An overview of the recent advances in the field of polyoxometalate, ionic liquid hybrids, is proposed with a special attention paid to their application in catalysis, more precisely biphasic and heterogeneous catalysis. Both components of the hybrids are separately outlined pointing to their useful properties and potential for catalysis, followed by the description of the hybrids preparation and synergy between components in a large range of organic transformations. And finally a vision on the future developments is proposed. 1. Polyoxometalates: General Aspects Polyoxometalates (POMs) are a class of anionic metal-oxygen clusters built by the connection of [MO]x polyhedra of the early transition metals in their highest oxidation states [1, 2]. Nevertheless, the strict rules for nomenclature, the polyoxometalate compounds [3], could be referred to also as hetero- or isopolyacids and hetero- or isopolyanions or polyoxoanions. The most studied polyoxo structures formers are molybdenum (VI) and tungsten (VI), structures resulting from accessibility of empty d-orbitals for metal-oxygen -bonding and favorable combination of ionic radius and charge. Polyoxo structures of the hexavalent Tc, Re, Ru, and Os, the pentavalent Cr, Mo, W, Tc, and Re, and tetravalent Ti, V, Cr Mo, and W are also known [4]. The formation of the polyoxometalate structures obeys generally on two principles: (i) each atom must occupy only one edge shared [MO]x polyhedron in which the metal is displaced toward the edge, as a result of the M–O -bonding and (ii) the structures with three and more terminal oxo groups are not observed (known as Lipscomb restriction) [4, 5]. Although the first polyoxometalates were reported over almost 200 years ago, continuously new structures are reported together with unusual properties and/or applications. Various reviews resume the main application domains of the polyoxometalates, for example, material science, medicine, or catalysis [6–9]. There are literally thousands of compounds in the polyoxometalate category which defers on their size, shape, and composition. Recently, Long et al. [10] proposed a very elegant way to classify the POM’s compounds in-as-called “polyoxometalate periodic table.” They proposed three broad groups taking into account essentially the anionic metal-oxygen cluster type.(i)Heteropolyanions: clusters including heteroatoms, such as [XM12O40]n？ anion, where M is generally Mo or W and X is a tetrahedral template. Inside this group, three main families could be attributed, Anderson [XM6O24n？], Keggin [XM12O40]n？, and Dawson structure
References
[1]
A. Dolbecq, E. Dumas, C. R. Mayer, and P. Mialane, “Hybrid organic-inorganic polyoxometalate compounds: from structural diversity to applications,” Chemical Reviews, vol. 110, no. 10, pp. 6009–6048, 2010.
[2]
P. Gouzerh and A. Proust, “Main-group element, organic, and organometallic derivatives of polyoxometalates,” Chemical Reviews, vol. 98, no. 1, pp. 77–111, 1998.
[3]
Y. P. Jeannin, “The nomenclature of polyoxometalates: how to connect a name and a structure,” Chemical Reviews, vol. 98, no. 1, pp. 51–76, 1998.
[4]
M. T. Pope and A. Müller, “Polyoxometalate chemistry: an old field with new dimensions in several disciplines,” Angewandte Chemie, vol. 30, no. 1, pp. 34–48, 1991.
[5]
M. T. Pope and A. Muller, Eds., Polyoxometalates: From Platonic Solids to Anti-Retroviral Activity, Kluwer Academic Publishers, Dordrecht, The Netherlands, 1994.
[6]
D. E. Katsoulis, “A survey of applications of polyoxometalates,” Chemical Reviews, vol. 98, no. 1, pp. 359–387, 1998.
[7]
J. T. Rhule, C. L. Hill, D. A. Judd, and R. F. Schinazi, “Polyoxometalates in medicine,” Chemical Reviews, vol. 98, no. 1, pp. 327–357, 1998.
[8]
N. Mizuno and M. Misono, “Heterogeneous catalysis,” Chemical Reviews, vol. 98, no. 1, pp. 199–217, 1998.
[9]
I. V. Kozhevnikov, “Catalysis by heteropoly acids and multicomponent polyoxometalates in liquid-phase reactions,” Chemical Reviews, vol. 98, no. 1, pp. 171–198, 1998.
