Fluorescence switch-on sensor for Cu2+ by an amide linked lower rim 1,3-bis(2-picolyl)amine derivative of calix[4]arene in aqueous methanol

In recent years, numerous researchers have focused on the development of catalytic methods for processing of biomass-derived sugars into alkyl lactates, which are widely used as non-toxic solvents and are the starting material for obtaining monomeric lactide. In this work, the transformation of fructose into methyl lactate on Sn-containing catalyst in the flow reactor that may be of practical interest was studied. The supported Sn-containing catalyst was ob-tained by a simple impregnation method of granular γ-Al2O3. The catalytic ex-periments were performed in a flow reactor at temperatures of 160-190 °C and pressure of 3.0 MPa. The 1.6-9.5 wt.% fructose solutions in 80% aqueous methanol were used as a reaction mixture. It was found that addition to a reac-tion mixture of 0.03 wt.% potassium carbonate leads to the increase in selec-tivity towards methyl lactate on 15% at 100% conversion of fructose. Prod-ucts of the target reaction С6Н12О6 + 2СН3ОН = 2С4Н8О3 + 2Н2О were ana-lyzed using 13C NMR method. The following process conditions for obtaining of 65 mol% methyl lactate yield at 100% fructose conversion were found: use of 4.8 wt.% fructose solution in 80% methanol, 180 °С, 3.0 МПа and a load on catalyst 1.5 mmol C6H12O6/mlcat/h at contact time of 11 minutes. The cata-lyst productivity is 2.0 mmol C4H8O3/mlcat/h and the by-productі are 1,3-dihydroxyacetone dimethyl acetal (20%) and 5-hydroxymethylfurfural (10%). It should be noted that a racemic mixture of L- and D-methyl lactates has been obtained by conversion of D-fructose on the SnO2/Al2O3 catalyst. The SnO2/Al2O3 catalyst was found to be stable for 6 h while maintaining full fruc-tose conversion at 55–70% methyl lactate selectivity. After regeneration the catalyst completely restores the initial activity.

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Analysis of Brassinosteroids in Soybean Seeds and Leaves by Liquid Chromatography-Tandem Mass Spectrometry

The Open Plant Science Journal ◽

10.2174/1874294701710010100 ◽

2017 ◽

Vol 10 (1) ◽

pp. 100-109

Author(s):

Hongxia Li ◽

Natasha Trzaskalski ◽

R.J. Neil Emery

Keyword(s):

Mass Spectrometry ◽

Liquid Chromatography ◽

Tandem Mass Spectrometry ◽

High Performance ◽

Soybean Seeds ◽

Tandem Mass ◽

Electrospray Tandem Mass Spectrometry ◽

Aqueous Methanol ◽

Chromatography Tandem Mass Spectrometry ◽

Liquid Chromatography Tandem Mass

Objective:A simple and fast high performance liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS/MS) method has been developed for the analysis of brassinosteroids (BRs) in plants without derivatization.Materials:The BRs (including castasterone, 24-epicastasterone, brassinolide and 24-epibrassinolide) have been extracted with ice cold 80% aqueous methanol solution.Method:Five different purification strategies have been tested for the purification and enrichment of BRs.Conclusion:This analytical method was sensitive, reliable, rapid and applicable to trace analysis in complex plant samples.

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Solubility and Thermodynamic Transfer Functions of Cesium Dianilinetetraisothiocyanatochromate(III)

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19980293 ◽

1998 ◽

Vol 63 (3) ◽

pp. 293-298

Author(s):

Vladislav Holba

Keyword(s):

Experimental Data ◽

Isopropyl Alcohol ◽

Transfer Functions ◽

Butyl Alcohol ◽

Aqueous Methanol ◽

Gibbs Energies ◽

Gibbs Energy Of Transfer ◽

Energy Of Transfer ◽

The Given ◽

Reference Electrolyte

The solubilities of cesium dianilinetetraisothiocyanatochromate(III) in water as well as in aqueous methanol, isopropyl alcohol, tert-butyl alcohol and acetonitrile were measured as a function of temperature and solvent composition. The Gibbs energies, enthalpies and entropies of transfer of the salt from water to the given solvents have been evaluated from experimental data. The contribution of [Cr(C6H5NH2)2(NCS)4]- ion to the Gibbs energy of transfer of the investigated salt has been calculated using the tetraphenylarsonium tetraphenylborate (TATB) reference electrolyte assumption.

