Potassium Peroxodisulfate Research Articles

Facile, mild and selective silica sulfuric acid catalyzed oxidation of benzylalcohols to benzaldehyde derivatives by potassium peroxodisulfate

An efficient, facile, and mild oxidation of a variety of primary benzylic alcohols to the corresponding aldehydes with potassium peroxodisulfate in the presence of a catalytic amount of sodium chloride and silica sulfuric acid (SSA) in acetonitrile as solvent is reported. It is a renowned fact that potassium peroxodisulfate acts as a powerful oxidizing agent and the control of conditions is difficult. For this purpose, SSA as a mild, efficient and reusable solid acid catalyst was used to afford the carbonyl compounds in excellent yields and short time. The structure of all of the resulting products was confirmed by FT-IR spectroscopy. KEY WORDS: Potassium peroxodisulfate, Silica sulfuric acid, Benzylic alcohol, Oxidizing agent Bull. Chem. Soc. Ethiop. 2013, 27(1), 131-136.DOI: http://dx.doi.org/10.4314/bcse.v27i1.14

Topologically Unique Heterometallic CuII/Li Coordination Polymers Self-Assembled from N,N-bis(2-Hydroxyethyl)-2-aminoethanesulfonic Acid Biobuffer: Versatile Catalyst Precursors for Mild Hydrocarboxylation of Alkanes to Carboxylic Acids

The facile aqueous medium reactions of copper(II) nitrate with BES biobuffer [(HOCH(2)CH(2))(2)N(CH(2)CH(2)SO(3)H), hereinafter referred as H(3)bes] in the presence of various benzenecarboxylic acids [benzoic (Hba), 3-hydroxybenzoic (Hhba), and 3,5-dihydroxybenzoic (Hdhba) acid] and lithium hydroxide gave rise to the self-assembly generation of three new heterometallic Cu(II)/Li materials, [Li(H(2)O)(4)][Cu(4)(μ(2)-Hbes)(4)(μ(2)-ba)]·H(2)O (1) and [Cu(4)(μ(3)-Hbes)(4)(L){Li(H(2)O)(2)}](n)·3nH(2)O {L = μ(2)-hba (2) and μ(2)-dhba (3)}. They were isolated as air-stable crystalline solids and fully characterized by infrared (IR) and UV-vis spectroscopy and electrospray ionization (ESI)-MS(±), elemental, thermal, and single-crystal X-ray diffraction analyses. The latter revealed that 1-3 have comparable packing patterns and unit cell parameters, being composed of similar [Cu(4)(μ-Hbes)(4)(μ-carboxylate)](-) cores and [Li(H(2)O)(4)](+) cations (in 1) or [μ-Li(H(2)O)(2)](+) groups (in 2 and 3), which are arranged into discrete 0D aggregates in 1 or infinite 3D noninterpenetrating metal-organic networks in 2 and 3. The topological analysis of the coordination polymers 2 and 3 disclosed the trinodal 3,3,4-connected underlying nets with an unprecedented topology defined by the point symbol of (4.6.8)(4)(4(2).6)(2)(6(2).16(2).18(2)), further simplification of which resulted in the binodal 4,4-connected nets with the pts (PtS) topology. Apart from representing very rare examples of coordination compounds derived from H(3)bes, 1-3 feature solubility in water and were applied as efficient and versatile catalyst precursors for the mild (60 °C) single-pot hydrocarboxylation, by CO and H(2)O, of various gaseous, linear, and cyclic C(n) (n = 2-9) alkanes into the corresponding C(n+1) carboxylic acids, in H(2)O/MeCN medium under homogeneous conditions and in the presence of potassium peroxodisulfate. Total yields (based on alkane) of carboxylic acids up to 78% were achieved, which are remarkable in the field of alkane functionalization under mild conditions, especially for a C-C bond formation reaction in aqueous acid-solvent-free medium.

