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Abstract The deposition of chemical reagent inks on paper is a crucial step in the development and fabrication of microfluidic paper-based analytical devices (μPADs). A pen-plotting approach, delivering chemical ink deposition using technical pens filled with reagents and inserted into a desktop electronic plotter, is shown herein to be a versatile, low-cost, simple, rapid, reproducible, and high-throughput solution. The volume of the deposited ink was quantified gravimetrically, confirming that nanoliter volumes of reagents can be deposited reproducibly (e.g. 7.55 ± 0.37 nL/mm for a plotting speed of 10 cm/s) in detection zones of μPADs, typically spatially defined using wax printing. This approach was further investigated with regard to deposition of reagents in different geometrical forms (circular and linear), so demonstrating its applicability for preparation of μPADs with flexible design and application. By adjusting the plotting speed for linear deposition, lines with a relatively large range of widths (≈628–1192 μm) were created. Circular deposition was also demonstrated via delivery of reagents within wax printed circular fluidic barriers of a range of diameters (inner diameter = 1.5–7 mm). These capabilities were practically demonstrated via the fabrication of μPADs, based upon differing detection principles for determination of aluminum in natural waters using Morin as the fluorescent reagent. Traditional μPADs based on digital image colorimetry (DIC) were produced using circular deposition, whilst distance-based μPADs exploited linear deposition. Both types of μPADs developed using this method showed excellent precision for determination of trace concentrations of aluminium (average RSDs = 3.38% and 6.45%, and LODs = 0.5 ng (0.25 ppm) and 2 ng (0.5 ppm), for traditional and distance-based detection, respectively). Graphical abstract Image 1 Highlights • A pen-plotting technique is characterized for chemical ink deposition on μPADs. • A gravimetric approach is introduced to measure the deposition volume. • Deposition is studied for different geometrical forms (circular and linear). • The effect of plotting parameters on deposition is investigated. • The approach is demonstrated by a fluorescence-based determination of Al in waters. [ABSTRACT FROM AUTHOR]

Background: Pigment Red 53 is a dangerous synthetic dye that is often added to cosmetics, even though its use in cosmetic products has been prohibited because of possible impacts on health. Faster and more sensitive detection of Pigment Red 53 is needed for onsite analysis to protect the community from illegal cosmetics that contain the dye. Indicator color charts are a kind of analytical method that can be used to detect Pigment Red 53 in cosmetic products, including lipstick, rouge, and eyeshadow. Such charts are practical, fast, and can be used for onsite analysis. Methods: In this study, an indicator for Pigment Red 53 detection was obtained through a reagent reaction that caused a specific color change. An indicator color chart was then produced by setting out in paper form the series of colors which resulted from the reaction of specific chemical reagents and Pigment Red 53 solutions at concentrations of 10, 20, 40, 60, 80, and 100 ppm. Results: The testing results showed that the indicator color chart may be used as an initial screening method for the detection of Pigment Red 53 in cosmetic products with a detectable minimum concentration of 10 ppm. Out of nine samples, only one (Eyeshadow 3) tested positive for Pigment Red 53. Further analysis was carried out on the indicator color chart and the results showed good agreement with TLC and UV–Vis spectrophotometry methods. Conclusion: The results reported in this paper demonstrate that the indicator color chart is a good prospective method for onsite analysis to detect Pigment Red 53 in cosmetic samples, with a lower detection limit compared to polymer‐based indicators. [ABSTRACT FROM AUTHOR]

Paper spray ionization can be used to study organic reactions in solution under ambient conditions by utilizing the rate acceleration that occurs in reactions in small volumes of solution. In this novel approach to performing reactions, reagents are transferred onto a triangular paper surface by drop-casting and charged droplets of the reaction product mixture are released by field evaporation and examined online by mass spectrometry. The increase in the rate of product formation is attributed to solvent evaporation, which increases reagent concentrations, changes the pH, and enhances intermolecular interactions. As a proof of principle, the Katritzky reaction between a pyrylium salt and mono- or diamines, including substituted anilines, was investigated. The influence of electronic and steric effects was evaluated straightforwardly. The carbon chain length of α,ω-diamines was found to control the formation of mono- versus disubstituted products, thus reflecting the strong destabilizing coulombic effects in the shorter carbon-chain systems. Information on the mechanism was provided by the observation of 2 H-pyran intermediates and mixed pyridinium-2 H-pyran ions. The rates of product formation in the base-assisted Katritzky reaction increase linearly from 0.1 to 10 equivalents of triethylamine. The reactive paper spray technique, owing to its speed and information content, has potential pedagogical value and provides a tool to explore organic reactions and correlate experimental results with current mechanistic understanding. [ABSTRACT FROM AUTHOR]

