Journal articles: 'Catalyse aqueuse'

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Khan, Mohammad Niyaz, and Ibrahim Isah Fagge. "Kinetics and Mechanism of Cationic Micelle/Flexible Nanoparticle Catalysis: A Review." Progress in Reaction Kinetics and Mechanism 43, no. 1 (March 2018): 1–20. http://dx.doi.org/10.3184/146867818x15066862094905.

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The aqueous surfactant (Surf) solution at [Surf] > cmc (critical micelle concentration) contains flexible micelles/nanoparticles. These particles form a pseudophase of different shapes and sizes where the medium polarity decreases as the distance increases from the exterior region of the interface of the Surf/H2O particle towards its furthest interior region. Flexible nanoparticles (FNs) catalyse a variety of chemical and biochemical reactions. FN catalysis involves both positive catalysis ( i.e. rate increase) and negative catalysis ( i.e. rate decrease). This article describes the mechanistic details of these catalyses at the molecular level, which reveals the molecular origin of these catalyses. Effects of inert counterionic salts (MX) on the rates of bimolecular reactions (with one of the reactants as reactive counterion) in the presence of ionic FNs/micelles may result in either positive or negative catalysis. The kinetics of cationic FN (Surf/MX/H2O)-catalysed bimolecular reactions (with nonionic and anionic reactants) provide kinetic parameters which can be used to determine an ion exchange constant or the ratio of the binding constants of counterions.

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Lukey, CA, MA Long, and JL Garnett. "Aromatic Hydrogen Isotope Exchange Reactions Catalyzed by Iridium Complexes in Aqueous Solution." Australian Journal of Chemistry 48, no. 1 (1995): 79. http://dx.doi.org/10.1071/ch9950079.

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Sodium hexachloroiridate (III) and sodium hexachloroiridate (IV) have been used as homogeneous catalysts for hydrogen isotope exchange between benzenoid compounds and water. The ideal solvent consisted of 50 mole % acetic acid/water, and the optimum temperature was found to be 160°C. Under these conditions the rate of incorporation of deuterium into benzene was significant (typically 15% D in 6 h), and reduction to iridium metal was minimized. The active catalytic species was identified as a solvated iridium(III) species, which is also postulated to be the active catalyst in solutions containing hexachloroiridate (IV). The kinetics of exchange in benzene catalysed by sodium hexachloroiridate (III) were elucidated, and found to be more complex than for the corresponding sodium tetrachloroplatinate (II) catalysed exchange, in that a two-term rate dependence was found for catalyst concentration and the reaction was inversely dependent on hydrogen ion concentration. The reaction was found to be independent of chloride ion concentration, this confirming that the active catalyst is a solvated species. Isotopic labelling in all compounds was confined to the aromatic ring, and most substituted benzenes exhibited deactivation of the ortho positions, indicating that a dissociative π-complex exchange mechanism was operating. This was confirmed by exchange into naphthalene, where it was found that labelling was predominantly in the β position. Facile exchange into nitrobenzene provided good evidence of homogeneous catalysis, and not catalysis by precipitated metal.

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Salvio, Riccardo, Roberta Cacciapaglia, Luigi Mandolini, Francesco Sansone, and Alessandro Casnati. "Diguanidinocalix[4]arenes as effective and selective catalysts of the cleavage of diribonucleoside monophosphates." RSC Adv. 4, no. 65 (2014): 34412–16. http://dx.doi.org/10.1039/c4ra05751a.

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Upper rim diguanidino-cone-calix[4]arenes catalyze the hydrolytic cleavage of diribonucleoside monophosphates in aqueous DMSO with good substrate selectivity and rate accelerations approaching 10⁵-fold in the most favourable substrate-catalyst combinations.

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Zhuang, Huimin, Bili Chen, Wenjin Cai, Yanyan Xi, Tianxu Ye, Chuangye Wang, and Xufeng Lin. "UiO-66-supported Fe catalyst: a vapour deposition preparation method and its superior catalytic performance for removal of organic pollutants in water." Royal Society Open Science 6, no. 4 (April 2019): 182047. http://dx.doi.org/10.1098/rsos.182047.

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A vapour deposition (VD) method was established for preparation of the UiO-66-supported Fe (Fe/UiO-66) catalyst, which provided the first case of the metal-organic framework (MOF)-supported Fe catalyst prepared by using the vapour-based method. The Fe loading was around 7.0–8.5 wt% under the present preparation conditions. The crystal structure of UiO-66 was not obviously influenced by the Fe loading, while the surface area significantly decreased, implicating most of the Fe components resided in the pores on UiO-66. The results for the methyl orange (MO) removal tests showed that MO in aqueous solution can be removed by UiO-66 by adsorption, and in contrast, it can be oxidized by H 2 O 2 with the catalysis of Fe/UiO-66. Further catalytic tests showed that Fe/UiO-66 was rather effective to catalyse the oxidation of benzene derivatives like aniline in water in terms of chemical oxygen demand (COD) removal efficiency. The catalytic test results for Fe/UiO-66 were compared to those of Fe/Al 2 O 3 with the same Fe loading and to the catalysts reported in the literature. This paper provides a general strategy for VD preparation of MOF-supported Fe catalyst on the one hand, and new catalysts for removing organic pollutants from water, on the other hand.

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Wang, Changlong, Lionel Salmon, Roberto Ciganda, Luis Yate, Sergio Moya, Jaime Ruiz, and Didier Astruc. "An efficient parts-per-million α-Fe2O3 nanocluster/graphene oxide catalyst for Suzuki–Miyaura coupling reactions and 4-nitrophenol reduction in aqueous solution." Chemical Communications 53, no. 3 (2017): 644–46. http://dx.doi.org/10.1039/c6cc08401j.

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α-Fe₂O₃ nanoclusters supported onto a graphene oxide catalyst are shown for the first time to catalyze Suzuki–Miyaura coupling and 4-nitrophenol reduction in aqueous solution with only parts-per-million loading.

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Voitko, K. V., O. M. Bakalinska, Yu V. Goshovska, Yu I. Sementsov, and M. T. Kartel. "Catalase-like properties of multilayer graphene oxides and their modified forms." Surface 12(27) (December 30, 2020): 251–62. http://dx.doi.org/10.15407/surface.2020.12.251.

