Catalytic combustion of carbon particulates over perovskite-type oxides

A Cu/Cr₂O₃ catalyst was prepared by co-precipitation method, studied in methanol dehydrocoupling to methyl formate in different gas streams and characterized by BET, XRD, TPR, TPD of NH₃ and CO₂, etc. The results demonstrate that the catalyst can catalyze the dehydrocoupling of methanol to methyl formate in high efficiency,e. g. 99% selectivity to methyl formate at 48% conversion of methanol. The results further indicate that metallic copper might be the active species for the formation of methyl formate     

Synthesis and Characterization of Organosilicon Substituted Fluorenyl Derivatives

Friedel‐Crafts cycloalkylation of biphenyl with 2,3‐dichlorobutyltrichlorosilane(Cl₃Si‐CH₂CHClCHClCH₃) at a temperature of 100°C in the presence of anhydrous aluminum chloride catalyst gave cyclized product, 9‐methyl‐9‐(2‐trichlorosilylethyl)fluorene 1a , in 33% yield. Methylation of 1a with nucleophilic reagent such as methyl magnesium chloride, gave 9‐methyl‐9‐(2‐trimethylsilylethyl)fluorene 2 while bromination of 2 with excess amount of bromine in DMF resulted in 2,7‐dibromo‐9‐methyl‐9‐(2‐trichlorosilyl)fluorene 3 in good yield. All the compounds were structurally identified by GC/MS, ¹H and ¹³C‐NMR spectroscopy.     

An unusual reaction of propargylamines with CH2I2 and Et3Al

N-{2-[(1-R-Cyclopropyl)methyl]prop-2-enyl}-N,N-dimethylamines were prepared in 80-90% yields by the reaction (5 h, 23-25 C) of propargylamines R-C=C-CH₂NMe₂ (where R = alkyl, Ph) with a system of reactants CH2I2-Et₃Al taken in the molar ratio [propargylamine]: [Et₃Al]: [CH₂I₂] = 1: 6: 6. In the case of phenyl-substituted propargyl- amine, N-({1-[(1-phenylcyclopropyl)methyl]cyclopropyl}methyl)-N,N-dimethylamine is selectively formed in 76% yield upon the elongation of the reaction time to 4 days.     

Stereoregularity of poly(methyl acrylate)

The stereoregularity of poly(methyl acrylate) and poly(methyl acrylate-αd) was determined from the NMR spectra. A method of quantitative determination of stereoregularity of poly(methyl acrylate) proposed in this paper is based on the fact that in the 100 Mc./sec. NMR spectrum the absorption peaks due to methylene protons in syndiotactic configurations overlap absorptions due to only one of two methylene protons in isotactic configurations. The stereostructure of poly(methy1 acrylates) polymerized with anionic catalysts such as Grignard reagents, n-butyllithium, and LiAlH₄ is generally richer in isotactic diads than in syndiotactic diads. For example, poly(methyl acrylate) polymerized with phenylmagnesium bromide as catalyst at ?20°C. consists of 99% isotactic and 1% syndiotactic diads. In radical polymerization, the isotacticity of poly(methyl acrylate) is independent of polymerization temperature. Poly(methyl acrylates) polymerized with a Ziegler-Natta catalyst consisting of Al(C₂H₅)₂Cl and VCl₄ have configurations similar to those polymerized by radical initiators. The stereoregularity of poly(methyl acrylate-α-d) resembled that of poly(methyl acrylate) polymerized under the same conditions.     

Abnormal reactions of 2‐methoxy‐4,9‐dimethyl‐1‐nitroacridine with selenous acid and selenium(IV) oxide. Synthesis of 1H‐selenopheno[2,3,4‐k,l]acridine‐1‐one: A new seleno‐containing ring system

Unusual course of the reaction was revealed on the oxidation of functionally substituted acridine containing the activated methyl groups by well‐known oxidants, such as selenous acid and selenium(IV) oxide. Treatment of 2‐methoxy‐4,9‐dimethyl‐1‐nitroacridine ( 5 ) with an excess of H₂SeO₃ in boiling ethanol gave a mixture of the normal reaction products, 2‐methoxy‐4‐methyl‐1‐nitro‐9‐formylacridine ( 11 ) (isolated yield 29%) and 2‐methoxy‐4‐methyl‐1‐nitroacridine‐9‐carboxylic acid ( 12 ) (36%), together with an abnormal product, 3‐methoxy‐5‐methyl‐1H‐selenopheno[2,3,4‐k,l]acridine‐1‐one ( 13 ) (21%), which is the first example of a new seleno‐containing ring system. With the use of SeO₂ the yield of selenolactone 13 was much lower. J. Heterocyclic Chem., 2011.     

