Showing papers on "Cyclohexanone published in 2006"
TL;DR: Asymmetric Michael additions of cyclohexanone to both aryl and alkyl nitrooleolefins in the presence of organocatalyst 2b and n-butyric acid afford adducts 5 with high diastereoselectivity and enantioselectivities.
297 citations
TL;DR: The computational study indicates that the mechanism of Sn-beta and Zr-beta catalysis is similar, and involves the following steps: adsorption of both the ketone and the alcohol on the Lewis acid center, deprotonation of the alcohol, carbon-to-carbon hydride transfer, proton transfer from the catalyst, and products exchange.
Abstract: The mechanism of the Meerwein-Ponndorf-Verley (MPV) reduction of cyclohexanone with 2-butanol catalyzed by Sn-beta and Zr-beta zeolites has been theoretically investigated using density functional theory (DFT) and the cluster approach. An experimental catalytic study has shown that the active sites in the MPV reaction catalyzed by Sn-beta are the same partially hydrolyzed Sn-OH groups that were found to be active for the Baeyer-Villiger (BV) reaction. The computational study indicates that the mechanism of Sn-beta and Zr-beta catalysis is similar, and involves the following steps: adsorption of both the ketone and the alcohol on the Lewis acid center, deprotonation of the alcohol, carbon-to-carbon hydride transfer, proton transfer from the catalyst, and products exchange. As in the aluminum alkoxide catalyzed reaction, the hydride shift occurs through a six-membered transition state, and the role of the hydrolyzed and therefore more flexible M-OH bond is just to facilitate the initial deprotonation of the alcohol.
195 citations
TL;DR: The most active copper triethanolamine (H 3 tea) complexes for the peroxidative oxidation of cyclohexane, in acetonitrile, were reported in this paper.
Abstract: The mono-, di-, tri-, tetra- and polynuclear copper(II) triethanolamine (H 3 tea) complexes [Cu(H 2 tea)(N 3 )] (1), [Cu 2 (H 2 tea) 2 (XC 6 H 4 COO) 2 ]. 2 H 2 O (X=4-H 2a, 4-CH 3 2b, 3-Cl 2c), [Cu 3 (H 2 tea) 2 -(4-OC6H4COO) 2 (H 2 O)].4H 2 O (3), [O C Cu 4 (tea) 4 -(BOH) 4 ][BF 4 ] 2 (4) and [Cu 2 (H 2 tea) 2 {μ-C 6 H 4 (COO) 2 -1,4} n ].2n H 2 O (5), respectively, are highly active and selective catalysts or catalyst precursors for the peroxidative oxidation of cyclohexane, in acetonitrile, to a cyclohexanol and cyclohexanone mixture, by aqueous hydrogen peroxide in acidic medium (liquid biphasic catalysis) at room temperature and atmospheric pressure. The effects on the catalytic activity of various factors, e.g., the relative amounts of cyclohexane, oxidant, catalyst, solvent and nitric acid, reaction time, catalyst recycling and impact of both carbon- and oxygen-centred radical traps (supporting mainly radical mechanisms) were investigated and allowed us to achieve yields and TONs up to ca. 39% and 380, respectively, corresponding to the most active copper systems so far reported for the oxidation of cyclohexane under mild conditions. The catalysts can be reused for recycling and, at least complex 4 maintains almost the same level of activity even after five reaction cycles. The preparation of the new complexes 1, 2b and 2c by self-assembly at room temperature, and their full characterization by IR spectroscopy, FAB-MS + , elemental and X-ray diffraction structural (for 1 and 2c) analyses are also reported.
158 citations
TL;DR: In this paper, the liquid phase photolytic oxidation of cyclohexane was studied and compared with photocatalytic oxidation over TiO2 with varying wavelengths of light exposure, slurry densities, and sources and pretreatments of catalyst material.
148 citations
TL;DR: Solid evidence is presented that, also in absence of oxygenates, ROOH initiation is actually a bimolecular reaction, involving concerted H abstraction from the alkane substrate by the nascent (.)OH.
