Highly efficient Suzuki cross-coupling reaction of biomaterial supported catalyst derived from glyoxal and chitosan

WOS: 000368090500005In this study a new chitosan based water soluble Schiff base was produced through carboxymethylation of chitosan and its Pd(II) complex were synthesized and characterized by FTIR, H-1 NMR, C-13 CP-MAS NMR, TG/DTG, SEM/EDAX, XRD, ICP-OES, UV-Vis, magnetic moment measurements, molar conductivity measurements. The catalytic activity of the complex was tested in Suzuki coupling reactions for synthesis of biaryls containing various substrates. The identifications of the biarlys were performed by H-1 NMR and GC-MS. The catalytic activity tests revealed that high selectivity was achieved with a small addition of the catalyst. Moreover by-product formation was not observed in the spectra of H-1 NMR and GC-MS. Mercury poisoning and leaching test confirmed that the catalyst has heterogeneous character. The reusability tests showed that the catalyst did not lose its activity after six runs. (C) 2015 Elsevier B.V. All rights reserved.Scientific and Technological Research Council of Turkey (TUBITAK) [113Z296]The authors thank The Scientific and Technological Research Council of Turkey (TUBITAK) (Project Number: 113Z296) for financial support

Production of palladium nanocatalyst supported on modified gum arabic and investigation of its potential against treatment of environmental contaminants

Removal of organic pollutants such as aromatic nitro compounds and dyes from wastewaters is very significant for environment, and the best strategy is their reduction/degradation in the presence of a metal catalyst. In this study, a new palladium nanocatalyst (GA-Sch-Pd) was prepared derived from modified gum arabic and characterized by FT-IR, TGA, FE-SEM, EDS, TEM, and XRD analyses. Then, the catalytic potential of GA-Sch-Pd nanocatalyst was tested in the catalytic reductions of different organic pollutants such as o-nitroaniline (o-NA), p-nitrophenol (p-NP), p-nitro-o-phenylenediamine (p-NPDA), p-nitroaniline (p-NA), congo red (CR), methylene blue (MB), and methyl orange (MO) by using NaBH4 in water. These tests showed GA-Sch-Pd nanocatalyst had high activity against reduction of nitroarenes and organic dyes at very short reaction durations. Moreover, GA-Sch-Pd nanocatalyst was easily separated and reused for several times. This study shows that GA-Sch-Pd nanocatalyst has a high potential for remediation of environmental pollutants in wastewaters

Cu(II) and Pd(II) complexes of water soluble O-carboxymethyl chitosan Schiff bases: Synthesis, characterization

WOS: 000359166300069PubMed: 26021275This study reports the synthesis of two new water soluble O-carboxymethyl chitosan Schiff bases (OCMCS-5 and OCMCS-6a) and their Cu(II) and Pd(II) complexes. Characterizations of these complexes were carried out with FTIR, elemental analysis, C-13 CPMAS, UV-vis, magnetic moment and molar conductivity techniques. The degrees of substitution (DS) for OCMCS-5a and OCMCS-6a were determined to be 0.48 and 0.44 in elemental analysis. The solubility test revealed that OCMCS-5a and OCMCS-6a dissolved thoroughly in water. The surface morphologies of chitosan (CS), OCMCS-5a, OCMCS-6a and their complexes were studied with SEM-EDAX. Thermal stability of the synthesized compounds was evaluated by TG/DTG and their crystallinity values were investigated with powder X-ray diffraction. Cu(II) and Pd(II) contents of the complexes were estimated with ICP-OES. The characterization studies demonstrated that the thermal stability and crystallinity values of the OCMCS-5a and OCMCS-6a were lower than those of CS.Scientific and Technical Research Council of Turkey (TUBITAK) [113Z296]; Aksaray University Scientific Research Projects Coordination [2012-20]; Science and Technology Application and Research Center of Aksaray University, TurkeyWe thank the Scientific and Technical Research Council of Turkey (TUBITAK; Project Number: 113Z296), Aksaray University Scientific Research Projects Coordination (Project Number: 2012-20) and Science and Technology Application and Research Center of Aksaray University, Turkey for their financial support. We thank Idris Sargin for his contribution in writing English version of the manuscript

