An insight into copper catalyzed allylation of alkyl zinc halides. Comparison of reactivity profiles for catalytic and stoichiometric alkylzinc-copper reagents

The γ-selective allylation of catalytic and stoichiometric alkylzinc-cuprates have been kinetically studied. The reactivity profiles generated by allylation reactions of n-butylzinc chloride catalyzed by CuX compounds (X = I, Br, Cl, CN, SCN) and also catalyzed by n-butylzinc-copper reagents and di n-butylzinc-copper reagents were evaluated. Reactivity profiles for allylation of stoichiometric n-butylzinc-copper reagents and di n-butylzinc-copper reagents were also prepared. All CuX compounds have been screened for the preparation of Grignard reagent derived n-butylzinc-copper reagents and di n-butylzinc-copper reagents.The evaluation of the profiles indicates that the active catalyst might be RCu(X)ZnCl and also to some degree, R₂CuZnCl · ZnClX, which both could favor formation of γ-product. All data supports the reductive elimination of σ-allyl Cu (III) complex formed at vinylic terminal to give γ-allylated product with a quite slow isomerization to σ-allyl Cu (III) complex formed at allylic terminal to give α-allylated product. In the allylation mechanism of zinc cuprates, the role of counter ion, ZnCl⁺ has been discussed.     

Non-destructive method for determination of hydroxyl value of soybean polyol by LS-SVM using HATR/FT-IR

This paper presents the use of least-squares support vector machine (LS-SVM) for quantitative determination of hydroxyl value (OHV) of hydroxylated soybean oils by horizontal attenuated total reflection Fourier transform infrared (HATR/FT-IR) spectroscopy. A least-squares support vector machine (LS-SVM) calibration model for the prediction of hydroxyl value (OHV) was developed using the range 1805.1-649.9 cm(-1). Validation of the method was carried out by comparing the OHV of a series of hydroxylated soybean oil predicted by the LS-SVM model to the values obtained by the AOCS standard method. A correlation coefficient equal to 0.989 and RMSEP = 4.96 mg of KOH/g was obtained. This study demonstrates a better prediction ability of the LS-SVM technique to determine OHV in hydroxylated soybean oil samples by HATR/FT-IR spectra.     

Infrared spectroscopy of racemic and enantiomeric forms of atenolol

The molecular structure of conformational isomorphs given by X-ray diffraction for racemic and enantiomeric atenolol were optimized at the HF/6-31G* level of theory and the infrared spectra of the structure were calculated. These spectra are used to characterize the differences between the various atenolol conformers. The spectra of the (R,S)- and S-atenolol solid forms were recorded and the bands corresponding to the functional groups identified with the aid of the calculated spectra, fitting analysis, temperature effect and H/D isotopic exchange. Particular attention was paid to the stretch vibration modes of the functional groups present in the atenolol.     

Chemo‐ and Regioselective Palladium‐Catalyzed Oxycyclization Reactions of Allendiols: Preparation of Five‐, Six‐, and Eight‐Membered Cycles

Positive discrimination : Chemo‐ and regioselective palladium‐catalyzed cycloetherification of allendiols, namely β,γ‐ and γ,δ‐allendiols, may occur by judicious choice of palladium‐catalyzed conditions owing to their potential ability to discriminate between both nucleophilic sites (see scheme).

     

Exploratory analysis of human urine by LC–ESI-TOF MS after high intake of olive oil: understanding the metabolism of polyphenols

Olive oil polyphenols have important biological properties which closely depend on their bioavailability; it is, therefore, essential to understand how polyphenols are absorbed, metabolized, and eliminated from the body. An analytical method based on rapid-resolution liquid chromatography (RRLC) coupled with mass spectrometric detection with a time-of-flight analyzer (RRLC–ESI-TOF MS) has been developed for analysis of the main olive oil phenolic compounds and their metabolites in human urine. Urine samples from ten healthy volunteers were collected before and 2, 4, and 6 h after intake of 50 mL extra-virgin olive oil. The proposed method includes liquid–liquid extraction with ethyl acetate, which provides extraction recoveries of the phenolic compounds studied between 35 and 75% from spiked urine samples. Good repeatability was obtained—the relative standard deviations (RSDs) of peak areas in intra-day and inter-day studies were 4.3 and 6.5%, respectively. Statistical studies enabled us to discriminate between urine samples before and after intake, and facilitated the search for m/z values enabling this discrimination. Based on the very accurate mass information and the isotopic pattern provided by the TOF MS analyzer, together with other available information, ten of these biomarkers and more than 50 metabolites, obtained through phase I and phase II biotransformation reactions, were tentatively identified. Additionally, kinetic studies were conducted on the metabolites identified as possible biomarkers; for most of the compounds concentrations were maximum in the first two hours.     