Samarium metal and samarium diiodide have become important tools as selective cyclopropanating agents in organic synthesis due to their high chemo- and stereoselectivity. Therefore, Sm and SmI2are the ideal reagents to prepare cyclopropane derivatives. This tutorial reviewhighlights C–C multiple bond cyclopropanation processes promoted by samarium or samarium diiodide. [ABSTRACT FROM AUTHOR]

Lawsone (2-hydroxy-1,4-naphthoquinone) reacts with latent fingermark deposits on paper surfaces to yield purple-brown impressions of ridge details which are also photoluminescent; this compound represents the first in a completely new class of fingermark detection reagents. [ABSTRACT FROM AUTHOR]

A statistical approach to evaluating the limit of detection ( cmin) was used for studying 12 test systems with visual indication based on reagent indicator paper, polyurethane foam, gelatin films, powdered methylsilicic acid, and reagent solutions. It was proposed to characterize the quality of test systems by relative width of the region of an unreliable response. The dependence of the characteristics of test systems on the material of the support, the type of analytical reaction, the conditions of color observation in the test system, and the number of observations were discussed. [ABSTRACT FROM AUTHOR]

A protocol for the reductive alkylation of unprotected aminocyclitols with supported reagents and scavengers is described. The method is operatively simple and provides the corresponding secondary amines in high yields and purities. [ABSTRACT FROM AUTHOR]

Abstract: Asymmetric conjugate addition of Grignard reagents to aryl substituted α,β-unsaturated carbonyl compounds (1) has been achieved with great regioselectivity (>20:1) and good to excellent diastereoselectivity (de up to 98%). The nucleophilicity and stereospecific blockade of the Grignard reagents play a key role in controlling the regioselectivities and diastereoselectivities of the conjugate addition reaction. [Copyright &y& Elsevier]

A new class of α-aromatic-N-hydroxylamines has been prepared by reaction of tert-butyl (phenylsulfonyl)alkyl-N-hydroxycarbamates with aromatic and heteroaromatic Grignard reagents. Reactions proceed via a base-assisted elimination of the phenylsulfonyl group leading to N-Boc nitrones. This methodology has been applied to the synthesis of zileuton. [ABSTRACT FROM AUTHOR]

Virtual compound libraries are increasingly being used in computer-assisted drug discovery applications and have led to numerous successful cases. This paper aims to examine the fundamental concepts of library design and describe how to enumerate virtual libraries using open source tools. To exemplify the enumeration of chemical libraries, we emphasize the use of pre-validated or reported reactions and accessible chemical reagents. This tutorial shows a step-by-step procedure for anyone interested in designing and building chemical libraries with or without chemoinformatics experience. The aim is to explore various methodologies proposed by synthetic organic chemists and explore affordable chemical space using open-access chemoinformatics tools. As part of the tutorial, we discuss three examples of design: a Diversity-Oriented-Synthesis library based on lactams, a bis-heterocyclic combinatorial library, and a set of target-oriented molecules: isoindolinone based compounds as potential acetylcholinesterase inhibitors. This manuscript also seeks to contribute to the critical task of teaching and learning chemoinformatics. [ABSTRACT FROM AUTHOR]

1,2-Indanedione has been extensively researched since the discovery of its fluorogenic reaction with amino acids in 1997 by Joullié et al. [1]. This current study compares the development of fingermarks on used train tickets by the three leading reagents for amino acids-ninhydrin, DFO and 1,2-indanedione. The train tickets are ideal for the task due to their high abundance and frequent use by a diverse population. However, their unique double-layer composition of a cellulose-based regular paper on one side and a thermally sensitive layer on the other requires an adjustment of the traditional development procedures. Heat, which is normally applied after dipping the specimens in the reagents solutions, had to be avoided due to darkening of the sensitive thermal layer. Instead, it has been replaced by air-drying in a fume-hood 24h prior to the recording of the results. Three groups, each containing 500 used train tickets had been treated by each of the three reagents. The results were expressed in terms of percentage of both comparable and partial fingermarks. In this study we controlled neither the quality of the fingerprint donors nor the conditions under which the latent fingermarks had been deposited or stored. However, the large number of similar exhibits which are randomly chosen allows tentative conclusions on the potential of each reagent, hence, a new criterion for the potential of fingermark development (PFD) is proposed. The PFD combines all the partial fingermarks and identifiable fingermarks (graded 1 and 2) thus, highlighting the sensitivity of the reagents. In this work, the superiority of 1,2-indanedione is demonstrated using both the traditional comparison tests as well as the suggested "PFD". [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, a double exponential approximating approach is described for a quite common kinetic model (mixed second-order formation of an intermediate followed by its first-order decay) under non-pseudo-first-order conditions (i.e., when the initial ratio of the two reactants is between 1 and 10). For the evaluation, first the exact kinetic curves predicted by the two-step model were calculated and then fitted to a double exponential function. The goodness of the fits and the estimated parameters of the double exponential function for both I and P concentrations were determined as a function of the rate constants and initial concentrations in the two-step model. It was found that the fit of the double exponential function is acceptable or very good under these conditions despite the fact that none of the reagents is in a large excess. Since UV-vis absorption spectroscopy is probably the most common technique to follow kinetic traces, we also made efforts to deal with the typical properties of monitoring the process through UV-vis. It was found that the experimental curves can be fitted quite well with a double exponential function if the reagents have minor absorption compared to the intermediate and/or product. The connection between the observed rate constants and the rate constants of the above-mentioned mechanism is also studied. [ABSTRACT FROM AUTHOR]