Highly Selective Synthesis of Methyl 1-Phenyl-1-(9-hydro-)fullerenylacetate

Isomerically pure methyl 1-phenyl-1-(9-hydro-)fullerenylacetat is synthesized in 75% yield by the reaction of C₆₀ with the carbanions of methyl phenylacetate in C₆H₆/THF mixed solvent under a purified N₂ atmosphere at 20°C.     

Transformations of methyl 6-methyl-2-methylsulfanyl-4-oxo-3,4-dihydro-3-pyrimidinylacetate under oxidative conditions

The oxidation of methyl 6-methyl-2-methylsulfanyl-4-oxo-3,4-dihydro-3-pyrimidinylacetate by reagents which oxidized the SMe group to SO₂Me gave the products of the further transformation of the corresponding 2-methylsulfonyl-substituted ester obtained: methyl 5,5-dichloro-6-methoxy-6-methyl-2,4-dioxohexahydro-3-pyrimidinylacetate (using Cl₂ in 70 or 50% MeOH), its mixture (about 1:10) with methyl 6-methyl-2,4-dioxo-1,2,3,4-tetrahydro-3-pyrimidinylacetate (Cl₂ in 30% MeOH) or only to the latter compound (Cl₂ in H₂O, m-ClC₆H₄CO₃H in CHCl₃, H₂O₂ in MeOH). The reaction did not take place with NaOCl in DMF. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 901–905, June, 2006.     

Role of metal Cu species on methyl laurate catalytic hydrogenation to oxygen-containing compounds

The Cu/γ-Al₂O₃ catalysts with different Cu loadings were prepared by impregnation method. The physicochemical properties of these Cu/γ-Al₂O₃ catalysts were characterized by H₂-TPR, XRD, and in-situ XPS. The catalytic hydrogenation performances of methyl laurate over Cu/γ-Al₂O₃ catalysts were studied. The results show that the hydrogenation performances of methyl laurate on Cu/γ-Al₂O₃ catalyst are related to the dispersion, crystallite size, and content of the active component Cu⁰. The 10CA catalyst has the best hydrogenation performances for methyl laurate to produce C₁₂ alcohol. At 300 °C, the conversion of methyl laurate and the selectivity of C₁₂ alcohol are 55.6% and 30.4%, respectively.     

Effect of excess halide on the palladium‐catalyzed insertion‐triggered radical copolymerization of methyl acrylate and 1‐hexene

[Pd₂(μ‐Cl)₂(C₆F₅)₂(tht)₂] ( 1 ) is a very efficient initiator of the radical polymerization of methyl acrylate, but it is not active in the polymerization of methyl methacrylate or in the copolymerization with 1‐hexene. The addition of an excess of NBu₄Cl to solutions of [Pd₂(μ‐Cl)₂(C₆F₅)₂(tht)₂] ( 1 ) provides an initiator system that copolymerizes methyl acrylate and 1‐hexene by an insertion‐triggered radical mechanism. Random copolymers are obtained with 11% incorporation of 1‐hexene in moderate yields (about 35%). Studies of the decomposition products obtained after the first insertion of methyl acrylate in the Pd? C₆F₅ bond of 1 show that the addition of excess halide in the presence of monomer favors the homolytic cleavage of the Pd? C bond, and the generation of the radicals that are active species in the polymerization, versus alternative evolution pathways. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5682–5691, 2006     

Heterocyclization of dimethyl malonate with SH acids and formaldehyde in the presence of catalysts

Three-component heterocyclization of dimethyl malonate with SH acids (H₂S, ethane-1,2-dithiol) and formaldehyde in the presence of 5 mol % of transition metal chlorides (FeCl₃, CoCl₂, NiCl₂) gave dimethyl 1,3-dithiane-5,5-dicarboxylate and dimethyl 1,4-dithiepane-6,6-dicarboxylate. The reactions in the presence of transition metal chlorides hydrates were accompanied by Krapcho decarboxylation with formation of methyl 1,3-dithiane-5-carboxylate and methyl 1,4-dithiepane-6-carboxylate.     

Phase-Transfer-Catalyzed Michaelis-Becker Synthesis of Dialkyl Methyl Phosphonates

A liquid–liquid phase-transfer-catalyzed (PTC) Michaelis-Becker reaction was adopted in the preparation of dialkyl methyl phosphonate (R = Me, iPr, nBu, and iBu). This was performed by the reaction of an appropriate dialkyl hydrogen phosphonate with methyl iodide in the presence of benzyl triethyl ammonium chloride and sodium hydroxide as PTC and base, respectively. A liquid–liquid two-phase system (H₂O/CH₂Cl₂) introduced a suitable situation for the preparation of dialkyl methyl phosphonates with bulky alkyl groups (R = iPr, nBu, and iBu), but with R = Me, the hydrolysis of dimethyl hydrogen phosphonate (reagent) reduced the yield to 22%. In this case, a solid–liquid PTC-free system was successfully applied and yield of over 80% was obtained.     

