Synthesis of Heptanoic Acid via the Oxidation of Octene-1 by Hydrogen Peroxide under Conditions of Phase-Transfer Catalysis

Results from studying the oxidation of octene-1 by a hydrogen peroxide solution to heptanoic acid in a two-phase liquid system under phase-transfer catalysis conditions are presented. Methyl(tri-n-octyl) ammonium tetra(oxodiperoxotungsto)phosphate [MeOct ₃ ⁿ N]₃{PO₄[WO(O₂)₂]₄} is used as a catalyst. The conditions of the formation of heptanoic acid with a yield of nearly 90% at temperatures below 100°C and atmospheric pressure in a single stage without organic solvents have been determined. The obtained experimental data provide the possibility to recommend this way for the synthesis of monocarboxylic acids from α-alkenes for the creation of green chemistry processes.     

On the Nature of Reaction-Controlled Phase Transfer Catalysts for Epoxidation of Olefin: A 31P NMR Investigation

[π-C₅H₅NC₁₆H₃₃]₃[PW₄O₁₆] was reported to be an excellent epoxidation catalyst which exhibited a unique reaction-controlled phase transfer behavior. In the paper, the composition and structural changes of the reaction-controlled phase transfer catalyst during and after reaction have been investigated by ³¹P NMR spectroscopy. The ³¹P MAS NMR confirmed that the original catalyst was a mixture of heteropoly tungstophosphates. When the catalyst reacted with hydrogen peroxide, the species PO₄[WO(O₂)₂]₄ ^3?, [(PO₄)WO(O₂)_{2 2}WO(O₂)₂(H₂O)]^3? and [(PO₃(OH))WO(O₂)_{2 2}]^2? were detected by in situ ³¹P NMR. It was also found that the P/W ratios and quaternary ammonium cations had great influence on the composition of heteropoly tungstophosphates. Although the catalyst with [(C₁₈H₃₇)₂N(CH₃)₂]⁺ was not a reaction-controlled phase transfer catalyst, it could be precipitated from the reaction solution when acetone was subsequently added to the solution. The ³¹P MAS NMR spectra of the recovered catalysts revealed that they had more low P/W ratio heteropoly tungstophosphates than fresh catalysts.     

Novel Two-Phase Catalysis with Organometallic Compounds for Epoxidation of Vegetable Oils by Hydrogen Peroxide

A series of new organometallic catalysts for epoxidized vegetable oils using H₂O₂ in a biphasic system were investigated. The effect of reaction parameters such as the amount of hydrogen peroxide, reaction time and temperature in the epoxidation of soybean oil are discussed in detail. A selectivity of 83.8% was obtained in 4 h at 60 °C, when [(C₁₈H₃₇)₂N(CH₃)₂]₃{PO₄[WO(O₂)₂]₄} was used as the catalyst. When methyltrioxorhenium (MTO), imidazole and CH₃CN were used as the catalyst, adduct, and solvent respectively, a selectivity of 99.90% was achieved in 4 h at 20 °C. The catalytic system was used for the epoxidation of other oils, whose results showed it was active in the epoxidation of long-chain unsaturated compounds. Furthermore, the reaction of H₂O₂ with methyltrioxorhenium was studied by UV–Vis spectroscopy, which revealed the active peroxorhenium complexes formed during the reaction. Epoxidation of these oils with organometallic compounds occurred through the interactions between the oils unsaturated sites HOMO π(C–C) and the unoccupied peroxo σ*(O–O) orbital.     

Sustainable Process for Production of Azelaic Acid Through Oxidative Cleavage of Oleic Acid

This work describes two sustainable methods for production and purification of azelaic acid (AA) to replace the current process of ozonolysis of oleic acid (OA). The first proceeds in two steps, coupling smooth oxidation of OA to 9,10‐dihydroxystearic acid (DSA) with subsequent oxidative cleavage by sodium hypochlorite. An alternative methodology is also proposed, using a chemocatalytic system consisting of H₂O₂/H₂WO₄ for direct oxidative cleavage of the double bond of OA at 373 K. A convenient technique for separation and purification of azelaic acid is also proposed.     