The SlipChip is a microfluidic device designed to perform multiplexed microfluidic reactions without pumps or valves. The device has two plates in close contact. The bottom plate contains wells preloaded with many reagents; in this paper plates with 48 reagents were used. These wells are covered by the top plate that acts as a lid for the wells with reagents. The device also has a fluidic path, composed of ducts in the bottom plate and wells in the top plate, which is connected only when the top and bottom plate are aligned in a specific configuration. Sample can be added into the fluidic path, filling both wells and ducts. Then, the top plate is “slipped”, or moved, relative to the bottom plate so the complementary patterns of wells in both plates overlap, exposing the sample-containing wells of the top plate to the reagent-containing wells of the bottom plate, and enabling diffusion and reactions. Between the two plates, a lubricating layer of fluorocarbon was used to facilitate relative motion of the plates. This paper implements this approach on a nanoliter scale using devices fabricated in glass. Stability of preloaded solutions, control of loading, and lack of cross-contamination were tested using fluorescent dyes. Functionality of the device was illustrated viacrystallization of a model membrane protein. Fabrication of this device is simple and does not require a bonding step. This device requires no pumps or valves and is applicable to resource-poor settings. Overall, this device should be valuable for multiplexed applications that require exposing one sample to many reagents in small volumes. One may think of the SlipChip as an easy-to-use analogue of a preloaded multi-well plate, or a preloaded liquid-phase microarray. [ABSTRACT FROM AUTHOR]

The thermal lens effect can be successfully explained by use of the presently available theories. However, the existing theories fail for cases where the sample concentration changes with time, i.e., when the sample undergoes a chemical reaction. The objective of this work is to demonstrate that the thermal lens technique can be used for the sensitive kinetic determination of fast chemical reactions. It is systematically approached from two different directions: the theoretical aspect which is described in this paper and the experimental section which will be reported in the following paper. Specifically, novel theories which are based on the parabolic as well as the aberrant model have been derived to describe the thermal lens signal for cases where the sample concentration changes with time. Based on the developed theories, computer calculations were then performed to simulate conditions for various chemical reactions. It was found that in all cases, both of the developed (parabolic and aberrant based) theories can be used successfully to determine not only the order of the reaction but also the reaction rate constant. [ABSTRACT FROM AUTHOR]

The reaction of enamines with 2 equiv of Et 3 Al and CH 2 I 2 at room temperature in CH 2 Cl 2 results in the formation of cyclopropyl amines in high yields (68–89%). Substituted 1-phenylcyclopropan-1-ols were also synthesized from trimethylsilyl enol ethers. The paper demonstrates the advantage of using aluminum carbenoids over traditional cyclopropanation reagents (diazomethane, Simmons–Smith and Furukawa reagents) for the preparation of cyclopropyl amines. [ABSTRACT FROM AUTHOR]

Biomass and water are recognized as a key renewable feedstock in sustainable production of chemicals, fuels and energy. Subcritical water (SubCW), or commonly referred as hot compressed water (HCW), is the water above boiling and below critical point (CP; 374 °C, 22.1 MPa). It has gained great attention in the last few decades as a green, cheap, and nontoxic reagent for conversion of biomass into valuable chemicals. In this paper, hydrothermal reactions of cellulose, as the model biomass substance, with subcritical water at mild temperature and pressure regimes have been studied. The experiments were done in a batch reactor in the temperature range of 220 ° -300 °C. The main products distributed in liquid, gaseous and solid phase were separated and quantified. The conversions to each group of products were found strongly dependent on the temperature and residence time. [ABSTRACT FROM AUTHOR]

This paper describes the use of common Lewis acids supported in imidazolium-based ionic liquids as the catalysts to promote the Biginelli reaction. The ionic liquid effect and the reaction mechanism are discussed on the basis of nuclear magnetic resonance (NMR), electrospray ionization mass spectrometry (ESI-MS), and theoretical calculations. Indeed, the results showed that the ionic medium plays a fundamental role in the synthesis of biologically active dihydropyrimidinones due to the stabilization of the charged intermediates proposed in the mechanism. When conducted in an ionic liquid as solvent, the reaction mechanism is more complex than in other Lewis acid catalyzed Biginelli reactions. [ABSTRACT FROM AUTHOR]

