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The copolymerization of ethylene (E) with isoprene (Ip) was performed catalyzed by a symmetrical catalyst exhibiting a silicon bridge [rac-Me 2 Si(2-Me-4-Ph-Ind) 2 ZrCl 2 with the combination of borate/TIBA activator. The effect of cocatalyst, Ip concentration, and polymerization temperature on the activity, molecular weight (Mw), distribution (MWD), comonomer composition, chain structure (regio- and stereoselectivity), and resulting side reactions were logically addressed. Gel-permeation chromatography (GPC) was used to characterize the Mw and polydispersity, while nuclear magnetic resonance (NMR) was employed for the chain structure of the polymers. The catalytic activity was significantly lower by increasing the Ip concentration in the feed, and the isoprene content in resulting polymers was lower under the reaction condition, leading to higher activity. Insertion of isoprene units in polymer structure demonstrates the higher regioselectivity for the 3,4 connections than the 1,4 connections and is expected to be a high-resistance polymer against acids. The MWD presented monomodal even with a higher concentration (1.44 mol/L) and did not appear as low Mw peaks of Ip. The Mw was higher with a broader MWD when purely TIBA was used as a cocatalyst, and it significantly reduced and presented a narrowed MWD with TEA in the cocatalyst. The higher efficiency of the catalyst for the higher insertion of Ip (C=C double bond) effectively modifies the polymer backbone. It is expected to be a promising candidate for easily degradable and favorable solutions for solving environmental problems caused by PE. wastes. [Display omitted] • Environmentally benign methodology reaction conditions (low temperature and pressure) are hallmarks of this approach. • Ethylene α-olefin (linear conjugated diene) copolymerization catalyzed with a symmetrical Single-site homogeneous catalyst. • Ethylene α-olefin (linear conjugated diene) copolymerization catalyzed with a symmetrical Single-site homogeneous catalyst. • The MWD demonstrated monomodal even with a higher concentration of isoprene (1.44 mol/L). • Increased insertion of isoprene may lead to easily degradable and beneficial solutions for PE waste environmental issues. [ABSTRACT FROM AUTHOR]

Abstract 5-Na/ZnO loaded SBA-15 has been prepared by one-pot method in atmospheric conditions (without employing hydrothermal treatment) and following wet impregnation method. The prepared catalyst was characterised by using several techniques viz., BET method for determination of surface area, FE-SEM for morphology of catalyst, XPS study to determine the oxidation state of constituent elements. The catalyst was utilised for transesterification from virgin cotton seed oil and the catalyst activity was dependant on its basic strength. Under optimal reaction conditions of catalyst amount 12 wt%, methanol to oil molar ratio of 24:1 at reaction temperature of 65 °C, the prepared catalyst yielded > 98% fatty acid methyl ester in 4 h of reaction duration. The catalyst was able to yield conversion level as good as ∼74% even in 5th cycle after regeneration. Leaching of < 5 ppm metal content was observed, in 4th and 5th cycle, which was within the ASTM specified limitations. The thermodynamic parameters for the reaction, viz. , activation energy E a , ΔH‡, ΔS‡, ΔG‡ were calculated as 77.3 kJ mol−1, 74.2 kJ mol−1, -0.064 kJ mol−1 and, + 93.2 kJ mol−1 respectively. Graphical abstract Image 1 Highlights • Synthesis of SBA-15 and impregnation of 5-Na/ZnO was performed in single step. • In situ method of synthesis saved lot of time and energy consumption compared to 2-step synthesis. • Prepared catalyst was employed for biodiesel production and reused for 5 consecutive runs. • The catalyst activity was found to be a function of its basic strength. [ABSTRACT FROM AUTHOR]

Abstract: Lithium impregnated calcium oxide has been prepared by wet impregnation method in nano particle form as supported by powder X-ray diffraction and transmission electron microscopy. Basic strength of the same was measured by Hammett indicators. Calcium oxide impregnated with 1.75 wt% of lithium was used as solid catalyst for the transesterification karanja and jatropha oil, containing 3.4 and 8.3 wt% of free fatty acids, respectively. The reaction parameters, viz., reaction temperature, alcohol to oil molar ratio, free fatty acid contents, amount of catalyst and amount of impregnated lithium ion in calcium oxide support, have been studied to establish the most suitable condition for the transesterification reaction. The complete transesterification of karanja and jatropha oils was achieved in 1 and 2h, respectively, at 65°C, utilizing 12:1 molar ratio of methanol to oil and 5 wt% (catalyst/oil, w/w) of catalyst. Few physicochemical properties of the prepared biodiesel samples have been studied and compared with standard values. [Copyright &y& Elsevier]

Present work demonstrates an easy route by sol-gel method, without using any template, for the synthesis of flower shaped tungsten (W) supported TiO 2 /SiO 2 catalyst for the triglyceride transesterification. The structure of the catalyst was established by powder X-ray diffraction and surface morphology and particle size by field emission scanning and high resolution transmission electron microscopy studies, respectively. The oxidation state of tungsten by X-ray photoelectron spectroscopy was found to be +6. Under the optimized reaction conditions of 5 wt% of 20-W/TiO 2 /SiO 2 -700 catalyst, 30:1 methanol to oil molar ratio and 65 °C reaction temperature, more than 98% fatty acid ethyl ester yield was obtained in 4 h. The kinetic and thermodynamic parameter of the reaction was also evaluated following the pseudo-first order equation. The catalyst was recycled in four consecutive runs and total metal contents in biodiesel was observed <5 ppm to maintain the stability of the catalyst. [ABSTRACT FROM AUTHOR]

In this study, first biocatalytic synthesis of clinically important imidazo[1,2- a]pyridine based compounds has been achieved. The Candida antarctica lipase B (CALB) enzyme was found suitable to catalyze the Groebke-Blackburn-Bienaymé (GBB) multicomponent reaction of substituted 2-aminopyridine, benzaldehyde and isocyanides to synthesize imidazo[1,2-a]pyridine derivatives in very good yields. Further, CALB enzyme was immobilized on mesoporous silica and characterized using FT-IR, XRD, SEM-EDS and HR-TEM to use as a reusable catalyst in this transformation. The immobilized catalyst CALB@SiO 2 displayed high catalytic efficiency up-to many cycles. In addition, preliminary mechanistic studies such as molecular docking and molecular dynamics (MD) simulation were performed which suggested that Thr40 and Ser105 residues are playing an important role in catalyzing the GBB-reaction. Image 1 • First biocatalytic synthesis of clinically important imidazo[1,2-a]pyridine. • CALB catalyzed Groebke-Blackburn-Bienaymé multicomponent reaction. • Immobilization of CALB@SiO 2 as reusable catalyst. • Computational investigations suggested Thr40 and Ser105 residues play an important role in catalysis. [ABSTRACT FROM AUTHOR]