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In this work, we fabricated gold nanoparticles (AuNPs) capped with both polyvinyl pyrrolidone (PVP) and iodine (I2) to act as efficient chemiluminescent coreactants for luminol. AuNPs synthesis was based on the direct chemical reduction of Au3+ with NaBH4 in the presence of PVP-I2 complex. The successful synthesis of PVP-I2@AuNPs was confirmed with scanning electron microscopy (SEM) and UV-vis spectrophotometry. Chemiluminescence (CL) intensity of luminol was greatly enhanced, upon its chemical reaction with chemisorbed I2 on AuNPs surfaces owing to the excellent catalytic activity of AuNPs. The PVP-I2@AuNPs/luminol CL sensing system was successfully applied for determination of Hg2+ ions and the results displayed linearity in a wide range from 0.5 to 2000 nM and an ultrasensitive response to 1.0 nM Hg2+. The detection limit of Hg2+ ions was 0.1 nM, which was 100 times lower than the limit value (10 nM) defined by the U.S. Environmental Protection Agency in drinkable water. This ultrasensitive luminogenic system for Hg2+ detection also exhibited excellent selectivity among 13 types of metals, suggesting that the luminol/PVP-I2@AuNPs system is a promising sensor for real-time detection of Hg2+. [ABSTRACT FROM AUTHOR]

While temporal considerations are of prime importance for chemical reactions, as well as for molecular stability, most chemical concepts (outside of the field of chemical kinetics) are not explicitly formulated on a diachronic basis (Earley in Found Chem 14:235, 2012). It will be argued here that a formulation explicitly incorporating temporal and epistemological considerations enables us to treat chemical reactions and chemical substances on ontologically equivalent terms, instead of assigning a more fundamental status to the latter. After all, in collision theory, a chemical substance is just a collision complex (a "resonance") that takes too long. How long qualifies as "too long", and "too long" in relation to what, are crucial questions that distinguish chemical substances from chemical reactions, and reversible reactions from irreversible ones, thereby introducing anthropocentric considerations into these distinctions. Too long for a lab chemist is very different from too long for an astrochemist studying chemical reactions between chemical substances in inter-stellar space on cosmological timescales. Examining several physical and chemical properties on the basis of which chemical substances are distinguished from one another, the role of temporal and anthropocentric considerations in defining molecular properties is emphasized. I conclude with some observations on the much-debated reduction of chemistry to other disciplines, arguing that such reduction depends on our aesthetic choices as to what kinds of observations demand explanation, and what kinds of explanation are acceptable. [ABSTRACT FROM AUTHOR]

In this paper, silver nanoparticles (Ag NPs) were successfully prepared in situ by chemical pulp fiber (CPF) without any additional reductants. In the green synthesis of Ag NPs, CPF acted as both a weak reductant and a stable carrier. The effect of different synthesis conditions was investigated, and the Ag NP load rate was up to 28.12 wt%. The size of the Ag NPs followed a standard Gaussian distribution, ranging from 10 to 50 nm, and a face-centered cubic structure was identified by XRD and TEM. In addition, the AgNPs/CPF composites exhibited good thermostability below 280 °C according to TG analysis. Owing to the high load rate and large specific surface area of Ag NPs, AgNPs/CPF composites exhibited excellent catalytic performance in the reduction of 4-nitrophenol to 4-aminophenol by NaBH4. The conversion rate was up to 95.91% after recycling 50 times, and the catalyst was easily separated from the reaction system. Based on the advantages of high conversion rate, excellent catalytic activity and reusability, AgNPs/CPF composites hold tremendous potential in eliminating nitrophenol and its derivatives from industrial pollution. [ABSTRACT FROM AUTHOR]