Abstract: Despite their industrial importance, the detailed reaction mechanism of autoxidation reactions is still insufficiently known. In this work, complementary experimental and theoretical techniques are employed to address the radical-chain initiation in the autoxidation of cyclohexane with a particular focus on the "lighting-off" of the oxidation by (added) cyclohexanone. We used a newly developed method to quantify the intrinsic rate of chain initiation as well as the rate enhancement by cyclohexanone and several other (oxygenated) molecules. On the basis of first principles, the hitherto assumed perhemiketale mechanism was found to be many orders of magnitude too slow to account for the observed initiation enhancement by the ketone. Instead, it is shown that the pronounced chain-initiation enhancement by the ketone is attributable to a newly proposed concerted reaction between cyclohexyl hydroperoxide and cyclohexanone, in which the (.)OH radical breaking away from the hydroperoxide abstracts an alphaH atom from the ketone, thereby energetically assisting in the cleavage of the RO--OH bond. This reaction is highly efficient in generating radicals as it quasi-excludes geminate in-cage recombination. As a result, the ketone oxidation product at a level of 1 mol % increases the initiation rate by one order of magnitude, and so acts as a highly efficient "autocatalyst" in autoxidation reactions. An analogous reaction with cyclohexanol, although estimated to be even faster, has only a marginal effect on the overall kinetics, owing to the fast subsequent formation of HO(2) (.) radicals that very rapidly terminate with other ROO(.) radicals. Finally, solid evidence is presented that, also in absence of oxygenates, ROOH initiation is actually a bimolecular reaction, involving concerted H abstraction from the alkane substrate by the nascent (.)OH.
144 citations
TL;DR: In this article, the authors investigated the effect of ceria in composite oxides for cyclohexanol de-hydrogenation and hydrogen transfer reactions, and showed that the presence of the ceria enhances the surface area and acid-base properties.
Abstract: CeO2–ZnO composite catalysts prepared by amorphous citrate method have been investigated for cyclohexanol dehydrogenation and hydrogen transfer reactions. The precursors and catalysts have been characterized by TGA, CHN analysis, XRD, UV–vis–NIR diffuse reflectance, SEM and acid–base measurements. The amorphous precursors in citrate process contain one molecule of citric acid per Ce4+ or Zn2+ ions. Structural studies of composite oxides indicate the presence of individual oxide phases along with non-equilibrium solid solutions in a limited composition range. The composite oxides contain low coordination Ce3+ and Ce4+ sites. Cyclohexanone was obtained as main product for cyclohexanol transformation reaction carried out over these mixed oxide catalysts due to dehydrogenation on basic sites. The presence of ceria in the composite oxide enhances the surface area and acid–base properties facilitating the dehydrogenation process. At low ceria content, the CeO2–ZnO composite oxide catalysts show higher catalytic activity for both cyclohexanol dehydrogenation and hydrogen transfer reactions due to higher basicity, surface area and smaller crystallite sizes. Hydrogen transfer activity is found to be higher on CeO2(10%)–ZnO catalyst prepared by citrate method compared to the catalyst prepared by decomposition from acetate precursor. This study demonstrates the promoting effect of ceria in CeO2–ZnO catalysts for reactions involving acid–base sites.
127 citations
TL;DR: The proline-catalyzed direct asymmetric Mannich reaction between cyclohexanone, formaldehyde, and various anilines is thermally accelerated and in situ reduction of the resulting ketones affords N-aryl amino alcohols in up to 86% yield.
Abstract: The proline-catalyzed direct asymmetric Mannich reaction between cyclohexanone, formaldehyde, and various anilines is thermally accelerated. With only 0.5 mol % of catalyst, Mannich products with up to 98% ee have been obtained after a short period of time in reactions performed under microwave irradiation. In situ reduction of the resulting ketones affords N-aryl amino alcohols in up to 86% yield.
