Urea Hydrogen Peroxide Complex Research Articles

STUDY ON THE SYNTHESIS OF UREA-HYDROGEN PEROXIDE AND APPLICATION FOR OXIDATION OF BENZYLIC ALCOHOLS UNDER MICROWAVE ACTIVATION

The Urea-Hydrogen Peroxide complex was synthesized from urea, hydrogen peroxide by using microwave assisted method and characterized by FT-IR. This Urea-Hydrogen Peroxide complex could be employed as an oxidizing agent for metal-free oxidation reaction of benzylic alcohols to carboxylic acids corresponding. This oxidation protocol, carried out under alkaline-water in microwave oven in presence of iodine as a catalyst, was efficient and compatible with a range of benzylic alcohols to afford a direct access to benzoic derivatives in very good yields up to 95.4% and high selectivities.

Convenient preparation of arylnitromethanes by oxidation of benzaldoximes with urea hydrogen peroxide

Arylnitromethanes were prepared by oxidation of aldoximes with sodium perborate or with urea hydrogen peroxide in the presence of boric acid. The use of urea hydrogen peroxide complex provides better and more stable yields of nitro compound and allows one to halve an acetic acid consumption. Only E-aldoximes are oxidized to arylnitromethanes while Z-isomers are transformed into complex mixtures not containing arylnitromethanes.

SYNTHESIS OF UREA-HYDROGEN PEROXIDE AND ITS APPLICATION FOR PREPARING THIOSULFINATE

The Urea-Hydrogen Peroxide complex (UHP) was synthesized from urea and hydrogen peroxide, characterized by FT-IR. This UHP complex could be employed as an oxidizing agent for metal-free oxidation reaction of disulfides to thiosulfinate compounds. This protocol was carried out under very mild conditions at 0oC in CH3CO2H solvent, was efficient and compatible with a range of alkyl, aryl or allyl disulfides to afford direct access to thiosulfinate compounds in very good yields up to 92% and high selectivities.

Evaluation and optimization of synthetic routes from dihydroartemisinin to the alkylamino-artemisinins artemiside and artemisone: A test of N-glycosylation methodologies on a lipophilic peroxide

10-Alkylamino-artemisinins including artemiside and artemisone display enhanced activities against malaria. Earlier, dihydroartemisinin (DHA) TMS ether was converted by trimethylsilyl bromide into the 10-β-bromide that with amine nucleophiles provided the amino-artemisinins. In an attempt to develop more economic approaches, direct N-glycosylation of DHA was examined but 2-deoxyartemisinin was invariably obtained. However, hydroxyl group activation by conversion into the 10β-halide in non-polar solvents with anhydrous HCl and Group I and II metal halides, oxalyl chloride or thionyl chloride with catalytic DMSO, and oxalyl bromide did succeed. The β-halides were converted in situ by thiomorpholine into artemiside, and by thiomorpholine-1,1-dioxide into artemisone respectively in scalable reactions. Hydrogen peroxide-acetonitrile or the urea-hydrogen peroxide complex efficiently oxidized the sulfide artemiside to the sulfone artemisone. Overall, a generalized approach to 10-alkylamino-artemisinins is now available.

A Mild, Efficient and Highly Selective Oxidation of Sulfides to Sulfoxides Catalyzed by Lewis Acid–Urea–Hydrogen Peroxide Complex at Room Temperature

Alkyl and aryl sulfides were oxidized to the corresponding sulfoxides with urea–hydrogen peroxide (UHP) in the presence of FeCl3 as a Lewis acid catalyst under simple and mild reaction conditions. The protocol is efficient and highly selective and sulfoxides were obtained as the sole oxidation products in high yields at room temperature.

Chemoselective Oxidation of Sulfides to Sulfoxides with Urea–Hydrogen Peroxide Complex Catalysed by Diselenide

A highly selective catalytic oxidation system has been developed for the conversion of sulfides into the corresponding sulfoxides using urea–hydrogen peroxide as stoichiometric oxidant in the presence of a catalytic quantity of diphenyl diselenide.

Vanadium (V) oxide mediated bromolactonization of alkenoic acids

A full account of our recently communicated method for the V2O5 mediated bromolactonization of alkenoic acids is presented. Here we describe the extensive evaluation of the metal oxide catalyst, terminal oxidant, halide source, solvent system, and reaction temperature that resulted in optimal conditions employing 0.05 equiv V2O5, 3 equiv urea-hydrogen peroxide complex (UHP), and 3 equiv of NH4Br in an acetone:H2O (6:1) solvent system at room temperature. Additionally, we have expanded the substrate scope of the reaction with the aim of evaluating the functional group tolerance of the transformation. Further, we present preliminary data of a related halogenation of β-diketones with our optimal conditions. Finally, we probed the role of urea in the transformation.

