Peroxides of higher aliphatic ethers

The oxidation of higher aliphatic ethers with oxygen at 50° yields two peroxides as the main oxidation products for each ether, namely a dihydroperoxy-dialkyl ether and a dihydroperoxy-dialkyl peroxide. The mass spectra of these compounds are recorded and the main fragmentation pattern is discussed.     

The Additive Influence of Propane-1,2-Diol on SDS Micellar Structure and Properties

Micellar systems are colloids with significant properties for pharmaceutical and food applications. They can be used to formulate thermodynamically stable mixtures to solubilize hydrophobic food-related substances. Furthermore, micellar formation is a complex process in which a variety of intermolecular interactions determine the course of formation and most important are the hydrophobic and hydrophilic interactions between surfactant–solvent and solvent–solvent. Glycols are organic compounds that belong to the group of alcohols. Among them, propane-1,2-diol (PG) is a substance commonly used as a food additive or ingredient in many cosmetic and hygiene products. The nature of the additive influences the micellar structure and properties of sodium dodecyl sulfate (SDS). When increasing the mass fraction of propane-1,2-diol in binary mixtures, the c.m.c. values decrease because propane-1,2-diol is a polar solvent, which gives it the ability to form hydrogen bonds, decreasing the cohesivity of water and reducing the dielectric constant of the aqueous phase. The values of ΔGm0 are negative in all mixed solvents according to the reduction in solvophobic interactions and increase in electrostatic interaction. With the rising concentration of cosolvent, the equilibrium between cosolvent in bulk solution and in the formed micelles is on the side of micelles, leading to the formation of micelles at a lower concentration with a small change in micellar size. According to the ¹H NMR, with the addition of propylene glycol, there is a slight shift of SDS peaks towards lower ppm regions in comparison to the D₂O peak. The shift is more evident with the increase in the amount of added propane-1,2-diol in comparison to the NMR spectra of pure SDS. Addition of propane-1,2-diol causes the upfield shift of the protons associated with hydrophilic groups, causing the shielding effect. This signifies that the alcohol is linked with the polar head groups of SDS due to its proximity to the SDS molecules.     

Novel approach to the synthesis of 3-acyl substituted indolizines. The synthesis of 3-(indolizinyl-2)alanine and 4-(indolizinyl-3) homoalanine derivatives

A novel approach to the synthesis of 3-acylindolizines and the transformations of some acids into tryptophane analogues are described. Reaction of ethyl 2-pyridinylacetate and methyl 2-quinolinylacetate with N-trifluoroacetyl-5-bromo-4-oxonorvaline methylester led to N-trifluoroacetyl-3-(1-ethoxycarbonylindolizinyl-2) alanine methyl ester and N-trifluoroacetyl-3-(3-methoxycarbonylpyrrolo [1,2-a]quinolinyl-2) alanine methyl ester, respectively. Treatment of ethyl 2-pyridinylacetate and 2-pyridinylacetonitrile, first with N,N-dimethylformamide dimethyl acetal (DMFDMA), followed by reaction with phenacyl bromide, gave the corresponding 3-benzoylindolizines, while the reaction of ethyl 2-pyridinylacetate and 2-pyridinylacetonitrile with DMFDMA, followed by treatment with (S)-N-trifluoroacetyl-5-bromo-4-oxonorvaline methyl ester, gave the corresponding N-trifluoroacetyl-4-oxo-4-(indolizinyl-3)homoalanine methyl esters.     

Twist-grain boundary phase induced by Au nanoparticles in a chiral liquid crystal host

We report on the stabilisation of the liquid-crystalline, twist-grain boundary A (TGB_A) phase in mixtures of a chiral liquid crystal and surface-functionalised spherical Au nanoparticles (NPs) of 10 nm diameter. The results, obtained by calorimetric, optical, small-angle X-ray and plasmon resonance measurements, demonstrate that a TGB_A phase, which is metastable for the pure liquid crystal host, can be effectively stabilised for a 3 K range in the presence of NPs. Moreover, the role of NPs size on the TGB_A stabilisation is briefly discussed.     

Evaluation of Bookkeeper mass deacidification based on historical book papers

Cellulose - Bookkeeper, the most widely used deacidification process based on MgO particles, was systematically evaluated on two sets of nonvaluable historical paper samples. Established analytical...     

