Extraction of water miscible organic dyes by reverse micelles of alkyl glucosides

The extraction of methyl orange or methylene blue from an aqueous phase to an organic phase of reverse micelles of alkyl glucosides was investigated. Dodecyl glucoside, a biodegradable and biocompatible surfactant, was employed as a kind of alkyl glucosides, since a stable Winsor II system consisting of the water-in-oil type microemulsion and aqueous phases was formed when an organic solution containing dodecyl glucoside was contacted with an aqueous solution. The water content in the reverse micellar organic phase increased with an increase in the concentration of dodecyl glucoside. The extraction ratio of dyes also increased with increasing the concentration of dodecyl glucoside. Furthermore, the extraction ratio of dyes was dramatically dependent upon the pH of an aqueous phase and temperature.     

(Polyfluoro)silane-mediated generation of azomethine ylides from imines and their cycloaddition leading to N-heterocycles

The novel generation and cycloaddition of azomethine ylides from an α-(trimethylsilyl)imine using (polyfluoro)silanes is described. The method was successfully applied to an efficient one-pot process. Namely, an azaallyl anion, generated by abstraction of the hydrogen α to an imino nitrogen, was treated with a di- or trifluorosilane to give an azomethine ylide intermediate below room temperature. The generated 1,3-dipole was smoothly trapped with dipolarophiles to afford nitrogen-containing five-membered heterocycles in good yields.     

Controlling the radiation degradation of carboxymethylcellulose solution

In this study, the effects of an irradiation on the viscosity of the carboxymethylcellulose (CMC) solution were investigated, and the methods to control the degradation of the CMC caused by an irradiation were developed. The viscosity of the CMC solution was decreased with an increase in the irradiation dose, but the extent of the degradation by an irradiation was found to decrease with an increase in the CMC concentration in the solution. The dependency of the irradiation sources showed that an electron beam radiation had degraded the CMC less severely than a gamma ray radiation. An addition of vitamin C as a radical scavenger to the solution was shown to be effective in preventing the decrease of the viscosity of the solution. Also, in the case of an irradiation at −70 °C, the decrease of its viscosity was efficiently inhibited. The degradation of CMC in the solution was confirmed by the molecular weight distribution.     

Microscopic observation and characterization of the oil bridge between dehulled-roasted sesame seeds

The formation of an oil bridge between adhesive seeds was observed microscopically. The geometry of the oil bridge was affected by the shape of the adhesive seeds. The capillary force of the oil bridge was estimated from the image captured by the microscope. The average capillary force was 127 μN, which was five times higher than the average gravity of the seeds. It was observed that several oil bridges formed between two seeds. These results indicated an adequate ability of the seeds to adhere. The capillary force of the oil bridge increased with surface oil content. The probability of formation of an oil bridge increased with surface oil content when the surface oil content was above 0.63%. The probability of formation of an oil bridge markedly increased when sucrose was added to the seeds.     

The mechanism for palladium catalyzed carbonylation of cinnamyl chloride

In the palladium catalyzed alkoxycarbonylation of cinnamyl chloride two mechanisms play a role. An associative mechanism was observed at low pressure, while an insertion mechanism was observed at high pressure or when an excess of ligand was used. Several putative intermediates of the catalytic alkoxycarbonylation have been synthesized and characterized, such as 5c of which an X-ray crystal structure was obtained.     

Chiral recognition of borneol by association with zinc(II) and l-tryptophan in the gas phase

Chiral recognition of the racemic borneol was obtained in the gas phase by using electrospray ionization time-of-flight mass spectrometry (ESI-TOFMS) and electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTMS). Both single stage MS and tandem MS were employed for investigating the chiral recognition depending strongly on the stereochemistry of the ligands in the zinc(II)-l-tryptophan-borneol multimeric cluster ions. It was found that the type of acid which was used for adjusting the pH of the mixed solution played an important role in the chiral recognition, which was obtained when acetic acid or propanoic acid was used as an additive. No chiral recognition was observed using hydrochloric acid or formic acid. Furthermore, the nozzle potential was an important parameter for optimizing the discrimination of chirality. In tandem MS, the difference in intensity between two diastereomeric complex ions showed chiral recognition behavior. Such a difference could be determined by two approaches. One was using the fragment ion as an internal standard, the other was a new approach of using the isotopic form of parent complex ion as an internal standard.     

Concise Construction of the ACDE Ring System of Calyciphylline A Type Alkaloids by a [5+2] Cycloaddition

A concise route for construction of the ACDE ring skeleton in calyciphylline A type alkaloids was developed using an intramolecular [5+2] cycloaddition reaction of an oxidopyrylium species bearing a tetrasubstituted olefin. Key to the success of this reaction was the combination of acid and base, which accelerated the construction of this skeleton containing a spiro ring and vicinal quaternary carbon centers. The resultant tricyclic ADE ring compound was converted to an ACDE ring model through C−H oxidation and an aza-Wittig reaction.     