The paper analyzes the potential yield of reaction products or the degree of conversion in a gas- solid system. Dependences of the degree of conversion for the solid phase on gas composition for various types of reactions are presented. They are used to assess the reactivity of the system. The data may be used in planning and implementation of respective processes. [ABSTRACT FROM AUTHOR]

Abstract: The analysis of phenylalanine (Phe) in serum is widely performed for the screening of newborn phenylketonuria (PKU). In this work, a novel spectrofluorimetric method for the determination of Phe was developed based on the fluorescence enhancement of Ruhemann''s purple, the reaction product between Phe and ninhydrin, upon coordination with Eu3+. A filter paper disc containing immobilized reactants (ninhydrin and Eu3+) was fabricated by sol–gel method. The experimental parameters affecting the determination of Phe, such as the concentrations of immobilized reagents, the pH value, the reaction time and temperature were optimized. Under optimum conditions, the fluorescence intensity of Phe–ninhydrin–Eu3+ system was linearly proportional to the concentration of Phe in the range from 5×10−5 to 2×10−3 molL−1, and the limit of detection was found to be 5.2×10−6 molL−1. The relative standard deviation was 2.6% for ten replicate measurements of 1.5×10−4 molL−1 of Phe. The method has merits of sensitivity, simplicity and low cost, and has been applied to the determination of Phe in artificial serum. [Copyright &y& Elsevier]

This paper introduces the preliminary design and optimization of a micro-Sequential Injection lab-on-valve system (μSI-LOV) with fluorescence detection for the direct determination of trace Zn2+in an unacidified seawater matrix. The method capitalizes on the sensitivity and selectivity of FluoZin-3, which was originally designed to measure zinc in living cells. The optimum reaction conditions, sources of blank signal and physical parameters of the μSIA-LOV are evaluated with the requirements of trace metal analysis in mind, namely high sensitivity and low background signals. A detailed investigation of the effect of sample and reagent sequencing on sensitivity is presented for the first time using μSIA-LOV. We find that the order of sequencing greatly influences peak shape and analytical sensitivity with the highest and smoothest peaks obtained when a large volume of sample (75 μL) is aspirated last in the sequence prior to flow reversal and detection. The optimized reaction conditions and reagent/sample sequencing protocol yield a detection limit of 0.3 nM Zn2+, high precision (RSD < 2.5%), a linear quantification range up to 40 nM and an analytical cycle of ∼1 min per sample. This work demonstrates that μSI-LOV is capable of attaining detection limits that are close to those needed for open ocean determinations of Zn2+without preconcentration or separation of the analyte from the seawater matrix. The low reagent consumption (50 μL per sample), full automation and minimal maintenance requirements of μSI-LOV make it well suited for shipboard analysis and, eventually, for development to meet the pressing need for trace element measurements in unattended locations. [ABSTRACT FROM AUTHOR]

The paper reviews the oxidation of oximes to nitrile oxides with hypervalent iodine reagents, especially PhI(OAc)2, and the synthetic uses of such a transformation. Side reactions attending the process are also discussed. [ABSTRACT FROM AUTHOR]

Overwhelming evidence has been previously reported for the existence of the so-called 'dimer nucleophile mechanism' in aromatic nucleophilic substitutions by amines in aprotic solvents, for which the most prominent feature is the fourth-order kinetics (third order in amine) that has been observed with many different substrate-nucleophile systems, especially those in which departure of the nucleofuge is the rate-determining step. The mechanism has been confirmed by several other features, although other alternative mechanisms were suggested to explain the fourth-order kinetics, no one has been able to explain the other above-mentioned features. The present paper affords additional experimental evidence and derivation of the kinetic expressions for reactions with good nucleofugues, where the first step is rate determining. The work involves studies of the reactions of 2,4-dinitrofluorobenzene and 2,4-dinitrochlorobenzene with aniline and with alkyldiamines in toluene. The novelty of this work lies in the selection of substrate-nucleophile systems exhibiting kinetic behavior that allows estimations of the different k's involved. The satisfactory agreement between the quotients of k's calculated from sets of data obtained under different reaction conditions hereby reported indicates that the assumptions made are correct and that the whole treatment applied to the kinetic data is justified. All together, the results fit well with the reaction scheme involving the dimer nucleophile mechanism, adding new evidence to this mechanism that it is well established in the current literature. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 735-742, 2010 [ABSTRACT FROM AUTHOR]

Abstract: The reaction of ‘active ester’ bidentate cross-linking reagents, phthalimido 4-chloroformylbutanoate (1) and phthalimido 4-(2-benzothiazolyloxycarbonyl)butanoate (2) with several protected d-glucose derivatives is described. These reactions are used to introduce the reactive group into cellulose (filter paper) with the aim of linking proteins and cellulose. [Copyright &y& Elsevier]

