Angewandte Chemie International EditionVolume 45, Issue 45 p. 7584-7588 Communication Silica-Immobilized Chromium Colloids for Cyclohexane Autoxidation† Eric Breynaert, Eric Breynaert Centrum voor Oppervlaktechemie en Katalyse, K. U. Leuven, Kasteelpark Arenberg 23, 3001 Heverlee, Belgium, Fax: (+32) 16-321-998Search for more papers by this authorIve Hermans Dr., Ive Hermans Dr. [email protected] Centrum voor Oppervlaktechemie en Katalyse, K. U. Leuven, Kasteelpark Arenberg 23, 3001 Heverlee, Belgium, Fax: (+32) 16-321-998Search for more papers by this authorBert Lambie, Bert Lambie Departement Chemie, K. U. Leuven, Celestijnenlaan 200F, 3001 Heverlee, BelgiumSearch for more papers by this authorGuido Maes Prof. Dr., Guido Maes Prof. Dr. Departement Chemie, K. U. Leuven, Celestijnenlaan 200F, 3001 Heverlee, BelgiumSearch for more papers by this authorJozef Peeters Prof. Dr., Jozef Peeters Prof. Dr. Departement Chemie, K. U. Leuven, Celestijnenlaan 200F, 3001 Heverlee, BelgiumSearch for more papers by this authorAndré Maes Prof. Dr., André Maes Prof. Dr. Centrum voor Oppervlaktechemie en Katalyse, K. U. Leuven, Kasteelpark Arenberg 23, 3001 Heverlee, Belgium, Fax: (+32) 16-321-998Search for more papers by this authorPierre Jacobs Prof. Dr., Pierre Jacobs Prof. Dr. Centrum voor Oppervlaktechemie en Katalyse, K. U. Leuven, Kasteelpark Arenberg 23, 3001 Heverlee, Belgium, Fax: (+32) 16-321-998Search for more papers by this author Eric Breynaert, Eric Breynaert Centrum voor Oppervlaktechemie en Katalyse, K. U. Leuven, Kasteelpark Arenberg 23, 3001 Heverlee, Belgium, Fax: (+32) 16-321-998Search for more papers by this authorIve Hermans Dr., Ive Hermans Dr. [email protected] Centrum voor Oppervlaktechemie en Katalyse, K. U. Leuven, Kasteelpark Arenberg 23, 3001 Heverlee, Belgium, Fax: (+32) 16-321-998Search for more papers by this authorBert Lambie, Bert Lambie Departement Chemie, K. U. Leuven, Celestijnenlaan 200F, 3001 Heverlee, BelgiumSearch for more papers by this authorGuido Maes Prof. Dr., Guido Maes Prof. Dr. Departement Chemie, K. U. Leuven, Celestijnenlaan 200F, 3001 Heverlee, BelgiumSearch for more papers by this authorJozef Peeters Prof. Dr., Jozef Peeters Prof. Dr. Departement Chemie, K. U. Leuven, Celestijnenlaan 200F, 3001 Heverlee, BelgiumSearch for more papers by this authorAndré Maes Prof. Dr., André Maes Prof. Dr. Centrum voor Oppervlaktechemie en Katalyse, K. U. Leuven, Kasteelpark Arenberg 23, 3001 Heverlee, Belgium, Fax: (+32) 16-321-998Search for more papers by this authorPierre Jacobs Prof. Dr., Pierre Jacobs Prof. Dr. Centrum voor Oppervlaktechemie en Katalyse, K. U. Leuven, Kasteelpark Arenberg 23, 3001 Heverlee, Belgium, Fax: (+32) 16-321-998Search for more papers by this author First published: 14 November 2006 https://doi.org/10.1002/anie.200602736Citations: 28 † This work was performed in the frame of IAP, GOA, IDECAT, and CECAT projects. E.B., I.H., and B.L. acknowledge fellowships from K. U. Leuven, FWO-Vlaanderen, and IWT, respectively. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Graphical Abstract In a stable condition: Oxyhydroxide colloids of chromium deposited on silica gel are selective, stable catalysts for the autoxidation of cyclohexane (CyH). The CrIII colloids, generated in situ, are immobilized by a column precipitation chromatographic technique (see picture). An increased yield of cyclohexanone (QO) is obtained. Supporting Information Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2006/z602736_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. References 1U. Schuchardt, D. Cardoso, R. Sercheli, R. Pereira, R. S. da Cruz, M. C. Guerreiro, D. Mandelli, E. V. Spinacé, E. L. Pires, Appl. Catal. A 2001, 211, 1. 10.1016/S0926-860X(01)00472-0 CASWeb of Science®Google Scholar 2 2aT. Maschmeyer, R. D. Oldroyd, G. Sankar, J. M. Thomas, I. J. Shannon, J. A. Klepetko, A. F. Masters, J. K. Beattie, C. R. Catlow, Angew. Chem. 1997, 109, 1713; 10.1002/ange.19971091521 Google ScholarAngew. Chem. Int. Ed. Engl. 1997, 36, 1639; 10.1002/anie.199716391 CASWeb of Science®Google Scholar 2bV. Kesavan, P. S. Sivanand, S. Chandrasekaran, Y. Koltypin, A. Gedanken, Angew. Chem. 1999, 111, 3729; 10.1002/(SICI)1521-3757(19991203)111:23<3729::AID-ANGE3729>3.0.CO;2-Y Google ScholarAngew. Chem. Int. Ed. 1999, 38, 3521. 10.1002/(SICI)1521-3773(19991203)38:23<3521::AID-ANIE3521>3.0.CO;2-S CASPubMedWeb of Science®Google Scholar 3R. A. Sheldon, J. K. Kochi, Metal-Catalyzed Oxidations of Organic Compounds, Academic Press, New York, 1981. Google Scholar 4G. Franz, R. A. Sheldon in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2000. Google Scholar 5S. Bhaduri, D. Mukesh, Homogeneous Catalysis: Mechanisms and Industrial Applications, Wiley, New York, 2000. 10.1002/0471220388 Google Scholar 6N. M. Emanuel, Z. K. Maizus, I. P. Skibida, Angew. Chem. 1969, 81, 91; 10.1002/ange.19690810302 Google ScholarAngew. Chem. Int. Ed. Engl. 1969, 8, 97. 10.1002/anie.196900971 CASWeb of Science®Google Scholar 7D. L. Vanoppen, D. E. De Vos, M. J. Genet, P. G. Rouxhet, P. A. Jacobs, Angew. Chem. 1995, 107, 637; 10.1002/ange.19951070522 Google ScholarAngew. Chem. Int. Ed. Engl. 1995, 34, 560. 10.1002/anie.199505601 CASWeb of Science®Google Scholar 8M. Nowotny, L. N. Pedersen, U. Hanefeld, T. Maschmeyer, Chem. Eur. J. 2002, 8, 3724. 10.1002/1521-3765(20020816)8:16<3724::AID-CHEM3724>3.0.CO;2-W CASPubMedWeb of Science®Google Scholar 9I. Hermans, P. A. Jacobs, J. Peeters, Chem. Eur. J. 2006, 12, 4229. 10.1002/chem.200600189 CASPubMedWeb of Science®Google Scholar 10I. Hermans, T. L. Nguyen, P. A. Jacobs, J. Peeters, ChemPhysChem 2005, 6, 637. 10.1002/cphc.200400211 CASPubMedWeb of Science®Google Scholar 11I. Hermans, P. A. Jacobs, J. Peeters, J. Mol. Catal. A 2005, 251, 221. 10.1016/j.molcata.2006.02.005 Web of Science®Google Scholar 12I. Hermans, P. A. Jacobs, J. Peeters, ChemPhysChem 2006, 7, 1142. 10.1002/cphc.200600074 CASPubMedWeb of Science®Google Scholar 13L. Vereecken, T. L. Nguyen, I. Hermans, J. Peeters, Chem. Phys. Lett. 2004, 393, 432. 10.1016/j.cplett.2004.06.076 CASWeb of Science®Google Scholar 14R. A. Sheldon, M. Wallau, I. W. C. E. Arends, U. Schuchardt, Acc. Chem. Res. 1998, 31, 485. 10.1021/ar9700163 CASWeb of Science®Google Scholar 15B. M. Weckhuysen, R. A. Schoonheydt, Zeolites 1994, 14, 360. 10.1016/0144-2449(94)90110-4 CASWeb of Science®Google Scholar 16J. Kornatowski, G. Zadrozna, M. Rozwadowski, B. Zibrowius, F. Marlow, J. A. Lercher, Chem. Mater. 