[10]
D.-L. Long, R. Tsunashima, and L. Cronin, “Polyoxometalates: building blocks for functional nanoscale systems,” Angewandte Chemie International Edition, vol. 49, no. 10, pp. 1736–1758, 2010.
[11]
T. Yamase, “Photo- and electrochromism of polyoxometalates and related materials,” Chemical Reviews, vol. 98, no. 1, pp. 307–325, 1998.
[12]
S. Liu and Z. Tang, “Polyoxometalate-based functional nanostructured films: current progress and future prospects,” Nano Today, vol. 5, no. 4, pp. 267–281, 2010.
[13]
A. B. Bourlinos, K. Raman, R. Herrera, Q. Zhang, L. A. Archer, and E. P. Giannelis, “A liquid derivative of 12-tungstophosphoric acid with unusually high conductivity,” Journal of the American Chemical Society, vol. 126, no. 47, pp. 15358–15359, 2004.
[14]
B. Xu, L. Xu, G. Gao, W. Guo, and S. Liu, “Effects of film structure on electrochromic properties of the multilayer films containing polyoxometalates,” Journal of Colloid and Interface Science, vol. 330, no. 2, pp. 408–414, 2009.
[15]
P. Gómez-Romero, “Polyoxometalates as photoelectrochemical models for quantum-sized colloidal semiconducting oxides,” Solid State Ionics, vol. 101–103, no. 1, pp. 243–248, 1997.
[16]
J. A. F. Gamelas, A. M. V. Cavaleiro, E. De Matos Gomes, M. Belsley, and E. Herdtweck, “Synthesis, properties and photochromism of novel charge transfer compounds with Keggin anions and protonated 2, -biquinoline,” Polyhedron, vol. 21, no. 25-26, pp. 2537–2545, 2002.
[17]
T. He and J. Yao, “Photochromism in composite and hybrid materials based on transition-metal oxides and polyoxometalates,” Progress in Materials Science, vol. 51, no. 6, pp. 810–879, 2006.
[18]
Y.-F. Song, D.-L. Long, C. Ritchie, and L. Cronin, “Nanoscale polyoxometalate-based inorganic/organic hybrids,” Chemical Record, vol. 11, no. 3, pp. 158–171, 2011.
[19]
R. Tayebee, F. Nehzat, E. Rezaei-Seresht, F. Z. Mohammadi, and E. Rafiee, “An efficient and green synthetic protocol for the preparation of bis(indolyl)methanes catalyzed by , with emphasis on the catalytic proficiency of Wells-Dawson versus Keggin heteropolyacids,” Journal of Molecular Catalysis A, vol. 351, pp. 154–164, 2011.
[20]
J. P. Jolivet, Metal Oxide Chemistry and Synthesis, John Willey & Sons, Chichester, UK, 2000.
[21]
M. T. Pope, “Polyoxo anions: synthesis and structure,” in Comprehensive Coordination Chemistry II: Transition Metal Groups, A. G. Wedd, Ed., vol. 4, pp. 635–678, Elsevier Science, New York, NY, USA, 2004.
[22]
B. Keita and L. Nadjo, “Polyoxometalate-based homogeneous catalysis of electrode reactions: recent achievements,” Journal of Molecular Catalysis A, vol. 262, no. 1-2, pp. 190–215, 2007.
[23]
M. Clemente-León, E. Coronado, A. Soriano-Portillo, C. Mingotaud, and J. M. Dominguez-Vera, “Langmuir-Blodgett films based on inorganic molecular complexes with magnetic or optical properties,” Advances in Colloid and Interface Science, vol. 116, no. 1-3, pp. 193–203, 2005.
[24]
J. Dupont, “On the solid, liquid and solution structural organization of imidazolium ionic liquids,” Journal of the Brazilian Chemical Society, vol. 15, no. 3, pp. 341–350, 2004.
[25]
J. Dupont, “From molten salts to ionic liquids: a “nano” journey,” Accounts of Chemical Research, vol. 44, no. 11, pp. 1223–1231, 2011.