The formation of N2O has been studied by means of isothermal lean-rich experiments at 150, 180 and 250 °C over Pt-Ba/Al2O3 and Pt/Al2O3 catalysts with H2 and/or C3H6 as reductants. This allows to provide further insights on the mechanistic aspects of N2O formation and on the influence of the storage component. Both gas phase analysis and surface species studies by operando FT-IR spectroscopy were performed. N2O evolution is observed at both lean-to-rich (primary N2O) and rich-to-lean (secondary N2O) transitions. The production of both primary and secondary N2O decreases by increasing the temperature. The presence of Ba markedly decreases secondary N2O formation. FT-IR analysis shows the presence of adsorbed ammonia at the end of the rich phase only for Pt/Al2O3 catalyst. These results suggest that: (i) primary N2O is formed when undissociated NO in the gas phase and partially reduced metal sites are present; (ii) secondary N2O originates from reaction between adsorbed NH3 and residual NOx at the beginning of the lean phase. Moreover, N2O reduction was studied performing temperature programming temperature experiments with H2, NH3 and C3H6 as reducing agents. The reduction is completely selective to nitrogen and occurs at temperature higher than 250 °C in the case of Pt-Ba/Al2O3 catalyst, while lower temperatures are detected for Pt/Al2O3 catalyst. The reactivity order of the reductants is the same for the two catalysts, being hydrogen the more efficient and propylene the less one. Having H2 a high reactivity in the reduction of N2O, it could react with N2O when the regeneration front is developing. Moreover, also ammonia present downstream to the H2 front could react with N2O, even if the reaction with stored NOx seems more efficient. [ABSTRACT FROM AUTHOR]

Using the effects of chemical polarization of nuclei, mechanism and elementary stages of photochemical reduction of 2,6-diphenyl-1,4-benzoquinone with thiols have been elucidated. The studied quinone is reduced with ethanethiol in two stages (transfer of electron followed by proton transfer). The final photolysis product is a derivative of dibenzofuran. [ABSTRACT FROM AUTHOR]

At present, air cooling and water quenching are traditional treatment methods for molten copper slag. However, the waste heat and valuable metals cannot be recovered efficiently by these methods. Exergy efficiency (EE) of this method is only 21.0%. This paper describes a feasibility of waste heat recovery and direct reduction of copper slag. To investigate the feasibility of this new thermal energy recovery and direct reduction system (TER-DR), thermodynamic compass method was applied. Based on physical and chemical recovery methods, TER-DR1 and TER-DR2 systems are put forward. TER-DR1 system decreases the exergy loss (EXL) and improves the EE to 57.3%, and 0.489 t DRI is acquired for every ton of copper slag. Exergy of six kinds of typical endothermic chemical reactions was analyzed. The exergy of reforming reaction of CH4 by CO2 is the highest and suitable for TER-DR system. Combined with chemical method, TER-DR2 system decreases EXL further and improves the EE to 61.3%. Steam, synthesis gas and DRI are produced by this method. By TER-DR2, for every ton of copper slag, 0.489 t DRI, 67.3 m3 CO and 67.3 m3 H2 are acquired. [ABSTRACT FROM AUTHOR]

Silver nanoparticle-decorated graphene oxide was prepared using a simple green chemical reduction method, and its performance being used for surface-enhanced Raman scattering detection and optical limiting was studied. TEM images, photoluminescence quenching effect and the characteristic absorption peaks of GO and silver nanoparticles confirm the successful preparation of GO-Ag nanocomposite. The Raman spectra results show that the vibration fingerprints of RhB and R6G moleculars are detected only on the GO-Ag substrate, revealing good potential of being used as surface-enhanced Raman scattering substrate for detecting organic molecules. Additionally, nonlinear optical absorption of GO-Ag was measured using z-scan technique with a nanosecond laser operating at the wavelength of 532 nm. The z-scan results show that the transmittance of GO-Ag aqueous suspension has a large decline of 90%, and the nonlinear optical absorption onset input fluence of GO-Ag dispersed PVA film is as low as 1.3 J/cm, indicating that GO-Ag is a good potential optical limiting material for the commonly used high-power 532 nm nanosecond pulsed laser. [ABSTRACT FROM AUTHOR]