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The catalytic system, that mimets catalase enzyme such as “multilayer graphene oxide /peroxide molecule” in aqueous media was investigated. The main factors that influence on catalyst’s effectiveness were determining. The catalytic activity of as-synthesized multilayered graphene oxides, and their modified forms (oxidized and nitrogen doped) were investigated in the decomposition of hydrogen peroxides at room temperature and physiological pHs by measuring the volume of released gases. A phosphate buffer with a pH of 5 to 8 was chosen as the reaction medium. The original and modified samples were characterized using XPS, TPD-MS, Boehm titration analyses. The effect of surface chemistry on the catalytic reaction proceeding has been studied. It was found that catalysis on the graphene plane is determined by the presence of heteroatoms in their structure. The catalytic process takes place in the kinetic zone over the entire accessible surface of the samples. The active sites of the catalysts contain a large amount of both nitrogen and oxygen-containing functional groups. In addition, the surface of graphene oxide is hydrophilic, which enhances the catalytic reaction in an aqueous medium. It has been established that the rate of hydrogen peroxide decomposition by reduced graphene oxide samples is lower than for samples modified with oxygen and nitrogen. The catalase-like activity of graphene increases in alkaline pH up to 7.8. Studies have shown that samples of multilayer graphenes with a high content of functional groups can be an alternative to the catalase enzyme as a catalyst for the decomposition of hydrogen peroxide in physiological solutions.

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Pradhan, Subhashis, Subhadip Dutta, and Rohith P. John. "A coordination driven self-assembled Pd6L8 nanoball catalyses copper and phosphine-free Sonogashira coupling reaction in both homogeneous and heterogeneous formats." New Journal of Chemistry 40, no. 8 (2016): 7140–47. http://dx.doi.org/10.1039/c5nj03658e.

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A self-assembled Pd₆L₈ nanocage catalysed copper free Sonogashira reaction under mild and aerobic conditions, at 100 ppm catalyst loading in aqueous medium in the homogeneous phase, and at 500 ppm in the heterogeneous phase.

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8

Khosravi, Kaveh, Mojgan Zendehdel, Shirin Naserifar, Fatemeh Tavakoli, Kobra Khalaji, and Atefeh Asgari. "Heteropoly acid/NaY zeolite as a reusable solid catalyst for highly efficient synthesis of gem-dihydroperoxides and 1,2,4,5-tetraoxanes." Journal of Chemical Research 40, no. 12 (December 2016): 744–49. http://dx.doi.org/10.3184/174751916x14792244600532.

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gem-Dihydroperoxides and 1,2,4,5-tetraoxanes were synthesised from aldehydes and ketones catalysed by heteropoly acid/NaY zeolite (HPA/NaY) as a new, effective and reusable solid catalyst using 30% aqueous hydrogen peroxide at room temperature. The reactions proceeded with high rates and excellent yields.

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Wang, Hui, Ambra Maria Fiore, Christophe Fliedel, Eric Manoury, Karine Philippot, Maria Michela Dell'Anna, Piero Mastrorilli, and Rinaldo Poli. "Rhodium nanoparticles inside well-defined unimolecular amphiphilic polymeric nanoreactors: synthesis and biphasic hydrogenation catalysis." Nanoscale Advances 3, no. 9 (2021): 2554–66. http://dx.doi.org/10.1039/d1na00028d.

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Triphenylphosphine-stabilised rhodium nanoparticles embedded in well-defined core-crosslinked micelles have been generated and used in aqueous biphasic catalysis. The conditions allowing core confinement and efficient catalyst recycle are outlined.

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Fan, Mengyang, Zhengyu Bai, Qing Zhang, Chengyu Ma, Xiao-Dong Zhou, and Jinli Qiao. "Aqueous CO2 reduction on morphology controlled CuxO nanocatalysts at low overpotential." RSC Adv. 4, no. 84 (2014): 44583–91. http://dx.doi.org/10.1039/c4ra09442e.

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The Cu_xO_180-2 catalyst obtained with 3D hierarchical nanosphere structures could catalyze CO₂ reduction in aqueous solution with very high catalytic activity and superb selectivity of produced formate, significantly outperforming Cu_xO catalysts without such special morphology.

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11

Labou, D., and S. G. Neophytides. "Catalytic and electrocatalytic activity of Pt-Ru/C electrode for hydrogen oxidation in alkaline and acid aqueous electrolytes: EMSI and EPOC effects." Chemical Industry and Chemical Engineering Quarterly 14, no. 2 (2008): 145–52. http://dx.doi.org/10.2298/ciceq0802145l.

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The kinetics of the oxidation of H2 on PtRu/C gas-diffusion electrode was studied by interfacing the electrode with aqueous electrolytes at different pH values. The conducting electrolytes were KOH and HClO4 aqueous solutions with different concentrations. It is shown that the nature of the aqueous electrolyte plays the role of an active catalyst support for the PtRu/C electrode which drastically affects its catalytic properties. During the aforementioned interaction, termed electrochemical metal support interaction (EMSI), the electrochemical potential of the electrons at the catalyst Fermi level is equalized with the electrochemical potential of the solvated electron in the aqueous electrolyte. The electrochemical experiments carried out at various pH values showed that the electrochemical promotion catalysis (EPOC) is more intense when the catalyst-electrode is interfaced with electrolytes with high pH values where the OH ionic conduction prevails. It was concluded that similar to the solid state electrochemical systems EPOC proceeds through the formation of a polar adsorbed promoting layer of OH ? -, electrochemically supplied by the OH species, at the three phase boundaries of the gas exposed gas diffusion catalyst-electrode surface.

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12

Engell, Karen M., Robert A. McClelland, and Poul E. Sørensen. "The decomposition of methyl hemiacetals of benzaldehyde in aqueous solution: a study of the effect of aromatic substitution." Canadian Journal of Chemistry 77, no. 5-6 (June 1, 1999): 978–89. http://dx.doi.org/10.1139/v99-102.

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The acid-base catalysed decomposition of hydrates and hemiacetals of carbonyl compounds are classical examples of reactions where (slow) proton transfer is coupled with heavy atom reorganization, i.e., CO bond breaking and solvent reorganization. We have studied the influence of m- and p-substitution in the carbonyl electrophile on the kinetics of the acid and base catalysis of the decomposition of methyl hemiacetals of benzaldehyde. The experimental data are well described by three-dimensional More O'Ferrall - Jencks energy contour diagrams according to principles developed by Jencks (the BEMA HAPOTHLE). Thus, for acid catalysis, a Cordes cross-interaction coefficient pxy' = δρ/δpKa = 0.15 indicates the coupled nature of the rate-limiting step in a class e mechanism, similar to conclusions reached from systematic substitution in the nucleophile. Our more extensive set of data for base catalysis permits a more rigorous analysis according to the BEMA HAPOTHLE. The data are consistent with a class n mechanism as also suggested earlier on the basis of substitution in the nucleophile. A slight upward curvature observed in the Hammett plots for the various catalysts is described by the direct correlation parameter py = -δρ/δσ = -0.11. This second derivative demonstrates the concerted nature of the CO bond cleavage and O-H formation in the transition state, which changes with changing substituent. A class n mechanism for base catalysis is also supported by the observation of a Cordes cross-interaction parameter pxy = -δρ/δpKa = -δβ/δσ = 0.03, which describes the experimentally observed decrease in Hammett ρ with increasing pKa of the catalyst. This change may be rationalized by the movement of a saddle point on a diagonal reaction coordinate in the energy contour diagram, as a resultant of shifts parallel and perpendicular to the coordinate, when the energy along one side of the diagram is changed. It is concluded that observed rate changes as a result of substitution in the electrophile are consistent with and present further confirmation of earlier suggested mechanisms of hemiacetal decomposition reactions.Key words: methyl hemiacetals of benzaldehydes, acid-base catalysed breakdown, Hammett plots, More O'Ferrall - Jencks diagrams.