Redox Power Changes of Caramels and Sugar Reductones in Beer

<p>Aerated or nitrogenated solutions of various sugars (10 % w/w) in deionized water, brewing water or phosphate buffers with dichlorophenolindophenol (DCIP) addition (10 mg/l) were heated 45 min at 60 °C and absorbance at 520 nm (?<sub>max</sub> of DCIP at pH 4.6) and 610 nm (?<sub>max</sub> of DCIP at pH >6) was measured. Reduction power of the solutions increased with the absence of oxygen, increasing pH value and the kind of sugar (FRU>LAC,MAL,GLU>SUC). Aerated solutions of various sugars were also autoclaved (10 min at 121 °C) and the absorbance at 420 nm was measured. The color of caramels from sugars was dependent on the kind of sugar (FRU> LAC,MAL,GLU>SUC), and it increased with increasing pH value. The formation of caramel pigments from ascorbic acid or maltose by oxidation with potassium peroxodisulfate or hydrogen peroxide was also compared. The formation of colored pigments is considered to be the mark of irreversible aging of food.</p>

Synthesis of tetraalkyl thiuram disulfides using different oxidants in recycling solvent mixture

A new optimized laboratory synthesis of tetraalkyl thiuram disulfides, starting from dialkyl amines and carbon disulfide in presence of three oxidants (hydrogen peroxide, potassium peroxodisulfate and sodium hypochlorite) and appropriate reaction medium: two mixtures of isopropyl alcohol - water used in two consecutive syntheses, was presented in this work. First synthesis was performed in a recycled azeotropic mixture of isopropyl alcohol - water 87.7% - 12.3%, and second in a filtrate obtained after first synthesis, which was a mixture of isopropyl alcohol - water 70.4% - 29.6%. After the second synthesis and filtration, recycled azeotropic mixture isopropyl alcohol - water 87.7% - 12.3% was regenerated from the filtrate by rectification. Considering this, the technology for beneficial use of recycling isopropyl alcohol - water mixture as reaction medium for tetraalkyl thiuram disulfides synthesis was developed. Such concept contributes to extraordinary economical benefit of implemented optimal laboratory synthesis at semi-industrial level. High yields of tetraalkyl thiuram disulfides syntheses were obtained at both laboratory and semiindustrial level. Structure and purity of synthesized compounds were confirmed by elemental analysis, as well as FTIR, 1H and 13C NMR, and MS spectral data.

Precipitation polymerization of N-tert-butylacrylamide in water producing monodisperse polymer particles

The precipitation polymerizations of N-tert-butylacrylamide (NtBAM) in water are demonstrated; for example, the polymerization with potassium peroxodisulfate using a 15 g L−1 (118 mmol L−1) concentration of NtBAM in the feed ([NtBAM]0) was performed at 70 °C for 12 h, quantitatively producing poly(N-tert-butylacrylamide) particles with a number-average diameter (d n) of 203 nm and a coefficient of variation (C v) of 4.7%. The particle sizes were controlled in the d ns range between 75 and 494 nm by changing the monomer feeds or adding an electrolyte such as NaCl. The solid contents in the resulting aqueous latex solutions ranged from 0.1 to 1.5%, whereas it increased to 4.8% by applying a “shot-growth” technique. The polymerization in water under a somewhat unique condition is described, which was started from a heterogeneous system due to the presence of significantly large amounts of monomers ([NtBAM]0 = 50 g L−1). This also provided monodisperse latexes with the d n of 370 nm in 96% yield, in which the solid content reached 4.9%.

Visible light assisted photocatalytic mineralization of Reactive Red 180 using colloidal TiO 2 and oxone

The photocatalytic degradation of Reactive Red 180 (RR180), a mono-azo textile dye, has been investigated using aqueous suspensions of titanium dioxide (TiO 2) under visible light irradiation. The photocatalytic degradation is monitored by measuring the decolorization rate and the total organic carbon (TOC) content reduction during the course of the reaction. The effect of catalyst concentration, substrate concentration, pH of the solution and addition of electron acceptors, such as hydrogen peroxide (H 2O 2), potassium peroxodisulfate (K 2S 2O 8) and potassium peroxomonosulfate (PMS or oxone), on the photocatalytic degradation of RR180 in the presence of colloidal titanium dioxide is also studied. The photocatalytic degradation rate is found to be depending on the ratio of TiO 2 to dye. Addition of oxone in the TiO 2–RR180 system increases the degradation rate by about 10 fold and is found to be promising for the degradation of Reactive Red 180 when compared with other electron acceptors. About 80% of the dye is mineralized in 5 h through visible light photocatalytic degradation in the presence of TiO 2 and oxone.