We have investigated the preparation of molybdenum powders by reducing the oxide compounds MoO, MgMoO, and CaMoO with magnesium vapor at residual argon pressures in the range 5-20 kPa and temperatures in the range 700-800°C. Using the MgMoO and CaMoO compounds as precursors, we have obtained molybdenum powders with specific surface areas of up to 20 m/g. The powders have a mesoporous structure. The reduction of the molybdenum compounds under such conditions was accompanied by separation of the reaction products due to the removal of magnesium oxide from the reaction zone. [ABSTRACT FROM AUTHOR]

In this work, the reduction and oxidation of hydrogen peroxide on Au single crystals is studied in weakly adsorbing electrolytes. Results are discussed in terms of the potential of zero charge and the adsorption strength of different anions, which in turn depend on the crystallographic orientation of the electrode. Close to the reaction onset, both reactions follow the same activity trend with Au(100) and Au(111) being the most and the least active surface planes, respectively. At high potentials, gold oxides inhibit the oxidation of HO, which seems to be controlled by a surface process. [ABSTRACT FROM AUTHOR]

Proceeding from TeCl and 1-octene a regioselective method was developed of the synthesis of trichloro(2-chlorooctyl)tellane. At adding methanol to this compound chlorine was easily replaced at room temperature by a methoxy group affording trichloro(2-methoxyoctyl)tellane. The reaction of TeBr with 1-octene in methanol resulted in tribromo(2-methoxyoctyl)tellane. A reduction of trichloro- and tribromo(2-methoxyoctyl)tellanes occurs the most selectively in the system NaBH4-water-THF giving 1,2-bis(2-methoxyoctyl)ditellane. The reactions are characterized by a high selectivity and quantitative yields of the products. [ABSTRACT FROM AUTHOR]

The authors describe a method for the fabrication of graphene micro-aerogels (GMA) using a multiple emulsion as a soft template. A mixed surfactant consisting of polymannitol oleate ester and polyoxyethylene castor oil was dissolved in toluene. An aqueous dispersion of graphene oxide was dropped into the above solution to produce a water-in-oil-in-water multiple emulsion. Hydrazine was used to reduce the graphene oxide. The partly reduced sheets of graphene oxide diffuse into the oil phase due to their low polarity. This induces the self-assembly of graphene sheets at the oil-water interface to finally form GMA. Following freeze drying and thermal annealing at 900 °C under Ar/H, GMA is obtained which possesses a microcapsule-like structure, high electrical conductivity (3250 S m), a large specific surface (1253 m g) and a well-defined porous structure. A glassy carbon electrode modified with the GMA shows ultrahigh sensitivity for the electrochemical detection of p-acetamidophenol. The differential pulse voltammetric peak current increases linearly over the 1 × 10 to 8.0 × 10 M p-acetamidophenol concentration range, and the detection limit is 5.7 × 10 M (at an S/N ratio of 3). The sensitivity is much better than that of sensors based on the use of graphene, graphene aerogel, or high density graphene aerogel. The method was successfully applied to the determination of p-acetamidophenol in tablets. The study also provides promising prospects in terms of graphene aerogel materials with improved electrochemical performance in electrocatalysis, supercapacitors and lithium ion batteries. [ABSTRACT FROM AUTHOR]

Gold nanoparticles are one of the most used nanomaterials. They are usually synthesized by the reduction of gold(III) chloride. However, the presence of halide ions in the reaction mixture is not always welcome. In some cases, these ions have detrimental influence on the morphology and structure of resulting nanoparticles. Here, we present a simple and halogen-free procedure to prepare gold nanoparticles by reduction of gold(III) oxide in neat oleylamine. The method provides the particles with an average size below 10 nm and dispersity of tens of percent. The process of nanoparticle formation was monitored using UV-Vis spectroscopy. The structure and chemical composition of the nanoparticles was determined by SEM, XPS and EDX. We also proposed the mechanism of reduction of gold(III) oxide based on MS, IR and NMR data. Importantly, the synthetic protocol is general and applicable for the preparation of other coinage metal nanoparticles from the corresponding metal oxides. For instance, we demonstrated that the absence of halogen enables efficient alloying of metals when preparing gold-silver bimetallic nanoparticles. [ABSTRACT FROM AUTHOR]