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13

Postigo, Lorena, Maria Ventura, Tomás Cuenca, Gerardo Jiménez, and Beatriz Royo. "Selective sulfoxidation with hydrogen peroxide catalysed by a titanium catalyst." Catalysis Science & Technology 5, no. 1 (2015): 320–24. http://dx.doi.org/10.1039/c4cy00965g.

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A cyclopentadienyl–silsesquioxane titanium complex efficiently catalyses the selective oxidation of sulfides to sulfoxides (85–98% yield in 5 min at ambient temperature) and sulfones with near-stochiometric amount of aqueous H₂O₂ in methanol.

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Khangarot, Rama Kanwar, Manisha Khandelwal, and Sumit Kumar Ray. "Syntheses and Applications of Singh’s Catalyst." Synthesis 52, no. 23 (August 19, 2020): 3577–82. http://dx.doi.org/10.1055/s-0040-1707235.

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Singh’s catalyst has emerged as one of the most promising and valuable catalysts in the field of asymmetric synthesis. Since its discovery, it has proven to be one of the best organocatalysts for asymmetric direct aldol reactions, and is equally efficient in aqueous and organic media. In this Short Review, we summarize reactions utilizing Singh’s catalyst under various conditions.1 Introduction2 Synthesis of Singh’s Catalyst3 Applications in Asymmetric Synthesis4 Conclusion

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15

Fu, Luman, Shuru Li, Zhongyuan Han, Huifang Liu, and Hengquan yang. "Tuning the wettability of mesoporous silica for enhancing the catalysis efficiency of aqueous reactions." Chem. Commun. 50, no. 70 (2014): 10045–48. http://dx.doi.org/10.1039/c4cc02988g.

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A series of mesoporous silica-based catalysts with finely-tuned surface wettability have been synthesized. Their catalysis efficiency towards aqueous hydrogenations is highly dependent on their surface wettability and can be five times higher than that of the commercial Pd/C catalyst.

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16

Kungumathilagam, Durairaj, and Kulanthaivel Karunakaran. "Kinetics and Mechanism ofmeso-Tetraphenylporphyrin Iron(III) Chloride Catalysed Oxidation of Indole-3-Acetic Acid by Peroxomonosulphate." Journal of Chemistry 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/186168.

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Mechanistic study onmeso-tetraphenylporphyrin iron(III) chloride (TPP) catalysed oxidation of indole-3-acetic acid by peroxomonosulphate (oxone) in aqueous acetonitrile medium has been carried out. The reaction follows a first order with respect to both substrate and oxidant. The order with respect to catalyst was found to be fractional. The order of reaction with respect to catalyst varies with a concentration of catalyst. Increase in percentage of acetonitrile decreased the rate. The reaction fails to initiate polymerization, and a radical mechanism is ruled out. Activation and thermodynamic parameters have been computed. A suitable kinetic scheme based on these observations is proposed. Significant catalytic activity is observed for the reaction system in the presence of TPP.

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17

Gong, Gui Zhen, Bo Di, and Wei Hua. "Effect of Catalysts on Oxidation of Ruqigou Coal with NaOCl." Advanced Materials Research 953-954 (June 2014): 1303–6. http://dx.doi.org/10.4028/www.scientific.net/amr.953-954.1303.

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The effect of molecular sieve, activated carbon, and nickel-based catalyst on oxidation of Ruqigou coal with NaOCl was investigated. The yields of diethyl ether-soluble fractions from reaction mixture are 67.3% for black test, 71.2% for molecular sieve, 68.6% for activated carbon and 70.3% for nickel-based catalyst, respectively. The results indicate that molecular sieve, nickel-based catalyst and activated carbon can all improve the oxidation reactivity of coal in aqueous NaOCl solution. Molecular sieve and nickel-based catalyst can convert most of the organic matters contained in coal into solvent-soluble species. The catalysis of molecular sieve is the highest, followed by nickel-based catalyst, activated carbon is relatively small.

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Hao, Wenyan, Yue Wang, Shouri Sheng, and Mingzhong Cai. "Synthesis of terminal arylacetylenes by a Stille coupling reaction catalysed by a MCM-41-supported bidentate phosphine palladium(O) complex." Journal of Chemical Research 2008, no. 11 (November 2008): 615–18. http://dx.doi.org/10.3184/030823408x360328.

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A variety of terminal arylacetylenes have been conveniently synthesised in good to high yields by Stille coupling of aryl halides with ethynyltributylstannane catalysed by a MCM-41-supported bidentate phosphine palladium(O) complex in an aqueous medium and under air. Our system not only avoids the requirement for water-free and oxygen-free conditions, but also solves the basic problem of palladium catalyst reuse.

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19

Wood, Alex B., Daniel E. Roa, Fabrice Gallou, and Bruce H. Lipshutz. "α-Arylation of (hetero)aryl ketones in aqueous surfactant media." Green Chemistry 23, no. 13 (2021): 4858–65. http://dx.doi.org/10.1039/d1gc01572a.

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α-Arylations can be run under micellar catalysis conditions using a Pd(i) pre-catalyst together with KO-t-Bu as base. Sequences using this coupling along with as many as four additional steps can be carried out in a 1-pot fashion, all in water.

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20

Banerji, Biswadip, K. Chandrasekhar, Sunil Kumar Killi, Sumit Kumar Pramanik, Pal Uttam, Sudeshna Sen, and Nakul Chandra Maiti. "Silver-catalysed azide–alkyne cycloaddition (AgAAC): assessing the mechanism by density functional theory calculations." Royal Society Open Science 3, no. 9 (September 2016): 160090. http://dx.doi.org/10.1098/rsos.160090.