PDMAA/Clay nanocomposite hydrogels based on two different initiations

The poly(N,N′-dimethylacrylamide)/clay (PDMMA/Clay) nanocomposite hydrogels cross-linked by inorganic clay Laponite XLG were prepared via free radical polymerization by using potassium peroxodisulfate (KPS) and azobisisobutryonitrile (AIBN) as initiators separately. The structure, morphology, swelling degree and mechanical properties of the hydrogels based on different initiation were investigated. The results indicated that the clay were exfoliated and dispersed randomly in the hydrogels, which acted as a multifunctional cross-linker. The swelling ratios of the nanocomposite hydrogels decreased with increasing the clay content. The hydrogel initiated by AIBN had better mechanical properties and swelling ratio than that initiated by KPS.

Mild, single-pot hydrocarboxylation of linear C 5–C 9 alkanes into branched monocarboxylic C 6–C 10 acids in copper-catalyzed aqueous systems

A single-pot method has been developed for the hydrocarboxylation of the liquid C 5–C 9 alkanes ( n-pentane, n-hexane, n-heptane, n-octane, n-nonane and 3-methylhexane) into the branched monocarboxylic C 6–C 10 acids bearing one more carbon atom. This method is characterized by a direct, selective and low-temperature (60 °C) hydrocarboxylation reaction of the alkane with carbon monoxide, water (which acts as a reagent besides being a solvent component) and potassium peroxodisulfate, in H 2O/MeCN medium. The hydrocarboxylations are markedly enhanced in the presence of a tetracopper(II) triethanolaminate complex as a homogeneous catalyst precursor. Total yields (based on alkane) of carboxylic acids up to 46% (with 97–99% overall selectivity) have been achieved, which are remarkable in the field of alkane functionalization under mild conditions, especially for a C–C bond formation reaction in aqueous acid-solvent-free medium. The regio- and bond selectivity parameters have been determined and a free radical mechanism has been proposed.

Preparation of superabsorbent hydrogels from poly(aspartic acid) by chemical crosslinking

Modified poly(aspartic acid)s containing pendant allyl groups were synthesized by the reaction of poly(succinimide) with an allyl amine in dimethylformamide. The contents of the allyl groups in the poly(aspartic acid) ranged from 2 to 17.4% confirmed by 1H NMR. Hydrogels were prepared using modified poly(aspartic acid) by chemical crosslinking using redox radical initiators including ammonium persulfate and potassium peroxodisulfate. The morphologies of the poly(aspartic acid)-based hydrogels were investigated by scanning electron microscopy (SEM). The water-absorbent experiments were carried out, and revealed that lightly cross-linked hydrogels resulted in effective water-absorbent properties. These results suggested that allyl group-modified poly(aspartic acid)s are useful in providing biodegradable hydrogels.

In Situ Reversible Tuning of Photoluminescence of Mn2+-Doped ZnS Quantum Dots by Redox Chemistry

Herein we report the development of a new method for in situ reversible tuning of photoluminescence properties of quantum dots (Qdots) by partial oxidation of population of the emitting species and subsequent chemical reduction of the oxidized form. The concept has been demonstrated using Mn(2+)-doped ZnS Qdots stabilized by acetyl acetonate. Treatment of an aqueous solution of the Qdots (with Mn(OAc)(2) being the source of Mn used for the synthesis of the Qdots) by potassium peroxodisulfate (KPS) led to reduction of intensity of emission due to Mn(2+) ((4)T(1)-(6)A(1)). Subsequent treatment of the solution containing KPS-treated Qdots with NaBH(4) led to regaining of intensity, thus providing reversibility to the tuning, which was possible for more than one cycle. Electron spin resonance (ESR) spectroscopic investigations revealed reduction of the population of Mn(2+) upon treatment with KPS, whereas it went back up upon further treatment with NaBH(4). Interestingly, a mixed population of oxidation states of Mn was indicated to be present in the Qdots prepared using KMnO(4) as the source of Mn. The fluorescence intensity of the Qdots so prepared increased upon treatment with NaBH(4) following synthesis, which was not possible when the source of Mn was Mn(OAc)(2). Transmission electron microscopic and X-ray diffraction studies indicated that oxidation and reduction did not change the sizes of Qdots significantly.