Abstract: Amide of an octanoic acid possessing an aryl group at C3 position is a highly potent ACAT inhibitor. In this paper, we describe a synthetic access to this class of compounds as optically active forms. The key reaction is substitution of the allylic picolinate of (S,Z)-8-(benzyloxy)oct-5-en-4-ol with a copper reagent derived from (benzo[d][1,3]dioxol-4-yl)MgBr and CuBr·Me2S to produce anti SN2′ product regio- and stereo-selectively. The product was hydrogenated to afford (S)-3-benzo[d][1,3]dioxol-4-yloctan-1-ol, which upon oxidation furnished the octanoic acid. Finally, the acid was converted with 2,6-(i-Pr)2C6H3NH2 to the target amide via acid chloride. In a similar way, the one-carbon long homolog was synthesized. [ABSTRACT FROM AUTHOR]

The halogen-lithium exchange reaction is of one of the most powerful method for the preparation of organolithium compounds, but its mechanism is still controversial. To afford some new elements, we synthesized a new suitable fast radical clock, bearing a phenyl group at the alkene C-terminal. The examination of some mechanistic clues, as well as the identification of the unexpected by-products allowed the conclusion that the reaction proceeds by a polar mechanism and no evidence for radicals were found. The second reaction discussed is the insertion of NO in the N&bond;Li bond of lithium amides. Evidence for the involving of paramagnetic and nitrosonium intermediates, as well as equilibria between different reactive species were essential for the proposal of a whole complex mechanism, which was confirmed by theoretical calculations. Finally, results on the addition of heteroaromatic organocuprates to α,β-unsaturated substrates are presented. Several reaction conditions were looked for to lead the reaction toward the more interesting 1,4-conjugated addition. Thus, addition of up to 6 equivalents of TMSCl to the reaction with arylcuprates leads to a clean addition yielding more than 95% of the 1,4-addition product. A further objective of the paper is to show how the search of unexpected routes of reaction allowed developing original pathways to lead them toward the formation of appealing functionalized compounds. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper studies the influence of the reagent vibration on the reaction O(1D)+HF-HO+F by using a quasi-classical trajectory method on the new ab initio 1A' ground singlet potential energy surface (Gomez-Carrasco et al 2007 Chem. Phys. Lett. 435 188-193). The product angular distributions which reflect the vector correlation are calculated. Four polarization-dependent differential cross sections (PDDCSs) which are sensitive to many photoinitiated bimolecular reaction experiments are presented in the center of the mass frame, respectively. The differential cross section indicates that the OH product mainly tends to the forward scattering, and other PDDCSs are also influenced by the vibration levels of HF. [ABSTRACT FROM AUTHOR]

This paper presents an experimental and theoretical investigation of the Pd-catalyzed Negishi coupling reaction and reveals a novel second transmetalation reaction between an Ar1-Pd-Ar2 species and the organozinc reagent Ar2-ZnX. Understanding of this second step reveals how homocoupling and dehalogenation products are formed. Thus, the second transmetalation generates Ar2PdAr2 and Ar1ZnCI, which upon reductive elimination and hydrolysis, respectively, give the homocoupling product Ar2-Ar2 and the dehalogenation product Ar1H. The ratio of the cross-coupling product Ar1 -Ar2 and the homocoupling product Ar2-Ar2 is determined by competition between the second transmetalation and reductive elimination steps. This mechanism is further supported by density functional theoretical calculations. Calculations on a series of reactions suggest a strategy in controlling the selectivity of cross-coupling and homocoupling pathways, which we have experimentally verified. [ABSTRACT FROM AUTHOR]

This work introduces, for the first time, simultaneous monitoring of fluorescence and absorbance using Bead Injection in a Lab-on-valve format. The aim of the paper is to show that when the target species, cells immobilized on a stationary phase, are exposed to reagents under well-controlled reaction conditions, dual monitoring yields valuable information. The applicability of this technique is demonstrated by the development of a Bead Injection method for automated measurement of cell density and intracellular hydrogen peroxide. [ABSTRACT FROM AUTHOR]

The article discusses the procedure and issues related to the use of the bathophenanthroline contact test for the detection of iron (II) ions. It describes the goals for the application of bathophenanthroline test in a paper conservation workshop. It is suggested that an aqueous ascorbic acid solution should be applied in this test to determine iron-containing ink. It also discourages the application of ascorbic acid solution in reducing the iron (III) ions to iron (II) in case the test is utilized to examine the effect of a conservation treatment for removal or neutralisation of the iron ion catalysis.