ChemInform Abstract: Bromolactonization of Alkenoic Acids Mediated by V2O5 via Bromide to Bromenium in situ Oxidation.

Abstract An efficient protocol for the bromolactonization of alkenoic acids is presented that obviates the use of molecular bromine or exogenous bromenium sources. Vanadium (V) oxide catalyzes the in situ oxidation of bromide salts to bromenium (Br + ) in a process mediated by urea–hydrogen peroxide complex. Initial mechanistic investigations indicate that the presence of urea does not accelerate the halolactonization reaction.

Oxidative Desulfurization of Coal Tar Pitch Using a Urea–Hydrogen Peroxide Complex/Carboxylic Anhydride System in THF

Abstract Oxidative desulfurization of coal tar pitch (CTP) using a urea–hydrogen peroxide complex with a carboxylic anhydride in THF was investigated. The sulfur content in CTP was reduced by more than 15% through the process.

Lactonization reactions through hydrolase-catalyzed peracid formation. Use of lipases for chemoenzymatic Baeyer–Villiger oxidations of cyclobutanones

A one-pot chemoenzymatic method has been described for the synthesis of γ-butyrolactones starting from the corresponding ketones through a Baeyer–Villiger reaction. The approach is based on a lipase-catalyzed perhydrolysis for the formation of peracetic acid, which is the responsible for the ketone oxidation. Optimization studies have been performed in the oxidation of cyclobutanone, finding Candida antarctica lipase type B, ethyl acetate and urea-hydrogen peroxide complex as the best system. The relative ratio of these reagents has also been analyzed in depth. This synthetic approach has been successfully extended to a family of 3-substituted cyclobutanones in high substrate concentration, yielding the corresponding lactones with excellent isolated yields and purities, under mild reaction conditions and after a simple extraction protocol.

Bromolactonization of alkenoic acids mediated by V2O5 via bromide to bromenium in situ oxidation

An efficient protocol for the bromolactonization of alkenoic acids is presented that obviates the use of molecular bromine or exogenous bromenium sources. Vanadium (V) oxide catalyzes the in situ oxidation of bromide salts to bromenium (Br+) in a process mediated by urea–hydrogen peroxide complex. Initial mechanistic investigations indicate that the presence of urea does not accelerate the halolactonization reaction.

A highly efficient eco-friendly AFO reaction using grinding technique: synthesis of 3-hydroxy-2-phenyl-4H-chromen-4-ones

2′-Hydroxychalcones, on reaction with urea-hydrogen peroxide complex (UHP) and potassium hydroxide moist with ethanol, under grinding conditions, provided 3-hydroxy-2-phenyl-4H-chromen-4-ones (3-hydroxyflavones or flavonols) in excellent yields. Epoxidation followed by oxidative cyclization takes place simultaneously in a single pot reaction.

Nitroalkanes as Key Compounds for the Synthesis of Amino Derivatives

The carbanion stabilizing effect of the nitro group makes nitroalkanes ideal reagents in carbon-carbon bond formation. Once introduced in a molecular framework, the nitro group is amenable to further transformations including reduction to primary amines. The aim of this review is to explore the utilization of nitroalkanes as effective substrates for the preparation of important target compounds featured by the amino group. These will include simple primary amines, diamines, amino acids, piperidines, pyrrolidines and heteroaromatic derivatives. A particular emphasis will be placed on the synthesis of enantioenriched amino derivatives mediated by organocatalysts or organometallic complexes. Keywords: Amines, asymmetric synthesis, nitroalkanes, nucleophilic additions, reductions, peroxytrifluoroacetic acid, urea-hydrogen peroxide complex, trifluoroacetic anhydride, anti cancer drug threo-dihydrosphingosine, adrenoceptor, norphenylephrine, antihypertensive drug, ritodrine, retroaldol process, enantioselective aza-Henry reaction

ChemInform Abstract: Methyltrioxorhenium Catalysis in Nonconventional Solvents. A Great Catalyst in a Safe Reaction Medium

AbstractReview: 105 refs.

Methyltrioxorhenium Catalysis in Nonconventional Solvents: A Great Catalyst in a Safe Reaction Medium

The requirement that chemical processes are sustainable, reflected in waste reduction and the use of safe reagents and reaction conditions, is becoming even more stringent as a result of pressure by society and governments to preserve the environment and protect human health. Catalysis offers numerous benefits related to green chemistry, including lowered energetic reaction requirements; catalytic, rather than stoichiometric, amounts of materials; increased selectivity; lowered consumption of processing and separation agents; and, in many cases, the use of less-toxic compounds. Our research group has for a long time been studying methyltrioxorhenium in the oxyfunctionalization of different substrates, by using H(2)O(2) or its urea-hydrogen peroxide complex as the primary oxidant. In this Review paper we aim to provide a full literature account on the catalytic activity and selectivity of methyltrioxorhenium in the oxyfunctionalization reaction, either in nonconventional solvents or under solvent-free conditions, with a particular emphasis on the use of ionic liquids as green reaction media.

