Using Urea Hydrogen Peroxide Research Articles

Enhancing acidogenic fermentation of waste activated sludge via urea hydrogen peroxide pretreatment: Performance and mechanisms

Improving the anaerobic treatment performance of waste activated sludge (WAS) to achieve resource recovery is an indispensable requirement to reduce carbon emissions, minimize and stabilize biosolids. In this study, a novel strategy by using urea hydrogen peroxide (UHP) to enhance SCFAs production through accelerating WAS disintegration, degrading recalcitrant substances and alleviating competitive suppression of methanogens. The SCFAs production and acetate proportion rose from 436.9 mg COD/L and 31.3% to 3102.6 mg COD/L and 54.1%, respectively, when UHP grew from 0 to 80 mg/g TSS. Mechanism investigation revealed that OH, O2 and urea were the major contributors to accelerate WAS disintegration with the sequence of OH>O2 > urea. Function microbes related to acidification and genes associated with acetate production ([EC:2.3.1.8] and [EC:2.7.2.1]) were upregulated while genes encoding propionic acid production ([EC:6.4.1.3] and [EC:6.2.1.1]) were downregulated. These results raised the application prospects of UHP in WAS resource utilization.

Polysorbate 80/UHP as a recyclable, bio-degradable and metal-free safer system for the fast oxidation of thiols

Herein, we describe an efficient, fast, mild and sustainable protocol for the oxidation of thiols using Urea Hydrogen Peroxide (UHP) to give the corresponding disulfides in good to excellent yields. The methodology uses polysorbate 80 as a greener solvent and catalyst which was, for the first time, recovered from the reaction medium and reused.

Synthesis, characterization, crystal structures, Hirshfeld surface analysis, DFT computational studies and catalytic activity of novel oxovanadium and dioxomolybdenum complexes with ONO tridentate Schiff base ligand

For the first time, two new oxovanadium and dioxomolybdenum Schiff base complexes, VOL(OMe) and MoO2L, were synthesized through the reaction of a ONO tridentate Schiff base ligand (H2L) derived from the condensation of 5-bromosalicylaldehyde and nicotinic hydrazide with oxo and dioxo acetylacetonate salts of vanadium and molybdenum, [VO(acac)2 and MoO2(acac)2], respectively. The synthesized ligand and complexes were characterized by various spectroscopic techniques like FT-IR, 1H NMR, 13C NMR, elemental analysis (CHN) and the most authentic single crystal X-ray diffraction analysis (SC-XRD). The geometry around the central metal ion in MoO2L was distorted octahedral as revealed by the data collected from diffraction studies. Non-covalent interactions that are responsible for crystal packing are explored by Hirshfeld surface analysis. Theoretical calculations of the synthesized compounds, carried out by DFT at B3LYP/Def2-TZVP level of theory, indicated that the calculated results are in agreement with the experimental findings. Moreover, the catalytic activities of both complexes were investigated for the selective oxidation of benzylic alcohols using urea hydrogen peroxide (UHP) in acetonitrile.

A novel binuclear iron(III)-salicylaldazine complex; synthesis, X-ray structure and catalytic activity in sulfide oxidation

A novel binuclear iron(III)-salicylaldazine complex has been synthesized and characterized by various techniques such as IR and UV–Vis spectroscopy and X-ray crystallography. The catalytic oxidation of sulfides in the presence of the aforementioned complex was explored at room temperature using urea hydrogen peroxide (UHP) as an oxidant. Effects of different reaction conditions consisting catalyst and oxidant amount, solvent effect and reaction time on the catalytic activity and selectivity in the reaction of methylphenylsulfide oxidation has been surveyed. Perfect selectivity toward sulfoxide was achieved after 15 min in CH3CN by choice of a properly optimized reaction condition.

Urea–hydrogen peroxide prompted the selective and controlled oxidation of thioglycosides into sulfoxides and sulfones

A practical method for the selective and controlled oxidation of thioglycosides to corresponding glycosyl sulfoxides and sulfones is reported using urea–hydrogen peroxide (UHP). A wide range of glycosyl sulfoxides are selectively achieved using 1.5 equiv of UHP at 60 °C while corresponding sulfones are achieved using 2.5 equiv of UHP at 80 °C in acetic acid. Remarkably, oxidation susceptible olefin functional groups were found to be stable during the oxidation of sulfide.