Chemistry for first year students has been identified by Tshwane University of Technology as one of the subjects with a low pass rate. It is apparent that students often memorize formulae and definitions, without understanding the underlying concepts required to work with abstract units of measure. We have found that the majority of students at this university are unable to balance reaction equations satisfactorily. They are also unable to predict the reaction yield, or identify limiting reagents. It is imperative that these and other related problems are overcome before any meaningful change to the high failure rate at first year level will be realized. All conventional forms of lecture presentation failed to make any significant impact on the success rate. Structured worksheets were developed and used, together with tactile models, to address the problems and the initial findings showed a marked improvement. It was discovered that the students' problems originated from their inability to understand the meaning of subscripts and coefficients in chemical equations. The worksheets and the impact they have made on the students' understanding of stoichiometry are shared in this paper. [ABSTRACT FROM AUTHOR]

Abstract: Properties of liquid crystalline polymer networks depend on the structure of the reagents as well as on the density of cross-linking bonds, which – in turn – is affected by the degree of ordering of the molecules during the reaction. Changing external conditions (including temperature, time of curing and various factors enforcing orientation of the monomers, such as preparation of cell surface or magnetic field) one can obtain different products. The influence of these external factors on the properties of cured epoxy monomers is studied in this paper. Liquid crystalline polymer networks were obtained as a result of curing three different epoxy compounds with 4,4′-diaminodiphenylmethane (DDM). All the three monomers have nematic phases in wide range of temperatures. The process of cross-linking, the final product of curing and the pure monomers were examined using polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS). Chemical structure of the products was confirmed using spectroscopic methods. The study demonstrates that setting up specific conditions for curing (a temperature corresponding to liquid crystallinity range of pure monomer and an external factor enforcing molecular alignment in liquid crystalline phase) may result in cured products with somewhat better organisation at the molecular level. [Copyright &y& Elsevier]

"Prebiotic soup" often features in discussions of origins of life research, both as a theoretical concept when discussing abiological pathways to modern biochemical building blocks and, more recently, as a feedstock in prebiotic chemistry experiments focused on discovering emergent, systems-level processes such as polymerization, encapsulation, and evolution. However, until now, little systematic analysis has gone into the design of well-justified prebiotic mixtures, which are needed to facilitate experimental replicability and comparison among researchers. This paper explores principles that should be considered in choosing chemical mixtures for prebiotic chemistry experiments by reviewing the natural environmental conditions that might have created such mixtures and then suggests reasonable guidelines for designing recipes. We discuss both "assembled" mixtures, which are made by mixing reagent grade chemicals, and "synthesized" mixtures, which are generated directly from diversity-generating primary prebiotic syntheses. We discuss different practical concerns including how to navigate the tremendous uncertainty in the chemistry of the early Earth and how to balance the desire for using prebiotically realistic mixtures with experimental tractability and replicability. Examples of two assembled mixtures, one based on materials likely delivered by carbonaceous meteorites and one based on spark discharge synthesis, are presented to illustrate these challenges. We explore alternative procedures for making synthesized mixtures using recursive chemical reaction systems whose outputs attempt to mimic atmospheric and geochemical synthesis. Other experimental conditions such as pH and ionic strength are also considered. We argue that developing a handful of standardized prebiotic recipes may facilitate coordination among researchers and enable the identification of the most promising mechanisms by which complex prebiotic mixtures were "tamed" during the origin of life to give rise to key living processes such as self-propagation, information processing, and adaptive evolution. We end by advocating for the development of a public prebiotic chemistry database containing experimental methods (including soup recipes), results, and analytical pipelines for analyzing complex prebiotic mixtures. [ABSTRACT FROM AUTHOR]

The article investigates the effectiveness of ozone in inhibiting the growth of two Aspergillus species, (A. flavus, A. niger) isolated from a nail affected by onychomycosis and from a biodeteriorated paper. Specifically, two main goals are to establish (i) whether differently aged colonies show different responses to the ozonization process, and (ii) whether a repeated ozone exposure can enhance the inhibition of the colony growing. The results prove a high sensibility of the strains considered to the proposed treatment: the growing of both is drastically reduced, and for A. niger completely stopped. Furthermore, ozonization induces pigments bleaching in fungal colonies. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports a simple one-step hydrothermal routine to prepare orthorhombic LiMnO2 powder for Li ion battery application. Employing Mn2O3 and LiOH as the starting materials, hydrothermal reaction operated under 160°C for 12h generated pure-phased o-LiMnO2 powder. The morphological change and reduction in grain size between the reagent and the resultant were revealed by SEM observation, which indicated that LiOH played two important roles in the process, one as the Li ion source to form orthorhombic LiMnO2 by intercalation and the other as the corrosive medium to control the morphology and reduce the particle size. Detailed investigation showed that the LiOH concentration and the hydrothermal temperature were two key factors influencing phase purity of the final product. Pure-phased o-LiMnO2 prepared under optimized hydrothermal conditions showed higher capacity and better cyclical performance than the commonly prepared o-LiMnO2 powder, and therefore promised potential application for lithium ion secondary batteries. [Copyright &y& Elsevier]