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‘Click reactions’ are the copper catalysed dipolar cycloaddition reaction of azides and alkynes to incorporate nitrogens into a cyclic hydrocarbon scaffold forming a triazole ring. Owing to its efficiency and versatility, this reaction and the products, triazole-containing heterocycles, have immense importance in medicinal chemistry. Copper is the only known catalyst to carry out this reaction, the mechanism of which remains unclear. We report here that the ‘click reactions’ can also be catalysed by silver halides in non-aqueous medium. It constitutes an alternative to the well-known CuAAC click reaction. The yield of the reaction varies on the type of counter ion present in the silver salt. This reaction exhibits significant features, such as high regioselectivity, mild reaction conditions, easy availability of substrates and reasonably good yields. In this communication, the findings of a new catalyst along with the effect of solvent and counter ions will help to decipher the still obscure mechanism of this important reaction.

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Yoon, D. S., K. Won, Y. H. Kim, B. K. Song, S. J. Kim, S. J. Moon, and B. S. Kim. "Continuous removal of hydrogen peroxide with immobilised catalase for wastewater reuse." Water Science and Technology 55, no. 1-2 (January 1, 2007): 27–33. http://dx.doi.org/10.2166/wst.2007.016.

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Hydrogen peroxide was continuously removed for wastewater reuse using an immobilised biocatalyst. A commercial catalase, which is an enzyme to decompose hydrogen peroxide to water and oxygen, was entrapped in chitosan beads. Hydrogen peroxide in aqueous solutions of varying pH, temperature and concentration was continuously removed through a reactor containing the catalase-entrapped chitosan beads at high efficiency for 24 h. Additional silicate coating of the chitosan beads resulted in significant improvements in the catalase performance under harsh conditions, which are often found in peroxide-based industrial processes. We expect that immobilisation of catalases can enhance their applicability for continuous degradation of hydrogen peroxide for wastewater reuse.

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22

Li, Jun, Guannan Tang, Yuchen Wang, Ya Wang, Zixi Li, and Hengfeng Li. "Poly(amic acid) salt-stabilized silver nanoparticles as efficient and recyclable quasi-homogeneous catalysts for the aqueous hydration of nitriles to amides." New Journal of Chemistry 40, no. 1 (2016): 358–64. http://dx.doi.org/10.1039/c5nj02497h.

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The reversible pH-response of the Ag–PAAS catalyst allows it to catalyze the selective hydration of various nitriles quasi-homogeneously in water and to be easily recovered by simply adjusting the pH value of the solution.

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23

Orazov, Marat, and Mark E. Davis. "Tandem catalysis for the production of alkyl lactates from ketohexoses at moderate temperatures." Proceedings of the National Academy of Sciences 112, no. 38 (September 8, 2015): 11777–82. http://dx.doi.org/10.1073/pnas.1516466112.

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Retro-aldol reactions have been implicated as the limiting steps in catalytic routes to convert biomass-derived hexoses and pentoses into valuable C2, C3, and C4 products such as glycolic acid, lactic acid, 2-hydroxy-3-butenoic acid, 2,4-dihydroxybutanoic acid, and alkyl esters thereof. Due to a lack of efficient retro-aldol catalysts, most previous investigations of catalytic pathways involving these reactions were conducted at high temperatures (≥160 °C). Here, we report moderate-temperature (around 100 °C) retro-aldol reactions of various hexoses in aqueous and alcoholic media with catalysts traditionally known for their capacity to catalyze 1,2-intramolecular carbon shift (1,2-CS) reactions of aldoses, i.e., various molybdenum oxide and molybdate species, nickel(II) diamine complexes, alkali-exchanged stannosilicate molecular sieves, and amorphous TiO2–SiO2 coprecipitates. Solid Lewis acid cocatalysts that are known to catalyze 1,2-intramolecular hydride shift (1,2-HS) reactions that enable the formation of α-hydroxy carboxylic acids from tetroses, trioses, and glycolaldehyde, but cannot readily catalyze retro-aldol reactions of hexoses and pentoses at these moderate temperatures, are shown to be compatible with the aforementioned retro-aldol catalysts. The combination of a distinct retro-aldol catalyst with a 1,2-HS catalyst enables lactic acid and alkyl lactate formation from ketohexoses at moderate temperatures (around 100 °C), with yields comparable to best-reported chemocatalytic examples at high temperature conditions (≥160 °C). The use of moderate temperatures enables numerous desirable features such as lower pressure and significantly less catalyst deactivation.

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Kaziro, RW, and JK Beattie. "The pH Dependence of the Ruthenium-Catalyzed Ferricyanide Oxidation of Cyclohexanol." Australian Journal of Chemistry 42, no. 8 (1989): 1273. http://dx.doi.org/10.1071/ch9891273.

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The oxidation of cyclohexanol to cyclohexanone by ferricyanide in alkaline aqueous solutions is catalysed by the addition of chlororuthenium compounds. In solutions of pH less than 11 the progress of the reaction is limited by the decomposition of the catalyst in its reduced state. The catalyst lifetime can be lengthened by an increase in the concentration of the ferricyanide oxidant. In solutions of pH 11.3-11.9 either of the oxidation or the reduction steps of the catalytic cycle can be made rate determining, by adjustment of the relative concentrations of cyclohexanol and ferricyanide . The decrease in rate with increase in pH is due to the pH dependence of the reaction of the oxidized catalyst. The rate constant decreases from 26 to 15 dm3 mol-1 s-l between pH 11.3 and 11.9. The rate constant for the ferricyanide oxidation of the reduced catalyst is pH-independent at (6 � 2)×102 dm3 mol-1 s-1 at 298 K, over the same pH range.

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Sharma, Priyamvada, Riya Sailani, Anita Meena, and Chandra Lata Khandelwal. "A kinetic and mechanistic study of the osmium(VIII)-catalysed oxidation of crotyl alcohol by hexacyanoferrate(III) in aqueous Alkaline medium." Journal of Chemical Research 44, no. 5-6 (January 20, 2020): 295–300. http://dx.doi.org/10.1177/1747519819900622.

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The kinetics and mechanism of the osmium(VIII)-catalysed oxidation of crotyl alcohol by hexacyanoferrate(III) in aqueous alkaline medium is studied. The role of the osmium(VIII) catalyst is delineated to account for the experimental observations. A plausible reaction mechanism is suggested. Activation parameters such as the energy and entropy of activation are evaluated by employing the Eyring equation and are found to be 36.833 kJ mol−1 and −141.518 J K−1 mol−1, respectively.

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Kumar, Atul, and Ratnakar Dutt Shukla. "β-Cyclodextrin catalysed C–C bond formation via C(sp3)–H functionalization of 2-methyl azaarenes with diones in aqueous medium." Green Chemistry 17, no. 2 (2015): 848–51. http://dx.doi.org/10.1039/c4gc02287d.