[26]
C. S. Consorti, P. A. Z. Suarez, R. F. De Souza et al., “Identification of 1,3-dialkylimidazoIium salt supramolecular aggregates in solution,” Journal of Physical Chemistry B, vol. 109, no. 10, pp. 4341–4349, 2005.
[27]
J. Dupont, P. A. Z. Suarez, R. F. De Souza, R. A. Burrow, and J.-P. Kintzinger, “C-H-π interactions in 1-n-butyl-3-methylimidazolium tetraphenylborate molten salt: solid and solution structures,” Chemistry: A European Journal, vol. 6, no. 13, pp. 2377–2381, 2000.
[28]
M. Antonietti, D. Kuang, B. Smarsly, and Y. Zhou, “Ionic liquids for the convenient synthesis of functional nanoparticles and other inorganic nanostructures,” Angewandte Chemie International Edition, vol. 43, no. 38, pp. 4988–4992, 2004.
[29]
A. Taubert, “Inorganic materials synthesis—a bright future for ionic liquids?” Acta Chimica Slovenica, vol. 52, no. 3, pp. 183–186, 2005.
[30]
A. Taubert and Z. Li, “Inorganic materials from ionic liquids,” Dalton Transactions, no. 7, pp. 723–727, 2007.
[31]
J. M. Martínez Blanes, B. M. Szyja, F. Romero-Sarria et al., “Multiple zeolite structures from one ionic liquid template,” Chemistry: A European Journal, vol. 19, pp. 2122–2130, 2013.
[32]
S. Werner, M. Haumann, and P. Wasserscheid, “Ionic liquids in chemical engineering,” in Annual Review of Chemical and Biomolecular Engineering, J. M. Prausnitz, M. F. Doherty, and M. A. Segalman, Eds., vol. 1, pp. 203–230, 2010.
[33]
Q. Zhang, S. Zhang, and Y. Deng, “Recent advances in ionic liquid catalysis,” Green Chemistry, vol. 13, no. 10, pp. 2619–2637, 2011.
[34]
S. Werner, M. Haumann, and P. Wasserscheid, “Ionic liquids in chemical engineering,” Annual Review of Chemical and Biomolecular Engineering, vol. 1, pp. 203–230, 2010.
[35]
K. R. Seddon, “Room-temperature ionic liquids: neoteric solvents for clean catalysis,” Kinetics and Catalysis, vol. 37, no. 5, pp. 693–697, 1996.
[36]
M. J. Earle and K. R. Seddon, “Ionic liquids. Green solvents for the future,” Pure and Applied Chemistry, vol. 72, no. 7, pp. 1391–1398, 2000.
[37]
H. Olivier-Bourbigou, L. Magna, and D. Morvan, “Ionic liquids and catalysis: recent progress from knowledge to applications,” Applied Catalysis A, vol. 373, no. 1-2, pp. 1–56, 2010.
[38]
J. A. Boon, J. A. Levisky, J. L. Pflug, and J. S. Wilkes, “Friedel-Crafts reactions in ambient-temperature molten salts,” Journal of Organic Chemistry, vol. 51, no. 4, pp. 480–483, 1986.
[39]
V. I. Parvulescu and C. Hardacre, “Catalysis in ionic liquids,” Chemical Reviews, vol. 107, no. 6, pp. 2615–2665, 2007.
[40]
J. Dupont, R. F. De Souza, and P. A. Z. Suarez, “Ionic liquid (molten salt) phase organometallic catalysis,” Chemical Reviews, vol. 102, no. 10, pp. 3667–3692, 2002.
[41]
Y. Gu and G. Li, “Ionic liquids-based catalysis with solids: state of the art,” Advanced Synthesis and Catalysis, vol. 351, no. 6, pp. 817–847, 2009.
[42]
G. Ranga Rao, T. Rajkumar, and B. Varghese, “Synthesis and characterization of 1-butyl 3-methyl imidazolium phosphomolybdate molecular salt,” Solid State Sciences, vol. 11, no. 1, pp. 36–42, 2009.
[43]
T. Rajkumar and G. Ranga Rao, “Synthesis and characterization of hybrid molecular material prepared by ionic liquid and silicotungstic acid,” Materials Chemistry and Physics, vol. 112, no. 3, pp. 853–857, 2008.