Avoiding Carbothermal Reduction: Distillation of Alkoxysilanes from Biogenic,Green, and Sustainable Sources

The direct depolymerization of SiO₂ to distillable alkoxysilanes has been explored repeatedly without success for 85 years as an alternative to carbothermal reduction (1900 °C) to Si_met, followed by treatment with ROH. We report herein the base‐catalyzed depolymerization of SiO₂ with diols to form distillable spirocyclic alkoxysilanes and Si(OEt)₄. Thus, 2‐methyl‐2,4‐pentanediol, 2,2,4‐trimethyl‐1,3‐pentanediol, or ethylene glycol (EGH₂) react with silica sources, such as rice hull ash, in the presence of NaOH (10 %) to form H₂O and distillable spirocyclic alkoxysilanes [bis(2‐methyl‐2,4‐pentanediolato) silicate, bis(2,2,4‐trimethyl‐1,3‐pentanediolato) silicate or Si(eg)₂ polymer with 5–98 % conversion, as governed by surface area/crystallinity. Si(eg)₂ or bis(2‐methyl‐2,4‐pentanediolato) silicate reacted with EtOH and catalytic acid to give Si(OEt)₄ in 60 % yield, thus providing inexpensive routes to high‐purity precipitated or fumed silica and compounds with single Si−C bonds.     

Avoiding Carbothermal Reduction: Distillation of Alkoxysilanes from Biogenic,Green, and Sustainable Sources

The direct depolymerization of SiO₂ to distillable alkoxysilanes has been explored repeatedly without success for 85 years as an alternative to carbothermal reduction (1900 °C) to Si_met, followed by treatment with ROH. We report herein the base‐catalyzed depolymerization of SiO₂ with diols to form distillable spirocyclic alkoxysilanes and Si(OEt)₄. Thus, 2‐methyl‐2,4‐pentanediol, 2,2,4‐trimethyl‐1,3‐pentanediol, or ethylene glycol (EGH₂) react with silica sources, such as rice hull ash, in the presence of NaOH (10 %) to form H₂O and distillable spirocyclic alkoxysilanes [bis(2‐methyl‐2,4‐pentanediolato) silicate, bis(2,2,4‐trimethyl‐1,3‐pentanediolato) silicate or Si(eg)₂ polymer with 5–98 % conversion, as governed by surface area/crystallinity. Si(eg)₂ or bis(2‐methyl‐2,4‐pentanediolato) silicate reacted with EtOH and catalytic acid to give Si(OEt)₄ in 60 % yield, thus providing inexpensive routes to high‐purity precipitated or fumed silica and compounds with single Si?C bonds.     

Application of vegetable oils for electrocatalytic synthesis of hydrocarbons

Conditions of Kolbe cross-electrosynthesis of 10-undecylenic and acetic acids are studied on different catalyst anodes. It is shown that the key anodic process stages are the stages of formation of vinyl radicals from anions of unsaturated and methyl radicals under electrosynthesis of acetate anions. As dependent on the conditions of the process, the main product formed on the anode of the Pt-10% Ir alloy is either hydrocarbon CH₃CH₂CH(CH₃)(CH₂)7CH₂CH₃ (58 wt %) being the product of addition of three methyl radicals to a vinyl radicals or olefin CH₂=CH(CH₂)₇CH₂CH₃ (57 wt %) being the product of dimerization of vinyl and methyl radicals.     

HYDROFORMYLATION OF MMA CATALYZED BY SILICA-SUPPORTED POLY-γ-AMINO PROPYLSILOXANE-Rh-Co BIMETALLIC COMPLEX

A silica-supported poly-γ- aminopropylsiloxane-rhodium-cobalt bimetallic complex(abbreviated as SiO_2-NH_2-Rh-Co)has been prepared and used as catalyst for hydroformylationof methyl methacrylate. The results showed that the catalyst could catalyze the reaction in95.6% conversion with 92.8% selectivity for the normal aldehyde, methyl β-formylisobu-tyrate. Such catalyst also showed high stability during the reaction and could be used repeat-edly.     

Methyl group internal rotation A–E line splittings in several torsionally excited states of methyl glycolate and 2-methoxyethanol

The rotational spectra of several torsional satellites of methyl glycolate and 2-methoxyethanol have been investigated.The methyl barrier to internal rotation in methyl glycolate increases with the torsional quantum number of the C-C skeletal torsion, for which A–E line splittings have been measured up to v_SK=3. The V₃ value determined from the A–E line splittings in the first excited state of the methyl internal rotation is nearly the same of that previously determined in the ground state.For 2-methoxyethanol the V₃ barrier as determined from the A–E line splittings in the ground state is about 20% lower than the value previously obtained from the splittings observed in the first excited state of the methyl internal rotation. The sequence of the A–E splittings in the first excited state of the O-C skeletal torsion (v_SK=1) is probably reversed with respect to the ground state, while in the v_SK=2 state the sequence is like that in the ground state.     