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Kinetics and Mechanism of Decomposition of 1,3-Bis(4-methylphenyl)triazene Catalyzed with Substituted Benzoic Acids in 25% Aqueous Methanol-General or Specific Catalysis?

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19942029 ◽

1994 ◽

Vol 59 (9) ◽

pp. 2029-2041

Author(s):

Oldřich Pytela ◽

Taťjana Nevěčná

Keyword(s):

Benzoic Acids ◽

Hammett Equation ◽

Aqueous Methanol ◽

Mechanism Of Decomposition ◽

Kinetics Of Decomposition ◽

Independent Variable ◽

Amino Derivatives ◽

Substituted Benzoic Acids ◽

The Individual ◽

Kinetics Of

The kinetics of decomposition of 1,3-bis(4-methylphenyl)triazene catalyzed with 13 substituted benzoic acids of various concentrations have been measured in 25 vol.% aqueous methanol at 25.0 °C. The rate constants observed (297 data) have be used as values of independent variable in a series of models of the catalyzed decomposition. For the catalytic particles were considered the undissociated acid, its conjugated base, and the proton in both the specific and general catalyses. Some models presumed formation of reactive or nonreactive complexes of the individual reactants. The substituent effect is described by the Hammett equation. The statistically best model in which the observed rate constant is a superposition of a term describing the dependence on proton concentration and a term describing the dependence on the product of concentrations of proton and conjugated base is valid with the presumption of complete proton transfer from the catalyst acid to substrate, which has been proved. The behaviour of 4-dimethylamino, 4-amino, and 3-amino derivatives is anomalous (lower catalytic activity as compared with benzoic acid). This supports the presumed participation of conjugated base in the title process.

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Transfer Thermodynamic Functions ∆Gt0, ∆Ht0 and T∆St0 of cis- and trans-[CoCl2(en)2]+ Isomers in Aqueous Mixtures of Methanol, tert-Butyl Alcohol and Acetonitrile

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20001455 ◽

2000 ◽

Vol 65 (9) ◽

pp. 1455-1463

Author(s):

Oľga Vollárová ◽

Ján Benko

Keyword(s):

Enthalpy Of Solution ◽

Transfer Functions ◽

Partial Molar Volumes ◽

Butyl Alcohol ◽

Aqueous Mixtures ◽

Aqueous Methanol ◽

Solvent Interactions ◽

Tert Butyl Alcohol ◽

Surface Charge Distribution ◽

Cis And Trans

The solubility, partial molar volume and standard integral molar enthalpy of solution of cis- and trans-[CoCl2(en)2]Cl in water, aqueous methanol, aqueous tert-butyl alcohol and aqueous acetonitrile are reported. The transfer functions ∆Gt0, ∆Ht0 and T∆St0 as well as partial molar volumes are used to obtain information on the solute-solvent interactions. Results obtained are discussed in terms of differences in the surface charge distribution in isomeric coordination species.

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Synthesis of N4-Substituted Derivatives of 1-[2-(Phosphonomethoxy)ethyl]cytosine and Its Diisopropyl Ester as a Model Reaction for the Synthesis of N4-Substituted Derivatives of Cidofovir

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20052066 ◽

2005 ◽

Vol 70 (12) ◽

pp. 2066-2074 ◽

Cited By ~ 3

Author(s):

Šárka Chalupová ◽

Antonín Holý ◽

Milena Masojídková

Keyword(s):

Secondary Amine ◽

Model Reaction ◽

Aqueous Methanol ◽

Derivatives Of ◽

Amine Salts

We have studied the reaction of 1-[2-(phosphonomethoxy)ethyl]cytosine (1) and its diisopropyl ester (2) with triethylammonium hydrogensulfite in 60% aqueous methanol. In the presence of some primary or secondary amine salts, at 25-70 °C, this reaction affords transaminated derivatives 4a-4e and 5a, 5b as main products accompanied by uracil compounds. However, with certain amines the reaction failed.

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Hybrid nanoparticle based fluorescence switch for recognition of ketoprofen in aqueous media

Molecular Systems Design & Engineering ◽

10.1039/d0me00065e ◽

2020 ◽

Vol 5 (8) ◽

pp. 1428-1436

Author(s):

Anu Saini ◽

Manpreet Kaur ◽

Mayank ◽

Anil Kuwar ◽

Navneet Kaur ◽

...

