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Zeolite Y encaged Ru(III) and Fe(III) complexes for oxidation of styrene, cyclohexene, limonene, and α-pinene: An eye-catching impact of H2SO4 on product selectivity.

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Title: Zeolite Y encaged Ru(III) and Fe(III) complexes for oxidation of styrene, cyclohexene, limonene, and α-pinene: An eye-catching impact of H2SO4 on product selectivity.
Authors: Godhani, Dinesh R.1 drgodhani@yahoo.com, Nakum, Haresh D.1, Parmar, Digvijaysinh K.1, Mehta, Jignasu P.1, Desai, Nisheeth C.1
Source: Journal of Molecular Catalysis A: Chemistry. Jan2017 Part A, Vol. 426, p223-237. 15p.
Subjects: Metal complexes, Ruthenium compounds, Zeolite Y, Oxidation, Styrene, Sulfuric acid, Cyclohexene
Abstract: A novel Ru(III) and Fe(III) complexes of ligands 1 and/or 2 {where 1 = 2,2′-((1E,1′E)-((azanediylbis(ethane-2,1-diyl))bis(azanylylidene))bis(methanylylidene))diphenol and 2 = 2,2′-((1E,1′E)-((azanediylbis(ethane-2,1-diyl))bis(azanylylidene))bis(methanylylidene)) bis(4-nitrophenol)} have been synthesized as ‘neat’ and zeolite Y encapsulated complexes. These catalysts are characterized by various analytical tools such as FTIR, UV–vis, elemental analysis, ICP-AES, molar conductivity, 1 H- and 13 C NMR, TGA, SEM, AAS, BET, magnetic susceptibility and powder XRD to endorse the complex formation, absence of peripheral redundant ligands and complexes, conservation of zeolite Y morphology and crystallinity, and the encapsulation of complexes without devastation in the zeolite Y framework. Out of these synthesized catalysts, 5Y is found to be a potent candidate for styrene (Conv. 76.1%, TOF: 2130 h −1 ), cyclohexene (Conv. 84.4%, TOF: 2351 h −1 ), limonene (Conv. 81.6%, TOF: 2273 h −1 ), and α-pinene (Conv. 72.6%, TOF: 2023 h −1 ) oxidation with high selectivity of respective allylic products excluding the styrene oxidation, which undergoes epoxidation only. The addition of H 2 SO 4 in an identical reaction catalyzed by 5Y not only surge the conversion up to 100% in a short time span with high TOF but also increase the selectivity of respective epoxidation products. This switchover in the selectivities could be credited to the presence of H 2 SO 4 that facilitates the heterolytic O O bond cleavage of metal hydroperoxide and stimulates the epoxidation over allylic oxidation. Furthermore, the results establish that the heterogeneous systems are effortlessly recovered and reused without ample drop in the activity and selectivity. [ABSTRACT FROM AUTHOR]
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Abstract:A novel Ru(III) and Fe(III) complexes of ligands 1 and/or 2 {where 1 = 2,2′-((1E,1′E)-((azanediylbis(ethane-2,1-diyl))bis(azanylylidene))bis(methanylylidene))diphenol and 2 = 2,2′-((1E,1′E)-((azanediylbis(ethane-2,1-diyl))bis(azanylylidene))bis(methanylylidene)) bis(4-nitrophenol)} have been synthesized as ‘neat’ and zeolite Y encapsulated complexes. These catalysts are characterized by various analytical tools such as FTIR, UV–vis, elemental analysis, ICP-AES, molar conductivity, 1 H- and 13 C NMR, TGA, SEM, AAS, BET, magnetic susceptibility and powder XRD to endorse the complex formation, absence of peripheral redundant ligands and complexes, conservation of zeolite Y morphology and crystallinity, and the encapsulation of complexes without devastation in the zeolite Y framework. Out of these synthesized catalysts, 5Y is found to be a potent candidate for styrene (Conv. 76.1%, TOF: 2130 h −1 ), cyclohexene (Conv. 84.4%, TOF: 2351 h −1 ), limonene (Conv. 81.6%, TOF: 2273 h −1 ), and α-pinene (Conv. 72.6%, TOF: 2023 h −1 ) oxidation with high selectivity of respective allylic products excluding the styrene oxidation, which undergoes epoxidation only. The addition of H 2 SO 4 in an identical reaction catalyzed by 5Y not only surge the conversion up to 100% in a short time span with high TOF but also increase the selectivity of respective epoxidation products. This switchover in the selectivities could be credited to the presence of H 2 SO 4 that facilitates the heterolytic O O bond cleavage of metal hydroperoxide and stimulates the epoxidation over allylic oxidation. Furthermore, the results establish that the heterogeneous systems are effortlessly recovered and reused without ample drop in the activity and selectivity. [ABSTRACT FROM AUTHOR]
ISSN:13811169
DOI:10.1016/j.molcata.2016.11.020