Herein, the facile synthesis of sulphonic acid functioned benzimidazolium based poly(ionic liquid) (SBPIL) is reported for the first time and we investigated its efficacy towards the removal of Cr(vi).

Senthilkumar S

Department of Chemistry

School of Advanced Sciences

Vellore Campus

Pundlik Rambhau Bhagat

Khiratkar A.G

Fulltext

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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RSC Advances

A polymer supported Pd-salen complex (PS-Pd-salen) was synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), Fourier-transform NMR spectroscopy (FT-NMR), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), surface area and pore size distribution by Brunauer-Emmett-Teller (BET). The heterogeneous catalytic performance of the PS-Pd-salen for the Suzuki-Miyaura coupling of variety of phenyl boronic acid with different aryl halides was successfully conducted in water with K2CO3 and 20 mg catalyst loading at room temperature. The coupling reactions with aryl iodides and bromides were achieved at room temperature with good to excellent yield; whereas the reactions with aryl chlorides were performed in aqueous-ethanol (1:1) at 90 °C. The product yields related with the substrates were optimized, and main reaction factors influencing the yields were also recognized. The results clearly indicated that the reaction constraints needed to achieve high yields are substrate-reliant. The hot filtration test verified heterogeneous nature of PS-Pd-salen complex. Moreover, the catalyst showed excellent reusability for five successive runs in slight compromising with its activity. © 2017 Elsevier B.V.

Journal of Organometallic Chemistry

A highly recoverable polymer-supported ionic salen-palladium complex as a catalyst for the Suzuki-Miyaura cross coupling in neat water

The synthesis of polymer supported zinc–salen complex (PS-Zn–salen) is described. The mononuclear zinc(II)–salen complex was characterized by Fourier-transform NMR spectroscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectrophotometry (FT-IR), thermogravimetric analysis, scanning electron microscopy, surface area and pore size distribution by Brunauer–Emmett–Teller. The synthesized PS-Zn–salen complex used as a recyclable heterogeneous catalyst for the efficient synthesis of hydantoins, thiohydantoins and Schiff bases in an aqueous medium. The isolated yields of hydantoins, thiohydantoins and Schiff bases achieved up to 89, 95 and 94%, respectively. In spite of conventional heterogeneous catalysts, current PS-Zn–salen complex shows thermal stability up to 280 °C. Moreover, the catalyst could be recovered easily by simple filtration and reused for next run with slightly declining its activity up to six successive runs. The FT-IR spectrum of recycle catalyst after 6th run confirmed that the catalyst was stable during the course of a reaction. The leaching of metal from the PS-Zn–salen is negligible, which was confirmed by AAS and hot filtration test. © 2017, Springer Science+Business Media B.V., part of Springer Nature.

Research on Chemical Intermediates

Facile access to polymer supported zinc–salen complex: highly efficient heterogeneous catalyst for synthesizing hydantoins, thiohydantoins and Schiff bases in aqueous medium

Abstract: Carboxyl-functionalized poly(ionic liquid) (CFPIL) was easily synthesized from its starting material and characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis and elemental analysis. The synthesized CFPIL was used as an efficient heterogeneous catalyst for the synthesis of β-amino ketones by three-component one-pot Mannich reaction between various aromatic aldehydes with amines and acetophenone at room temperature under solvent-free condition. The effect of the amount of catalyst and reaction time were investigated. The results showed that CFPIL has good to moderate catalytic activity and reusability. The catalytic process was simple and the catalyst could be easily recovered by filtration and washed with ethanol to reuse for the next experiment without significant loss of catalytic activity. Graphical Abstract: [Figure not available: see fulltext.]. © 2017, Springer Science+Business Media B.V.