112 citations
TL;DR: The enantioselective direct aldol reaction, organocatalyzed by recoverable BINAM-prolinamide derivatives can be highly accelerated by a catalytic amount of a carboxylic acid without a detrimental of the obtained enanti-oselectivities as discussed by the authors.
Abstract: The enantioselective direct aldol reaction, organocatalyzed by recoverable BINAM-prolinamide derivatives can be highly accelerated by a catalytic amount of a carboxylic acid without a detrimental of the obtained enantioselectivities. From the study of suitable acids and reaction conditions, benzoic acid in aqueous DMF or in water was shown to give the best results with high yields and enantioselectivities. Thus, the reaction between p -nitrobenzaldehyde and acetone catalyzed by ( S a )-BINAM- l -Pro and benzoic acid can be carried out at −20 °C in only 8.5 h to give the expected product with 86% ee. In the case of butan-2-one, the iso - and the anti -isomers are obtained in a 1:1 isomer ratio up to 99% ee. Cyclohexanone gives the anti -aldol in up to 99% dr and 97% ee in only 2 h. The opposite diastereoselectivity is obtained in the case of cyclopentanone with lower ee up to 65% for the syn and 85% for the anti -isomer.
101 citations
TL;DR: In this article, the possibility of recovery of organic acids from waste salt solution, derived from the manufacture of cyclohexanone, by means of single anion-exchange membrane electrodialysis was studied.
90 citations
TL;DR: In this paper, simple prolinamide phenols 1a−f were synthesized and their catalytic effects on the direct asymmetric aldol reactions in organic solvents and in water were evaluated.
Abstract: Simple prolinamides 1a–f were synthesized, and their catalytic effects on the direct asymmetric aldol reactions in organic solvents and in water were evaluated. Prolinamide phenols 1a–d were found to be effective catalysts for the reaction of aromatic aldehydes with cyclohexanone in neat ketone and in water. The anti-aldol products were obtained with up to 98/2 anti/syn ratio and 96% ee in neat ketone, 98/2 anti/syn ratio and 99% ee in water, respectively.
90 citations
TL;DR: In this paper, the authors present a thorough study on the autoxidation of cyclohexane, a model substrate for other saturated hydrocarbons, and find strong evidence that the subsequent propagation of ketone is much slower than assumed, and can only account for some 25% of ring-opened products.
Abstract: In this article, we present a thorough study on the autoxidation of cyclohexane, a model substrate for other (saturated) hydrocarbons. Despite the industrial impact of autoxidation reactions, a detailed mechanism is still missing. We present a combined experimental and computational study on the formation of both the major products (cyclohexylhydroperoxide, cyclohexanol and cyclohexanone), and the formation of ring-opened side-products. Up to now, these by-products, mainly adipic acid, were thought to originate from cyclohexanone. However, we found strong evidence that the subsequent propagation of ketone is much slower than assumed, and can only account for some 25% of ring-opened products. On the other hand, the hitherto completely overlooked propagation of the hydroperoxide, via fast αH-abstraction by chain-carrying peroxyl radicals, is identified as the major source of not only alcohol and ketone, but also by-products. In the case of N-hydroxyphthalimide (NHPI) catalysed oxidations, where mostly phthalimide N-oxyl (PINO ) radicals are propagating the chain, the situation is slightly different, as PINO reacts more selectively with the alkane substrate than peroxyl radicals. This results in an increase in hydroperoxide selectivity. Lowering of the ROOH concentration by its, e.g. cobalt-catalyzed decomposition, leads to an enhanced catalytic efficiency, as a result of the shift in the ROO + NHPI ⇌ ROOH + PINO equilibrium to the more efficient PINO chain carrier.
TL;DR: In this paper, the authors used Co/ZSM-5 catalysts for the cyclohexane oxidation and showed that the Co-ZSM5 catalyst achieved about 10 millmol% conversion of liquid cyclomethane and 97% selectivity of KA-oil under the pressure of 1.0 MPa O 2.