Radical-Initiator-Induced Solid-State Polymerization of Butadiyne Nanocrystals in Water and Their Dispersion Stabilization

Butadiyne nanocrystals in water are usually polymerized by UV or gamma-ray irradiation to give polydiacetylene (PDA) nanocrystals. In this study, we confirmed that solid-state polymerization of 1,6-di(N-carbazolyl)-2,4-hexadiyne (DCHD) and 5,7-dodecadiyn-1,12-diyl bis[N-(butoxycarbonyl-methyl)carbamate] (4BCMU) could be stimulated by water-soluble radical initiators. The radical initiators used were potassium peroxodisulfate, three kinds of azo-type compounds and a redox initiator. In all cases, the solid-state polymerization was confirmed by color change into blue indicating that PDA modified by the radical residues at the end was formed. However, nanocrystal cohesion occurred especially when the concentration of the initiators was high or the dispersion was kept for a long time. In order to improve the dispersion stability, two kinds of surfactants, i.e., sodium dodecyl sulfate (SDS) or dodecyltrimethylammonium chloride (DTMAC), were added to the DCHD nanocrystal aqueous dispersion. As a result, when anionic SDS was added, the solid-state polymerization of nanocrystals proceeded without coagulation and quantitative conversion was confirmed for all initiators. Cationic DTMAC has no effect on dispersion stabilization. PDA nanocrystal surfaces in water are negatively charged in nature and electric interaction of nanocrystals with the cations results in decrease of surface charge and aggregation of nanocrystals.

Comparative analysis of oxidative synthesis of N-alkyl, N,N-dialkyl and N-cykloalkyl-O-isobutyl thioncarbamate

A optimized synthesis of N-alkyl, N,N-dialkyl- and N-cycloalkyl-O-isobutyl thioncarbamates by aminolysis of sodium isobutylxanthogenic acid (NaiBXAc) and primary, secondary and cycloalkyl amines was developed at laboratory scale and applied at semi-industrial level. Studies on dependence of N-n-propyl-O-isopropylthiocarbamate yield and purity with respect to reaction parameters: reaction time and molar ratio of n-propylamine and NaiBXAc, were performed. In such way, optimal reaction conditions for synthesis of N-alkyl, N,N-dialkyl- and N-cycloalkyl-O-isobutyl thioncarbamates, by aminolysis of NaiBXAc, were established. Also, comparative results of thioncarbamates synthesis starting from potassium isobutyl xanthate (KiBX) and corresponding amines in presence of different oxidants: hydrogen peroxide, sodium hypochlorite and new oxidative agent potassium peroxodisulfate were evaluated. Synthesized compounds have been fully characterized by FTIR, 1H and 13C NMR and MS data, elemental analysis and purity have been determined by gas chromatographic method (GC). According to our knowledge, ten synthesized thioncarbamates are for the first time characterized. Synthesized compounds could be used as selective reagents for flotation of copper and zinc ores. The presented methods offer several benefits, namely, high product yields and purity, simple operation, mild reaction conditions without use of hazardous organic solvents, while some of them could be implemented on industrial scale production.

Preparation of diblock copolymer PBA-b-PSt by DPE method in emulsion

Diblock copolymer poly (butyl acrylate)-b-polystyrene (PBA-b-PSt) was prepared by two steps in a complete emulsion system, using DPE (1, 1-diphenylethylene) as free radical control agent. In the first step, butyl acrylate (BA), initiator potassium peroxodisulfate (KPS) and DPE were emulsion polymerized to form P(BA-DPE) precursor. Then the precursor was heated in the presence of a second monomer styrene (St), and block copolymer was synthesized successfully. The structures, molecular weight of precursor and block copolymer were characterized by FTIR, UV–VIS, 1H-NMR and SEC/MALLS. Influence of DPE on polymerization kinetics was also investigated. Meantime, thermal properties of block copolymer were analyzed by TGA and DSC.

