Supported Schiff Base Research Articles

A selective heterogeneous cellulose supported Schiff base Cu(II) catalyst for Chan–Evans–Lam coupling

A selective heterogeneous cellulose supported Schiff base Cu(II) catalyst for Chan–Evans–Lam coupling

Antimicrobial corrosion study of the epoxy coating with the graphene oxide supported Schiff base quaternary ammonium salt additives

In order to effectively inhibit microbial corrosion, the compounds of Schiff base quaternary ammonium salt (SQAS) and graphene oxide (GO) were used as filler added into the epoxy resin coating. The mechanical, hydrophobic and anti-microbial corrosion properties in simulated seawater of SQAS-GO inhibitor coating on carbon steel were investigated by grid test, contact angle test, electrochemical test and surface topography analysis, respectively. These results suggested that 0.5% SQAS-GO strengthened the anti-microbial corrosion performance of the epoxy resin coating. The electrochemical test results also demonstrated that the impedance value of the 0.5% SQAS-GO coating (6.31 ×1010 ohm cm2) was two orders of magnitude higher than that of the pure epoxy coating (1.09 ×108 ohm cm2) after being immersed in simulated seawater for 14 days. Moreover, molecular dynamics simulation of inhibitor provided the theoretical support for the experimental results.

Enantioselective Aza‐Diels Alder reaction catalyzed by clay supported Schiff base complex†

AbstractClay supported catalysts based on 2‐ hydroxy naphthaldehyde and amino acids, their copper and titanium complexes have been described. The catalysts were found to be active toward the synthesis of pyrano‐, furanoquinolines through Aza‐Diels Alder reaction. The catalysts gave good yield and high enantioselectivity. The catalysts were environmentally friendly, economical, synthetically robust and reusable.

Solvent-free synthesis of 1-amidoalkyl-2-naphthols using magnetic nanoparticle-supported 2-(((4-(1-iminoethyl)phenyl)imino)methyl)phenol Cu (II) or Zn (II) Schiff base complexes

Two magnetic nanoparticle-supported 2-(((4-(1-iminoethyl)phenyl)imino)methyl)phenols were successfully synthesized, characterized, and applied in the one-pot three-component reaction of substituted benzaldehydes, 2-naphthol, and amides for synthesis of 1-amidoalkyl-2-naphthols. These three-component processes occurred under solvent-free reaction conditions at 80 °C. The magnetically recoverable supported Schiff base metal catalysts can be reused several times in the model reaction. The synthesized catalysts are also easily separated from the reaction mixture by applying an external magnet. This procedure offers the advantages of simple, operational procedure as well as no use of hazardous organic solvents.

Synthesis and characterization of VO–vanillin complex immobilized on MCM‐41 and its facile catalytic application in the sulfoxidation reaction, and synthesis of 2,3‐dihydroquinazolin‐4(1H)‐ones and disulfides in green media

AbstractIn this work, a vanillin complex is immobilized onto MCM‐41 and characterized by FT‐IR, X‐ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetric analysis, and BET techniques. This supported Schiff base complex was found to be an efficient and recoverable catalyst for the chemoselective oxidation of sulfides into sulfoxides and thiols into their corresponding disulfides (using hydrogen peroxide as a green oxidant) and also a suitable catalyst for the preparation of 2,3‐dihydroquinazolin‐4(1H)‐one derivatives in water at 90°C. Using this protocol, we show that a variety of disulfides, sulfoxides, and 2,3‐dihydroquinazolin‐4(1H)‐one derivatives can be synthesized in green conditions. The catalyst can be recovered and recycled for further reactions without appreciable loss of catalytic performance.

CoFe2O4@SiO2@ Co (III) salen complex nanoparticle as a green and efficient magnetic nanocatalyst for the oxidation of benzyl alcohols by molecular O2

In the presence of cobalt (III) salen complex, selective oxidation of alcohols to carbonyl compounds was studied by molecular oxygen using isobutyraldehyde as an oxygen acceptor. The effect of cobalt (III) salen complex in the oxidation reaction was studied, and the results showed that Co (III) salen complex is very active and selective in the oxidation of various alcohols. Also, the effect of important factors including catalyst amount, solvent and temperature was investigated on the reaction. Furthermore, the catalytic activities of CoFe2O4@SiO2‐supported Schiff base metal complex as well as the effect of molecular oxygen (O2) as a green oxidant were studied. The results showed that benzaldehyde was the major product and the heterogeneous catalyst was highly reusable.