Abstract: Heterogeneous oxidation of liquid cyclohexane by molecular oxygen was carried out over metal-containing ZSM-5 catalysts in a solvent-free system. Among those M-ZSM-5 and M/ZSM-5 catalysts tested, Co-containing ZSM-5 catalysts including Co/ZSM-5 (prepared by ion-exchange and calcination) and Co-ZSM-5 (prepared by ion-exchange and drying) showed the best activity for the oxidation of cyclohexane to cyclohexanone and cyclohexanol. Co/ZSM-5 had almost the same activity as Co-ZSM-5 for the cyclohexane oxidation; however, the leaching of cobalt from Co-ZSM-5 readily occurred. Co/ZSM-5 (calcined) catalyst could achieve about 10 mol% conversion of cyclohexane and 97% selectivity of KA-oil (the mixture of cyclohexanone and cyclohexanol) at 393 K under the pressure of 1.0 MPa O 2 . In addition, other factors like the temperature, the pressure, the time, various metals, the tert -butylhydroperoxide (TBHP) addition, and the catalyst reuse were investigated carefully. For the titled oxidation, Co/ZSM-5 was recyclable, and could behave as a truly heterogeneous catalyst.
TL;DR: In this paper, the liquid phase ammoximation of cyclohexanone with ammonia and hydrogen peroxide was conducted over Ti-MWW and the catalytic performance of the reaction depends greatly on the operating conditions, especially the method of adding substrates.
TL;DR: Bismuth triflate catalyzed direct-type Mannich reaction of cyclohexanone, aromatic aldehyde, and aromatic amine proceeded smoothly in water to afford the corresponding β-amino ketone with very good yield and moderate to good anti selectivity.
TL;DR: In this paper, a novel process involving the coupling of the dehydrogenation of cyclohexanol and the hydrogenation of furfural has been studied for the synthesis of 2-methylfuran over the same Cu-Zn-Al catalyst, realizing good energy efficiency, optimal hydrogen ultilization, and environmentally benign process.
TL;DR: In this article, the authors presented the oxidation of cyclohexane catalyzed by a family of mononuclear iron(III) complexes using hydrogen peroxide or tert-butyl hydroperoxide as oxidant, in acetonitrile solution.
Abstract: In this work, we present the oxidation of cyclohexane catalyzed by a family of mononuclear iron(III) complexes: [Fe(BMPA)Cl 3 ] 1 , [Fe(MPBMPA)Cl 3 ] 2 , [Fe(PBMPA)Cl 2 ] 3 and [Fe(PABMPA)Cl 2 ](ClO 4 ) 4 using hydrogen peroxide or tert -butyl hydroperoxide as oxidant, in acetonitrile solution. These complexes were able to oxidize the cyclohexane into cyclohexanol and cyclohexanone with good yields. It was also possible to characterize by gas chromatography and mass spectrometry the by-products, cyclohexyl hydroperoxide and tert -butyl cyclohexyl peroxide. Adipic acid (AA) was also formed in the reaction and it was determined by titration. The reactions with hydrogen peroxide exhibited much greater yields (about 30% for all the complexes) than when tert -butyl hydroperoxide was employed (about 17% of yield with complex 1 ). The alcohol/ketone ratio in the reactions with hydrogen peroxide after 24 h was around 1.5, indicating cyclohexanol selectivity, while with tert -butyl hydroperoxide the ratio was around 0.7–1.0. In conclusion, the studied complexes can be considered good catalysts to oxidize the cyclohexane in mild conditions.
TL;DR: In this article, various hydrotalcite-like compounds (HTs) were prepared for use as catalysts in the Baeyer-Villiger (BV) oxidation of cyclohexanone with H2O2/benzonitrile as oxidant and benzoneitrile itself as the solvent.