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β-Cyclodextrin catalysed C(sp³)–H functionalization of 2-alkyl-azaarenes with homocyclic as well as heterocyclic diones in water has been developed. This biomimetic catalyst oriented methodology provides a sustainable protocol for C–H functionalization, an area mainly dominated by transition metals.

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Kungumathilagam, D., and K. Karunakaran. "Kinetics and mechanism of meso-tetraphenylporphyriniron(III) chloride (TPP) catalysed oxidation of indole by sodium perborate." Polish Journal of Chemical Technology 15, no. 2 (July 1, 2013): 107–11. http://dx.doi.org/10.2478/pjct-2013-0031.

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Developing catalyst is very significant for biologically important reactions which yield products, used as drugs. Mechanistic study on meso-tetraphenylporphyriniron(III) chloride (TPP) catalysed oxidation of indole by sodium perborate in aqueous acetic acid medium have been carried out. The reaction follows a fractional order with respect to substrate and catalyst. The order with respect to oxidant was found to be one. Increase in the percentage of acetic acid and increase in the concentration of [H+] decreased the rate. The reaction fails to initiate polymerization, and a radical mechanism is ruled out. Activation and thermodynamic parameters have been computed. A suitable kinetic scheme based on these observations has been proposed. Significant catalytic activity is observed for the reaction system in the presence of TPP.

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Sadjadi, Samahe, Fatemeh Koohestani, and Majid Heravi. "Biochar-Based Graphitic Carbon Nitride Adorned with Ionic Liquid Containing Acidic Polymer: A Versatile, Non-Metallic Catalyst for Acid Catalyzed Reaction." Molecules 25, no. 24 (December 16, 2020): 5958. http://dx.doi.org/10.3390/molecules25245958.

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A novel biochar-based graphitic carbon nitride was prepared through calcination of Zinnia grandiflora petals and urea. To provide acidic and ionic-liquid functionalities on the prepared carbon, the resultant biochar-based graphitic carbon nitride was vinyl functionalized and polymerized with 2-acrylamido-2-methyl-1-propanesulfonic acid, acrylic acid and the as-prepared 1-vinyl-3-butylimidazolium chloride. The final catalytic system that benefits from both acidic (–COOH and –SO3H) and ionic-liquid functionalities was applied as a versatile, metal-free catalyst for promoting some model acid catalyzed reactions such as Knoevenagel condensation and Biginelli reaction in aqueous media under a very mild reaction condition. The results confirmed high activity of the catalyst. Broad substrate scope and recyclability and stability of the catalyst were other merits of the developed protocols. Comparative experiments also indicated that both acidic and ionic-liquid functionalities on the catalyst participated in the catalysis.

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Fischer, Alfred, George N. Henderson, and Trevor A. Smyth. "Reactions of the 1-hydroxy-1,4-dimethylcyclohexadienyl cation, an intermediate in the solvolysis of 1,4-dimethyl-4-nitrocyclohexa-2,5-dien-1-ol." Canadian Journal of Chemistry 64, no. 6 (June 1, 1986): 1093–101. http://dx.doi.org/10.1139/v86-184.

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Solvolysis of 1,4-dimethyl-4-nitrocyclohexa-2,5-dien-1-ol in mixed aqueous organic solvents gives the diastereomers of 1,4-dimethylcyclohexa-2,5-diene-1,4-diol, 1,4-dimethylcyclohexa-3,5-diene-1,2-diol, 2-nitro-p-xylene, 2,4-dimethylphenol (all derived from the title cation, itself formed by ionization of the nitro group as nitrite), and 2,5-dimethylphenol. In aqueous methanol the diastereomers of 4-methoxy-1,4-dimethylcyclohexa-2,5-dienol are also obtained. Significant yields of 2,5-dimethylphenol are only obtained on the acid-catalysed further reaction of the dienediol (or the methoxydienol) and involve the intermediate formation of 1,4-dimethylcyclohexa-3,5-diene-1,2-diol. In the absence of added base the acid released in the solvolysis catalyses this reaction and leads to the aromatization of the dienes.

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30

Zhu, Lei, Taku Kitanosono, Pengyu Xu, and Shū Kobayashi. "Chiral Cu(II)-catalyzed enantioselective β-borylation of α,β-unsaturated nitriles in water." Beilstein Journal of Organic Chemistry 11 (October 27, 2015): 2007–11. http://dx.doi.org/10.3762/bjoc.11.217.

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The promising performance of copper(II) complexes was demonstrated for asymmetric boron conjugate addition to α,β-unsaturated nitriles in water. The catalyst system, which consisted of Cu(OAc)2 and a chiral 2,2′-bipyridine ligand, enabled β-borylation and chiral induction in water. Subsequent protonation, which was accelerated in aqueous medium, led to high activity of this asymmetric catalysis. Both solid and liquid substrates were suitable despite being insoluble in water.

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31

Bashpa, P., P. Rajendran, and K. Bijudas. "Oxidation of Cyclohexanol and Cyclohexanone by Monochromate Ions in Organic Solvents and on Solvent Free Microwave Irradiation under Phase Transfer Catalysis - A Comparative Study." Asian Journal of Chemistry 33, no. 9 (2021): 2033–37. http://dx.doi.org/10.14233/ajchem.2021.23285.

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Oxidation of cyclohexanol and cyclohexanone were carried out by acidified monochromate ions in ethyl acetate and toluene under phase transfer catalysis and also in solvent free condition under microwave irradiation. The extraction of monochromate ions from aqueous medium to organic phase was carried by employing various phase transfer catalysts in the presence of mineral acids. The effect of [catalyst] and [mineral acid] on extraction of monochromate from aqueous phase to organic phase was also studied. The product obtained, namely adipic acid obtained with both reactants was characterized by its melting point and infrared spectral technique. The reaction was over within 15 min with more than 85% yield at a temperature of 323 K under microwave irradiation where as it gave around 70% yield at 353 K within 150 min under phase transfer catalysis condition. The enhanced reaction rate and high yield of product substantiate the application of phase transfer catalytic technique under microwave irradiation for organic synthesis. A suitable mechanism for the oxidation of substrates by monochromate under phase transfer catalysis is also suggested.

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32

Dyson, Paul J., David J. Ellis, and Thomas Welton. "A temperature-controlled reversible ionic liquid - water two phase - single phase protocol for hydrogenation catalysis." Canadian Journal of Chemistry 79, no. 5-6 (May 1, 2001): 705–8. http://dx.doi.org/10.1139/v01-084.