Oxidation of Alcohols on a Supported Schiff Base–Molybdenum(VI) Complex

Oxidation of Alcohols on a Supported Schiff Base–Molybdenum(VI) Complex

Synthesis and Metal Ion Uptake Studies of Silica Gel-Immobilized Schiff Base Derivatives and Catalytic Behaviors of their Cu(II) Complexes

New silica supported Schiff base ligands were prepared by the condensation reaction of 4,6-diacetylresorcinol with silica-gel derivatives, which modified with 3-aminopropyltriethoxysilane and N-(2-aminoethyl) -3-aminopropyltrimethoxysilane. Metal ion uptake capacities of these compounds were studied towards of selected transition metal (Cd(II), Cu(II), Co(II), Mn(II), Pb(II) and Ni(II)) cations in an aqueous medium. In addition, Cu(II) complexes of these ligands were prepared by using heterogeneous reaction conditions. The synthesized compounds were characterized by using elemental analysis, FT-IR, DR-UV-vis., CP/MAS 13C-NMR, AAS, XRD and TGA techniques. Moreover, the morphological and chemical properties of these compounds were investigated by using a scanning electron microscope (SEM) coupled to an energy-dispersive X-ray spectrometer (EDX). The catalytic performances of the Cu(II) complexes were investigated on H2O2 decomposition. These complexes displayed good catalytic activities towards the decomposition of H2O2 as heterogeneous catalysts.

Study of Catalytic Activity of Silica Supported Schiff Base Complexes

Study of Catalytic Activity of Silica Supported Schiff Base Complexes

ChemInform Abstract: A Catalysis Study of Mesoporous MCM‐41 Supported Schiff Base and CuSO4·5H2O in a Highly Regioselective Synthesis of 4‐Thiazolidinone Derivatives from Cyclocondensation of Mercaptoacetic Acid.

AbstractBoth in‐situ generated imines [e.g. from (II) and (III)] and pre‐synthesized imines [e.g. (V)] can react with mercaptoacetic acid (I) to give the thiazolidinones [e.g. (IV)] in high yields.

Photo-catalytic degradation of methylene blue over nano titanium/nickel oxide prepared from supported Schiff base complex on titanium dioxide

A novel nano compound TiO2/[NiL(PBu3)] (where L = (E)-1-[(2-Amino-5-nitrophenyl)iminio-methyl]naphthalene-2-olate) containing tridentate ONN Schiff bases was synthesized. The compound calcinated to Ni-doped TiO2 at 650 °C. The structure and morphology of the obtained nano particles were identified by IR, XRD, FE-SEM, TEM and EDX techniques. Based on the XRD and EDX results of the new nano materials, the Schiff base complex supported on TiO2 nano oxide. SEM and TEM micrographs of the TiO2/complex and Ni-doped TiO2 show that the resulting new materials have nano structure. The photo-catalytic activities of the samples were investigated by carrying out the photodegradation of methylene blue in aqueous solution under visible light. It was found that the Ni-doped TiO2 samples enhanced the photo-catalytic efficiency of bare TiO2 in photo-degrading the methylene blue. The reasons of this enhanced photo-catalytic activity were also discussed. Kinetic research showed that the reaction rate constant of calcined Ni-doped TiO2 is 8.10 × 10−2 min−1 which is approximately 2.45 times higher than the apparent reaction rate constant of uncalcined Ni-doped TiO2 (3.30 × 10−2 min−1). Based on the present study, it could be considered as a promising photo-catalyst for the further industrial application.

A catalysis study of mesoporous MCM-41 supported Schiff base and CuSO4·5H2O in a highly regioselective synthesis of 4-thiazolidinone derivatives from cyclocondensation of mercaptoacetic acid

Mesoporous MCM-41 supported Schiff base and CuSO4·5H2O shows high catalytic activity in the cyclocondensation of mercaptoacetic acid with imines (or aldehydes and amines) to afford pharmaceutically important thiazolidinone derivatives. The catalytic reactions involving two-components or three-components afforded the desired product in high yields (up to 98% and 99%). Moreover, the catalyst works well with respect to recyclability, giving the product in 85% and 83% yields after recycling six times.

Synthesis and characterization of Ni and Zn Schiff base complexes supported on modified MCM-41 as reusable catalysts for various oxidation reactions

Using post grafting method, two hybrids composite materials were prepared by anchoring Nickel and Zinc Schiff base complexes onto amino-modified MCM-41(Ni-MCM-41 and Zn-MCM-41). The prepared catalysts have been characterized by FT-IR spectroscopy, thermogravimetric analysis, and transmission electron microscopy, powder X-ray diffraction and N2 adsorption–desorption isotherms. The catalysts showed excellent catalytic efficiency in oxidation reaction of sulfides to sulfoxides and oxidative coupling of thiols to their corresponding disulfides using urea hydrogen peroxide as oxidant under mild reaction conditions. The supported Schiff base complexes can be recovered easily and reused many times without significant loss in catalytic activity and selectivity.