New tetraarylphosphonium (TAP)-supported alkyl- and arylcarbodiimides were synthesized and used as coupling reagents for esterification reactions, amidation reactions and dehydration reactions of hydroxyesters. Taking advantage of the solubility properties imparted by the tetraarylphosphonium unit, a simple precipitation and filtration allowed complete separation of the urea by-products. This paper describes the structure optimization study of the various TA1P-supported carbodiimide reagents to obtain the desired reactivity and solubility profile. Furthermore, we have demonstrated that the diimide reagent can be regenerated from the urea to recycle the reagents. [ABSTRACT FROM AUTHOR]

tert-Butylation of diphenylamine (DPA) with tert-butanol (TBA) in the liquid phase was studied over various zeolite catalysts H-MOR, H-BEA, H-Y and H-ZSM-5 (H-MOR CBV 21A and 90A, H-BEA CP 811E, 814E and 814Q, H-Y CBV 720 and H-ZSM-5 CBV 5020) to evaluate whether zeolite catalysts can be efficient as an alternative to the other catalysts in preparation of tert-butylated diphenylamines. The influence of catalyst and the reaction conditions on tert-butylation of diphenylamine with TBA as alkylating agent on catalytic activity and para-selectivity was studied. Catalyst screening revealed that H-BEA and H-Y are the most suitable zeolite catalysts in the alkylation of DPA with TBA. Among them, H-BEA CBV 814E showed the best results in the catalytic activity (91% conversion of DPA), selectivity (99% selectivity to 4-TBDPA, 91% selectivity to 4,4′-DTBDPA) and dialkylation (0.62 4,4′-DTBDPA/4-TBDPA ratio). Subsequent optimization of reaction conditions in the tert-butylation of DPA with TBA over H-BEA CBV 814E showed that the most suitable reaction temperature is 180 °C. The study of influence of reactant's molar ratio showed that TBA/DPA molar ratio 4:1 is the most suitable, but the excess of TBA is so high that it produces significant amount of isobutylene dimer (15%). However, TBA/DPA molar ratio 2:1 is comparable to 4:1, it is even better when considering the most important parameter—selectivity to 4,4′-DTBDPA and produces almost no isobutylene dimer (below 1%). The amount of catalyst charged into reaction system also significantly influences reaction parameters. Study shows that within wide range of catalyst charge (2.5% up to 30% as of DPA charge), the highest reasonable amount of catalyst with the best outcome can be obtained with 0.7 g (20% as of DPA charge) of catalyst charge in the reaction system. tert-Butylation of diphenylamine with tert-butanol over H-BEA zeolite catalyst appears to be an alternative to other catalysts in industrial preparation of tert-butylated diphenylamines. This paper presents the first original complex outlook on the tert-butylation of diphenylamine over zeolite catalysts. [Copyright &y& Elsevier]

This paper is concerned with performing laboratory scale alkali-catalyst transesterification for biodiesel reaction and ranking conversion and performance between a stirred tank reactor, and oscillatory flow meso reactors in both batch and continuous mode. The results show that a comparative conversion can be achieved for the same reaction conditions, thereby demonstrating that batch and continuous meso reactor configurations can be used for a high throughput screening biodiesel reactions. [ABSTRACT FROM AUTHOR]

Abstract: A new method has been established for the determination of aminomethylbenzoic acid using sodium 1,2-naphthoquinone-4-sulfonate as the chemical derivative chromogenic reagent. This method is based on the formation of a pink compound from the reaction of aminomethylbenzoic acid and sodium 1,2-naphthoquinone-4-sulfonate. The nucleophilic substitution reaction proceeds quantitatively in pH 12.0 buffer solution. The stoichiometric ratio of the reaction, maximum absorption wavelength and the value of ɛ 430 were 1:1, 430nm, and 2.87×103 Lmol−1 cm−1, respectively. Beer''s law was obeyed in the range of 0.80–80mg/L of aminomethylbenzoic acid. The data have been filled to a linear regression equation A =0.03183+0.01658C (mg/L), with a correlation coefficient of 0.9996. The detection limit is 0.11mg/L, R.S.D. is 0.54%, and average recovery is over 99.6%. This paper further improves the determination of aminomethylbenzoic acid compared to the previous methods. The kinetic property and reaction mechanism have also been discussed. This proposed method has been successfully applied to the determination of aminomethylbenzoic acid in injection of aminomethylbenzoic acid with satisfactory results. [Copyright &y& Elsevier]