Abstract: Various Mg/Al, Mg/Al/Sn and Mg/Al/Zr hydrotalcite-like compounds (HTs) were prepared for use as catalysts in the Baeyer–Villiger (BV) oxidation of cyclohexanone with H2O2/benzonitrile as oxidant and benzonitrile itself as the solvent. The reaction gave water and benzamide as byproducts, the latter can be recycled in an appropiate process. Analysis of the solids revealed that tin and zirconium are in fact incorporated into the HT structure. The solids containing Mg/Al and Mg/Al/Sn and their calcination products (viz. Mg/Al and Mg/Al/Sn mixed oxides) were found to be effective catalysts for the BV oxidation of cyclohexanone. The Sn solids exhibited a higher activity than a more conventional catalyst obtained from an HT containing Mg and Al only (17% in the best case). Also, the catalyst containing tin was active when we used H2O2/acetonitrile system as oxidant. The solids containing Zr were found to promote the decomposition of the hydrogen peroxide and hence to adversely influence the oxidation reaction. A mechanism accounting for the experimental results is proposed. The reaction was conducted under very mild conditions (viz. atmospheric pressure and a temperature of 70 °C), and conversions obtained were higher than 80% in some cases and 100% selectivity after 6 h. The most active catalyst, which was that containing the largest amount of tin, retained full activity after three reuses.
TL;DR: In this article, the synthesis of multifunctional organic catalysts, easily obtained by the condensation of (S)-proline with 1,1′-binaphthyl-2,2′-diamine is reported.
Abstract: The synthesis of multifunctional organic catalysts, easily obtained by the condensation of (S)-proline with 1,1′-binaphthyl-2,2′-diamine is reported. These C2 as well as C1 symmetric prolinamides were shown to be able to promote the direct aldol condensation between acetone, methoxyacetone or cyclohexanone and different aldehydes in very good yields and high enantioselectivities.
TL;DR: A highly convenient multigram scale one step synthesis of methyl 2-(formamido)acrylate was developed and the versatility of the formyl protection was established by its removal under mild conditions.
Abstract: Enantioselectivities up to >99% ee were achieved in the rhodium-catalyzed asymmetric hydrogenation of N-formyl dehydroamino esters using monodentate phosphoramidites as chiral ligands. The substrates were synthesized by condensation of methyl isocyanoacetate with a range of aldehydes and with cyclohexanone. A highly convenient multigram scale one step synthesis of methyl 2-(formamido)acrylate was developed. This compound was used in the synthesis of methyl 2-(formamido)cinnamate via a solvent free Heck reaction. Moreover, full conversion and >99% ee were obtained in 1 h in the hydrogenation of methyl 2-(formamido)acrylate with 0.2 mol % catalyst and 2 bar hydrogen pressure. The versatility of the formyl protection was established by its removal under mild conditions.
TL;DR: In this paper, the catalytic activity of MCM-41 molecular sieves in the Si/Al ratios 25, 50, 75 and 100 were characterised using powder X-ray diffraction (XRD), FT-IR and BET surface area analyser.
Abstract: Mesoporous Al-MCM-41 molecular sieves in the Si/Al ratios 25, 50, 75 and 100 were synthesized under hydrothermal condition. They were characterised using powder X-ray diffraction (XRD), FT-IR and BET surface area analyser. The catalytic activity of these materials was tested for the slurry phase acetalization of cyclohexanone with methanol (MET), ethylene glycol (EG) and pentaerythritol (PEN) at 40–120 °C. MET conversion was found to be higher than that of EG and PEN. Hydrophobic property of catalyst and alcohols and also the steric properties of alcohols were suggested to play an important role in the acetalization. For MET and EG, Al-MCM-41 (100) was found to be more active than other catalyst but for PEN, Al-MCM-41 (25) was found to be more active. The reaction was also studied over H 3 PW 12 O 40 supported MCM-41, commercially available heteropolyacid (H 3 PW 12 O 40 · n H 2 O) and zeolites (HM, Hβ and ZSM-5). Zeolites showed less activity for EG, PEN but comparable activity to MET. The requirement of Bronsted acid sites for the reaction was clearly established by running the reaction in the absence of catalyst.
