Using EGA-GC to Analyze Nicotine N-oxide in Order to Explain Low Nicotine Concentrations in E-cigarette Liquids

Evolved-gas analysis coupled with gas chromatography (EGA-GC) was used to analyze e-cigarette liquids. Previous analyses of e-cigarette liquids have shown that the determined concentration of nicotine is lower than the advertised concentration. A possible explanation for this phenomenon is that the nicotine in the liquids is being oxidized to nicotine N-oxide by exposure to air and thus reducing the concentration of nicotine. This study focused on analyzing samples of thermally-rearranged nicotine N-oxide. Using EGA-GC, a calibration curve was generated for nicotine N-oxide concentration, which could potentially be used to explain reduced nicotine concentrations in e-cigarette liquids

Synthesis of Enantiopure Oxygen- and Nitrogen-Containing Heterocycles by Diastereoselective Ring-Closing Metathesis Reaction in Perhydro-1,3-benzoxazine Derivatives

Producción CientíficaDiastereoselective ring‐closing metathesis reactions on chiral trienic perhydro‐1,3‐benzoxazines derived from (−)‐8‐aminomenthol featuring two diastereotopic olefin chains is described. The diastereochemical outcome of the cyclization appeared to be dependent on the length and position of the olefin chains in perhydro‐1,3‐benzoxazine, the degree of substitution of the double bonds and the ruthenium catalyst used. After separation of the diastereomers, and removal of the chiral auxiliary, enantiopure oxygen‐ and nitrogen‐containing heterocycles were obtained.Ministerio de Economía, Industria y Competitividad (Project FEDER-CTQ2014-59870-P)Junta de Castilla y León (Ref. Project FEDER-VA115P17

Luminescent solar concentrators. 2: Experimental and theoretical analysis of their possible efficiencies

Experimental techniques are developed to determine the applicability of a particular luminescing center for use in a luminescent solar concentrator (LSC). The relevant steady-state characteristics of eighteen common organic laser dyes are given. The relative spectral homogeneity of such dyes are shown to depend upon the surrounding material using narrowband laser excitation. We developed three independent techniques for measuring self-absorption rates; these are time-resolved emission, steady-state polarization anisotropy, and spectral convolution. Preliminary dye degradation and prototype efficiency measurements are included. Finally, we give simple relationships relating the efficiency and gain of an LSC to key spectroscopic parameters of its constituents

Synthetic utility and reactivity of N-alkynylazoles

textThe chemistry of N-alkynylazoles is a newly emerging area of chemistry with particular interest in heterocycle synthesis. Synthetic preparations of this class of molecule have shown an increasing presence in literature, however, the synthetic utility of this class of molecule remains underexplored. Herein, it is shown that N-alkynlazoles are a versatile synthetic intermediate and may have utility as covalent modifiers of cysteine residues in polypeptides.Pharmaceutical Science

(4+2)-cycloaddition of nitroalkenes with ynamines; formation of a 4H-1,2-oxazine 2-oxide derivative

The formation of a thermally unstable (4+2)-cycloadduct, a 4H-1,2-oxazine 2-oxide derivative ( ), from the reaction of 1-nitrocyclopentene with 1-phenyl-2-(1-pyrrolidinyl)acetylene has been proven by the structure elucidation of isoxazole derivative which results from thermal rearrangement and by the structure determination of the 1,3-dipolar adducts of with electron-deficient acetylenes

Synthesis and characterization of novel 1,2-oxazine-based small molecules that targets acetylcholinesterase

Thirteen 2-oxazine-based small molecules were synthesized targeting 5-lipoxygenase (LOX), and acetylcholinesterase (AChE). The test revealed that the newly synthesized compounds had potent inhibition towards both 5-LOX and AChE in lower micro molar concentration. Among the tested compounds, the most active compound, 2-(2-acetyl-6,6-dimethyl-4-phenyl-5,6-dihydro-2H-1,2-oxazin-3- yl)methyl-1H-isoindole-1,3(2H)-dione (2a) showed inhibitory activity towards 5-LOX and AChE with an IC50 values of 1.88, and 2.5 μM, respectively. Further, the in silico molecular docking studies revealed that the compound 2a bound to the catalytic domain of AChE strongly with a highest CDOCKER score of -1.18 kcal/mol when compared to other compounds of the same series. Additionally, 2a showed a good lipophilicity (log P = 2.66), suggesting a potential ability to penetrate the blood-brain-barrier. These initial pharmacological data revealed that the compound 2a could serve as a drug-seed in developing anti-Alzheimer's agents. © 2014 Elsevier Ltd. All rights reserved

Enantioselective and Regiodivergent Copper-Catalyzed Electrophilic Arylation of Allylic Amides with Diaryliodonium Salts.

A catalytic enantioselective and regiodivergent arylation of alkenes is described. Chiral copper(II)bisoxazoline complexes catalyze the addition of diaryliodonium salts to allylic amides in excellent ee. Moreover, the arylation can be controlled by the electronic nature of the diaryliodonium salt enabling the preparation of nonracemic diaryloxazines or β,β'-diaryl enamides.We are grateful to EPSRC, GSK and the University of Cambridge (E.C., H.P.J.M. & M.T.) and the ERC and EPSRC for fellowships (M.J.G.). Mass spectrometry data were acquired at the EPSRC UK National Mass Spectrometry Facility at Swansea University.This is the final version of the article. It first appeared from ACS via http://dx.doi.org/10.1021/jacs.5b0393

Coloration of Polyester Fibers for Securities Protection from Counterfeit

В статье "Окраска полиэфирных волокон для защиты ценных бумаг от подделки" рассмотрены результаты модификации полиэфирных волокон с люминесцентными красителями с помощью механизма крейзинга

Shrinking droplets in electrospray ionization and their influence on chemical equilibria

We investigated how chemical equilibria are affected by the electrospray process, using simultaneous in situ measurements by laser-induced fluorescence (LIF) and phase Doppler anemometry (PDA). The motivation for this study was the increasing number of publications in which electrospray ionization mass spectrometry is used for binding constant determination. The PDA was used to monitor droplet size and velocity, whereas LIF was used to monitor fluorescent analytes within the electrospray droplets. Using acetonitrile as solvent, we found an average initial droplet diameter of 10 µm in the electrospray. The PDA allowed us to follow the evolution of these droplets down to a size of 1 µm. Rhodamine B-sulfonylchloride was used as a fluorescent analyte within the electrospray. By spatially resolved LIF it was possible to probe the dimerization equilibrium of this dye. Measurements at different spray positions showed no influence of the decreasing droplet size on the monomer-dimer equilibrium. However, with the fluorescent dye pair DCM and oxazine 1 it was shown that a concentration increase does occur within electrosprayed droplets, using fluorescence resonance energy transfer as a probe for the average pair distanc