Catalytic activities of novel silica-supported multifunctional Schiff base ligand & metal complexes under microwave irradiation

In this paper, a novel solid phase supported Schiff base ligand (L1: MDPMP) was prepared from 2-hydroxy-5-((2-methoxyphenyl)diazenyl) benzaldehyde (L: HMDB) and silica-gel, activated with 3-aminopropyltriethoxysilane (APTES). Cu (II), Co (II), Ni (II) and Mn (II) complexes of silica-supported ligand (L1: MDPMP) were obtained. The ligand and its four metal complexes were characterized by using NMR (1H and 13C), FT-MIR/FIR, elemental analysis, ICP-OES, TGA and Scanning Electron Microscope (SEM). Their catalytic performances in catalytic oxidation of cyclohexane were investigated for the selective oxidation of cyclohexane under microwave power. Silica-supported L1–Cu (II) complex was observed well selective catalytic properties for the oxidation of cyclohexane to cyclohexanol and cyclohexanone.

Synthesis and Characterization of Graphene Oxide Supported Schiff Base Palladium Catalyst and Its Catalytic Performance to Suzuki Reaction

Synthesis and Characterization of Graphene Oxide Supported Schiff Base Palladium Catalyst and Its Catalytic Performance to Suzuki Reaction

Epoxidation of α,β-Unsaturated Ketones Catalyzed by Schiff Base Functionalized MCM-41 and Potassium Carbonate

Mesoporous molecular sieves MCM-41 supported Schiff base was prepared from MCM-41,3-chloropropyltriethoxysilane,dis-thiocarbohydrazone and salicylide.Both as-prepared supported catalyst and K2CO3 were used to catalyze the epoxidation of α,β-unsaturated ketones in the presence of H2O2.All products from these oxidations were characterized by1H NMR and IR.The effects of reaction conditions such as metal salts,solvents,reaction temperature,the loading of catalyst,and reaction time on the oxidation reaction were investigated.It was found that the epoxidation products of α,β-unsaturated ketones were easily obtained with excellent yields(up to 93%) at room temperature in a short time.Especially,the heterogeneous catalyst can be reused four times without significant loss of its catalytic activity.

Efficient and Clean Catalytic Hydrogenolysis of Aromatic Ketones by Silica Supported Schiff Base Modify Chitosan-Palladium Catalyst

An silica supported chitosan-Schiff base Pd(II) catalyst was prepared in a simple way and characterized by XRD, FT-IR, SEM-EDS, XPS and TG, and the ability of this complex to catalyze hydrogenolysis of 1-tetralone into 1,2,3,4-tetrahydronaphthalene was also investigated in the presence of hydrogen. It has been revealed that the catalyst had high catalytic activity for hydrogenolysis of 1-tetralone at ambient temperature and normal pressure of hydrogen. Especially, the hydrogenolysis of 1-tetralone in ethanol solvent gave excellent results and the 100% conversion of 1-tetralone and the 100% selectivity for 1,2,3,4-tetrahydronaphthalene were obtained under optimized reaction conditions. The influences of reaction temperature, reaction time and solvent on the hydrogenolysis of 1-tetralone were also investigated. It has been also revealed that the catalyst was efficient and eco-friendly for the hydrogenolysis of carbonyl that connected with a benzene ring to give corresponding aromatic hydrocarbons.

ChemInform Abstract: Synthesis of β‐Amino Alcohols Catalyzed by Poly(vinyl chloride)‐Supported Schiff Base Metal Complexes.

AbstractA Ni(II) complex of PVC‐supported 2‐[(2‐aminoethylimino)methyl]phenol is found to be a highly effective catalyst in the synthesis of β‐amino alcohols by ring opening of epoxides with amines.

Study on the Epoxidation ofα,β-Unsaturated Ketones Catalyzed by MCM-41 Supported Schiff Base

The novel mesoporous molecular sieves MCM-41 supported Schiff base was prepared by MCM-41 and Schiff base, which was synthesized by 3-chloropropyltriethoxysilane, 1,2-cyclohexanediamine with 2-phenyl-2H-1,2,3-triazole-4-carbaldehyde. The catalyst was characterized by methods of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The epoxidation of α,β-unsaturated ketones catalyzed by MCM-41 supported Schiff base was studied in the presence of H2O2. The reaction con- ditions such as metal salts, different solvents, reaction temperature, the catalyst amount, and reaction time were investigated. It was found that the epoxidation of α,β-unsaturated ketones was easily obtained in excel- lent yields (up to 99%) using acetonitrile as the solvent at room temperature in short time. Especially, the heterogeneous catalyst can be reused four times without significant loss of its catalytic activity.

Synthesis of β-amino alcohols catalyzed by poly(vinyl chloride)-supported Schiff base metal complexes

Eight transition metal complexes of various Schiff bases supported on poly(vinyl chloride) (PVC) were prepared and characterized. These metal complexes were screened as heterogeneous catalysts in the synthesis of β-amino alcohols by ring opening of epoxides with amines. The best catalyst was identified as a Ni(II) complex of PVC-supported 2-[(2-aminoethylimino)methyl]phenol and it was used in the synthesis of a number of different β-amino alcohols. The catalyst was found to be reusable for up to five cycles.