Measuring Submicron-Sized Fractionated Particulate Matter on Aluminum Impactor Disks

Sub-micron sized airborne particulate matter (PM) is not collected well on regular quartz or glass fiber filter papers. We used a micro-orifice uniform deposit impactor (MOUDI) to fractionate PM into six size fractions and deposit it on specially designed high purity thin aluminum disks. The MOUDI separated PM into fractions 56-100 nm, 100-180 nm, 180-320 nm, 320-560 nm, 560-1000 nm, and 1000-1800 nm. Since the MOUDI has a low flow rate (30 L/min), it takes several days to collect sufficient carbon on 47 mm foil disks. The small carbon mass (20-200 microgram C) and large aluminum substrate (~25 mg Al) present several challenges to production of graphite targets for accelerator mass spectrometry (AMS) analysis. The Al foil consumes large amounts of oxygen as it is heated and tends to melt into quartz combustion tubes, causing gas leaks. We describe sample processing techniques to reliably produce graphitic targets for (14)C-AMS analysis of PM deposited on Al impact foils.     

Synthesis, characterization and aggregation behaviour of novel peripherally tetra-substituted octacationic water soluble metal-free and metallophthalocyanines

In this study, a new phthalonitrile derivative 3 bearing 1,3-bis[3(dimethylamino)phenoxy]propan-2-ol 1, metal-free phthalocyanine (Pc) 4, metallophthalocyanines (MPcs) 5–7 and their quaternized derivatives 4a–7a were synthesized. Metal-free Pc 4 was prepared by cyclotetramerization of phthalonitrile derivate 3 and MPcs 5–7 were synthesized by heating 3 with NiCl₂, CoCl₂ and CuCl₂ in n-pentanol in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, respectively. Quaternization of the dimethylamino functionality produced quaternized octacationic water soluble metal-free, Ni, Co and Cu Pcs which were soluble in water, DMF, DMSO. The aggregation behaviour of these compounds were investigated in different concentrations of chloroform for metal-free, Ni, Co and Cu Pcs. The effect of solvents on absorption spectra were studied in various organic solvents. The novel compounds were characterized using IR, ¹H-, ¹³C NMR, UV–vis and MS spectral data.     

Thickness and refractive index of DPPC and DPPE monolayers by multiple-beam interferometry

The thickness and refractive index of 1,2-dipalmitoyl-sn-glycero-3-phosphatidyl choline (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) monolayers Langmuir--Blodgett (LB) deposited on mica were measured in dry air and bulk water using multiple-beam interferometry (MBI). Measurements of thickness using atomic force microscopy (AFM) of identical monolayers, and X-ray reflectivity (XRR) of the monolayers on quartz were taken for comparison. The measurement of the properties of solid-supported monolayers in dry air allows lipid optical properties to be determined free from solvent effects. The thickness and refractive index measured by MBI were 25.5?±?0.6 Å and 1.485?±?0.007 for DPPE monolayers, and 23.9?±?0.5 Å and 1.478?±?0.006 for DPPC monolayers in dry air. These thicknesses are consistent with the other techniques used in this work as well as other measurements in the literature. The refractive indices of solid-supported lipid monolayers have not been previously measured. The values are higher than previous measurements on black lipid films done by reflectometry, which is attributed to increased lipid packing density and the absence of hydrocarbon solvents. Applying water to the monolayers had no measurable effect on their properties, indicating that any change in hydration was below detection.

Dual Amperometric Immunosensor for Improving Cancer Metastasis Detection by the Simultaneous Determination of Extracellular and Soluble Circulating Fraction of Emerging Metastatic Biomarkers

This paper reports the development of a dual immunosensor using magnetic microcarriers (MBs) and amperometric transduction at dual screen‐printed carbon electrodes (SPdCEs) for the simultaneous determination of two biomarkers: interleukin‐13 receptor α2 (IL‐13Rα2) and E‐cadherin (E‐CDH), with both extracellular and soluble fraction; oncogenic and tumor suppressor markers, respectively, of great relevance in metastatic processes. The implemented methodology involved the formation of sandwich‐type immunocomplexes using specific capture antibodies immobilized onto carboxylic acid magnetic microbeads (HOOC‐MBs), and biotinylated detector antibodies labeled with streptavidin?horseradish peroxidase conjugates (Strep‐HRP). The amperometric detection was performed by addition of hydrogen peroxide in the presence of hydroquinone (HQ) as the redox mediator. The dual immunosensing platform provided linear calibration ranges suitable for the determination of both biomarkers in liquid and solid clinical specimens as well as excellent selectivity against other cancer biomarkers. This simple handling dual bioplatform was applied to the determination of the soluble and extracellular fraction of the target biomarkers in serum and paraffined‐embedded tissues from colorectal cancer (CRC) patients diagnosed at different tumor grade. The obtained results reveal great potential of this configuration to improve the reliability in diagnosing metastatic CRC.