Tungstoborates as Highly Active Catalysts for Cycloalkane Oxygenation Using Hydrogen Peroxide

Abstract

Keggin-type tungstoborates [BW₁₂O₄₀]^5-, H_x[BW₁₁O₃₉]^9-x)- and [BM(H₂O)W₁₁O₃₉]^6-, M = Fe^III, Mn^III or Ru^III proved to be highly active catalysts for the H₂O₂ oxidation of cyclooctane and cyclohexane to the corresponding ketone, alcohol and alkyl hydroperoxide derivatives. High turnover numbers and high selectivity for the hydroperoxide were observed.

Keywords

polyoxometalates - cycloalkanes - oxidation - hydrogen peroxide - tungstoborates

References

• 1 Sheldon RA. Kochi JK. Metal-Catalyzed Oxidations of Organic Compounds   Academic Press; New York: 1981. 
• 2 Activation and Functionalization of Alkanes   Hill CL. Wiley; New York: 1989. 
• 3 Shilov AE. Shul’pin GB. Activation and Catalytic Reactions of Saturated Hydrocarbons in the Presence of Metal Complexes   Kluwer; Dordrecht: 2000. 
• 4 Schuchart U. Cardoso D. Sercheli R. Pereira R. Cruz RS. Guerreiro MC. Mandelli D. Spinacé EV. Pires EL. Appl. Catal., A  2001,  211:  1 
• 5 Chen JD. Dakka J. Sheldon RA. Appl. Catal., A  1994,  108:  L1 
• 6 Catalytic Oxidations with Hydrogen Peroxide as Oxidant   Strukul G. Kluwer; Dordrecht: 1992. 
• 7 Sanderson WR. Pure Appl. Chem.  2000,  72:  1289 
• 8 Shul’pin GB. Shilov AE. Süss-Fink G. Tetrahedron Lett.  2001,  42:  7253 
• 9 Shul’pin GB. J. Chem. Research, Synop.  2002,  351 
• 10 Shul’pin GB. Süss-Fink G. Smith JRL. Tetrahedron  1999,  55:  5345 
• 11 Simões MMQ. Conceição CMM. Gamelas JAF. Domingues PMDN. Cavaleiro AMV. Cavaleiro JAS. Ferrer-Correia AJV. Johnstone RAW. J. Mol. Catal. A: Chem.  1999,  144:  461 
• 12 Domingues P. Simões MMQ. Cardoso AM. Cavaleiro AMV. Cavaleiro JAS. Johnstone RAW. Ferrer-Correia AJ. Rapid Commun. Mass Spectrom.  1999,  13:  93 
• 13 Hansen CB. Agterberg FPW. van Eijndhoven AMC. Drenth W. J. Mol. Catal. A: Chem.  1995,  102:  117 
• 14 Neumann R. Prog. Inorg. Chem.  1998,  47:  317 
• 15 Hill CL. Prosser-McCartha CM. Coord. Chem. Rev.  1995,  143:  407 
• 16 Hill CL. In Activation and Functionalization of Alkanes   Hill CL. Wiley; New York: 1989.  Chap. 8.
• 17 Mizuno N. Kiyoto I. Nozaki C. Misono M. J. Catal.  1999,  181:  171 
• 18 Süss-Fink G. Gonzalez L. Shul’pin GB. Appl. Catal., A  2001,  217:  111 
• 19 Zhang X. Pope MT. J. Mol. Catal. A: Chem.  1996,  114:  201 
• 20 Duncan DC. Chambers RC. Hecht E. Hill CL. J. Am. Chem. Soc.  1995,  117:  681 
• 21 Aubry C. Chottard G. Platzer N. Brégeault JM. Thouvenot R. Chauveau F. Huet C. Ledon H. Inorg. Chem.  1991,  30:  4409 
• 22 Santos ICMS. Simões MMQ. Pereira MMMS. Martins RRL. Neves MGPMS. Cavaleiro JAS. Cavaleiro AMV. J. Mol. Catal. A: Chem.  2003,  195:  253 
• 24 Tézé A. Michelon M. Hervé G. Inorg. Chem.  1997,  36:  505 
• 26 Barton DHR. Launay F. Le Gloahec VN. Li T. Smith F. Tetrahedron Lett.  1997,  38:  8491 
• 28 Neumann R. Khenkin AM. Inorg. Chem.  1995,  34:  5753 

23

The reactions were typically carried out by heating a solution of 1 mmol of the cycloalkane and 1.5 µmol of the catalyst in 1.5 mL of acetonitrile at 80 ºC. The oxidant used was 30% aqueous H₂O₂. Aliquots were withdrawn from the reaction mixture and injected directly into a GC-MS (fused silica Supelco capillary column, SPB-5, with 30 m × 0.25 mm i.d.; 0.25 µm film thickness). The percentages of each compound in the reaction mixture were estimated directly from the corresponding chromatographic peak areas.

25

For BFe an aqueous solution of BW₁₁ was added to a solution of Fe(NO₃)₃·9H₂O (order of addition reversed in comparison with BMn). TBA₄H₂BFe(H₂O)W₁₁O₃₉·H₂O Yield, 91%. Anal. Found: W, 55.0; Fe, 1.48; C, 20.53; H, 4.09, N, 1.56; hydration H₂O, 0.51. Calcd: W, 54.4; Fe, 1.50; C, 20.60; H, 4.03, N, 1.50; hydration H₂O, 0.48; IR (cm^-1): 997 (m), 956(vs), 900(vs), 825(vs), 757 (s, sh), 528 (m). For preparation of BRu RuCl₃·H₂O was used. TBA₄H₂BRu(H₂O)W₁₁O₃₉·2H₂O Yield, 89%. Anal. Found: W, 54.2; Ru, 2.56; C, 20.58; H, 4.11, N, 1.72; hydration H₂O, 1.02. Calcd: W, 53.5; Ru, 2.69; C, 20.30; H, 4.02, N, 1.48; hydration H₂O, 0.95; IR (cm^-1): 998 (m), 950 (vs), 902 (vs), 825 (vs), 743 (s, sh), 530 (m). µ = 1.99 µ_B.

27

The decomposition of H₂O₂ during the reaction was monitored by titration of aliquots with ceric sulphate. At the end of the reactions, the total of unused H₂O₂ and hydroperoxide produced was estimated by titration with ceric sulphate. From the yields of hydroperoxide (and cyclohexanol and cyclohexanone) determined by gas chromatography, the amount of H₂O₂ used in the reaction could be determined.