Simple synthesis of sandalwood odorant rac‐Osyrol® and its ethoxy homologue

Abstractrac‐Osyrol® (3,7‐dimethyl‐7‐methoxyoctane‐2‐ol), a commercially important sandalwood odorant has been prepared from dihydromyrcene in three steps. The key steps in the synthesis are the epoxidation of terminal double bond using urea hydrogen peroxide (UHP) and regioselective reduction of epoxide using Vitride®. The same strategy has been applied to the synthesis of its ethoxy homologue. Copyright © 2015 John Wiley & Sons, Ltd.

Simple and Efficient One-Pot Synthesis of 2-Substituted Benzimidazoles from θ-Diaminoarene and Aryl Aldehydes

An easy and efficient one-pot condensation method for the synthesis of substituted benzimidazoles from θ-phenylenediamines with aryl aldehydes using urea hydrogen peroxide (UHP) and I2 in dimethylsulfoxide (DMSO) provides wide substrate scope with good to excellent yields and simple and quick isolation of the products.

Efficient oxidative coupling of thiols and oxidation of sulfides using UHP in the presence of Ni or Cd salen complexes immobilized on MCM-41 mesoporous as novel and recoverable nanocatalysts

Oxidation of sulfides to sulfoxides and oxidative coupling of thiols into their corresponding disulfides were carried out using urea-hydrogen peroxide (UHP) as oxidizing agent and immobilized Ni or Cd complexes on MCM-41 as stable, heterogeneous, efficient and recoverable catalysts under mild reaction conditions. These supported complexes were characterized by FT-IR spectroscopy, thermogravimetric analysis (TGA), powder X-ray diffraction (XRD) and N2 adsorption–desorption isotherms. A variety of aromatic and aliphatic sulfides and thiols with different functional groups were successfully oxidized with short reaction times in good to excellent yields at room temperature. Catalysts were easily recovered and reused for several consecutive runs without significant loss of their catalytic activity and efficiency.

Bidentate salen Cu(II) complex functionalized on mesoporous MCM-41 as novel nano catalyst for the oxidative coupling of thiols into disulfides using urea hydrogen peroxide (UHP)

Functionalized Copper(II) complex into nano dimensional mesoreactor was successfully prepared. The Copper(II) complex with N–O donor Schiff base ligand was readily trapped into mesoporous silica MCM-41 through the post grafting method. N–O Chelating Schiff-base-MCM-41 has been derived from 5-bromo-salicylaldehyde and 3-aminopropyltriethoxysilane which was functionalized on MCM-41 via silicon alkoxide route. This compound was characterized by FT-IR, TGA, small angle X-ray diffraction patterns, ICP/MS analysis and N2 sorption–desorption analysis. The catalytic property of Cu–salen–MCM-41 was considered for the preparation of disulfides using urea hydrogen peroxide as oxidant. The reaction progress is simple and proceeds under mild and heterogeneous conditions in acetonitrile at the ambient of temperature. The corresponding disulfides have been achieved with high purity and good to excellent yields; also, no over oxidation to sulfoxide or sulfone was observed in all cases. The catalyst can be recovered and reused several times without significant loss of stability and activity.

Synthesis of 14,15-EET from Arachidonic Acid Using Urea–Hydrogen Peroxide as the Oxidant

14,15- Epoxyeicosatrienoic acid (14,15-EET) is an endogenous bioactive lipid with pharmacological benefits in multiple cardiovascular diseases. We describe here a practical synthesis of 14,15-EET from arachidonic acid using urea–hydrogen peroxide (UHP) as the oxidant.

A novel iron complex containing an N,O-type bidentate oxazoline ligand: Synthesis, X-ray studies, DFT calculations and catalytic activity

A five-coordinated Fe(III) complex with the distorted trigonal bipyramidal configuration was synthesized by reactions of FeCl3⋅6H2O and 2-(2′-hydroxyphenyl)oxazoline (Hphox) as a bidentate ON donor oxazoline ligand. Complex [Fe(phox)2Cl] was fully characterized, including by single-crystal X-ray structure analysis. DFT calculations were accompanied with experimental results in order to obtain a deeper insight into the electronic structure and vibrational normal modes of complex. Oxidation of sulfides to sulfoxides in one-step was conducted by this complex as catalyst using urea hydrogen peroxide (UHP) in mixture of CH2Cl2/CH3OH (1:1) under air at room temperature. The results show that using this system in oxidation of sulfides, sulfoxides are obtained as the main products, together with variable amounts of sulfones (⩽13%), depending on the nature of the substrate.