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An ionic liquid water system that undergoes a reversible two phase single phase transformation dependent upon temperature has been used as a novel medium for the transition-metal-catalyzed hydrogenation of a water soluble substrate. At room temperature, the ionic liquid 1-octyl-3-methylimidizolium tetrafluoroborate, containing [Rh(η4-C7H8)(PPh3)2][BF4] catalyst, forms a separate layer to water containing 2-butyne-1,4-diol. In a stirred autoclave the mixture was pressurized with hydrogen to 60 atm (1 atm = 101.325 kPa) and heated to 80°C giving a homogeneous single phase solution. On cooling to room temperature, two phases reform, with the ionic liquid phase containing the catalyst and the aqueous phase containing a mixture of 2-butene-1,4-diol and butane-1,4-diol products that can be simply removed without catalyst contamination.Key words: ionic liquids, biphasic catalysis, hydrogenation, rhodium.

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33

Horozova, Elena, Nina Dimcheva, and Zinaida Jordanova. "Catalytic Decomposition of 3-Chloroperoxybenzoic Acid by Immobilized Catalase in a Non-Aqueous Medium." Zeitschrift für Naturforschung C 55, no. 1-2 (February 1, 2000): 55–59. http://dx.doi.org/10.1515/znc-2000-1-211.

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Abstract Catalytic activities of catalase (CAT) immobilized on graphite - GMZ™ , soot - “NORIT ” and “PM -100” to mediate decomposition of 3-Cl-C6H4COOOH (3-CPBA)in acetonitrile have been investigated. Under these conditions, the kinetic parameters Km, k, Ea, Vmax , and Zo were calculated. Conclusions on a probable mechanism of the catalytic process observed were drawn from the calculated values of ΔG*, ΔH*, and ΔS*. A quantitative UV-spectrophotometrical approach was used as the basic analytical tool. The electrochemical reduction of oxygen generated in enzyme catalysed 3-CPBA decomposition was examined with polarization curves method.

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34

Mutti, Francesco G. "Alkene Cleavage Catalysed by Heme and Nonheme Enzymes: Reaction Mechanisms and Biocatalytic Applications." Bioinorganic Chemistry and Applications 2012 (2012): 1–13. http://dx.doi.org/10.1155/2012/626909.

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The oxidative cleavage of alkenes is classically performed by chemical methods, although they display several drawbacks. Ozonolysis requires harsh conditions (−78°C, for a safe process) and reducing reagents in a molar amount, whereas the use of poisonous heavy metals such as Cr, Os, or Ru as catalysts is additionally plagued by low yield and selectivity. Conversely, heme and nonheme enzymes can catalyse the oxidative alkene cleavage at ambient temperature and atmospheric pressure in an aqueous buffer, showing excellent chemo- and regioselectivities in certain cases. This paper focuses on the alkene cleavage catalysed by iron cofactor-dependent enzymes encompassing the reaction mechanisms (in case where it is known) and the application of these enzymes in biocatalysis.

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35

Lewandowski, Grzegorz. "Comparison of the methods of the phase transfer catalysis and hydroperoxide in the epoxidation of 1,5,9-cyclododecatriene." Polish Journal of Chemical Technology 9, no. 3 (January 1, 2007): 101–4. http://dx.doi.org/10.2478/v10026-007-0065-0.

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Comparison of the methods of the phase transfer catalysis and hydroperoxide in the epoxidation of 1,5,9-cyclododecatriene The process of the epoxidation of cis, trans, trans-1,5,9-cyclododecatriene (CDT) to 1,2-epoxy-5,9-cyclododecadiene (ECDD) with the 30% aqueous hydrogen peroxide under the phase transfer conditions and with tert-butyl hydroperoxide under the homogeneous conditions was investigated. Onium salts such as Aliquat® 336, Arquad® 2HT, methyltrioctylammonium bromide and the Na2WO4/H3PO4 catalyst system are very active under the phase transfer catalysis (PTC) conditions for the selective epoxidation of cis, trans, trans-1,5,9-cyclododecatiene (PTC method). These catalytic systems were found to be as active and selective as the homogeneous phase system Mo(CO)6/TBHP (hydroperoxide method).

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36

Malikova, N. N., N. I. Ali-zade, and T. M. Nagiev. "PHYSICO-CHEMICAL FEATURES OF CATALASE BIOMIMETIC SENSORS." Azerbaijan Chemical Journal, no. 4 (December 12, 2020): 65–68. http://dx.doi.org/10.32737/0005-2531-2020-4-65-68.

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The physicochemical features of biomimetic sensor have been studied, using various materials as a transducer. It is shown that biomimetic sensor prepared on the basis of a smart material and semiconductors had a number of technological advantages. It was found that among the selected various materials, the biomimetic sensor prepared from the smart material TPhPFe3+OH/Al2O3 and the semiconductor Si proved to be the most effective. The developed biomimetic sensor is differed by high activity, sensitivity, stability and reproducibility with the possibility of expanding the range of detectable trace concentration of H2O2 in aqueous solutions to 10-6 mass %

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37

Tee, Oswald S., and N. Rani Iyengar. "Enolization of the benzocyclohexadienone formed during the bromination of 1-naphthol in aqueous solution." Canadian Journal of Chemistry 65, no. 8 (August 1, 1987): 1714–18. http://dx.doi.org/10.1139/v87-286.

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Benzo-4-bromo-2,5-cyclohexadienone (5) has been observed in the aqueous bromination of 1-naphthol and the kinetics of its enolization to 4-bromo-1-naphthol have been studied in the pH range 0–7. This process is catalyzed by the proton, hydroxide ion, water, buffer acids, and by buffer bases. For catalysis by general bases the Brønsted β = 0.59 whereas catalysis by general acids has a value of α ~ 0. These findings are very similar to those obtained previously for the 4-bromo-2,5-cyclohexadienone 2b, formed during the aqueous bromination of 2,6-dimethylphenol. The mechanistic implications of the results are discussed. The enolization of the related dienone 8, formed from bromine and 1-naphthol-2-carboxylic acid, was also studied. At acidic pHs the dienone 8 is much more reactive than 5, with the 2-COOH behaving as an internal catalyst having an "effective molarity" of about 110 M. The enolization of 8 is also catalyzed by buffer bases.

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38

Stan, Catalina Daniela, Igor Cretescu, Cristina Pastravanu, Ioannis Poulios, and Maria Drăgan. "Treatment of Pesticides in Wastewater by Heterogeneous and Homogeneous Photocatalysis." International Journal of Photoenergy 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/194823.