[44]
T. Rajkumar and G. Ranga Rao, “Characterization of hybrid molecular material prepared by 1-butyl 3-methyl imidazolium bromide and phosphotungstic acid,” Materials Letters, vol. 62, no. 25, pp. 4134–4136, 2008.
[45]
W.-L. Chen, B.-W. Chen, H.-Q. Tan, Y.-G. Li, Y.-H. Wang, and E.-B. Wang, “Ionothermal syntheses of three transition-metal-containing polyoxotungstate hybrids exhibiting the photocatalytic and electrocatalytic properties,” Journal of Solid State Chemistry, vol. 183, no. 2, pp. 310–321, 2010.
[46]
T. Zhang, J. Brown, R. J. Oakley, and C. F. J. Faul, “Towards functional nanostructures: ionic self-assembly of polyoxometalates and surfactants,” Current Opinion in Colloid and Interface Science, vol. 14, no. 2, pp. 62–70, 2009.
[47]
C. L. Hill, “Progress and challenges in polyoxometalate-based catalysis and catalytic materials chemistry,” Journal of Molecular Catalysis A, vol. 262, no. 1-2, pp. 2–6, 2007.
[48]
M. Masteri-Farahani and S. Shahbazi, “Preparation of Keggin-type polyoxometalate hybrid nanomaterial with one pot multicomponent reaction in reverse micelle nanoreactors,” Inorganic Chemistry Communications, vol. 15, pp. 297–300, 2012.
[49]
C. Li, J. Gao, Z. Jiang et al., “Selective oxidations on recoverable catalysts assembled in emulsions,” Topics in Catalysis, vol. 35, no. 1-2, pp. 169–175, 2005.
[50]
C. Li, Z. Jiang, J. Gao et al., “Ultra-deep desulfurization of diesel: oxidation with a recoverable catalyst assembled in emulsion,” Chemistry: A European Journal, vol. 10, no. 9, pp. 2277–2280, 2004.
[51]
H. Lü, J. Gao, Z. Jiang et al., “Ultra-deep desulfurization of diesel by selective oxidation with [C18H37N(CH3)3]4[H2NaPW10O36] catalyst assembled in emulsion droplets,” Journal of Catalysis, vol. 239, no. 2, pp. 369–375, 2006.
[52]
W. Zhu, G. Zhu, H. Li et al., “Oxidative desulfurization of fuel catalyzed by metal-based surfactant-type ionic liquids,” Journal of Molecular Catalysis A, vol. 347, no. 1-2, pp. 8–14, 2011.
[53]
W. Zhu, G. Zhu, H. Li et al., “Catalytic kinetics of oxidative desulfurization with surfactant type polyoxometalates based ionic liquids,” Fuel Processing Technology, vol. 106, pp. 70–76, 2013.
[54]
J. Zhang, A. Wang, X. Li, and X. Ma, “Oxidative desulfurization of dibenzothiophene and diesel over [Bmim]3PMo12O40,” Journal of Catalysis, vol. 279, no. 2, pp. 269–275, 2011.
[55]
J. Li, B. Hu, and C. Hu, “Deep desulfurization of fuels by heteropolyanion-based ionic liquid,” Bulletin of the Korean Chemical Society, vol. 34, pp. 225–230, 2013.
[56]
W. Zhu, W. Huang, H. Li et al., “Polyoxometalate-based ionic liquids as catalysts for deep desulfurization of fuels,” Fuel Processing Technology, vol. 92, no. 10, pp. 1842–1848, 2011.
[57]
Y. Chen, F. Zhang, Y. Fang et al., “Phosphotungstic acid containing ionic liquids immobilized on magnetic mesoporous silica rod catalyst for the oxidation of dibenzothiophene with H2O2,” Catalysis Communications, vol. 38, pp. 54–58, 2013.
[58]
K. Yamaguchi, C. Yoshida, S. Uchida, and N. Mizuno, “Peroxotungstate immobilized on ionic liquid-modified silica as a heterogeneous epoxidation catalyst with hydrogen peroxide,” Journal of the American Chemical Society, vol. 127, no. 2, pp. 530–531, 2005.
