Catalizador de Jacobsen inmovilizado en Al-MCM-41 y en Si-MCM-41 modificada con grupos amino y su actividad en la epoxidación enantioselectiva heterogénea utilizando dimetildioxirano generado in situ como oxidante

RESUMEN: En este trabajo se investigó la actividad catalítica del catalizador de Jacobsen inmovilizado en Al-MCMC-41 y en NH2-Si-MCM-41 en la epoxidación enantioselectiva de tres olefinas proquirales, utilizando dimetildioxirano generado in situ como agente oxidante. Con este agente oxidante, el catalizador no sufrió cambios significativos en su estructura química. El catalizador se reutilizó exitosamente, cuando se inmovilizó por enlace químico covalente a través del ligando de salen.ABSTRACT: The enantioselective epoxidation of three prochiral olefins over Jacobsen's catalyst immobilized on Al-MCM-41 and NH2-Si-MCM-41 in the presence of in situ generated DMD as the oxygen source was investigated. Experimental results indicate that the catalyst did not significantly suffer any change in its chemical structure. Therefore, the reusability of catalyst could be successfully achieved when it was immobilized by chemical bonding of the salen ligand

One-pot oximation–Beckmann rearrangement of ketones and aldehydes to amides of industrial interest: Acetanilide, caprolactam and acetaminophen

High yielding one-pot oximation–Beckmann rearrangement of ketones to amides in ktrifluoroacetic acid has been conducted on several ketones and aldehydes. The substrate reactivity showed to depend on both oximation and Beckmann rearrangement reaction rate. In this synthetic procedure, trifluoroacetic acid acts as solvent, acid catalyst and organocatalyst and can be easily recycled

New Catalytic Processes Developed in Europe During the 1980s

This paper constitutes the result of an attempt to make an inventory of the innovative catalytic processes developed in Europe, mainly in the European Community, during the period 1980-1990. Over 160 processes were examined, but it turned out to be impossible to consider about 70 of them, for lack of minimum information. The essential of the work is constituted of tables listing new processes in (i) petroleum refining, (ii) emission control, (iii) large chemical processes and (iv) smaller chemicals processes, production of fine chemicals, and miscellaneous. This corresponds to nearly 50 processes. Some of the major innovations are discussed. In addition, we present about 40 processes which were still at the development stage in 1990. This last list indicates, perhaps better than the first ones, the push for innovation of catalytic chemistry and the direction it follows

Tuning The Acidic Properties Of Aluminas Via Sol-gel Synthesis: New Findings On The Active Site Of Alumina-catalyzed Epoxidation With Hydrogen Peroxide