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The effect of different heterogeneous and homogeneous photocatalytic systems on the oxidative degradation of mepiquat chloride in aqueous solutions was investigated. In the case of heterogeneous reactions, the influence of five factors was studied: the type of catalyst, photocatalyst concentration, pH, pesticide concentration, and the presence of H2O2and/or Fe3+. For homogeneous catalysis, other factors were studied: the oxidising agent and the light source. Nearly complete degradation of mepiquat chloride was obtained after about 180 minutes in the presence of an acid medium (pH3) using a UV-A lamp and TiO2P-25 catalyst (0.5 g/L), for an initial pesticide concentration of 10 ppm. Degradation rates corresponding to homogeneous photocatalysis were lower compared to those corresponding to the use of TiO2as the photocatalyst.

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39

Steven, Alan. "Micelle-Mediated Chemistry in Water for the Synthesis of Drug Candidates." Synthesis 51, no. 13 (May 21, 2019): 2632–47. http://dx.doi.org/10.1055/s-0037-1610714.

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Micellar reaction conditions, in a predominantly aqueous medium, have been developed for transformations commonly used by synthetic chemists working in the pharmaceutical industry to discover and develop drug candidates. The reactions covered in this review are the Suzuki–Miyaura, Miyaura borylation, Sonogashira coupling, transition-metal-catalysed CAr–N coupling, SNAr, amidation, and nitro reduction. Pharmaceutically relevant examples of these applications will be used to show how micellar conditions can offer advantages in yield, operational ease, amount of waste generated, transition-metal catalyst loading, and safety over the use of organic solvents, irrespective of the setting in which they are used.1 Introduction2 Micelles as Solubilising Agents3 Micelles as Nanoreactors4 Designer Surfactants5 A Critical Evaluation of the Case for Chemistry in Micelles6 Scope of Review7 Suzuki–Miyaura Coupling8 Miyaura Borylation9 Sonogashira Coupling10 Transition-Metal-Catalysed CAr–N Couplings11 SNAr12 Amidation13 Nitro Reduction14 Micellar Sequences15 Summary and Outlook

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40

Ayoub, Muhammad, Abrar Inayat, Sintayehu Mekuria Hailegiorgis, and Aamir Hussain Bhat. "Synthesis of Alumina Based Alkaline Catalyst for Biodiesel-Derived Glycerol to Polyglycerol." Advanced Materials Research 1133 (January 2016): 33–37. http://dx.doi.org/10.4028/www.scientific.net/amr.1133.33.

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Biodiesel which comes from pure renewable resources provide an alternative fuel option for future. The rapid growth of the biodiesel industry will result in overproduction of less value glycerol and create a superfluity of this impure by-product. The synthesis of alkaline alumina catalyst for polyglycerol production via solvent free base-catalyzed etherification of low value glycerol is reported. The etherification of biodiesel derived glycerol to polyglycerol was studied in a heterogeneous catalysis under solvent free system, using alkalines over γ – alumina catalysts. All the catalysts were prepared by incipient-wetness impregnation of an aqueous solution of alkaline compounds on γ – alumina as a support. The effects of alkaline compound, reaction temperature, catalyst amount, and reaction time in conversion of glycerol to polyglycerol were investigated. The catalyst with potassium loaded on γ -alumina gave the highest basicity and the best catalytic activity for this reaction. The highest glycerol conversion into polyglycerol production was obtained with high yield 79.5% over prepared catalyst respectively. Industrially, the findings attained in this study might contribute towards promoting the biodiesel industry through utilization of its by-products.

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41

Fajerwerg, K., J. N. Foussard, A. Perrard, and H. Debellefontaine. "Wet oxidation of phenol by hydrogen peroxide: the key role of pH on the catalytic behaviour of Fe-ZSM-5." Water Science and Technology 35, no. 4 (February 1, 1997): 103–10. http://dx.doi.org/10.2166/wst.1997.0096.

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This paper presents an original approach to the treatment of phenolic aqueous wastes using H2O2 with Fe-ZSM-5 as a heterogeneous catalyst. The Fe-ZSM-5 zeolite with MFI structure allows a total elimination of phenol and a significant total organic carbon (TOC) removal at 90°C and atmospheric pressure in a batch reactor. The studies with this Fe-ZSM-5 catalyst deal mainly with the influence of external diffusion and pH on the oxidation process. It appears that the phenol degradation and the toxicity reduction, on the one hand, and the leaching-off of Fe(III) ions in the solution, on the other hand, depend strongly on the pH. In these conditions, an optimum value exists at pH = 5. At higher pH values, the system becomes less effective. At lower values, a significant leaching-off will induce homogeneous catalysis and the degradation of the catalyst. Generally speaking, when this heterogeneous catalyst is used in the presence of H2O2, the reaction rates depend on the degree of hydroxylation of the aromatic compound in contact with the catalyst. So, a chain radical mechanism could be envisaged.

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42

Zahalka, Hayder A., and Yoel Sasson. "Esterification of 1,4-dichlorobutane with sodium formate under solid–liquid phase transfer catalysis. A kinetic study." Canadian Journal of Chemistry 67, no. 2 (February 1, 1989): 245–49. http://dx.doi.org/10.1139/v89-040.

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Kinetic data are reported regarding the esterification of 1,4-dichlorobutane with sodium formate catalyzed by quaternary ammonium salts as a model for reactions in series, under solid–liquid phase transfer conditions. The process was found to follow a consecutive first-order mechanism of the general type A → R → S. The reactivity of the quaternary ammonium salts with regard to the counteranion was Cl− > Br− > 1− > HSO4−. The reaction rate was linearly dependent on catalyst concentration up to 12 mol% of catalyst relative to the substrate. Above this concentration the rate was constant and independent of the amount of the catalyst. The activation energy of the two consecutive steps was found to be similar (21 kcal/mol). Therefore, the product distribution (R/S) is not appreciably affected by temperature. A mechanism termed "Thin aqueous boundary layer" is suggested for nucleophilic displacement reactions under solid–liquid phase transfer conditions. Keywords: phase transfer catalysis, series reactions, kinetic study.

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43

Zhang, Ting, Yi Wang, Shu Rong Yu, and Hui Xia Feng. "Comparative Studies of Two Fenton-Like Catalysts: Fe₂O₃ and Fe₂O₃/Attapulgite." Advanced Materials Research 518-523 (May 2012): 696–700. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.696.

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Fe2O3 and Fe2O3/attapulgite(ATP) catalyst was used for Fenton reaction to degrade an anion surfactant, sodium dodecyl benzene sulfonate(SDBS)，in an aqueous solution. Comparative studies indicated that Fe2O3/ATP-catalyzed Fenton system and Fe2O3-catalyzed Fenton system have the same catalysis capability. These two systems all have a widely pH range (2-10), and the catalysts can be reused and have no secondary pollutants. It also can be seen that Fe2O3/ATP-catalyzed Fenton-like reaction has much efficiency than Fe2O3-catalyzed Fenton reaction.