2001, 13, 4447. 10.1021/cm0011864 CASWeb of Science®Google Scholar 17A. M. Baele, D. Grandjean, J. Kornatowski, P. Glatzel, F. M. F. de Groot, B. M. Weckhuysen, J. Phys. Chem. B 2006, 110, 716. 10.1021/jp0531006 CASPubMedWeb of Science®Google Scholar 18A. K. Sinha, K. Suzuki, Angew. Chem. 2005, 117, 275; 10.1002/ange.200461284 Google ScholarAngew. Chem. Int. Ed. 2005, 44, 271. 10.1002/anie.200461284 CASWeb of Science®Google Scholar 19See, for example: I. C. Chisem, J. Rafelt, M. T. Shieh, J. Chisem, J. H. Clark, R. Jachuck, D. Macquarrie, C. Ramshaw, K. Scott, Chem. Commun. 1998, 1949. 10.1039/a805420g CASWeb of Science®Google Scholar 20E. Breynaert, A. Maes, Anal. Chem. 2005, 77, 5048. 10.1021/ac050546+ CASPubMedWeb of Science®Google Scholar 21S. Music, M. Maljkovic, S. Popovic, R. Trojko, Croat. Chem. Acta 1999, 72, 789, and references therein. CASWeb of Science®Google Scholar 22See, for example: Google Scholar 22aT. Tsuzuki, P. G. McCormick, Acta Mater. 2000, 48, 2795; 10.1016/S1359-6454(00)00100-2 CASWeb of Science®Google Scholar 22bM. Ocaña, J. Eur. Ceram. Soc. 2001, 21, 931; 10.1016/S0955-2219(00)00288-0 Web of Science®Google Scholar 22cM. Bañobre-López, C. Vázquez, J. Rivas, M. A. López-Quintela, Nanotechnology 2003, 14, 318; 10.1088/0957-4484/14/2/342 CASWeb of Science®Google Scholar 22dM. V. Borysenko, V. M. Bogatyrov, E. N. Poddenezhny, A. A. Boiko, A. A. Chuiko, J. Sol–Gel Sci. Technol. 2004, 32, 327; 10.1007/s10971-004-5811-7 CASWeb of Science®Google Scholar 22eD.-W. Kim, S.-I. Shin, J.-D. Lee, S.-G. Oh, Mater. Lett. 2004, 58, 1894; 10.1016/j.matlet.2003.11.023 CASWeb of Science®Google Scholar 22fW. S. Zhang, E. Brück, Z. D. Zhang, O. Tegus, W. F. Li, P. Z. Si, D. Y. Geng, K. H. J. Buschow, Phys. B 2005, 358, 332. 10.1016/j.physb.2005.01.469 CASWeb of Science®Google Scholar 23B. M. Weckhuysen, I. E. Wachs, R. A. Schoonheydt, Chem. Rev. 1996, 96, 3327. 10.1021/cr940044o CASPubMedWeb of Science®Google Scholar 24See Supporting Information. Google Scholar 25H. Stünzi, W. Marty, Inorg. Chem. 1983, 22, 2145. 10.1021/ic00157a012 CASWeb of Science®Google Scholar 26For example, at pH 4.68 the ion-exchange capacity (determined with CrCl3) was found to be 0.024 meq g−1, in good agreement with those determined for PbII, CuII, and NiII at the same pH value.[27] The pH value of 4.68 is above that of our synthesis (4.0), and more than twice that of the point of zero charge (PZC), determined to be 2.12 by potentiometric titration. Google Scholar 27H. H. Tran, F. A. Roddick, J. A. O'Donnell, Water Res. 1999, 33, 2992. 10.1016/S0043-1354(99)00017-2 CASWeb of Science®Google Scholar 28B. M. Weckhuysen, R. A. Schoonheydt, F. E. Mabbs, D. Collison, J. Chem. Soc. Faraday Trans. 1996, 92, 2431. 10.1039/ft9969202431 CASWeb of Science®Google Scholar 29Even if the Cr colloids have a specific surface area as high as 1000 m2 g−1, a loading of 5 mg Cr per g support would induce only a negligible increase in surface area. Google Scholar 30W. Buijs, R. Raja, J. M. Thomas, H. Wolters, Catal. Lett. 2003, 91, 253. 10.1023/B:CATL.0000007162.32473.85 CASWeb of Science®Google Scholar 31P. G. Harrison, N. C. Lloyd, W. Daniell, J. Phys. Chem. B 1998, 102, 10672, and references therein. 