Zeolite encapsulated Ru(III), Cu(II) and Zn(II) complexes of benzimidazole as reusable catalysts for the oxidation of organic substrates

Abstract

Ru(III), Cu(II) and Zn(II) complexes of benzimidazole (BzlH) have been synthesized in the supercages of zeolite-Y by the flexible ligand method and were characterized by spectroscopic (IR, UV-Vis and ESR) studies, XRD and thermogravimetric analysis, surface area, and pore volume measurements. The zeolite encapsulated complexes catalyzed the oxidation of ethylbenzene, benzoin, and cyclohexanol. Various parameters, such as concentration of oxidant and catalyst, reaction time, temperature of the reaction and type of solvents have been optimized to obtain the maximum transformation of ethylbenzene to a mixture of acetophenone, benzaldehyde and styrene. Under the optimized reaction conditions, [Ru(BzlH)]-Y gave 80.4 % conversion of ethylbenzene in 1 h. All these zeolite encapsulated complexes were more selective towards acetophenone formation. Oxidation of benzoin catalyzed by [Cu(BzlH)]-Y, [Ru(BzlH)]-Y and [Zn(BzlH)]-Y encapsulated complexes resulted in 75.5, 78.7 and 59.9 % conversion respectively to give benzaldehyde as exclusive product. A maximum conversion of 39.1 % cyclohexanol with [Cu(BzlH)]-Y was achieved to give cyclohexanone. The activity of neat complexes towards these reactions was also carried out. The encapsulated catalysts were significantly more active than neat complexes and recyclable without much loss in catalytic activity.

Solvent‐Free Oxidation of Benzyl Alcohol Using Modified Zeolitic Imidazolate Frameworks‐8 (ZIF‐8) Catalysts

“…Appropriate catalyst selection can significantly influence the success of attaining the desired product yield. Some heterogeneous catalysts that have been employed in the alcohol oxidation reaction include AuÀ Pd nanoparticles, [7] perovskite LaMO 3 (M = Cr, Mn, Co, Ni, and Fe), [8] high-entropy oxides (e. g. HP- (FeCrCoNiCu) x O y , HE-MOF, MW-HEO), [9][10][11] Ce Oxysulfate Clusters (MCe 70 , M = Ce, Cu, Ni, Co, and Fe), [12] as well as porous materials like zeolites, [13] nitrogen-doped carbon-encapsulated metallic Co nanoparticles, [14] and Metal-Organic Frameworks (MOFs). [15] Among heterogeneous catalysts, MOFs stand out as porous materials with promising potential across various organic reactions.…”

Direct Hydroxylation of Benzene with Hydrogen Peroxide Using Fe Complexes Encapsulated into Mesoporous Y-Type Zeolite

“…In particular, the catalytic hydroxylation of benzene to phenol using environmentally friendly oxidants, such as hydrogen peroxide (H 2 O 2 ) [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ], molecular oxygen (O 2 ) in combination with reducing agents [ 13 , 14 , 15 , 16 , 17 , 18 ], and H 2 O with electrochemical [ 19 ] or photochemical reaction systems [ 20 , 21 ] has attracted considerable attention. One of the most attractive areas in catalysis is the development of inorganic–organic hybrid materials that are active for oxidation reactions [ 12 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. Many researchers have reported the oxidation of organic substrates (benzene [ 12 , 24 , 32 , 33 , 34 ], phenol [ 25 , 26 ], cyclohexane [ 23 , 27 , 33 ], cyclohexene [ 23 , 28 , 30 , 31 , 33 ], and sulfides [...…”

“…One of the most attractive areas in catalysis is the development of inorganic–organic hybrid materials that are active for oxidation reactions [ 12 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. Many researchers have reported the oxidation of organic substrates (benzene [ 12 , 24 , 32 , 33 , 34 ], phenol [ 25 , 26 ], cyclohexane [ 23 , 27 , 33 ], cyclohexene [ 23 , 28 , 30 , 31 , 33 ], and sulfides [ 34 ]) with H 2 O 2 as an oxidant using transition metal complexes encapsulated in Y-type zeolite.…”

Atenolol oxidation by Zeolite X encapsulated Cu (II)-L complex (L = a Schiff base ligand)

“…Zeolites are good inorganic supports for immobilization of coordination compounds. Zeolite encapsulated metal complexes (ZEMC) are containing metal complexes immobilized through encapsulation in the super cages of zeolites and the reactivity and selectivity of encapsulated complexes are the same free complexes [24][25][26][27][28]. Zeolites are unique among all types of compounds with porous and porous structures, because they have a regular crystal structure with high chemical and thermal stability.…”