Synthesis and Characterization of Dealuminated Ultra-Stable Zeolite Y Supported Cesium Salt of Phosphotungstic Acid for the Esterification of Acrylic Acid with Butanol

Wastewater containing 10–20 wt% of acrylic acid (AA) is released from petrochemical industries during the manufacture of AA, acrylic ester, water-soluble resin and flocculants. This untreated wastewater could have detrimental effects on the environment due to its high chemical oxygen demand. Heterogeneously catalyzed esterification of this wastewater with alcohol in a reactive distillation column (RDC) could be a promising treatment method to recover AA from the wastewater. Considering the importance of a water-resistant catalyst in this method, this work has synthesized and tested a potential catalyst, cesium salt of phosphotungstic acid (Cs_xH_3-xPW) supported on dealuminated ultra-stable zeolite Y (DUSY), for the esterification of AA with 1-butanol (BuOH). The catalysts were synthesized through impregnation using various solvents, DUSY with different compositions of silicon (Si) to aluminium (Al), compositions of cesium (Cs) and precursor loadings. The 30%(Cs_1.5(IWI)H_1.5PW_IWI)_DEE/DUSY₆₀ was the best catalyst, giving reasonably high yield and low leaching. The BA yield obtained was 9.53% at 80°C, stirring speed of 500 rpm, catalyst loading of 10 wt% and M_AA:BuOH of 1:3 for 4 h.     

Modification of jute by acrylic acid in the presence of Na3PO4 and K2S2O8 as catalysts under thermal treatment

Jute fabric was modified using acrylic acid (AA) as the finishing agent in the presence of K₂S₂O₈ and Na₃PO₄ catalysts separately or in selected combinations, employing a pad–dry–cure technique. Treatment with 10% acrylic acid at 30°C and at pH 7 produced optimum effects: a batching time of 45–60 min at 30°C, followed by drying of the batched fabric at 95°C for 5 min and curing of the dried fabric at 140°C for 5 min produced most balanced improvements in the textile related properties. Na₃PO₄ catalyst allowed esterification of AA with cellulosic, hemicellulosic, and lignin constituents of jute, and K₂S₂O₈ catalyst allowed radical polymerization of free acrylic acid or jute-bound acrylic acid moieties; the said processes ultimately lead to some degree of crosslinking of the chain polymers of jute. Examination of the surface morphology of untreated and treated jute fabrics by scanning electron microscopy revealed a good degree of masking effect on the unit cells of jute and intercellular regions by a cohesive film of polyacrylic acid or its salts, particularly when K₂S₂O₈ was used either alone or in combination with Na₃PO₄ as catalyst. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:63–74, 1998     

Preparation of Highly Active Alumina-Pillared Clay Montmorillonite-Supported Platinum Catalyst for Hydrodesulfurization

Effect of Pt precursor and pretreatment on hydrodesulfurization (HDS) activity of Pt/Al-PILM catalyst was examined to prepare highly active Pt-supported HDS catalyst. The order of HDS activities of Pt/alumina-pillared clay montmorillonite (Al-PILM) catalysts prepared by various Pt precursors was Pt(C₅H₇O₂)₂ > H₂PtCl₆ · 6H₂O > [Pt(NH₃)₄](NO₃)₂ > [Pt(NH₃)₄]Cl₂ · H₂O > H₂Pt(OH)₆. This order was in accordance with that of Pt dispersion. Thus, high Pt dispersion is essential factor to prepare highly active Pt/Al-PILM catalyst for HDS reaction. On the other hand, the effect of pretreatment on the HDS activities of Pt/Al-PILM catalysts prepared by various Pt precursors was also evaluated. The UC-TPS Pt/Al-PILM catalyst showed the highest HDS activity among various pretreated Pt/Al-PILM catalysts, in which uncalcined catalyst was sulfided by temperature programmed sulfidation (TPS). We assumed that high HDS activity of UC-TPS Pt/Al-PILM catalyst is caused by partly sulfided Pt particle with high dispersion. It is concluded that the highly active Pt/Al-PILM catalyst for the HDS reaction could be prepared by using Pt(C₅H₇O₂)₂ as a precursor and UC-TPS treatment.     

Homogeneous catalysts of redox reactions based on heteropoly acid solutions. II. Synthesis of catalyst for pilot industrial production of methylethylketone