Formal Synthesis of Sarain A: Intramolecular Cycloaddition of an Eight‐Membered Cyclic Nitrone to Construct the 2‐Azabicyclo[3.3.1]nonane Framework

An enantioselective route to the tetracyclic skeleton of sarain A has been developed. Asymmetric reduction of an ynone introduced a chiral center which was transferred to the contiguous tertiary stereogenic centers through an Ireland–Claisen rearrangement. The 2‐azabicyclo[3.3.1]nonane framework was constructed by an unprecedented intramolecular cycloaddition of an eight‐membered cyclic nitrone. Using the steric bias of the bicyclic system, the quaternary carbon atom was constructed by a stereoselective aldol reaction. Further ring formations were performed by ring‐closing metathesis for the 13‐membered ring and an iodoamidation reaction for the pyrrolidine ring. The present synthesis has successfully provided an alternative route to the late‐stage intermediate of Overman’s synthesis.     

Protrusion and deformation of an elastic particle at an advancing front interface

The response of an elastic particle to an extensional field close to an advancing liquid–gas interface in a capillary was examined both from an experimental and theoretical viewpoint. Experimental evidence is given on both the protrusion and deformation of an elastic particle at an advancing front interface. To interpret our experimental results, we followed and extended Hoffman's approach to the case of deformable particles. A hybrid approach was followed where the height of the bump was calculated theoretically as an equilibrium between capillary and drag forces for a given deformation of the particle, whereas the latter was supplied by an independent experimental measurement. For an elastic particle, the height of the bump goes through a maximum and further on decay almost linearly when plotted against the dimensionless parameter introduced by Hoffman. The difference between the theoretical prediction and the experimental data is discussed in relation to the asymmetry of the bump profiles observed in the experiment that could be responsible for a larger contribution of capillary forces from those calculated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1362–1374, 2003     

无色孔雀绿光氧化反应的途径

前一篇文章已说明,无色孔雀绿(LMG)经光氧化生成孔雀绿(MG⁺)染料是一个复杂的光化学过程。萘加入反应溶液猝灭了LMG的激发态,但却使反应速率升高。对这一实验结果我们曾推断为:可能是由于萘与LMG之间发生了电子转移作用。本文将对这一推断作进一步实验论证,并将说明在没有电子受体参加时,LMG的光氧化主要通过其激发三线态途径进行。已得到的实验结果证明,我们的上述推断是正确的,现予以报道。     

Microfabricated electroosmotic pump for capillary-based sequential injection analysis

A microfabricated electroosmotic pump with an integrated serpentine isolation channel was developed on a glass chip and applied to a capillary-based sequential injection analysis (SIA) system for an enzyme inhibition assay. The pump chip contains an anode reservoir, an ion-exchange membrane electric field decoupler (EFD) that also serves as a cathode reservoir, parallel pump channels and an isolation channel. A two-step etching process was adopted to etch the pump channels to a depth of 20 μm and the isolation channel to a depth of 90 μm. The pump flow rate was very stable: the relative standard deviation (RSD) of the pump rate was 1.9% for propulsion and 2.3% for aspiration. The pump chip was successfully applied to a capillary-based sequential injection analysis system with a confocal fluorescence detector. For repetitive analysis of a 13 μM fluorescein solution, an RSD of 0.6% was attained, which demonstrated the flow stability of the EOF pump. The system was then applied to an enzyme inhibition assay, the diethylenetriaminepentaacetic acid (DTPA) inhibition of the β-galactosidase-catalyzed hydrolysis of fluorescein di(β-d-galactopyranoside). Reproducible results (RSD<3.0%) were obtained.     

Search for Non-Protein Protease Inhibitors Constituted with an Indole and Acetylene Core

A possible inhibitor of proteases, which contains an indole core and an aromatic polar acetylene, was designed and synthesized. This indole derivative has a molecular architecture kindred to biologically relevant species and was obtained through five synthetic steps with an overall yield of 37% from the 2,2′-(phenylazanediyl)di(ethan-1-ol). The indole derivative was evaluated through docking assays using the main protease (SARS-CoV-2-M^pro) as a molecular target, which plays a key role in the replication process of this virus. Additionally, the indole derivative was evaluated as an inhibitor of the enzyme kallikrein 5 (KLK5), which is a serine protease that can be considered as an anticancer drug target.     