Solvent-free synthesis of β-amino ketones using carboxyl-functionalized poly(ionic liquid) at room temperature

Abstract: Esters of levulinic acid (LA) are bio-based compounds having widespread applications and have the remarkable potential to be blended with commercial diesel or gasoline. In this study, a sulphonic acid-functionalized benzimidazolium based poly ionic liquid (SAFBPIL) catalyst was prepared and characterized by NMR, FT-IR, elemental analysis (C, H, N, S), TGA and BET surface area. Brønsted acidity was determined by anion-exchange/neutralization titration method and was found to be 5.55 mmol/g. The heterogeneous ionic liquid catalyst showed an excellent thermal stability up to 270 °C. Experiments were carried at different temperatures, LA to ethanol molar ratios, catalyst loadings and duration of the reaction in a batch reactor. The highest conversion was obtained at 70 °C using an initial LA:ethanol molar ratio of 1:10 and a catalyst loading of 15 wt% in 9 h. It was observed that ethyl levulinate (EL) could be effectively obtained over SAFBPIL with a selectivity higher than 99.5%. This is due to more acidic sites exhibited on SAFBPIL catalyst under optimized conditions. Herein, we are reporting for the first time an esterification of LA to EL using a new SAFBPIL as a catalyst. The catalyst was recycled for five runs without significant loss of catalytic activity. © 2017, Springer Science+Business Media, LLC, part of Springer Nature.

Catalysis Letters

Sulphonic Acid-Functionalized Benzimidazolium Based Poly Ionic Liquid Catalyzed Esterification of Levulinic Acid

Polymer-supported Zn-salen (PS-Zn-salen) complexes were synthesized, characterized and used as a catalyst for one-pot oxidative esterification of aldehydes with alcohols. The PS-Zn-salen heterogeneous catalyst exhibited a high-performance for the oxidative esterification of aldehydes to the corresponding methyl/ethyl esters using hydrogen peroxide as a green oxidant. Due to the synergistic effect of polymer support, the heterogeneous catalyst presented superior catalytic activity and afford 100% conversion of 3,4,5-trimethoxybenzaldehyde and 4-chlorobenzaldehyde to corresponding esters under optimized conditions. The different alcohol substrates study (viz. methyl alcohol, ethyl alcohol, allyl alcohol and benzyl alcohol) showed reasonable selectivity for esters, indicating the scope of the catalysts. Significantly, the synthesized complexes possess good hydrophobic/heterogeneous properties, which permit facile reclamation of the catalyst by using mere filtration. Moreover, the effect of counter anions of complex also studied which indicated that there is no appreciable influence on the conversion of product. The catalyst was reused up to 5th successive run with the average conversion of ester 87.4%. Mechanistic studies have recognized that this “one pot” direct oxidative esterification proceeds through acid formation, proven by a GC–MS. The catalyst is also found to be very stable, up to 280 °C, confirmed by the thermo gravimetric study. © 2017 Elsevier B.V.

Journal of Molecular Liquids

Polymer supported Zn-salen complexes: An effective one-pot oxidative esterification of aldehydes to carboxylic esters

A novel adsorbent for enhanced absorption of chromium(iii).

Synthesis of a graft-copolymer adsorbent through a green route and studies on its interactions with chromium(iii) through active functional groups: kinetics and improved adsorption supported by SEM-EDX and AFM

In the present work, we have designed and synthesized a thermally stable catalyst based on functionalized benzimidazolium perchlorate ionic liquid and tested its efficacy towards metal free and solvent free transamidation of amides and amines. The ionic liquid comprising the perchlorate ion has shown remarkably better activity than those which contain other anions and accordingly a plausible mechanism for the catalytic activity is arrived. The developed catalytic system has shown excellent activity towards the transamidation of alicyclic and aromatic amines with acetamide, benzamide and p-nitrobenzamide under mild conditions. Furthermore, the transamidation of nicotinamide with benzylamine in presence of the ionic liquid catalyst was found to occur with very good yields and thus provides a facile route for the synthesis of pharmaceutically significant compounds. The catalyst has exhibited very good thermal stability upto 203 °C and very good recyclability upto 5 runs without significant loss in its activity. © 2015 Elsevier B.V. All rights reserved.

Journal	Data powered by TypesetRSC Advances
Publisher	Data powered by TypesetRoyal Society of Chemistry (RSC)
ISSN	20462069
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