The homogeneous catalyst used in the 2005–2006 scale-up of the oxidation of n-butylenes into methylethylketone to the industrial level is a chloride-free aqueous solution of palladium complexes in a modified 0.25 M solution of Mo-V-P heteropoly acid with the molecular formula H₁₂P₃Mo₁₈V₇O₈₅ (HPA-7′). Its advantages are increased oxidative capacity in the primary oxidation of n-C₄H₈ and increased thermal stability, which allows quick catalyst regeneration with atmospheric oxygen at 160–170°C. The paper describes the preparation of a pilot lot of the catalyst with a total volume of 50 L; the starting substances were V₂O₅, MoO₃, and H₃PO₄. The key point of the synthesis was dissolving V₂O₅ while stirring in a dilute and cooled H₂O₂ solution. This formed V(V) peroxide complexes, which decompose at elevated temperature to give a 0.0175 M H₆V₁₀O₂₈ solution. This solution was stabilized by adding a calculated amount of H₃PO₄ to give a more stable 0.0125 M H₉PV₁₄O₄₂ solution. Since the H₉PV₁₄O₄₂ solution occupied a large volume, its synthesis was performed three times in a 300-L reactor. In the main 500-L reactor, MoO₃ was dissolved in water with stirring, while adding the remaining portion of H₃PO₄. The resulting mixture was evaporated, gradually introducing all of the previously obtained portions of the dilute H₉PV₁₄O₄₂ solution. The resulting HPA-7′ solution was evaporated to ～100 L and filtered twice, separating the insignificant amount of the precipitate. The filtered solution was again evaporated to 50 L, and a calculated amount of PdCl₂ was added to it while stirring at 70–80°C. A total of 27 lots of the (Pd + 0.25 M HPA-7′) catalyst with a total volume of 1350 L were obtained. All apparatuses of the pilot industrial unit for MEK synthesis were filled with this catalyst.     

Hybrid peroxotungstophosphate organized catalysts highly active and selective in alkene epoxidation

Heterogenization of homogeneous catalysts is still a challenge but can improve drastically the processability of these compounds. Hybridization of polyoxometalates offers an efficient heterogenization route of homogeneous epoxidation catalysts. The Keggin [PW₁₂O₄₀]^3 − and the Ventruello {PO₄[WO(O₂)₂]₄}^3 − species were inserted by electrostatic interactions in a poly(ampholytic) polymeric matrix in order to prevent the leaching of these species. The presence of the polymeric matrix allows to tune the catalyst performance in cyclooctene epoxidation and to improve the selectivity to epoxide. Indeed, the hydrophobicity of the matrix induces a quick desorption of hydrophilic epoxide species. Their over-oxidation and the catalyst species deactivation by over-adsorption of epoxide are then avoided.     

Polymerization of Methyl Methacrylate with Nickel(II) and Palladium(II) Iminopyridyl Mononuclear Bimetallic Complexes

Methyl methacrylate polymerizations with a series of Pd(II) or Ni(II) bimetallic catalysts having general formula [(2-C₅H₄N)–C=N–(Z)–N=C–(2-C₅H₄N)] [MX₂]₂ {Z = (2,6-C₆H₂R₂)₂CH(4-C₆H₅); R = Me, iPr, MX₂ = PdCl₂, NiBr₂} in combination with methylaluminoxane showed that bimetallic Pd(II) catalysts are much more active than their bimetallic Ni(II) nickel and monometallic analogs to give syndiorich poly(methyl methacrylate) with moderate molecular weight.     

A Novel 3D Photoactive Coordination Polymer with Alternate Cd(H<Subscript>2</Subscript>O)<Superscript>2+</Superscript> and Mg(Hen)<Superscript>3+</Superscript> Units and Sandwich-Shaped Cluster Linkages

A novel organic–inorganic hybrid, cadmium(II)-magnesium(II)-molybdenum(V) phosphate, {Cd[(PO₄)₂(HPO₄)₂Mo₆O₁₁(OH)₄]₂}[Cd(H₂O)]₂[Mg(Hen)]₂{Cd[(PO₄)₃(HPO₄)Mo₆O₁₀(OH)₃Cl₂]₂}·(H₂en)₄·(Hen)₂·(en)₂·9H₂O (en = ethylenediamine), was prepared under hydrothermal conditions and characterized by single-crystal X-ray diffraction, X-ray powder diffraction, elemental analysis, inductively coupled plasma (ICP) analysis, thermogravimetric analysis, fluorescence, FT-IR and bond valence sum calculations. As revealed by single-crystal X-ray diffraction studies, the sandwich-shaped clusters of [Cd(Mo₆P₄)₂] are interconnected by additional [Mg(Hen)] units and [Cd(H₂O)] fragments to form an extended three-dimensional supramolecular framework with channels occupied by ethylenediamine molecules, protonated ethylenediamine cations and water molecules. Luminescent measurement of the title compound exhibits intensive blue and greenish-blue radiation emission upon excitation with ultraviolet light.     