TL;DR: In this article, nano-scale silver supported mesoporous molecular sieve Ag/MCM-41 was directly prepared by one-pot synthesis method and the prepared sample was characterized by XRD, TEM, and N2 sorption.
Abstract: Nano-scale silver supported mesoporous molecular sieve Ag/MCM-41 was directly prepared by one-pot synthesis method. The prepared sample was characterized by XRD, TEM, and N2 sorption. The results showed that the sample of Ag/MCM-41 had no appreciable incorporation of silver into the mesoporous matrix of MCM-41 with good crystallinity, and silver nanoparticles were dispersed inside or outside of the channels in the mesoporous host. The catalytic performance of the sample for the cyclohexane liquid-phase oxidation into cyclohexanone and cyclohexanol by oxygen in the absence of solvents without inducing agents was investigated. The 83.4% selectivity to cyclohexanol and cyclohexanone at 10.7% conversion of cyclohexane was obtained over Ag/MCM-41 catalyst at 428 K for 3 h. The turn over numbers (TONs) of Ag/MCM-41 was up to 2946. The catalytic activity of Ag/MCM-41 was also compared with Ag/TS-1 as well as Ag/Al2O3. The results indicated that Ag/MCM-41 showed superior activity to both Ag/TS-1 and Ag/Al2O3. A calcined Ag/MCM-41 was found to be an efficient catalyst for the cyclohexane oxidation into cyclohexanol and cyclohexanone using oxygen as oxidant.
TL;DR: In this article, the catalytic activity of these materials (M-TUD-1) was tested in the liquid phase oxidation of cyclohexane with tert-butylhydroperoxide (TBHP) as oxidant.
TL;DR: Four mutants of the cyclo hexanone monooxygenase (CHMO) evolved as catalysts for Baeyer-Villiger oxidation of 4-hydroxycyclohexanone were investigated as catalystal matches, finding that a mutant with a single exchange, Phe432Ser, was shown to be as robust and more selective as a catalyst than the wild-type CHMO.
Abstract: Four mutants of the cyclohexanone monooxygenase (CHMO) evolved as catalysts for Baeyer−Villiger oxidation of 4-hydroxycyclohexanone were investigated as catalysts for a variety of 4-substituted and 4,4-disubstituted cyclohexanones. Several excellent catalytic matches (mutant/substrate) were identified. The most important, however, is the finding that, in a number of cases, a mutant with a single exchange, Phe432Ser, was shown to be as robust and more selective as a catalyst than the wild-type CHMO. All biotransformations were performed on a laboratory scale, allowing full characterization of the products. The absolute configurations of two products were established. A model suggesting a possible role of the 432 serine residue in enantioselectivity control is proposed.
TL;DR: In this paper, LiOH·H 2 O was found to be a dual activation catalyst for tandem cross-aldol condensation between cyclic/acyclic ketones and aromatic/heteroaromatic/styryl/alkyl aldehydes leading to an efficient and easy synthesis of α,α-α-bis(aryl/ALKylmethylidene)ketones at r.t.
Abstract: Commercially available lithium hydroxide monohydrate (LiOH·H 2 O) was found to be a novel ‘dual activation’ catalyst for tandem cross-aldol condensation between cyclic/acyclic ketones and aromatic/heteroaromatic/styryl/alkyl aldehydes leading to an efficient and easy synthesis of α,α′-bis(aryl/alkylmethylidene)ketones at r.t. in short times. The reaction of aryl, heteroaryl, styryl and alkyl aldehydes with acyclic and five/six-membered cyclic ketones afforded excellent yields after 2 min to 1.25 h. The reaction conditions were compatible with various electron withdrawing and electron donating substituents, e.g. Cl, F, NO 2 , OMe and NMe 2 . The rate of the cross-aldol condensation was influenced by the nature of the ketone and electronic and steric factors associated with the aldehyde. The reaction took place at a faster rate for acyclic ketone (e.g., acetone) than that for cyclic ketone (e.g., cyclohexanone). In case of cycloalkanones, the rate of the reaction was dependent on the size of the ring of the cycloalkanone. The cross-aldol condensation of cyclopentanone was faster than that of cyclohexanone for a common aldehyde. In case of reactions involving aliphatic aldehyde having α-hydrogen atom no self-aldol condensation of the aldehyde took place.