Polymeric material prepared from Schiff base based on O-carboxymethyl chitosan and its Cu(II) and Pd(II) complexes

WOS: 000374612400025In this study, a new eco-friendly Schiff base based on O-carboxymethyl chitosan ([OCMCS-7a]) and its copper(II) and palladium(II) complexes were synthesized. Characterizations of [OCMCS-7a] and its metal complexes were conducted using FTIR, H-1 NMR, C-13 NMR, TG/DTG, XRD, SEM-EDAX, ICP, UV-VIS, GC-MS, elemental analysis, magnetic moment and molar conductivity measurements. The degree of substitution (DS) of [OCMCS-7a] was determined by elemental analysis to be 0.44. It was shown by the solubility test that [OCMCS-7a] was completely soluble in water. Surface images of chitosan, [OCMCS-7a] and its Cu(II) and Pd(II) complexes were investigated using the SEM-EDAX technique. Their thermal behaviors and crystallinities of the synthesized complexes were determined by TG/DTG and X-ray powder diffraction techniques, respectively. The metal contents of the obtained complexes were determined using an ICP-OES instrument. From the analyses, it was noted that the thermal stabilities and crystallinities of [OCMCS-7a] and its complexes decreased compared to chitosan. As a consequence of surface screening, it was also noted that the surface structure of the chitosan was smoother than that of the obtained compounds. (C) 2016 Elsevier B.V. All rights reserved.Scientific and Technological Research Council of Turkey (TUBITAK) [113Z296]We would like to thank The Scientific and Technological Research Council of Turkey (TUBITAK) (Project Number: 113Z296) for financial support

Cationic palladium(II) catalysts on O-carboxymethyl chitosan schiff base for Suzuki coupling reactions

WOS: 000385564600005In this study, catalytic activity of two different cationic O-Carboxymethyl chitosan Schiff base palladium (II) complexes in Suzuki coupling reactions and synthesis of biarlys having different functional groups, and reusability of the catalysts were tested. Chemical structures of the synthesized biaryls were elucidated by GC-MS and H-1-NMR; and no by-products were observed in the spectra. Cationic palladium (II) catalysts high turnover numbers and selectivity were recorded for the reactions. Mercury test demonstrated that the reaction mechanism proceed a homogeneous route. Reusability tests of cationic biocatalysts showed that their catalytic activity were still highly efficient even after six cycles.Scientific and Technical Research Council of Turkey (TUBITAK) [113Z296]; Aksaray University Scientific Research Projects Coordination [201220]; Science and Technology Application and Research Center of Aksaray University, TurkeyThis work was financial support by the Scientific and Technical Research Council of Turkey (TUBITAK; Project Number: 113Z296), Aksaray University Scientific Research Projects Coordination (Project Number: 201220). Science and Technology Application and Research Center of Aksaray University, Turkey

Construction of new biopolymer (chitosan)-based pincer-type Pd(II) complex and its catalytic application in Suzuki cross coupling reactions

WOS: 000394919100067In this paper we described the fabrication, characterization and application of a new biopolymer (chitosan)-based pincer-type Pd(II) catalyst in Suzuki cross coupling reactions using a non-toxic, cheap, ecofriendly and practical method. The catalytic activity tests showed remarkable product yields as well as TON (19800) and TOF (330000) values with a small catalyst loading. In addition, the catalyst indicated good recyclability in the Suzuki C-C reaction. This biopolymer supported catalyst can be used with various catalyst systems due to its unique properties, such as being inert, green in nature, low cost and chemically durable.Aksaray University Scientific Research Projects [2016-021]The authors thank Aksaray University Scientific Research Projects Coordination for their financial support (Project Number: 2016-021)