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44

Zhang, Hong Liang, Chang Jin Tang, Fei Gao, and Lin Dong. "Synthesis and Catalytic Activity of Fe-MCM-41 Nanoparticles." Advanced Materials Research 933 (May 2014): 17–22. http://dx.doi.org/10.4028/www.scientific.net/amr.933.17.

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Mesostructured Fe-MCM-41 nanoparticles have been hydrothermally prepared for the first time with assistance of binary surfactants (CTAB and F127). The formation of nanoparticles consists of two steps, that is, the hydrolysis of silica precursor via catalysis by an acidic ferric salt, followed by facile assembly into mesostructured nanocomposites with cationic micelles by addition of condensation catalyst. In the hydroxylation of phenol with aqueous H2O2, Fe-MCM-41-NP displayed higher activity than a Fe-MCM-41 sample with normal particle size (Fe-MCM-41-LP).

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45

Fabbri, Claudia, Claudia Aurisicchio, and Osvaldo Lanzalunga. "Iron porphyrins-catalysed oxidation of α-alkyl substituted mono and dimethoxylated benzyl alcohols." Open Chemistry 6, no. 2 (June 1, 2008): 145–53. http://dx.doi.org/10.2478/s11532-008-0005-8.

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AbstractThe mechanisms of oxidation of a series of a-alkyl substituted mono and dimethoxylated benzyl alcohols catalysed by mesotetrakis(4-N-methylpyridynium)porphyrin iron (III) chloride (FeTMPyPCl) and meso-tetrakis(4-sulfonatophenyl)porphyrin iron (III) chloride (FeTSPPCl) in aqueous solution with KHSO5 as oxygen atom donor and by meso-tetrakis(pentafluorophenyl)-porphyrin iron (III) chloride (FeTPFPPCl) in dichloromethane employing iodosylbenzene as oxidant have been investigated. In the highly polar aqueous medium an electron transfer mechanism is operating. With FeTMPyPCl, which is a much more efficient catalyst than FeTSPPCl due to the presence of stronger electron withdrawing substituents, formation of side-chain oxidation products accompanies generation of nuclear oxidation products. In the low polar solvent dichloromethane, two competing mechanism have been suggested: hydrogen atom transfer and formation of a complex between the active species iron-oxo porphyrin radical cation and the substrate.

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46

Sohn, Jong Rack, and Dong Cheol Shin. "Characterization and Acid Catalytic Properties of NiO Supported on ZrO₂ and Modified with MoO₃." Solid State Phenomena 124-126 (June 2007): 1797–800. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.1797.

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Nickel oxide supported on zirconia and modified with MoO3 for acid catalysis was prepared by drying powdered Ni(OH)2-Zr(OH)4 with ammonium heptamolybdate aqueous solution, followed by calcining in air at high temperature. The characterization of prepared catalysts was performed using FTIR, Raman, XRD, and DSC. MoO3 equal to or less than 15 wt% was dispersed on the surface of catalyst as two-dimensional polymolybdate or monomolybdate, while for MoO3 above 15 wt%, crystalline orthorhombic phase of MoO3 was formed. The high acid strength and acidity were responsible for the Mo=O bond nature of the complex formed by the interaction between MoO3 and ZrO2. The catalytic activity for cumene dealkylation was correlated with the acidity of the catalyst measured by the ammonia chemisorption method

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47

Milgrom, Lionel. "Why is catalase so fast?" International Journal of High Dilution Research - ISSN 1982-6206 15, no. 4 (August 18, 2021): 38. http://dx.doi.org/10.51910/ijhdr.v15i4.865.

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ded network of hydrogen-bonded water and H2O2 molecules, stretching out far beyond the enzymesâ€™ active sites, into the cell's internal aqueous medium. As catalases function, they provide coherent oxidative â€˜pulsesâ€™, which rapidly spread throughout the H-bonded network, effectively â€˜unzippingâ€™ H2O2Â molecules as far as they extend from the enzyme. Result/discussion: This 'memory-of-water'-like mechanism predicts catalase H2O2 disproportionation should occur outside the enzyme. An experimental protocol is proposed to test this prediction. If successful, it would suggest a) holistic re-appraisal of the conventional mechanistic framework of enzyme kinetics is required, and b) should encourage more research into understanding the biochemical effects of CAM therapies. Keywords: Holistic biochemistry; catalase enzymes; hydrogen peroxide disproportionation; hydrogen-bonded networks; memory of water.

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48

Gangwal, V. R., B. G. M. van Wachem, B. F. M. Kuster, and J. C. Schouten. "Platinum catalysed aqueous alcohol oxidation: model-based investigation of reaction conditions and catalyst design." Chemical Engineering Science 57, no. 24 (December 2002): 5051–63. http://dx.doi.org/10.1016/s0009-2509(02)00434-7.

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GANGWAL, V., J. VANDERSCHAAF, B. KUSTER, and J. SCHOUTEN. "Noble-metal-catalysed aqueous alcohol oxidation: reaction start-up and catalyst deactivation and reactivation." Journal of Catalysis 232, no. 2 (June 10, 2005): 432–43. http://dx.doi.org/10.1016/j.jcat.2005.03.026.

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Kobayashi, Shū. "Asymmetric catalysis in aqueous media." Pure and Applied Chemistry 79, no. 2 (January 1, 2007): 235–45. http://dx.doi.org/10.1351/pac200779020235.

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Lewis acid catalysis has attracted much attention in organic synthesis because of unique reactivity and selectivity attained under mild conditions. Although various kinds of Lewis acids have been developed and applied in industry, these Lewis acids must be generally used under strictly anhydrous conditions. The presence of even a small amount of water handles the reactions owing to preferential reactions of the Lewis acids with water rather than the substrates. In contrast, rare earth and other metal complexes have been found to be water-compatible. Several catalytic asymmetric reactions in aqueous media, including hydroxymethylation of silicon enolates with an aqueous solution of formaldehyde in the presence of Sc(OTf)3-chiral bipyridine ligand or Bi(OTf)3-chiral bipyridine ligand, Sc- or Bi-catalyzed asymmetric meso-epoxide ring-opening reactions with amines, and asymmetric Mannich-type reactions of silicon enolates with N-acylhydrazones in the presence of a chiral Zn catalyst have been developed. Water plays key roles in these asymmetric reactions.

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Journal articles on the topic 'Catalyse aqueuse'

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