An Organic–Inorganic Hybrid Polymer Based on Molybdenum(V) Phosphate and Cadmium(II) Complex

An unusual organic–inorganic hybrid polymer, [Cd(pztt)(H₂O)₂]₄[CdMo ₁₂ ^V O₂₄(OH)₆ (HPO₄)₄(H₂PO₄)₂(PO₄)₂]·10H₂O (pztt = 3-(pyrazin-2-yl)-5-(1H-1,2,4-triazol-3-yl)-1,2,4-triazliyi) (1), have been hydrothermally synthesized and structurally characterized by the elemental analysis, TG, IR, UV–Vis, PXRD and the single-crystal X-ray diffraction. In compound 1, the sandwich-type {Cd[Mo₆P₄O₃₁]₂} units are modified with Cd(pztt)(H₂O)₂ fragments to lead bi-supported dimer clusters, which are further linked by binuclear complex subunits [Cd₂(pztt)₂(H₂O)₄] to yield unusual 1-D chains. The 1-D chains are further packed into 2-D and 3-D supramolecular assemblies via strong hydrogen-bonding interactions. In addition, the electrochemical behavior of 1-CPE and the photoluminescence properties of 1 in the solid state at room temperature have been investigated in detail.     

Formations of a nonanuclear peroxo molybdate and its heptanuclear precursor

Coupling reaction of peroxo heptanuclear and dinuclear molybdenum complexes K₆[Mo₇O₂₂(O₂)₂]·9H₂O (1) and K₂[Mo₂O₃(O₂)₄(H₂O)₂]·2H₂O (2) results in the formation of a nonanuclear peroxo molybdate K₈[Mo₉O₂₅(O₂)₆]·9H₂O (3) in a weak acidic solution, which is promoted by the existence of lactic acid. The activation of peroxo group in compound 3 shows obvious O–O bond activation in comparison with 1, which is based on structural data and infra-red analyses.     

Photooxidation of Benzene to Phenol by Al2O3-Supported Fe(III)-5-Sulfosalicylic Acid (ssal) Complex

Selective oxidation of benzene with H₂O₂ to phenol has been developed using a novel Fe(III) complex bearing 5-sulfosalicylic acid ligands immobilized alumina catalyst under visible light irradiation. The catalyst activity was evaluated by the photooxidation of benzene to phenol. The results indicate the best result with 100% conversion of benzene and 27.64% selectivity for phenol at low catalyst loading (0.7 mmol/g alumina). The catalyst was used for at least 4 cycles without any appreciable loss of activity.     

Syntheses,structures and properties of two copper-2-picolinic-acid germanomolybdate hybrids with mixed organic components

Two inorganic–organic hybrids based on saturated α-Keggin-type germanomolybdates with mixed organic components [H₂DAP]₂[Cu(PA)₂][α-GeMo₁₂O₄₀]·8H₂O (1) and [NH₄]₂[H₈L] [Cu(PA)₂][α-GeMo₁₂O₄₀]·8H₂O (2) (DAP = 1.2-diaminopropane, HPA = 2-picolinic acid, H₆L = 1,3-bis[tris(hydroxymethyl)methylamino]propane) have been obtained via the conventional aqueous solution method and structurally characterized by elemental analysis, IR spectra, thermogravimetric (TG) analysis and single-crystal X-ray diffraction. 1 stands for an one-dimensional linear organic–inorganic hybrid germanomolybdate chain constructed from classical Keggin [α-GeMo₁₂O₄₀]^4 − units supported by [Cu(PA)₂] linkers, whereas 2 represents the first hybrid germanomolybdate containing the H₆L component and consists of a saturated α-Keggin polyanion [α-GeMo₁₂O₄₀]^4 −, a diprotonated [H₈L]^2 + cation, a copper coordination complex [Cu(PA)₂], two ammonium cations [NH₄]⁺ and eight lattice water molecules. Furthermore, the electrochemical and electrocatalytic properties of 1 and 2 have also been investigated in detail.     

Selective ammoximation of ketones and aldehydes catalyzed by a trivanadium-substituted polyoxometalate with H2O2 and ammonia

The ammoximation of different ketones and aldehydes to their corresponding oximes catalyzed by K₆[PW₉V₃O₄₀]·4H₂O was carried out with hydrogen peroxide and ammonia in isopropanol at room temperature. High yields of oximes were obtained in this catalytic system. This catalytic system was proved to be heterogeneous by the ammoximation activity of removal of catalyst and the elemental analysis of the filtrate after reaction. A possible procedure for the ammoximation catalyzed by K₆[PW₉V₃O₄₀]·4H₂O with H₂O₂ and NH₃·H₂O was proposed. The fresh and used catalysts were characterized by IR and ³¹P MAS NMR, which revealed the good stability of the catalyst.     