Ullmann type N-Arylation reactions of Iodo pyrazoles with phenyl boronic acid in Cu2O catalyst

Ullmann tipi reaksiyonlar bakır katalizörü kullanılarak pirazollerin N-arilasyonu gerçekleştirmek için en etkili yöntemlerden birisidir. Geleneksel yöntemlerle gerçekleştirilen Ullmann reaksiyonu yüksek sıcaklıklarda ve stokiyometrik oranda bakır reaktifleri kullanılarak sert reaksiyon koşulları altında gerçekleşmektedir. Daha verimli bakır katalizörlerinin gelişmesi ile bu alanda yapılan çalışmalar devam ederek hafif koşullar altında oldukça verimli bakır/ligant sistemleri geliştirildi. Ullmann tipi reaksiyonların verimliliğini arttırmak için birçok bakır/ligant kombinasyon reaksiyonlarının nispeten yumuşak koşullar altında gerçekleştirdiği bilinmesine rağmen, son yıllarda ligant içermeyen ve "yeşil" çözücülerle ya da çözücüsünden arındırılmış daha basit katalizör sistemleri üzerine çalışmalar yapılmaktadır. Bu çalışmada pirazollerin ılıman şartlarda N-arilasyonuna katkı sağlaması amacıyla fenil boronik asit ile 4-iyodo-1H-pirazol (I-Pz) veya 4-iyodo-3,5-dimetil-1H-pirazolün (I-DMPz) Cu2O katalizörlüğünde N-arilasyonu ile 4-Iyodo-1-fenil-1H-pirazol (Ph-IPz) ve 4-Iyodo-3,5-dimetil-1-fenil-1H-pirazol (Ph-IDMPz) bileşikleri literatürdeki yönteme göre uyarlanarak sentezlenmiştir. 4-İyodo pirazollerin fenil boronik asit ile N-arilleme reaksiyonları Cu2O katalizörlüğünde, atmosferik koşullarda, oda sıcaklığında ve metil alkol içerisinde herhangi bir baz ve ligant kullanılmadan gerçekleştirilmiştir. Böylece daha ılıman koşullarda Ullmann reaksiyonu ile ilk defa Ph-IPz ve Ph-IDMPz’ın sentezi gerçekleştirilmiştir. Sentezi gerçekleşen Ph-IPz ve Ph-IDMPz’in yapıları FT-IR, NMR ve GC-MS kütle spektrumları alınarak karakterize edilmiştir. Bileşiklerin NMR ve FT-IR spektrumunda hem pirazole hem de fenil grubuna ait karakteristik pikler gözlenmiştir.Elde edilen Ph-IPz ve Ph-IDMPz bileşiklerinin 1H-NMR spektrumlarında N-H proton piklerinin görülmemesi fenil grubunun pirazole NH’dan bağlandığının bir göstergesidir. 13C-NMR spektrumlarında 4-sübstitüe pirazoller için belirleyici olan C4 karbon piklerindeki kaymalar da bileşiklerin yapılarını doğrulamaktadır.Ullmann type reactions are one of the most effective methods to carry out the N-arylation of the pyrazole using copper catalyst. The Ullmann reaction carried out by conventional methods occur under hard reaction conditions using copper reagents at stoichiometric ratio and at high temperatures. With the development of more efficient copper catalysts, studies in this field have been continued and very efficient copper/ligand systems have been developed under mild conditions. Although it is known that many of copper / ligand system reactions are carried out under relatively mild conditions to increase the efficiency of Ullmann type reactions, in recent years, studies have been made on simpler catalyst systems which are ligand free and "green" solvents or solvent free. In this study, in order to contribute to N-arylation of pyrazoles in mild conditions, 4-Iodo-1- phenyl -1H-pyrazole (Ph-IPz) and 4-iodo-3,5-dimethyl-1-phenyl-1H-pyrazole (Ph-IDMPz) compounds were synthesized according to the methods adapted from literature with N-arylation reaction of 4-Iodo-1H-pyrazole (4-IP) or 4-iodo-3,5-dimethyl-1H-pyrazole (4-IDMPz) with phenyl boronic acid in the prences of Cu2O catalyst. N-Arylation reactions of 4-iodopyrazols with phenyl boronic acit were carried out the presence of Cu2O catalyst, at atmospheric conditions, at room temperature, in methyl alcohol and without the use of any base and ligand. In this way , the synthesis of Ph-IPz and Ph-IDMPz was carried out for the first time with Ullmann reaction under the milder conditions. Synthesized ligands Ph-IPz and Ph-IDMPz were characterized by FT-IR, NMR and GC-MS mass spectra. The NMR and FT-IR spectra of the compounds showed characteristic peaks of both the pyrazole and the phenyl group. The absence of N-H proton peaks in the 1 H-NMR spectra of the obtained Ph-IP 2 and Ph-IDMP 2 compounds indicates that the phenyl group is attached from the pyrazole NH. The shifts in the C4 carbon peaks which are determinant for 4- substituted pyrazoles in the 13C-NMR spectra also confirm the structure of the compounds