10.1021/jp9822135 CASWeb of Science®Google Scholar 32The Cr speciation in solution was modeled using PHREEQC, in combination with the Lawrence Livermore National Library (LLNL 85 2005-02-02) database; precipitation was disabled during the modeling because of the slow kinetics. http://www.geo.vu.nl/users/posv/phreeqc/index.html (PHREEQC for Windows, version 2.12.04 built using PREEQC 2.12.1-669). Google Scholar 33Powder (ca. 200 mg) was dissolved in concentrated perchloric acid (1 mL), HNO3 (2 mL), and HCl (1 mL). Google Scholar Citing Literature Volume45, Issue45November 20, 2006Pages 7584-7588 ReferencesRelatedInformation

The H-bond interaction between glycine and H2O has been studied by a combined theoretical (DFT(B3LYP)/6-31++G(**)) and experimental (matrix-isolation FT-IR) methodology. The 1:1 and 1:2 complexes of the most stable conformation (I) of glycine appear to be neutral complexes which have been vibrationally characterized in detail. The higher stoichiometry complexes (glycine).(H2O)n with n larger than 3 are demonstrated to be zwitterionic H-bonded complexes. A set of characteristic IR absorption bands for this zwitterionic structure has been observed in low-temperature Ar matrices. This would be the first experimental IR evidence for proton transfer occurring between the NH2 and COOH groups of amino acids by a H-bonded water molecular channel in isolated conditions.

The conformational equilibria of neutral serine are studied by experimental matrix-isolation Fourier transform infrared spectroscopy in combination with density functional theory (DFT) calculations. The geometries and energies of the low-energy conformers of serine were optimized using the DFT(B3LYP)/6-31++G** method. In addition, we calculated the infrared frequencies and intensities of the most stable conformers in order to assist in the assignment of the vibrational bands in the experimental spectrum. The calculated relative energies suggest that four conformers are sufficiently stable to appear in the gas phase and all could be distinguished in the experimental matrix infrared spectra. We also calculated theoretical rotamerization constants and compared these with experimental determined constants. For the equilibria SER2/SER1 and SER3/SER1, a deviation between the experimental rotamerization constant and the theoretical constant was found. A relatively strong intramolecular H-bond in conformers SER2 and SER3 is at the origin of this discrepancy.

The experimental and theoretical rotamerization constants for the rotameric equilibrium between the two most stable conformations of the alpha-amino acid alanine are compared. The experimental technique of matrix-isolation Fourier transform infrared spectroscopy in combination with the density functional theory (DFT) (B3LYP) and the 6-31++G** basis set is used for this study. A large disagreement between the experimental and theoretical value of the equilibrium constant is found. A relatively strong intramolecular H-bond in conformation II is at the origin of this discrepancy. From the difference between the experimental and theoretical rotamerization constant, a DeltaS degrees value of -6.6 J K(-1) mol(-1) is found for the intramolecular H-bond formation.