Tellurium tetrabromide readily reacted with 2-allylphenol at room temperature in acetonitrile to give previously unknown tribromo(2,3-dihydro-1-benzofuran-2-ylmethyl)-λ4-tellane in quantitative yield. The reduction of the product afforded bis(2,3-dihydro-1-benzofuran-2-ylmethyl)ditellane and benzyl(2,3-dihydro-1-benzofuran-2-ylmethyl)tellane. [ABSTRACT FROM AUTHOR]

The W-AlO system at T = 2400 K and standard pressure (controlled Ar + H atmosphere) has been calculated by stochastic simulation. It is shown that the presence of hydrogen leads to the formation of aluminum hydrides, hydrogen oxides, and aluminum hydroxides; the compounds from the two latter groups (except for water) can interact directly with tungsten. The main chemical reactions occurring in the system are determined, based on which a conclusion about the cyclic character of the processes is drawn. Some recommendations on the composition and pressure of controlled atmosphere for growing sapphire crystals are given. [ABSTRACT FROM AUTHOR]

In methanol, FeCl reacted readily with L1H ( L1H = bis(1-isoquinolylcarbonyl)amide) and afforded a complex having the formula [Fe( L2)Cl] ( 1) { L2 = N-((1-isoquinolyl)(methoxy)methyl)isoquinoline-1-carboxamide ion}. This reaction involves reduction of one of the two carbonyl groups present in L1H to (methoxy)methyl group. A plausible mechanism for the conversion of L1H to L2 has been proposed. Determination of molecular structure of 1 confirmed this conversion. Fe(III) ion is surrounded by three nitrogen atoms of the ligand and two chloride ions, imparting a rare distorted trigonal bipyramidal NCl coordination environment. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

In this paper, the results of the study of the reduction of basic lead sulphate with a gas (CO + CO) mixture are presented. This is a secondary reaction during the reduction of lead sulphate. The change in the both lead and PbS content in the reaction products, depending on the process temperature and the composition of the gaseous phase, was established. The comparison of the rate of the reduction reaction of lead sulphate and basic lead sulphate shows that the process proceeding with a higher output is the reduction of basic lead sulphate. [ABSTRACT FROM AUTHOR]

The article presents a study regarding the chemical reduction of N-(2-nitro-4-R-phenyl) pyridinium salts and their reaction with N-(2-amino-4-R-phenyl)pyridinium chlorides. The study identified the two simultaneous chemical transformations that complicate the analysis of this reaction, which include the reduction and the intramolecular cyclization. The article also presents a table that shows the results of the study.

In an aqueous buffer system, serious reverse and side reactions were found in the asymmetric reduction of 2-octanone with Saccharomyces cerevisiae. However, some nonionic surfactants added to the aqueous buffer system improved the bioreduction process by decreasing the reverse and side reaction rates in addition to effectively increasing the average positive reaction rate. Further, a shorter carbon chain length of hydrophilic or hydrophobic moieties in surfactants resulted in a higher yield of (S)-2-octanol. The alkylphenol ethoxylate surfactants had a less influence than polyoxyethylenesorbitan trialiphatic surfactants on the product e.e. It suggested that the product e.e. resulting from the change of carbon chain length of the hydrophobic moieties varied markedly compared with the change of carbon chain length of the hydrophilic moiety. Emulsifier OP-10 and Tween 20 markedly enhanced the yield and product e.e. at the concentration of 0.4 mmol L−1 with a yield of 73.3 and 93.2%, and the product e.e. of 99.2 and 99.3%, respectively, at the reaction time of 96 h. [ABSTRACT FROM AUTHOR]