Synthesis of polymethyl methacrylate (PMMA) by batch emulsion polymerization

Poly (methyl methacrylate) was synthesized by batch emulsion polymerization with Methyl Methacrylate as the monomer potassium peroxo-disulfate as the initiator, sodium stearate as the emulsifier and distilled water as a medium. The kinetics of free radical polymerization was studied. The kinetics has been modeled, assuming homogeneous nucleation and the resulting equation were solved using Runge-kutta method. Degree of conversion and rate of polymerization were studied. Key words: Polymethyl methacrylate, emulsion polymerization, free radical polymerization, homogeneous nucleation, emulsifier.

Use of amidoximated hydrogel for removal and recovery of U(VI) ion from water samples

Poly(acrylamidoxime-co-2-acrylamido-2-methylpropane sulfonic acid) (PAMSA) hydrogel was prepared by copolymerization of acrylonitrile and 2-acrylamido-2-methylpropane sulfonic acid as monomer, N,N′-methylenebis(acrylamide) as crosslinking agent and potassium peroxodisulfate as initiator. Amidoximated copolymer network was prepared by the reaction of copolymer network with hydroxylamine hydrochloride. A batch procedure was used for the determination of the characteristics of the U(VI) solid phase extraction from the amidoximated hydrogel. The determination of U(VI) was performed by spectrophotometric method using arsenazo-III as complexing agent. Optimal pH value for the quantitative preconcentration was 3, and full desorption was achieved with 3 mol L −1 HClO 4. The adsorption process can be well described by the pseudo-second-order kinetic model, and the equilibrium adsorption isotherm was closely fitted with the Langmuir model. A preconcentration factor of 20 and the three sigma detection limit of 2.8 μg L −1 ( n = 20) were achieved for uranium(VI) ions. The PAMSA hydrogel was used for separating and preconcentrating the uranyl ion existing in sea water samples, thermal spring water samples and the certified reference materials (TMDA 64; fortified lake water sample).

Mild, Single‐Pot Hydrocarboxylation of Gaseous Alkanes to Carboxylic Acids in Metal‐Free and Copper‐Promoted Aqueous Systems

A direct, selective and highly efficient method has been developed for the hydrocarboxylation of C(n) gaseous alkanes into C(n+1) carboxylic acids, in aqueous acid-solvent-free medium at low temperatures. The approach is based on a metal-free or copper-promoted reaction of ethane, propane or n-butane with carbon monoxide and water, in a H(2)O/MeCN medium at 50-60 degrees C, in the presence of potassium peroxodisulfate. The effects of various reaction parameters, such as the absence or presence of a copper promoter, solvent composition, temperature, time, CO and alkane pressure, were studied. A free radical mechanism was confirmed by radical trap experiments involving acyl radical formation, oxidation and subsequent hydroxylation by water. Remarkable yields (based on alkane) of carboxylic acids in the 34-41 % range were achieved even in the metal-free systems, although in the presence of a tetracopper(II) triethanolaminate derived promoter they reach superior values of 58 and 87 % for the hydrocarboxylations of propane and n-butane, respectively; in these cases, branched isobutyric and 2-methylbutyric acids were the predominant products. From a green perspective, important features of the present alkane hydrocarboxylations include the exceptional metal-free, mild and acid-solvent-free reaction conditions, the operation in aqueous medium with a rare hydroxylating role of water, with high selectivities, and yields of carboxylic acids. Taken together, these conditions correspond to the mildest and the most efficient method so far reported for the oxidative functionalisation of gaseous alkanes.