Sustainable preparation of gold nanoparticles via green chemistry approach for biogenic applications

Novel premises of ‘Green Nanotechnology’ have tremendous impacts towards industrial scale revolution. The furtive extracted from natural precursors have driven to the generation of biogenic resources for the fabrication of cutting-edge nanomaterials in simple and cost-effective process. This inspection is an intension of the coupling hypothesis of Nanotechnology via ‘Green-Chemistry’ avenue. So, as to diminish the negative effects of technological applications in the health of human beings and the environment, society is focused towards a greener future. Nanoscience assures a promising future by its improvement in green chemistry to develop the 'Greenary Nanoscience and Nanotechnology'. The improvement and execution of chemical assisted processes in order to reduce the usage of harmful substances, the ‘Green Chemistry’ approach is one and only remarkable authentication, which attributed to long range surface area and higher pore volume of gold-nanoparticles. As of now, the efficient biogenic mechanism dramatically reduces the utilization and hazardous reagents have been employed to low-price natural and waste products to yield value-added nanomaterials with extensive relevance, suggesting an economical and green solution to environmental issues. In depth investigation of this critical review illustrates, novel biogenic screening platform was also conducted against antimicrobial strains and degradation of gold-nanoparticles products well explored-from selection precursors evolved from natural extracts, as well as eventually disintegration into bio-degradable yet potentially recyclable byproducts.     

2D separations on a 1D chip: gradient elution moving boundary electrophoresis-chiral capillary zone electrophoresis

A new method is described for two-dimensional (2D) separations using a microfluidic chip normally employed for single dimension electrophoresis. The method employs a combination of gradient elution moving boundary electrophoresis (GEMBE) and chiral capillary zone electrophoresis (CZE). The simplicity of the first dimension GEMBE method enables its implementation in the injection channel of a conventional electrophoresis chip, simplifying the design and operation of the device. The method was used for high resolution 2D chiral separations of a mixture of amino acids considered as possible signatures of extant or extinct life for solar system exploration. The enantiomers of aspartic acid, glutamic acid, serine, alanine, and valine were all resolved as well as glycine (achiral) and several unidentified impurities, giving an estimated peak capacity of 35 for the region between valine and glycine. The results highlight the need for high peak capacity separations for chiral amino acid analysis if accurate enantiomeric ratios are to be determined.     

Theoretical and experimental study of the nanoparticle-driven blue phase stabilisation

We have studied theoretically and experimentally the effects of various types of nanoparticles (NPs) on the temperature stability range [Formula: see text] T (BP) of liquid-crystalline (LC) blue phases. Using a mesoscopic Landau-de Gennes type approach we obtain that the defect core replacement (DCR) mechanism yields in the diluted regime [Formula: see text] T (BP)(x) [Formula: see text] 1/(1 - xb) , where x stands for the concentration of NPs and b is a constant. Our calculations suggest that the DCR mechanism is efficient if a local NP environment resembles the core structure of disclinations, which represent the characteristic property of BP structures. These predictions are in line with high-resolution ac calorimetry and optical polarising microscopy experiments using the CE8 LC and CdSe or aerosil NPs. In mixtures with CdSe NPs of 3.5nm diameter and hydrophobic coating the BPIII stability range has been extended up to 20K. On the contrary, the effect of aerosil silica nanoparticles of 7.0nm diameter and hydrophilic coating is very weak.     

Study of the Chlorination of Avobenzone in Sea Water by Gas Chromatography–High Resolution Mass Spectrometry

Disinfection is an important step in the purification of drinking and swimming pool water. The most common procedure includes chlorination, which efficiently eliminates microorganisms. However, the reaction of active chlorine with dissolved organic matter produces numerous organochlorine compounds posing a hazard to the environment and human health. UV filters belong to emerging contaminants, as their application to skin protection from UV irradiation becomes increasingly popular all over the world. Certain components of UV filters were detected in swimming pools and result in the emergence of new ecotoxicants. In the present study, 40 compounds, including numerous brominated derivatives, which result from the chlorination of avobenzone in sea water, were identified by gas chromatography–high resolution mass spectrometry. In addition, the applicability of photocatalysis to the destruction of chlorination products was studied. The procedure was found to be rather efficient and allows a decrease in the total amount of avobenzone transformation products by a factor of 10. The only compound class demonstrating stability under the applied conditions is exemplified by halogenated acetophenone derivatives.