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Author(s): Nuntaporn Moonrungsee [sup.1], Somkid Pencharee [sup.2], Jaroon Junsomboon [sup.3], Jaroon Jakmunee [sup.4], Nipat Peamaroon [sup.1] Author Affiliations: (1) grid.443781.d, Department of Chemistry, Faculty of Science and Technology, Rambhai Barni [...], A simple and low cost colorimetric procedure using an Android smartphone was developed for determination of copper(II) in copper supported silica catalysts. The developed software was installed in a smartphone for measuring the intensity of the blue color produced by the reaction between copper(II) and 2-carboxy-2'-hydroxy-5'-sulfoformazyl-benzene in an acidic solution. More than one sample can be measured by taking only one photo shot. Under the selected conditions, the linear range from 0 to 5 mg/L was obtained with the detection and quantitation limits of 0.04 and 0.13 mg/L, respectively. The method provided a good precision with the percent relative standard deviation values less than 5%. The percent recoveries were in the range of 97-104%. The results corresponded well with those obtained by atomic absorption spectrophotometry. This developed method is convenient, rapid and simple with an uncomplicated device.

Although the chemical and biotechnology industries have preferred to use continuous-flow systems because of their high productivity and efficiency, fine chemical production has been conducted using batch systems because the [...], Chemical manufacturing is conducted using either batch systems or continuous-flow systems. Flow systems have several advantages over batch systems, particularly in terms of productivity, heat and mixing efficiency, safety, and reproducibility (1-4). However, for over half a century, pharmaceutical manufacturing has used batch systems because the synthesis of complex molecules such as drugs has been difficult to achieve with continuous-flow systems (5, 6). Here we describe the continuous-flow synthesis of drugs using only columns packed with heterogeneous catalysts. Commercially available starting materials were successively passed through four columns containing achiral and chiral heterogeneous catalysts to produce (R)-rolipram (7), an anti-inflammatory drug and one of the family of γ-aminobutyric acid (GABA) derivatives (8). In addition, simply by replacing a column packed with a chiral heterogeneous catalyst with another column packed with the opposing enantiomer, we obtained antipole (S)-rolipram. Similarly, we also synthesized (R)-phenibut, another drug belonging to the GABA family. These flow systems are simple and stable with no leaching of metal catalysts. Our results demonstrate that multistep (eight steps in this case) chemical transformations for drug synthesis can proceed smoothly under flow conditions using only heterogeneous catalysts, without the isolation of any intermediates and without the separation of any catalysts, co-products, by-products, and excess reagents. We anticipate that such syntheses will be useful in pharmaceutical manufacturing.

Methane is an underused resource, in part because technologies for converting it into more-valuable chemicals are highly underdeveloped, presenting a major challenge for chemists[sup.,] . On , Shan et al. [...]

Author(s): Lili Lin [1]; Wu Zhou [2, 3]; Rui Gao [4, 5]; Siyu Yao [1]; Xiao Zhang [6]; Wenqian Xu [7]; Shijian Zheng [8]; Zheng Jiang [9]; Qiaolin Yu [1]; [...]

Abstract: The rate enhancement of the hydrolysis of p-nitrophenyl acetate (PNPA) by seven catalysts, four amino acids and three enzymes, was determined at pH 7.0 and pH 8.0. All seven [...]

A Ziegler-Natta catalyst was modified with a metallocene catalyst and its polymerization behavior was examined. In the modification of the Ti[Cl.sub.4] catalyst supported on Mg[Cl.sub.2] (Mg[Cl.sub.2]-Ti) with a rac-ethylenebis(indenyl)zirconium dichloride (rac-Et[(Ind).sub.2]Zr[Cl.sub.2]. EIZ) catalyst, the obtained catalyst showed relatively low activity but produced high isotactic polypropylene. These results suggest that the EIZ catalyst might block a non-isospecific site and modify a Ti-active site to form highly isospecific sites. To combine two catalysts in olefin polymerization by catalyst transitioning methods, the sequential addition of catalysts and a co-catalyst was tried. It was found that an alkylaluminum like triethylaluminum (TEA) can act as a deactivation agent for a metallocene catalyst. In ethylene polymerization, catalyst transitioning was accomplished with the sequential addition of bis(cyclopentadienyl)zirconium dichloride ([Cp.sub.2]Zr[Cl.sub.2])/methylaluminoxane (MAO), TEA, and a titanium tetrachloride/vanadium oxytrichloride (Ti[Cl.sub.4]/VO[Cl.sub.3], Ti-V) catalyst. Using this method, it was possible to control the molecular weight distribution (MWD) of polyethylene in a bimodal pattern. In the presence of hydrogen, polyethylene with a very broad MWD was obtained due to a different hydrogen effect on the [Cp.sub.2]Zr[Cl.sub.2] and Ti-V catalyst. The obtained polyethylene with a broader MWD exhibited more apparent shear thinning., INTRODUCTION Metallocene catalysts have been studied extensively with regard to polyolefin chemistry. Compared with other olefin polymerization catalysts, the metallocene catalysts have higher activity and greater versatility for controlling the [...]

GENERAL INTRODUCTION Although fermentation dates the use of biocatalytic transformations as centuries old, it has only been in recent decades that chemists have begun to rationally exploit the synthetic potential [...]

Dinitrogen ([N.sub.2]) was reduced to ammonia at room temperature and 1 atmosphere with molybdenum catalysts that contain tetradentate [[HIPT[N.sub.3]N].sup.3-] triamidoamine ligands {such as [HIPT[N.sub.3]N]Mo([N.sub.2]), where [[HIPT[N.sub.3]N].sup.3-] is [[[{3,5-[(2,4,6-i-[Pr.sub.3] [C.sub.6][H.sub.2]).sub.2][C.sub.6][H.sub.3] NC[H.sub.2]C[H.sub.2]}.sub.3]N]].sub.3-]} [...]

The hydrosilylation reaction, the addition of a Si-H unit to a C-C double bond to form an alkylsilane (Fig. 1A) (1-3), enables the production of silicon polymers used in silicon [...], The hydrosilylation reaction enables the production of silicon polymers. Platinum-carbene complexes are reported that catalyze the hydrosilylation reaction of alkenes with remarkable efficiency and exquisite selectivity and avoid the formation of platinum colloids. By-products, typically encountered with previous catalytic systems, are suppressed with these platinum derivatives.