[59]
R. Tan, C. Liu, N. Feng et al., “Phosphotungstic acid loaded on hydrophilic ionic liquid modified SBA-15 for selective oxidation of alcohols with aqueous H2O2,” Microporous and Mesoporous Materials, vol. 158, pp. 77–87, 2012.
[60]
J. Cuan and B. Yan, “Photofunctional hybrid materials with polyoxometalates and benzoate modified mesoporous silica through double functional imidazolium ionic liquid linkage,” Microporous and Mesoporous Materials, vol. 163, pp. 9–16, 2014.
[61]
H. Zhao, L. Zeng, Y. Li et al., “Polyoxometalate-based ionic complexes immobilized in mesoporous silica via a one-pot procedure: efficient and reusable catalyst for H2O2 mediated alcohol oxidations in aqueous media,” Microporous and Mesoporous Materials, vol. 172, pp. 67–76, 2013.
[62]
R. Yu, X.-F. Kuang, X.-Y. Wu, C.-Z. Lu, and J. P. Donahue, “Stabilization and immobilization of polyoxometalates in porous coordination polymers through host-guest interactions,” Coordination Chemistry Reviews, vol. 253, no. 23-24, pp. 2872–2890, 2009.
[63]
E. Poli, J.-M. Clacens, and Y. Pouilloux, “Synthesis of peroxophosphotungstate immobilized onto polymeric support as heterogeneous catalyst for the epoxidation of unsaturated fatty esters,” Catalysis Today, vol. 164, no. 1, pp. 429–435, 2011.
[64]
B. S. Chhikara, S. Tehlan, and A. Kumar, “1-Methyl-3-butylimidazolium decatungstate in ionic liquid: an efficient catalyst for the oxidation of alcohols,” Synlett, vol. 2005, no. 1, pp. 63–66, 2005.
[65]
Y. Liu, K. Murata, and M. Inaba, “Liquid-phase oxidation of benzene to phenol by molecular oxygen over transition metal substituted polyoxometalate compounds,” Catalysis Communications, vol. 6, no. 10, pp. 679–683, 2005.
[66]
Y. Leng, J. Wang, D. Zhu, L. Shen, P. Zhao, and M. Zhang, “Heteropolyanion-based ionic hybrid solid: a green bulk-type catalyst for hydroxylation of benzene with hydrogen peroxide,” Chemical Engineering Journal, vol. 173, no. 2, pp. 620–626, 2011.
[67]
P. Zhao, Y. Leng, and J. Wang, “Heteropolyanion-paired cross linked copolymer: an efficient heterogeneous catalyst for hydroxylation of benzene with hydrogen peroxide,” Chemical Engineering Journal, vol. 204–206, pp. 72–78, 2012.
[68]
X.-X. Han, Y.-F. He, C.-T. Hung, S.-L. Liu, S.-J. Huang, and S.-B. Liu, “Efficient and reusable polyoxometalate-based sulfonated ionic liquid catalysts for palmitic acid esterification to biodiesel,” Chemical Engineering Science.
[69]
Y. Leng, J. Wang, D. Zhu, X. Ren, H. Ge, and L. Shen, “Heteropolyanion-based ionic liquids: reaction-induced self-separation catalysts for esterification,” Angewandte Chemie International Edition, vol. 48, no. 1, pp. 168–171, 2009.
[70]
Y. Leng, J. Wang, D. Zhu, Y. Wu, and P. Zhao, “Sulfonated organic heteropolyacid salts: recyclable green solid catalysts for esterifications,” Journal of Molecular Catalysis A, vol. 313, no. 1-2, pp. 1–6, 2009.
[71]
K. Li, L. Chen, H. Wang, W. Lin, and Z. Yan, “Heteropolyacid salts as self-separation and recyclable catalysts for transesterification of trimethylolpropane,” Applied Catalysis A, vol. 392, no. 1-2, pp. 233–237, 2011.
[72]
Y. Qiao, L. Hua, J. Chen, N. Theyssen, W. Leitner, and Z. Hou, “The cooperative role of zwitterions and phosphotungstate anion in epoxidation reaction,” Journal of Molecular Catalysis A, vol. 380, pp. 43–48, 2013.