Salen copper(II) complex heterogenized on mesoporous MCM-41 as nano-reactor catalyst for the selective oxidation of sulfides using urea hydrogen peroxide (UHP)

MCM-41 silica spheres were synthesized and functionalized with 3-aminopropyltriethoxysilane (3-APTES). The Schiff base has been derived from amino groups and 5-boromo salicylaldehyde, then a tetra dentate Cu(II)–Schiff base complex was prepared. This compound was characterized by X-ray diffraction, nitrogen physisorption, UV–Vis spectrometer, transmission electron micrographys (TEM), IR-spectra, and TGA/DTA technique. The prepared grafting Cu-salen-MCM-41 over a mesoporous surface was found to be an efficient and selective catalyst for the oxidation of different sulfides into sulfoxides with urea hydrogen peroxide (UHP) giving excellent yields at room temperature. The results showed that Cu-salen-MCM-41 is an effective catalyst for the oxidation of sulfides and can be repeatedly used and regenerated with no significant decrease in its catalytic ability. They also showed that the prepared material retained a good mesoporous structure and the best catalytic properties.

Synthesis, X-ray Studies, and Catalytic Efficacy of a Novel Iron Complex Containing an N,O-Type Bidentate Thiazoline Ligand

The reactions of FeCl3·6H2O and 2-(2′-hydroxyphenyl)-2-thiazoline as a bidentate O-N donor thiazoline ligand (thoz) afford a five-coordinate FeIII complex [Fe(thoz)2Cl] with a distorted square pyramidal configuration. Complex [Fe(thoz)2Cl] was isolated as air-stable crystalline solids and fully characterized, including by single-crystal X-ray structure analysis. Complex [Fe(thoz)2Cl] shows very efficient reactivity in the oxidation of sulfides to their corresponding sulfoxides using urea hydrogen peroxide (UHP) as the oxidant at room temperature in air.

Cassava (Manihot esculenta Crantz of cv. KU50) peroxidase and its potential for the detection of some thiol compounds based on the inhibitory effect of 3,3′,5,5′-tetramethylbenzidine oxidation

Cassava peroxidase (CSP) isolated from cassava leaves (Manihot esculenta Crantz of cv. KU50) was purified by DEAE and concanavalin-A column chromatography. CSP was a haem-containing cationic glycoprotein with the molecular weight of 38 and 44kDa determined by MALDI-TOF-MS. Its kinetic catalysis in the presence and absence of some thiols were investigated and compared to those of horseradish and soybean peroxidases by using urea hydrogen peroxide (UHP) and 3,3′,5,5′-tetramethylbenzidine (TMB) as substrates. Inhibitory effects of some pesticides containing thiol groups such as thiosemicabazide, thiourea and thiophanate-methyl on TMB oxidation were graphically demonstrated their ability to be either competitive or noncompetitive inhibitors, depending on their properties. The degrees of inhibition were expressed as Ki and IC50 values. The applicable range for the detection of thiosemicabazide in solution was found to be in the range of 10–100μM, whereas those of thiourea and thiophanate-methyl were 40–400μM and 10–460μM, respectively. On the contrary, the inhibitory effects of some phenolic pollutants; 4-nitrophenol, 4-phenylphenol and pentachlorophenol on TMB oxidation were not significantly observed and the phenomenon was discussed.

Synthesis, X-ray studies, DFT calculations and catalytic activity of a novel iron complex containing an N,O-type bidentate oxazine ligand

The reactions of FeCl3·3H2O and 2-(2′-hydroxyphenyl)-5,6-dihydro-1,3-oxazine (N–O) as a bidentate O,N donor ligand afforded a five-coordinated iron(III) complex, [Fe(N-O)2Cl], with a distorted trigonal bipyramidal configuration. The complex [Fe(N-O)2Cl] was isolated as an air-stable crystalline solid and was fully characterized, including by single-crystal X-ray structure analysis. The complex [Fe(N-O)2Cl] shows very efficient reactivity in the oxidation of sulfides to their corresponding sulfoxides using urea hydrogen peroxide (UHP) as the oxidant at room temperature under air. To get an insight into the electronic structure of the complex, the experimental studies have been accompanied by density functional theory (DFT) computations.