Keyword(s):

Aqueous Media ◽

Fluorescent Chemosensors ◽

Fluorescence Switch ◽

Nanomolar Detection ◽

Hybrid Nanoparticle

Hybrid nanoassembly, fluorescent chemosensors, selective response to ketoprofen, and nanomolar detection.

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Clitorienolactones and Isoflavonoids of Clitorea ternatea Roots Alleviate Stress-Like Symptoms in a Reserpine-Induced Zebrafish Model

Molecules ◽

10.3390/molecules26144137 ◽

2021 ◽

Vol 26 (14) ◽

pp. 4137

Author(s):

Muhammad Afiq Ngadni ◽

Muhammad Tayyab Akhtar ◽

Intan Safinar Ismail ◽

Anis Irfan Norazhar ◽

Soo Yee Lee ◽

...

Keyword(s):

Mental Illnesses ◽

Array Detector ◽

Diode Array ◽

Root Extract ◽

Diode Array Detector ◽

Aqueous Methanol ◽

Zebrafish Model ◽

Metabolite Profiles ◽

Ultrahigh Performance Liquid Chromatography ◽

As Stress

Clitorea ternatea has been used in Ayurvedic medicine as a brain stimulant to treat mental illnesses and mental functional disorders. In this study, the metabolite profiles of crude C. ternatea root extract (CTRE), ethyl acetate (EA), and 50% aqueous methanol (50% MeOH) fractions were investigated using ultrahigh-performance liquid chromatography–diode array detector–tandem mass spectrometry (UHPLC–DAD–MS/MS), while their effect on the stress-like behavior of zebrafish, pharmacologically induced with reserpine, was investigated. A total of 32 compounds were putatively identified, among which, a series of norneolignans, clitorienolactones, and various flavonoids (flavone, flavonol, isoflavone, and isoflavanone) was found to comprise the major constituents, particularly in the EA and 50% MeOH fractions. The clitorienolactones, presently unique to the species, were present in both the free and glycosylated forms in the roots. Both the EA and 50% MeOH fractions displayed moderate effects on the stress-induced zebrafish model, significantly decreasing freezing duration and elevating the total distance travelled and average velocity, 72 h post-treatment. The results of the present study provide further evidence that the basis for the use of C. ternatea roots in traditional medicine to alleviate brain-related conditions, such as stress and depression, is attributable to the presence of clitorienolactones and the isoflavonoidal constituents.

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Optimising the DPPH Assay for Cell-Free Marine Microorganism Supernatants

Marine Drugs ◽

10.3390/md19050256 ◽

2021 ◽

Vol 19 (5) ◽

pp. 256

Author(s):

Yehui Gang ◽

Tae-Yang Eom ◽

Svini Dileepa Marasinghe ◽

Youngdeuk Lee ◽

Eunyoung Jo ◽

...

Keyword(s):

Water Content ◽

Antioxidant Activities ◽

Fermented Foods ◽

Solution Stability ◽

Marine Microorganism ◽

Marine Microorganisms ◽

Dpph Assay ◽

Aqueous Methanol ◽

Potential Applications ◽

Pseudoalteromonas Rubra

Antioxidants prevent ageing and are usually quantified and screened using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. However, this assay cannot be used for salt-containing samples, such as the cell-free supernatants of marine microorganisms that are aggregated under these conditions. Herein, the DPPH solvent (methanol or ethanol) and its water content were optimized to enable the analysis of salt-containing samples, aggregation was observed for alcohol contents of >70%. The water content of methanol influenced the activities of standard antioxidants but did not significantly affect that of the samples. Based on solution stability considerations, 70% aqueous methanol was chosen as the optimal DPPH solvent. The developed method was successfully applied to the cell-free supernatants of marine bacteria (Pseudoalteromonas rubra and Pseudoalteromonas xiamenensis), revealing their high antioxidant activities. Furthermore, it was concluded that this method would be useful for the screening of marine microorganism–derived antioxidants, which also has numerous potential applications, such as salt-fermented foods.

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Polarography of o‐Mercaptobenzoic Acid in Aqueous Methanol and Dioxane

Journal of The Electrochemical Society ◽

10.1149/1.2123798 ◽

1982 ◽

Vol 129 (1) ◽

pp. 90-94 ◽

Cited By ~ 4

Author(s):

K. C. Gupta ◽

Tejinder Kaur

Keyword(s):

Aqueous Methanol

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