Compression induced chiral symmetry breaking of monolayers comprised of banana-shaped achiral molecules at an air-water interface: Williams-Bragg approach

Chirality of monolayers comprised of banana-shaped achiral molecules at an air-water interface was investigated theoretically, and a forming mechanism of chiral structure as an assembly of achiral molecules was argued. A model of such monolayers was constructed taking into account the short-range repulsive interaction between constituent banana-shaped achiral molecules, and the free energy density functional of the model was derived as a generalization of Williams-Bragg approach. It was predicted that chiral symmetry breaking occurs by monolayer compression, where two-dimensional characteristics of monolayers at an interface plays an important role in the formation of chiral structure by banana-shaped achiral molecules.     

羟基新戊醛的间接电氧化研究

在离子交换膜电解槽内,将电解溴离子生成的溴单质作为氧化剂,使羟基新戊醛变成羟基新戊酸.研究了反应温度、pH、反应物浓度及阳极电位对电流效率和选择性的影响.结果表明,槽内式间接电氧化法制取羟基新戊酸的电流效率和选择性都较高,电流效率可达91.4%.选择性一般在90%以上.     

Prevention of evaporation of small-volume sample solutions for capillary electrophoresis using a mineral-oil overlay.

The suppression of evaporation of water from small volumes of sample solutions or reagents for capillary electrophoresis by the use of a mineral-oil overlay was investigated in affinophoresis applications, in which the affinity constant of a mutant protein of recombinant human galectin-1 to a lactose affinophore, a triply negative charged ion having a lactoside as an affinity ligand, was determined. When an injection was carried out from a minimum of 20 microL of an aqueous solution beneath the oil overlay, no oil contamination inside the capillary was observed, provided the capillary was cleanly cut so that the end was flat, and the polyimide coating had been removed for a distance of about 2 mm from the end. Affinophoresis was carried out using 20 microL of an affinophore solution covered with an oil overlay. The abnormalities in the electropherograms as the result of the evaporation of the water from the solution during storage prior to use in an automatic operation of a capillary electrophoresis instrument were suppressed, with respect to the formation of a base line gap, an increase in the detection time of a marker ion and an increase in the initial current. A solution in a vial could be used repeatedly for a longer period of time when overlaid with mineral oil than in the absence of an overlay. The use of a mineral-oil overlay is a simple but very efficient technique for solving the problem of the evaporation of water from small volumes of aqueous solutions for use in capillary electrophoresis.     

KNaY-zeolite catalyzed dehydration of methyl lactate

A promising catalyst,KNaY was prepared by an ion exchange method with aqueous potassium chloride solution.Comparedwith NaY,KNaY was an effective catalyst for the dehydration of methyl lactate to methyl acrylate.Under the optimized conditions,an improved yield of 37.9 mol%was achieved.     

CdS量子点与曙红Y间的荧光共振能量转移研究

在水溶液中,量子点与有机荧光染料之间可能发生荧光共振能量转移(FRET)。本文以发射波长470nm的Cd S量子点为供体,曙红Y为受体,建立了Cd S量子点-曙红Y的FRET体系,研究了该体系的FRET参数。该体系受体供体数目比为8,猝灭效率为45.6%,增强效率为20.1%;供体-受体间的距离为4.4nm;临界能量转移距离为2.4nm。     

A facile synthesis of phytosphingosine from diisopropylidene-D-mannofuranose

In the present study, an efficient method with a high overall yield for preparing phytosphingosine and an analogue was developed. Starting with commercially available 2,3;5,6-di-O-isopropylidene-d-mannofuranose, a variety of lipid moieties were incorporated to obtain phytosphingosine and an analogue. Through an eight-step manipulation, phytosphingosine was obtained with an overall yield of 57%.     

Analysis of ephedrine in ephedra callus by acetonitrile modified capillary zone electrophoresis

A simple method has been developed for the quantitative determination of ephedrine in ephedra callus. The dependence of effective mobility of ephedrine on pH was investigated, and a simulated equation was obtained. The separation was performed in an uncoated capillary and detected at 185 nm. A new Tris–NaOH–H₃PO₄ run buffer was used and the pH was adjusted to 3.20. To increase the solubility of hydrophobic analytes and improve the separation efficiency, 15% acetonitrile was used in the buffer as a modifier. The content of ephedrine in an ephedra callus sample and an ephedra herba sample were determined with this method, and the result was satisfactory.     

Alkylation of α-methylnaphthalene with long-chain olefins catalyzed by rare earth lanthanum modified HY zeolite

Modified HY zeolites impregnated with an optimum amount of lanthanum was found to be an effective catalyst for the clean alkylation of α-methylnaphthalene with long-chain olefins. It was found that Brönsted acid was the main catalytically active center and that the reaction required an optimal concentration of acidic sites. The deactivated LaHY zeolite catalyst can be regenerated by temperature-programmed calcination.