This study answers several pending questions about alumina-catalyzed epoxidation with aqueous 70 wt% H2O2. To evaluate the effect of the water-to-aluminum tri-sec-butoxide molar ratio, this was systematically changed from 1 to 24. The xerogels were calcined at 450 °C and gave different γ-Al2O3's with distinct textural and acidic properties. A combination of 27Al MAS NMR and TPD-NH3 results of calcined aluminas allowed us to assign the type Ia Al{single bond}OH sites as the catalytic sites for epoxidation. The type Ib Al{single bond}OH sites have no function in catalytic epoxidation, because ethyl acetate poisons these sites. The strong acid sites of types IIa, IIb, and III Al{single bond}OH groups are responsible for the undesired H2O2 decomposition and decreased oxidant selectivity. © 2006 Elsevier Inc. All rights reserved.244192101Thornton, J., (2001) Pure Appl. Chem., 73, p. 1231Graedel, T.E., (2001) Pure Appl. Chem., 73, p. 1243Ward, D.K., Ko, E.I., (1995) Ind. Eng. Chem. Res., 34, p. 421Schubert, U., Hüsing, N., (2000) Synthesis of Inorganic Materials, , Wiley-VCH, Weinheim p. 205Dumeignil, F., Sato, K., Imamura, M., Matsubayashi, N., Payen, E., Shimada, H., (2005) Appl. Catal. A Gen., 287, p. 135Trueba, M., Trasatti, S.P., (2005) Eur. J. Inorg. Chem., p. 3393Grabowska, H., Syper, L., Zawadzki, M., (2004) Appl. Catal. A Gen., 277, p. 91Kim, Y., Kim, C., Yi, J., (2004) Mater. Res. Bull., 39, p. 2103Valente, J.S., Bokhimi, X., Hernandez, F., (2003) Langmuir, 19, p. 3583Wang, J.A., Bokhimi, X., Novaro, O., Lopez, T., Tzompantzi, F., Gomez, R., Navarrete, J., Salinas, E.L., (1999) J. Mol. Catal. A Chem., 137, p. 239Dumeignil, F., Sato, K., Imamura, M., Matsubayashi, N., Payen, E., Shimada, H., (2003) Appl. Catal. A Gen., 241, p. 319van Vliet, M.C.A., Mandelli, D., Arends, I.W.C.E., Schuchardt, U., Sheldon, R.A., (2001) Green Chem., 3, p. 243Silva, J.M.S., Vinhado, F.S., Mandelli, D., Schuchardt, U., Rinaldi, R., (2006) J. Mol. Catal. A Chem., 252, p. 186Mandelli, D., van Vliet, M.C.A., Sheldon, R.A., Schuchardt, U., (2001) Appl. Catal. A Gen., 219, p. 2001Arends, I.W.C.E., Sheldon, R.A., (2002) Top. Catal., 19, p. 133Cesquini, R.G., Silva, J.M.S., Woitiski, C.B., Mandelli, D., Rinaldi, R., Schuchardt, U., (2002) Adv. Synth. Catal., 344, p. 911Rinaldi, R., Schuchardt, U., (2005) J. Catal., 236, p. 335Rinaldi, R., Schuchardt, U., (2004) J. Catal., 227, p. 109Amenomiya, Y., Morikawa, Y., Pleizier, G., (1977) J. Catal., 46, p. 431Peri, J.B., (1975) J. Phys. Chem., 79, p. 1582Rinaldi, R., Sepulveda, J., Schuchardt, U., (2004) Adv. Synth. Catal., 346, p. 281Rebek, J., McCready, R., (1979) Tetrahedron Lett., 45, p. 4337Digne, M., Sautet, P., Raybaud, P., Euzen, P., Toulhoat, H., (2004) J. Catal., 226, p. 54Knözinger, H., Ratnasamy, P., (1978) Catal. Rev.-Sci. Eng., 17, p. 31Hiemstra, T., Vanriemsdijk, W.H., Bolt, G.H., (1989) J. Colloid Interface Sci., 133, p. 91Lefler, J.E., Miller, D.W., (1977) J. Am. Chem. Soc., 99, p. 480Duer, M.J., (2004) Introduction to Solid-State NMR Spectroscopy, , Blackwell Publishing, Oxford p. 235Nielsen, U.G., Skibsted, J., Jakobsen, H.J., (2001) Chem. Commun., p. 2690Walker, G.S., Pyke, D.R., Werrett, C.R., Williams, E., Bhattacharya, A.K., (1999) Appl. Surf. Sci., 147, p. 228Bhatia, S., Beltramini, J., Do, D.D., (1990) Catal. Today, 7, p. 309Tanabe, K., (1970) Solid Acids and Bases and Their Catalytic Properties, , Academic Press, New YorkTanabe, K., Misono, M., Ono, Y., Hattori, H., (1989) New Solid Acids and Bases and Their Catalytic Properties, , Elsevier, AmsterdamWang, J.A., Bokhimi, X., Morales, A., Novaro, O., López, T., Gómez, R., (1999) J. Phys. Chem. B, 103, p. 299Deubel, D.V., Frenking, G., Gisdakis, P., Herrmann, W.A., Rösch, N., Sundermeyer, J., (2004) Acc. Chem. Res., 37, p. 645Cotton, F.A., Wilkinson, G., Murillo, C., Bochmann, M., (1999) Advanced Inorganic Chemistry. sixth ed., , Wiley, New York p. 1303Vacque, V., Sombret, B., Huvenne, J.P., Legrand, P., Suc, S., (1997) Spectrochim. Acta Part A, 53, p. 55Landry, C.C., Pappe, N., Mason, M.R., Apblett, A.W., Tyler, A.N., MacInnes, A.N., Barron, A.R., (1995) J. Mater. Chem., 5, p. 331Kabalka, G.W., Pagni, R.M., (1997) Tetrahedron, 53, p. 7999Buffon, R., Schuchardt, U., (2003) J. Braz. Chem. Soc., 14, p. 34

CrAPO-catalyzed oxidations of alkylaromatics and alcohols with TBHP in the liquid phase (redox molecular sieves, part 8)

Chromium-substituted aluminophosphates were synthesized and characterized. Chromium-aluminophosphoates (CrAPO-5 and CrAPO-11) catalyze the oxidn. of ethylbenzene, p-ethyltoluene, n-propylbenzene, n-butylbenzene, diphenylmethane, p-ethylanisole, and primary, secondary benzylic alcs. to the corresponding ketones or acids with TBHP at 80-100 DegC. The main parameters affecting reaction rates are competitive adsorption and diffusion. The activity of used CrAPO-5 is completely recovered by recalcination at 500 DegC. Oxidn. of 4-methoxybenzyl alc. gave 4-methoxybenzoic acid (100% conversion of reactant; 87% selectivity toward product)