[73]
C. Venturello, E. Alneri, and M. Ricci, “A new, effective catalytic system for epoxidation of olefins by hydrogen peroxide under phase-transfer conditions,” Journal of Organic Chemistry, vol. 48, no. 21, pp. 3831–3833, 1983.
[74]
C. Venturello and R. D'Aloisio, “Quaternary ammonium tetrakis(diperoxotungsto)phosphates(3-) as a new class of catalysts for efficient alkene epoxidation with hydrogen peroxide,” Journal of Organic Chemistry, vol. 53, no. 7, pp. 1553–1557, 1988.
[75]
C. Venturello, R. D'Aloisio, J. C. J. Bart, and M. Ricci, “A New peroxotungsten heteropoly anion with special oxidizing properties: synthesis and structure of tetrahexylammonium tetra(diperoxotungsto)phosphate(3-),” Journal of Molecular Catalysis, vol. 32, no. 1, pp. 107–110, 1985.
[76]
I. V. Kozhevnikov, G. P. Mulder, M. C. Steverink-de Zoete, and M. G. Oostwal, “Epoxidation of oleic acid catalyzed by peroxo phosphotungstate in a two-phase system,” Journal of Molecular Catalysis A, vol. 134, no. 1–3, pp. 223–228, 1998.
[77]
H. Li, Z. Hou, Y. Qiao et al., “Peroxopolyoxometalate-based room temperature ionic liquid as a self-separation catalyst for epoxidation of olefins,” Catalysis Communications, vol. 11, no. 5, pp. 470–475, 2010.
[78]
M. Bagheri, M. Masteri-Farahani, and M. Ghorbani, “Synthesis and characterization of heteropolytungstate-ionic liquid supported on the surface of silica coated magnetite nanoparticles,” Journal of Magnetism and Magnetic Materials, vol. 327, pp. 58–63, 2013.
[79]
E. Rafiee and S. Eavani, “Polyoxometalate-based acid salts with tunable separation properties as recyclable Br？nsted acid catalysts for the synthesis of β-keto enol ethers,” Catalysis Communications, vol. 25, pp. 64–68, 2012.
[80]
M. Rostami, A. R. Khosropour, V. Mirkhani, I. Mohammadpoor-Baltork, M. Moghadam, and S. Tangestaninejad, “ : a novel and powerful catalyst for the synthesis of 4-arylidene-2-phenyl-5(4)-oxazolones under ultrasonic condition,” Comptes Rendus Chimie, vol. 14, no. 10, pp. 869–877, 2011.
[81]
M. Rostami, A. Khosropour, V. Mirkhani, M. Moghadam, S. Tangestaninejad, and I. Mohammadpoor-Baltork, “Organic-inorganic hybrid polyoxometalates: efficient, heterogeneous and reusable catalysts for solvent-free synthesis of azlactones,” Applied Catalysis A, vol. 397, no. 1-2, pp. 27–34, 2011.
[82]
A. Davoodnia, A. Zare-Bidaki, and H. Behmadi, “A rapid and green method for solvent free synthesis of 1,8-dioxodecahydroacridines using tetrabutylammonium hexatungstate as reusable heterogeneous catalyst,” Chinese Journal of Catalysis, vol. 33, pp. 1797–1801, 2012.
[83]
H. Yasuda, L.-N. He, T. Sakakura, and C. Hu, “Efficient synthesis of cyclic carbonate from carbon dioxide catalyzed by polyoxometalate: the remarkable effects of metal substitution,” Journal of Catalysis, vol. 233, no. 1, pp. 119–122, 2005.
[84]
Y. Dai, B. D. Li, H. D. Quan, and C. X. Lü, “[Hmim]3PW12O40: a high-efficient and green catalyst for the acetalization of carbonyl compounds,” Chinese Chemical Letters, vol. 21, no. 6, pp. 678–681, 2010.
[85]
Y. Ishii, H. Tanaka, and Y. Nishiyama, “Selectivity in oxidation of sulfides with hydrogen peroxide by [n-C5H5N+(CH2)15CH3]3PM12O40？？3？ and [p-C5H5N+(CH2)15CH3]3{PO4[M(O)(O2)2]4}3？ (M = Mo or W),” Chemistry Letters, vol. 23, pp. 1–4, 1994.