TL;DR: In this article, a new series of 4,4′-disubstituted prolines (1a-h) was developed and tested as organocatalysts in the direct catalytic asymmetric aldol reaction of several aliphatic ketones with aldehydes.
Abstract: A new series of 4,4′-disubstituted prolines (1a–h) has been developed and tested as organocatalysts in the direct catalytic asymmetric aldol reaction of several aliphatic ketones with aldehydes. Catalyst 1g affords the best enantioselectivities for this transformation. The reaction was carried out in DMF using a catalyst loading of 10 mol % at −10 °C to give the aldol products in up to 97 % ee for acetone. In the cases of cyclohexanone and cyclopentanone, the corresponding anti-products were obtained in 94 % ee.
TL;DR: DBU was found to be the most effective promoter allowing the reaction to proceed smoothly at room temperature and to give the corresponding O-acyl cyanohydrin adducts in higher yields for a variety of substituted cyclohexanones, cyclopentanone, acetone or pentan-3-one and various acyl cyanides.
Abstract: The reaction of cyclohexanone with benzoyl cyanide catalyzed by amines provides the corresponding O-benzoyl cyanohydrin adducts in moderate to good yields under mild conditions. Among the catalysts, DBU was found to be the most effective promoter allowing the reaction to proceed smoothly at room temperature and to give the corresponding O-acyl cyanohydrin adducts in higher yields for a variety of substituted cyclohexanones, cyclopentanone, acetone or pentan-3-one and various acyl cyanides.
TL;DR: In this article, a mechanism involving adsorption of the nitrile and cyclohexanone onto the catalyst is proposed that is consistent with the experimental results, based on the proposed mechanism, the presence of a surfactant should result in improved conversion and catalytic activity.
TL;DR: Cobalt-doped mesoporous titania with anatase crystalline structure was prepared using 1-dodecylamine as template by cogellation method as discussed by the authors.
TL;DR: In this article, the reaction of thiobarbituric acid with different diarylidene ketones yields the spiro compounds 2a-c. The structures of the compounds are ascertained from their analytical and spectral data.
TL;DR: Amino-functionalized MCM-41 was used to immobilize Cu/Co-Cl 16 Pc complex, i.e. for liquid phase oxidation of alkanes under mild reaction conditions.
Abstract: Amino-functionalized MCM-41 (NH 2 -MCM-41) was used to immobilize Cu/Co-Cl 16 Pc complex, i.e. Cu/Co-AM(PS) for liquid phase oxidation of alkanes under mild reaction conditions. Higher rates of reaction and better catalytic activity values were obtained for Cu/Co-AM(PS) as compared to Cu/Co-Cl 16 Pc grafted on (i) amino-functionalized SiO 2 [Cu/Co-ASiO 2 ] and (ii) non-functionalized MCM-41 [Cu/Co-M(I)] catalysts along with neat metal complex under identical conditions. The catalysts were evaluated by comparing two different oxidants: (i) TBHP and (ii) O 2 /aldehyde. The rate of conversion and percent selectivity differ for the above two oxidants due to differences in stability of radical species and in their homolytic/heterolytic pathways. The homolytic dissociation of oxygen favors a higher rate of conversion in the case of TBHP, whereas the heterolytic mechanism favors a higher selectivity for cyclohexanone in the case of O 2 /aldehyde. The catalysts were characterized by XRD, MAS NMR, N 2 -adsorption, microanalysis, UV-vis, FTIR and cyclic voltammetry. The UV-vis spectra reveal a blue shift for the metal phthalocyanine-immobilized samples, indicating unimolecular dispersion of metal complex within the channels of MCM-41. Cyclic voltammetry results suggest some coordinative interaction of the amino group of NH 2 -MCM-41 with the metal on grafting with the complex.