Preparation of water-dispersible TiO2 nanoparticles from titanium tetrachloride using urea hydrogen peroxide as an oxygen donor

TiO2 nanoparticles were prepared from titanium tetrachloride (TiCl4) in CH2Cl2 at 80 °C for 30 h, 42 h and 70 h using urea hydrogen peroxide (UHP) as an oxygen donor with a TiCl4 : UHP molar ratio of 1 : 2. The XRD patterns and Raman spectroscopy results showed that the products consisted of anatase TiO2. IR and solid-state 13C NMR with cross polarization and magic angle spinning techniques revealed the presence of urea. TEM observation revealed that the products prepared by the reactions for 30 and 42 h consisted of water-dispersible spheroid nanoparticles with a long axis of ~5 nm, while an aggregation of nanoparticles was evident upon reaction for 70 h. Thermogravimetry, inductively-coupled plasma emission spectrometry and CHN analysis showed that the amount of urea increases in the following order: TiO2_42h, TiO2_70h, TiO2_30h. The photocatalytic activity of the products dispersible in water (TiO2_30h and TiO2_42h) was estimated based on the degradation behaviour of methylene blue, and TiO2_42h showed higher photocatalytic activity than TiO2_30h. It is proposed that TiCl4 was directly oxidized by UHP to form anatase TiO2 in the early stage of the process.

Molybdatophosphoric acid as an efficient catalyst for the catalytic and chemoselective oxidation of sulfides to sulfoxides using urea hydrogen peroxide as a commercially available oxidant

An efficient procedure for the chemoselective oxidation of alkyl (aryl) sulfides to the corresponding sulfoxides using urea hydrogen peroxide (UHP) in the presence of a catalytic amount of molybdatophosphoric acid at room temperature is described. The advantages of described method are: generality, high yield and chemoselectivity, short reaction time, low cost and compliment with green chemistry protocols.

Molybdatophosphoric acid as an efficient catalyst for the catalytic and chemoselective oxidation of sulfides to sulfoxides using urea hydrogen peroxide as a commercially available oxidant

An efficient procedure for the chemoselective oxidation of alkyl (aryl) sulfides to the corresponding sulfoxides using urea hydrogen peroxide (UHP) in the presence of a catalytic amount of molybdatophosphoric acid at room temperature is described. The advantages of described method are: generality, high yield and chemoselectivity, short reaction time, low cost and compliment with green chemistry protocols.

Synthesis, characterization and catalytic study of a novel iron(III)-tridentate Schiff base complex in sulfide oxidation by UHP

An hydrazone Schiff base-iron(III) complex using salicylidene benzoyl hydrazine (L) as ligand has been synthesized and characterized by elemental analyses, IR, 1H and 13C NMR and UV–Vis spectroscopy. Oxidation of sulfides to sulfoxides in one-step was conducted by this complex catalyst using urea hydrogen peroxide (UHP) in mixture of CH 2Cl 2/CH 3OH (1:1) under air at room temperature. The effect of the reaction conditions on the oxidation of methylphenylsulfide was studied by varying the amount of the catalyst, reaction temperature, reaction time and the amount of UHP. The results showed that using this system in the oxidation of sulfides, sulfoxides were obtained as the main products, together with variable amounts of sulfones (⩽9%), depending on the nature of the substrate.

One‐Pot Synthesis of Nitrones from Primary Amines and Aldehydes Catalyzed by Methyltrioxorhenium

One-pot condensation/oxidation of primary amines and aldehydes using urea-hydrogen peroxide (UHP) as the stoichiometric oxidant in the presence of methyltrioxorhenium (MTO) as catalyst affords nitrones in a simple and regioselective manner. UHP is a practical and safe source of H2O2, and its use here instead of aqueous H2O2 solutions also simplifies greatly the workup procedure as extractions with organic solvents can be avoided. Typically, at the end of the reaction the solid urea is simply filtered off. From a sustainability point of view, this one-pot synthesis is simple to perform, takes place under mild conditions, has a high atom economy, and releases water as the only by-product.