Surface Tension of Binary Mixtures of 1-Alkyl-3-Methyl-Imidazolium Bis(trifluoromethylsulfonyl)imide Ionic Liquids with Alcohols

New experimental surface tension data have been provided at 283.15, 298.15, 313.15 K and atmospheric pressure for binary mixtures of 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide and 1-octyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ionic liquids with the alcohols: methanol, ethanol, 1-propanol, 2-propanol, l-butanol and 1-pentanol. The experimental results show that the surface tensions of these mixtures depend systematically on the alkyl chain length of the ionic liquid and alcohol, composition and temperature. Surface tension changes on mixing have been calculated and adequately fitted by the Redlich–Kister polynomial equation. The adjustable parameters and the standard deviations between experimental and calculated values are reported.     

Regioselective synthesis of 1- and 4-substituted 7-oxopyrazolo[1,5-a]pyrimidine-3-carboxamides

The synthesis of 7-substituted pyrazolo[1,5-a]pyrimidine-3-carboxamides was studied. First, methyl 7-hydroxypyrazolo[1,5-a]pyrimidine-3-carboxylate (5) was prepared in three steps from methyl 5-amino-1H-pyrazole-4-carboxylate (3). Treatment of 5 with POCl₃ gave the highly reactive 7-chloro derivative 10, which was reacted with amines, benzyl alcohol, and phenylboronic acid in the presence of Pd-catalyst to give the corresponding 7-substituted derivatives 11. Hydrolysis of the esters 5 and 11 followed by amidation gave the corresponding carboxamides 16a–h and 15. Regioselectivity of N-alkylation of 7-hydroxypyrazolo[1,5-a]pyrimidine-3-carboxylic acid derivatives 5 and 16 was tunable by the carboxy function. Alkylation of the secondary amides 16a–f furnished the 1-alkyl derivatives 17a–f, whereas the ester 5 and the tertiary amides 16g,h gave the 4-alkyl derivatives 14a–d and 16m,n, selectively.     

Zeolitic adsorption in course of pollutants mitigation and environmental control

The review focuses on the adsorption and selectivity properties of the inland natural zeolites clinoptilolite and mordenite towards a broad spectrum of environmental pollutants incl. radioactive and compare some of them partially to selected foreign samples. A series of elution experiments into a broad spectrum of individual isomolar metal solutions by means of NH₄ ⁺—exchanged clinoptilolite—and mordenite-rich tuffs was done to prove the affinity sequence of both minerals untill the steady-state approaching. Among the all recorded breakthrough profiles onto mordente-rich tuff the ammonium exchanged tuff yielded the best uptake performance towards Cs. Three various clinoptilolite-rich tuff samples (Hungarian, American and Slovakian) were compared to each other in order to evaluate the iodide removal in dynamic regime by using the Ag exchanged tuff.     

Headspace stir bar sorptive extraction followed by thermal desorption and gas chromatography with mass spectrometry to determine musk fragrances in sludge samples without sample pretreatment

A direct, simple and solvent‐free method based on headspace stir bar sorptive extraction and thermal desorption gas chromatography with mass spectroscopy was developed to determine 13 musk fragrances (six polycyclic musks, three nitro musks and four macrocyclic musks) in sludge without sample treatment. The optimal headspace stir bar sorptive extraction conditions were achieved when a polydimethylsiloxane stir bar was exposed for 45 min in the headspace of a 10 mL vial filled with 100 mg of sludge mixed with 0.2 mL of water stirred at 750 rpm at 80°C. The stir bar was then desorbed in the thermal desorption gas chromatography and mass spectrometry system, obtaining limits of detection between 5 and 30 ng/g. The method applicability was tested with sewage sludge from two urban wastewater treatment plants and from a potable water treatment plant. Results showed galaxolide and tonalide to be the most abundant musk fragrances found in wastewater treatment plants with maximal concentrations of 9240 and 7500 ng/g, respectively. Maximum concentration levels between 35 and 635 ng/g were found for musk ketone, musk moskene, traseolide, phantolide and celestolide in this kind of samples. Concentrations below the limits of quantitation of phantolide, galaxolide, tonalide and musk ketone were found in sludge from a potable water treatment plant.     

Carbohydrate analysis: From sample preparation to HPLC on different stationary phases coupled with evaporative light‐scattering detection

After 20 years of development, evaporative light‐scattering detection (ELSD) has become the mainstream choice for the detection of various classes of natural products. ELSD continues to grow in popularity as a “quasi‐universal” technique because of the specificity of the detection method, which is based on the scattering of laser light from nonvolatile analyte particles. It represents an attractive alternative compared to other types of detection, such as refractive index detection and/or ultraviolet detection. This review presents issues concerned with the separation of carbohydrates in plant materials by HPLC and ELSD, as well as the advantages and limitations relating to the ELSD method. Additionally, an overview of possible ELSD applications in the analysis of carbohydrates in natural products is presented.     

Assessing Alkali-Metal Effects in the Structures and Reactivity of Mixed-Ligand Alkyl/Alkoxide Alkali-Metal Magnesiates

Advancing the understanding of using alkali-metal alkoxides as additives to organomagnesium reagents in Mg−Br exchange reactions, a homologous series of mixed-ligand alkyl/alkoxide alkali-metal magnesiates [MMg(CH₂SiMe₃)₂(dmem)]₂ [dmem=2-{[2-(dimethylamino)ethyl]methylamino} ethoxide; M=Li, 1 ; Na, 2 ; (THF)K, 3 ] has been prepared. Structural and spectroscopic studies have established the constitutions of these heteroleptic/heterometallic species, which are retained in arene solution. Evaluation of their reactivity towards 2-bromoanisole has uncovered a marked alkali-metal effect with potassium magnesiate 3 being the most efficient of the three ate reagents. Studies probing the constitution of the exchange product from this reaction suggest that the putative [KMgAr₂(dmem)]₂ (Ar=o-OMe−C₆H₄) intermediate undergoes redistribution into its single metal components [KAr]_n and [MgAr(dmem)]₂ ( 5 ). This process can be circumvented by using a different potassium alkoxide containing an aliphatic chain such as KOR’ (R’=2-ethylhexyl) which undergoes co-complexation with Mg(CH₂SiMe₃) to give [KMg(CH₂SiMe₃)₂(OR’)]₂ ( 7 ). This ate, in turn, reacts quantitatively with 2-bromoanisole furnishing [KMgAr₂(OR’)]₂ ( 9 ) which is stable in solution as a bimetallic compound. Collectively this work highlights the complexity of these alkali-metal mediated Mg−Br exchange reactions, where each reaction component can have a profound effect not only on the success of the reaction; but also the stability of the final metalated intermediates prior to their electrophilic interception.     

Iron-modified zeolite BETA: efficient catalyst in methyllaurate, 2-hexyl-1,3-dioxolane, 4-methyl-2-propyltetrahydro-2H-pyran-4-ol and 4-methyl-2-phenyl-tetrahydro-2H-pyran-4-ol synthesis

Research on Chemical Intermediates - Several types of modified zeolite BETA38 with different iron loading were prepared. Prepared materials were characterized using different techniques (XRD, XRF,...