Photocatalytic activity of divalent ion (copper,zinc and magnesium) doped NiAl2O4

Nickel aluminate (NiAl₂O₄) and doped nickel aluminate (Ni_1-xM_xAl₂O₄; M = Mg, Zn, Cu; x = 0.1) were prepared by sol-gel method using citric acid. The synthesized compounds were analyzed by various techniques such as powder XRD, FTIR, SEM-EDAX and UV-DRS. The lattice parameter was found to increase with the copper, zinc and magnesium doping in nickel aluminate. The band gap was decreased from 3.0 eV (NiAl₂O₄) to 2.9 (zinc doped), 2.7 eV (magnesium doped) and increased to 3.1 eV in the case of copper doping. The catalytic study was carried out for a cationic (methylene blue) and an anionic dye (methyl orange). The percentage degradation of methyl orange using Zn_0.1Ni_0.9Al₂O₄ and Mg_0.1Ni_0.9Al₂O₄ was found to be 92% (180 min) and 96% (90 min). 93% (120 min) and 97% (120 min) degradation of methylene blue was observed using zinc doped and magnesium doped nickel aluminate respectively. These results are comparatively higher than its parent analogue (94% (180 min) degradation against methyl orange and 91% (120 min) against methylene blue). Whereas the percentage degradation was found to be less in the case of Cu_0.1Ni_0.9Al₂O₄ (83% (180 min) against methyl orange and 90% (120 min) against methylene blue).     

Komplementär diastereoselektive Cobalt-Methylierungen des Vitamin-B12-Derivates «Cobester»

Complementary Diastereoselective Cobalt Methylations of the Vitamin-B₁₂ Derivative Cobester Treatment of heptamethyl cob(I)yrinate ( 2 ) in toluene/tetrahydrofurane (ca. 4:1) with methyl p-toluenesulfonate under exclusion of O₂ and with protection from light leads to the selective formation of the heptamethyl Coβ-methylcob(III)yrinate (perchlorate 1b ) in 75% yield. In contrast, methylation of 2 with methyl iodide under the same conditons results in the isomeric heptamethyl Coα-methyulcob(III)yrinate (perchlorate 1a ) in 73% yield, besides 7% of 1b . This complementary diastereoface-selectivity of the methylation at the Co-center results from alkylation under kinetic control and apparently involves two mechanistically distinct alkylation processes. A radical mechanism is considered to account for the stereochemically unusual outcome of the reaction with methyl iodide.     

Synthesis and properties of poly(aryl ether ether ketone) copolymers with pendant methyl groups

Polyether ether ketone and polyether ether ketone copolymers were prepared by the nucleophilic substitution reaction of 4,4′-difluorobenzophenone with hydroquinone and with varying mole proportions of hydroquinone and methyl hydroquinone using sulfolane solvent in the presence of anhydrous K₂CO₃. The polymers were characterised by different physico-chemical techniques. The crystallinity of the polymers was found to decrease with increase in concentration of the methyl hydroquinone units in the polymer. Thermogravimetric studies showed that all the polymers were stable upto 430 °C with a char yield above 49% at 900 °C in N₂ atmosphere. The glass transition temperature was found to increase and the crystalline melting temperature and activation energy were found to decrease with increase in concentration of the methyl hydroquinone units in the polymer.     

Rhodium‐Catalyzed 1,4‐Addition of Lithium 2‐Furyltriolborates to Unsaturated Ketones and Esters for Enantioselective Synthesis of γ‐Oxo‐Carboxylic Acids By Oxidation of the Furyl Ring with Ozone

Rhodium‐catalyzed 1,4‐addition of lithium 5‐methyl‐2‐furyltriolborate ([ArB(OCH₂)₃CCH₃]Li, Ar=5‐methyl‐2‐furyl) to unsaturated ketones to give β‐furyl ketones was followed by ozonolysis of the furyl ring for enantioselective synthesis of γ‐oxo‐carboxylic acids. [Rh(nbd)₂]BF₄ (nbd=2,5‐norbornadiene) chelated with 2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl (binap) or 2,3‐bis(diphenylphosphino)butane (chiraphos) gave high yields and high selectivities in a range of 91–99 % ee at 30 °C in a basic dioxane/water solution. The corresponding reaction of unsaturated esters, such as methyl crotonate, had strong resistance under analogous conditions, but the 1,4‐adduct was obtained in 70 % yield and with 94 % ee when more electron‐deficient phenyl crotonate was used as the substrate.