Microwave assisted synthesis of biarlys by C-C coupling reactions with a new chitosan supported Pd(II) catalyst

WOS: 000381167800013In this study a new type chitosan-based support has been produced for Pd(II) catalyst and its catalytic performance in Suzuki C-C reactions has been studied under microwave irradiation without using any solvent. The chemical identification of the catalyst was performed using TG/DTG, FTIR, UV-Vis ICP-OES, SEM/EDAX, C-13 NMR, molar conductivity, XRD and magnetic moment techniques. The performance of this new Pd(II) catalyst was studied in Suzuki C-C reactions. The Pd(II) catalyst exhibited a good catalytic performance in very short time (4 min) by giving high TONs and TOFs with low amount of the catalyst (0.015 mol%). The catalyst also had reusability and did not lose its activity until six runs.Scientific and Technological Research Council of Turkey (TUBITAK) [113Z296]We would like to thank the Scientific and Technological Research Council of Turkey (TUBITAK) (Project Number: 113Z296) for financial support

Synthesis and characterization of diblock, triblock, and multiblock copolymers containing Poly(3-hydroxy butyrate) units

A poly[(R,S)-3-hydroxybutyrate] macroinitiator (PHB-MI) was obtained through the condensation reaction of poly[(R,S)-3-hydroxybutyrate] (PHB) oligomers containing dihydroxyl end functionalities with 4,4'-azobis(4-cyanopentanoyl chloride). The PHB-MI obtained in this way had hydroxyl groups at two end of the polymer chain and an internal azo group. The synthesis of ABA-type PHB-b-PMMA block copolymers [where A is poly(methyl methacrylate) (PMMA) and B is PHB] via PHB-MI was accomplished in two steps. First, multiblock active copolymers with azo groups (PMMA-PHB-MI) were prepared through the redox free-radical polymerization of methyl methacrylate (MMA) with a PHB-MI/Ce(IV) redox system in aqueous nitric acid at 40°C. Second, PMMA-PHB-MI was used in the thermal polymerization of MMA at 60°C to obtain PHB-b-PMMA. When styrene (S) was used instead of MMA in the second step, ABCBA-type PMMA-b-PHB-b-PS multiblock copolymers [where C is polystyrene (PS)] were obtained. In addition, the direct thermal polymerization of the monomers (MMA or S) via PHB-MI provided AB-type diblocks copolymers with MMA and BCB-type triblock copolymers with S. The macroinitiators and block copolymers were characterized with ultraviolet-visible spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography, cryoscopic measurements, and thermogravimetric analysis. The increases in the intrinsic viscosity and fractional precipitation confirmed that a block copolymer had been obtained. © 2004 Wiley Periodicals, Inc