A novel and efficient catalytic epoxidation of olefins with adducts derived from methyltrioxorhenium and chiral aliphatic amines

Nitrogen-based adducts derived from methyltrioxorhenium(VII) and chiral aliphatic amines have been synthesized and applied to the efficient catalytic epoxidation of olefins with urea hydrogen peroxide complex as the primary oxidant. These complexes retain their catalytic activity when microencapsulated in polystyrene. A moderate steroinduction was obtained in the epoxidation of prochiral olefins with complexes between methyltrioxorhenium and chiral trans-1,2-cyclohexyldiamine. The values of steroinduction were found to increase after the microencapsulation process.

Back to basics: finding an optimal cerumenolytic (earwax solvent)

An in vitro study was conducted to assess the effectiveness of the commonly used aqueous and organic cerumenolytic (earwax solvent). Three agents were included in the study: olive oil, sodium bicarbonate and urea-hydrogen peroxide complex 5% in glycerol. Distilled water was used as a control. The disintegration of preformed wax plug was noted at specific intervals. The test tube containing distilled water as a control was found to be most effective and fastest in completely disintegrating the wax. This was closely followed by sodium bicarbonate. In contrast, the organic products, namely urea-hydrogen peroxide complex 5% in glycerol showed very little cerumenolytic effect. Olive oil, the most commonly used solution, was ineffective in disintegrating the wax plug even after 24 hours. The study shows aqueous cerumenolytics are more effective than organic agents.

A green synthesis of isatoic anhydrides from isatins with urea–hydrogen peroxide complex and ultrasound

The oxidation of isatins at room temperature, using the cheap and environmentally friendly urea–hydrogen peroxide complex and ultrasonic irradiation, has been investigated. The ultrasonic irradiation dramatically reduces the reaction time. With easy and reproducible reaction procedures, different isatoic anhydrides were obtained in excellent yield and with high purity.

Participation of new active species in epoxidation with cetylpyridinium dodecatungstate/FAp/urea–H 2O 2 system

We have developed an efficient catalytic solid-phase system for epoxidations that uses cetylpyridinium dodecatungstate ((CetylPy) 10[H 2W 12O 42]) catalyst/fluorapatite (FAp) disperse phase with a solid urea–hydrogen peroxide complex (urea–H 2O 2). The solid system was reusable and retained its high catalytic activity, although the catalyst was not fixed on the solid-phase. The reaction rate was first-order with respect to substrate concentration and amount of the catalyst. The solid-phase activation of polyoxometalates with urea–H 2O 2 was studied using FT-IR and solid-state NMR spectroscopy, and no known degraded peroxo-species was observed to form. Based on these kinetic and spectroscopic studies, we propose that the active species is a new, stable peroxo-species with the framework of the parent dodecatungstate, of which the terminal W( O) 2 site is specifically transformed to peroxo-type of W O(O 2), in the system. Much higher efficiency of the dodecatungstate compared with the phsphotungstate or the decatungstate is considered to be due to the non-degraded, site-specific peroxo-species.

Synthetic, spectral and catalytic activity studies of ruthenium bipyridine and terpyridine complexes: Implications in the mechanism of the ruthenium(pyridine-2,6-bisoxazoline)(pyridine-2,6-dicarboxylate)-catalyzed asymmetric epoxidation of olefins utilizing H 2O 2

Various Ru(L 1)(L 2) ( 1) complexes (L 1 = 2,2′-bipyridines, 2,2′:6′,2″-terpyridines, 6-(4 S)-4-phenyl-4,5-dihydro-oxazol-2-yl-2,2′-bipyridinyl or 2,2′-bipyridinyl-6-carboxylate; L 2 = pyridine-2,6-dicarboxylate, pyridine-2-carboxylate or 2,2′-bipyridinyl-6-carboxylate) have been synthesized (or in situ generated) and tested on epoxidation of olefins utilizing 30% aqueous H 2O 2. The complexes containing pyridine-2,6-dicarboxylate show extraordinarily high catalytic activity. Based on the stereoselective performance of chiral ruthenium complexes containing non-racemic 2,2′-bipyridines including 6-[(4 S)-4-phenyl-4,5-dihydro-oxazol-2-yl]-[2,2′]bipyridinyl new insights on the reaction intermediates and reaction pathway of the ruthenium-catalyzed enantioselective epoxidation are proposed. In addition, a simplified protocol for epoxidation of olefins using urea hydrogen peroxide complex as oxidizing agent has been developed.