The role of phosphoric acid in the anodic electrocatalytic layer in high temperature PEM fuel cells

The poisoning effect and the role of H₃PO₄ (PA) at the anodic electrocatalytic layer of a high temperature polymer electrolyte membrane (HT PEM based on ADVENT TPS^®) fuel cell are discussed under the light of cyclic voltammetry, CO stripping, and X-ray photoelectron spectroscopy (XPS) experiments. The catalytic layer was based on both the pyridine-modified multi-wall carbon nanotubes, 30 wt% Pt/(ox.MWCNT)–Py, and on commercial 30 wt% Pt/C, with varying PA loadings on the electrode. At low PA loadings (<3 gPA/gPt), the electrochemically active surface area of Pt decreases significantly under H₂ anode long-term operation, approaching surface Pt utilization <10 %. This degradation is attributed to the formation of pyrophosphoric or triphosphoric acid as well as catalytically H₂ reduced PA species, which block the Pt surface area. As was explicitly detected by means of XPS PA species were displaced from the Pt surface under H₂ or CO exposure. The poisoning effect is reversible as these species can be hydrated back to orthophosphoric acid. The reduced species can be reoxidized into PA at 750 mV versus RHE. On the other hand, the electrochemical interface is stable at PA loadings exceeding 3 gPA/gPt, thus approaching Pt surface utilization >80 % in the long term. This is believed to be a consequence of the more uniform distribution of PA, thus eliminating the PA displacement from the Pt interphase. It is hypothesized that the minimization of the PA poisoning effect at PA > 3 gPA/gPt, may also be a result of more efficient hydration of the catalytic layer that is being achieved through the hydration of the PA in the membrane and in the catalyst layer by the cathodically produced water vapors.     

A rare polyoxometalate based on mixed niobium-based polyoxoanions [GeNb18O54]14 − and [Nb3W3O19]5 −

Polyoxoniobate [GeNb₁₈O₅₄]^14 − and polyniobotungstate [Nb₃W₃O₁₉]^5 − are firstly found to co-crystallize at the same crystal to form a rare organic–inorganic hybrid polyoxometalate H[Cu(en)₂(H₂O)]₈[Cu(en)₂(H₂O)₂]₂{K₄[Cu(en)₂]₂[Cu(en)₂(GeNb₁₈O₅₄)]₂}[Nb₃W₃O₁₉]·32H₂O (1). Interestingly, in 1, the crescent-shaped polyoxoanions [GeNb₁₈O₅₄]^14 − can form dimeric secondary building units (SBUs) {[GeNb₁₈O₅₄]₂[K₂(H₂O)₅]₂} via the linkage of K⁺ cations. These dimeric SBUs can be further bridged by copper complexes to generate 1D infinite double strand chains with completely different isolated polyoxoanions [Nb₃W₃O₁₉]^5 − filling the gaps between chains.     

Synthesis,characterization and catalytic properties of a copper complex containing decavanadate nanocluster,Na2[Cu(H2O)6]2{V10O28}·4H2O

A copper complex containing decavanadate nanocluster, Na₂[Cu(H₂O)₆]₂{V₁₀O₂₈}·4H₂O, was prepared by reaction of Cu(NO₃)₂·4H₂O and NH₄VO₃ in an aqueous solution at pH = 4 and its structure was characterized using IR, CV and X-ray crystallography. It was found to be a highly efficient and effective catalyst for the azide alkyne cycloaddition and one-pot three-component (A³) coupling of aldehydes, amines, and alkynes to produce 1,2,3-triazoles and propargylamines respectively in high yields without any co-catalyst or activator.     

Solid phosphoric acid oligomerisation: Manipulating diesel selectivity by controlling catalyst hydration

Solid phosphoric acid (SPA) catalyst is traditionally used in crude oil refineries to produce unhydrogenated motor-gasoline by propene and butene oligomerisation. SPA is also used in High-Temperature Fischer–Tropsch refineries (HTFT) to produce synthetic fuels albeit with a different emphasis. The petrol/diesel ratio of an HTFT refinery is very different from crude refining and it is often necessary to shift this ratio depending on market requirements. The influence of hydration was investigated as a means of improving diesel selectivity. This was achieved by studying SPA over a hydration range of 99–110% H₃PO₄, a temperature range of 140–230 °C and using C₃–C₆ model and synthetic FT-derived olefinic feedstocks. A direct correlation was found between the selectivity towards diesel range products and the distribution of the phosphoric acid species viz. H₃PO₄, H₄P₂O₇ and H₅P₃O₁₀. For various olefinic feedstocks, diesel selectivity increased with decreasing catalyst hydration with a maximum around 108% H₃PO₄ for propene oligomerisation. Commercial tests confirmed the increase in diesel selectivity with lowered catalyst hydration.