterocyclic systems.     

Oligodeoxynucleotides Containing Diastereomeric O2′,C3′‐linked Bicyclic Nucleotide Units for Functionalization of the Major Groove of Nucleic Acid Duplexes: A Summary and Novel Derivatives*

The synthesis and evaluation of a range of piperazino‐derivatized diastereomeric O2′,C3′‐linked bicyclic nucleotides are described. A new and optimized protocol is presented for the synthesis of the bicyclic scaffold on which the piperazino moiety is appended. At low salt concentration, the C2″‐S‐configured piperazino‐modified oligonucleotides display significantly enhanced hybridization affinity toward complementary DNA and RNA targets relative to the unmodified oligonucleotide control, whereas no melting transition is observed for hybrids formed with the C2″‐R‐configured piperazino‐modified oligonucleotides. Upon derivatization of the piperazino moiety with a 1‐pyrenebutanoyl group, all modified oligonucleotides display strong DNA binding and profound DNA hybridization selectivity.