[86]
N. M. Gresley, W. P. Griffith, A. C. Laemmel, H. I. S. Nogueira, and B. C. Parkin, “Studies on polyoxo and polyperoxo-metalates part 5: peroxide-catalysed oxidations with heteropolyperoxo-tungstates and -molybdates,” Journal of Molecular Catalysis A, vol. 117, no. 1–3, pp. 185–198, 1997.
[87]
K. Sato, M. Hyodo, M. Aoki, X.-Q. Zheng, and R. Noyori, “Oxidation of sulfides to sulfoxides and sulfones with 30% hydrogen peroxide under organic solvent- and halogen-free conditions,” Tetrahedron, vol. 57, no. 13, pp. 2469–2476, 2001.
[88]
N. Mizuno and K. Kamata, “Catalytic oxidation of hydrocarbons with hydrogen peroxide by vanadium-based polyoxometalates,” Coordination Chemistry Reviews, vol. 255, no. 19-20, pp. 2358–2370, 2011.
[89]
B. S. Chhikara, R. Chandra, and V. Tandon, “Oxidation of alcohols with hydrogen peroxide catalyzed by a new imidazolium ion based phosphotungstate complex in ionic liquid,” Journal of Catalysis, vol. 230, no. 2, pp. 436–439, 2005.
[90]
J. M. Tatibou？t, “Methanol oxidation as a catalytic surface probe,” Applied Catalysis A, vol. 148, pp. 213–252, 1997.
[91]
S. Ivanova, X. Nitsch, F. Romero-Sarria et al., “New class of acid catalysts for methanol dehydration,” Studies in Surface Science and Catalysis, vol. 175, pp. 601–604, 2010.
[92]
S. Ivanova, X. Nitsch, F. Romero-Sarria et al., “Ionic liquid protected heteropoly acids for methanol dehydration,” Catalysis Today, vol. 171, no. 1, pp. 236–241, 2011.
[93]
L. Dermeche, N. Salhi, S. Hocine, R. Thouvenot, and C. Rabia, “Effective Dawson type polyoxometallate catalysts for methanol oxidation,” Journal of Molecular Catalysis A, vol. 356, pp. 29–35, 2012.
[94]
N. Mizuno, K. Yamaguchi, K. Kamata, and Y. Nakagawa, “Mechanisms,” in Homogeneous and Heterogeneous Epoxidation Catalysis, T. Oyama, Ed., Elsevier B. V, 2008.
[95]
Y. Román-Leshkov, C. J. Barrett, Z. Y. Liu, and J. A. Dumesic, “Production of dimethylfuran for liquid fuels from biomass-derived carbohydrates,” Nature, vol. 447, no. 7147, pp. 982–985, 2007.
[96]
B. Kamm, “Production of platform chemicals and synthesis gas from biomass,” Angewandte Chemie International Edition, vol. 46, no. 27, pp. 5056–5058, 2007.
[97]
Q. Bao, K. Qiao, D. Tomida, and C. Yokoyama, “Preparation of 5-hydroymethylfurfural by dehydration of fructose in the presence of acidic ionic liquid,” Catalysis Communications, vol. 9, no. 6, pp. 1383–1388, 2008.
[98]
C. Moreau, A. Finiels, and L. Vanoye, “Dehydration of fructose and sucrose into 5-hydroxymethylfurfural in the presence of 1-H-3-methyl imidazolium chloride acting both as solvent and catalyst,” Journal of Molecular Catalysis A, vol. 253, no. 1-2, pp. 165–169, 2006.
[99]
S. Hu, Z. Zhang, Y. Zhou et al., “Conversion of fructose to 5-hydroxymethylfurfural using ionic liquids prepared from renewable materials,” Green Chemistry, vol. 10, no. 12, pp. 1280–1283, 2008.
[100]
Q. Zhao, L. Wang, S. Zhao, X. Wang, and S. Wang, “High selective production of 5-hydroymethylfurfural from fructose by a solid heteropolyacid catalyst,” Fuel, vol. 90, no. 6, pp. 2289–2293, 2011.