Catalytic hypervalent iodine oxidation of alcohols to corresponding aldehydes or ketones using 2,2,6,6-tetramethylpiperidinyl-1-oxy and potassium peroxodisulfate

An efficient, facile, and mild oxidation of alcohols to the corresponding aldehydes or ketones with potassium peroxodisulfate and 2,2,6,6-tetramethylpiperidinyl-1-oxy in the presence of a catalytic amount of iodobenzene is reported. The oxidation proceeded in a mixed solvent to afford carbonyl compounds in moderate to excellent yields. A possible mechanism for the oxidation is proposed.

The use of D-optimal design to model the effects of process parameters on mineralization and discoloration kinetics of Fenton-type oxidation

The aim of this experimental investigation was to study kinetics of Fenton and modified Fenton oxidation applied to miscellaneous dye solutions. Several bench scale laboratory tests for the treatment of colored wastewaters containing model pollutant compounds, reactive azo dyes C.I. Reactive Violet 2 (RV2) and C.I. Reactive Yellow 3 (RY3) were performed. In order to examine the effects of initial Fe 2+ concentration, oxidant/catalyst molar ratio and oxidant type on TOC reduction and color removal, the following reactants were used: classic Fenton's reagent (Fe 2+/H 2O 2) and modified Fenton's reagent, where potassium peroxodisulfate, alone and in combination with hydrogen peroxide, was selected as oxidant. Response surface methodology (RSM), particularly D-optimal design, was used for the purpose. This research contributed in several ways: (i) evaluation of more effective Fenton oxidant on pollutant content reduction, in terms of TOC and color removal, (ii) assessment of the optimal reactant doses, (iii) describing the RV2 kinetic behavior in applied systems and (iv) determining the apparent rate constants. Mineralization was described by pseudo-first-order kinetics with observed rate constant k m = 0.0133 min −1. A kinetic model describing discoloration was composed of two first-order in-series reactions with discoloration rates; k 1 = 0.9447 min −1 and k 2 = 0.0236 min −1, at optimal operating conditions and with the highest initial organic load.

Metal‐Free and Copper‐Promoted Single‐Pot Hydrocarboxylation of Cycloalkanes to Carboxylic Acids in Aqueous Medium

AbstractA simple and effective method for the transformation, under mild conditions and in aqueous medium, of various cycloalkanes (cyclopentane, cyclohexane, methylcyclohexane, cis‐ and trans‐1,2‐dimethylcyclohexane, cycloheptane, cyclooctane and adamantane) into the corresponding cycloalkanecarboxylic acids bearing one more carbon atom, is achieved. This method is characterized by a single‐pot, low‐temperature hydrocarboxylation reaction of the cycloalkane with carbon monoxide, water and potassium peroxodisulfate in water/acetonitrile medium, proceeding either in the absence or in the presence of a metal promoter. The influence of various reaction parameters, such as type and amount of metal promoter, solvent composition, temperature, time, carbon monoxide pressure, oxidant and cycloalkane, is investigated, leading to an optimization of the cyclohexane and cyclopentane carboxylations. The highest efficiency is observed in the systems promoted by a tetracopper(II) triethanolaminate‐derived complex, which also shows different bond and stereoselectivity parameters (compared to the metal‐free systems) in the carboxylations of methylcyclohexane and stereoisomeric 1,2‐dimethylcyclohexanes. A free radical mechanism is proposed for the carboxylation of cyclohexane as a model substrate, involving the formation of an acyl radical, its oxidation and consequent hydroxylation by water. Relevant features of the present hydrocarboxylation method, besides the operation in aqueous medium, include the exceptional metal‐free and acid‐solvent‐free reaction conditions, a rare hydroxylating role of water, substrate versatility, low temperatures (ca. 50 °C) and a rather high efficiency (up to 72% carboxylic acid yields based on cycloalkane).

A Direct and Convenient Synthesis of Periodoarenes Using Molecular Iodine

Molecular iodine exhaustively iodinates aromatic hydrocarbons in the presence of potassium peroxodisulfate, concentrated sulfuric acid, and trifluoroacetic acid to give the periodinated aromatic compounds. Benzene and other moderately activated and deactivated arenes are readily converted into the corresponding periodinated derivatives in good to high yields.