Vilsmeier-Haack type cyclizations proved to be particularly efficient for generating parts of the polycyclic cores of many alkaloids, although only monocyclizations have so far been reported. With the goal of rapidly and efficiently constructing polycyclic alkaloids, we decided to exploit the Vilsmeier-Haack reaction by utilizing iminium ions successively generated and trapped with tethered nucleophiles. To develop such a strategy, we had to set the first cyclization. This constitutes a great challenge in itself because amide activation conditions are usually not compatible with tethered nucleophiles, except for indoles and aromatic rings which have already been reported. This paper describes the comprehensive study of intramolecular addition of silyl enol ethers, allylsilanes, and enamines to chemoselectively activated formamides, aliphatic amides, and lactams. Good to excellent yields were obtained for the 5-exo, 6-exo, and 6-endo modes of cyclization. Moreover, we demonstrated that the species in solution after the cyclization are iminium ions. This is highly encouraging for the development of bis-cyclization strategies. An expeditious total synthesis of (±)-tashiromine is also reported. [ABSTRACT FROM AUTHOR]

N‐Acyliminium reagents formed from 3,4‐dihydro‐β‐carboline and acyl chlorides were used for amidoalkylation of indole, pyrrole, and thiophene. #This paper is dedicated to the memory of Professor Atanas Venkov. [ABSTRACT FROM AUTHOR]

The Tollens test for aldehydes has been used for over 100 years but no reason has been given for adding sodium hydroxide to the silver nitrate before the solution is cleared with ammonia. In this paper, a mechanism is proposed which explains why the addition of alkali makes the test much more sensitive. [ABSTRACT FROM AUTHOR]

Some additional evidences on the mechanism of new rearrangment of dihalocyclopropane–dihalomethylvinyl reaction assisted by Hiyama reagent Cr+2/Cr+3 are discussed. [ABSTRACT FROM AUTHOR]

A chemical interaction between an atmospheric pressure plasma jet and liquid media is of great interest for biomedical applications. In this paper, the visualization method and typical results of the 2-D distribution of oxidizing substances generated by the plasma jet were reported using the gel visualization reagent. The plasma jet generator consists of a glass tube and two electrodes. As a result, the distribution of oxidizing substances was able to be visualized around the contact point between the plasma jet and the reagent in atmospheric air. The interesting distribution patterns depending on the supplied gas were visually obtained by the reagent. In addition, its relative concentration distribution was also obtained by an absorbance measurement. [ABSTRACT FROM PUBLISHER]

The paper reports the site-selective generation and use of a Pd(II) reagent on a chip. Researchers have found that the mediated electrochemical conditions developed for recycling a Pd(II) reagent in a preparative scale oxidation can be used without modification for generating Pd(II) reagents on the surface of a chip. The Pd(II) reagent generated in this fashion can be confined to preselected locations on a chip by adding a reactive substrate to the solution over the chip. In principle, one can imagine using analogous strategies to conduct a wide variety of transition-metal-based chemistry in a chip-based environment. Efforts to explore the scope of this chemistry and its overall utility for building chip-based molecular libraries are currently underway.

Highlights: [•] Hybrids from lignocelluloses and Ag were successfully prepared. [ • ] Environmentally-friendly sonochemistry method was introduced. [•] The reaction parameters have influence on the hybrids. [•] Reducing reagents favored the growth of Ag nanostructures. [ABSTRACT FROM AUTHOR]

Abstract: Succinoylation and benzoylation of ball-milled eucalyptus wood using succinic anhydride and benzoyl chloride as acylating reagent, respectively, were investigated at room temperature using dimethyl sulfoxide/N-methylimidazole (DMSO/NMI) as reaction medium without additional catalysts. The effects of the corresponding acylating reagent dosage (1–5:1 for succinoylation and 0.5–5:1 for benzoylation) and reaction time (0.35–5h for succinoylation and 0.5–3h for benzoylation) on the extent of acylation, measured by weight percent gain (WPG), were studied. WPG of succinoylation and benzoylation was in the range of 70.8–144.7% and 17.3–43.1%, respectively. The efficiency of acylation at room temperature significantly increased in DMSO/NMI compared with ionic liquid 1-butyl-3-methylimidazolium chloride because of the role of NMI as solvent, base and catalyst. Fourier transform infrared (FT-IR), and solid-state cross-polarization/magic-angle spinning (CP/MAS) 13C nuclear magnetic resonance (NMR) spectroscopy studies provided evidence for the occurrence of succinoylation and benzoylation reactions and the attachment of functional groups via ester bonds. [Copyright &y& Elsevier]

Abstract: Wood meal was dissolved under identical conditions in the ionic liquid 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) and homogeneously esterified with butyryl chloride and lauroyl chloride in the presence of triethylamine as a neutralizer. The effect of the molar ratio of reagent to the hydroxyl groups in wood on the properties of the esterified wood and the possible mechanism of the homogeneous esterification of wood in this reaction medium were studied. Furthermore, the physicochemical properties of the esterified wood were characterized by FTIR, solid-state CP/MAS 13C NMR, TGA/DTG and SEM. The results confirmed that the homogeneous modifications were successfully processed and highly substituted wood esters could be obtained by reacting the dissolved wood in this homogeneous system. [Copyright &y& Elsevier]