Microwave-assisted peroxidative oxidation of toluene and 1-phenylethanol with monomeric keto and polymeric enol aroylhydrazone Cu(II) complexes

Sutradhar, Manas; Alegria, Elisabete C. B. A.; Barman, Tannistha Roy; Scorcelletti, Francesco; Silva, M. Fátima C. Guedes da; Pombeiro, Armando J. L.

doi:10.1016/j.mcat.2017.07.006

Cited by 41 publications

(27 citation statements)

References 54 publications

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“…Also, when using peroxides, a new trend is the reaction under the influence of microwave heating, which, in comparison with the traditional process, allows obtaining high yields in a short time. [7]).…”

Section: Introductionmentioning

confidence: 99%

Supported Gold Nanoparticles as Catalysts in Peroxidative and Aerobic Oxidation of 1-Phenylethanol under Mild Conditions

et al. 2020

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The efficiency of Au/TiO2 based catalysts in 1-phenylethanol oxidation was investigated. The role of support modifiers (La2O3 or CeO2), influence of gold loading (0.5% or 4%) and redox pretreatment atmosphere, catalyst recyclability, effect of oxidant: tert-butyl hydroperoxide (TBHP) or O2, as well as the optimization of experimental parameters of the reaction conditions in the oxidation of this alcohol were studied and compared with previous studies on 1-octanol oxidation. Samples were characterized by temperature-programmed oxygen desorption (O2-TPD) method. X-ray photoelectron spectroscopy (XPS) measurements were carried out for used catalysts to find out the reason for deactivation in 1-phenylethanol oxidation. The best catalytic characteristics were shown by catalysts modified with La2O3, regardless of the alcohol and the type of oxidant. When O2 was used, the catalysts with 0.5% Au, after oxidative pretreatment, showed the highest activity in both reactions. The most active catalysts in 1-phenylethanol oxidation with TBHP were those with 4% Au and the H2 treatment, while under the same reaction conditions, 0.5% Au and O2 treatment were beneficial in 1-octanol oxidation. Despite the different chemical nature of the substrates, it seems likely that Au+(Auδ+) act as the active sites in both oxidative reactions. Density functional theory (DFT) simulations confirmed that the gold cationic sites play an essential role in 1-phenylethanol adsorption.

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Section: Introductionmentioning

confidence: 99%

Supported Gold Nanoparticles as Catalysts in Peroxidative and Aerobic Oxidation of 1-Phenylethanol under Mild Conditions

et al. 2020

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“…Several transition metal complexes have already exhibited high catalytic activity in different organic oxidative transformations, such as oxidation of alkanes or alcohols, epoxidation, carboxylation, hydrocarboxylation, in C-C couplings, CO 2 reduction, etc. [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The efficiency of metal complexes in catalysis is highly dependent on their structural configuration and electronic properties [10,11,[15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

“…The commencement of clean synthetic catalytic routes can be implemented by using green oxidants, green solvents or solvent free processes, energy saving beneficial techniques and involves the design of efficient catalysts from environmental and economic perspectives [28][29][30]. Based on the nature of the catalyst precursors, both homogeneous and heterogeneous (supported) catalysts have been reported by us towards oxidative by us towards oxidative catalytic reactions [3][4][5][6][7][8][9][29][30][31][32][33][34][35][36][37][38][39][40]. Although many catalysts have been developed to overcome ecological drawbacks, namely those using cheap and abundant metals, like copper and iron, metal catalytic systems operating under sustainable conditions are still challenging.…”

Section: Introductionmentioning

confidence: 99%

Cu(II) and Fe(III) Complexes Derived from N-Acetylpyrazine-2-Carbohydrazide as Efficient Catalysts Towards Neat Microwave Assisted Oxidation of Alcohols

et al. 2019

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The mononuclear Cu(II) complex [Cu((kNN O-HL)(H 2 O) 2 ] (1) was synthesized using N-acetylpyrazine-2-carbohydrazide (H 2 L) and characterized by elemental analysis, IR spectroscopy, ESI-MS and single crystal X-ray crystallography. Two Fe(III) complexes derived from the same ligand viz, mononuclear [Fe((kNN O-HL)Cl 2 ] (2) and the binuclear [Fe(kNN O-HL)Cl(µ-OMe)] 2 (3) (synthesized as reported earlier), were also used in this study. The catalytic activity of these three complexes (1-3) was examined towards the oxidation of alcohols using tert-butyl hydroperoxide (TBHP) as oxidising agent under solvent-free microwave irradiation conditions. Primary and secondary benzyl alcohols (benzyl alcohol and 1-phenylethanol), and secondary aliphatic alcohols (cyclohexanol) were used as model substrates for this study. A comparison of their catalytic efficiency was performed. Complex 1 exhibited the highest activity in the presence of TEMPO as promoter for the oxidation of 1-phenylethanol with a maximum yield of 91.3% of acetophenone. Catalysts 2019, 9, 1053 2 of 15 catalytic reactions [3-9,29-40]. Although many catalysts have been developed to overcome ecological drawbacks, namely those using cheap and abundant metals, like copper and iron, metal catalytic systems operating under sustainable conditions are still challenging. Considering all the above mentioned points herein we present the synthesis of a new mononuclear Cu(II) complex, [Cu((kNN O-HL)(H 2 O) 2 ] (1), derived from the N-acetylpyrazine-2-carbohydrazide (H 2 L) ligand. Two Fe(III) complexes, the mononuclear [Fe((kNN O-HL)Cl 2 ] (2) and the binuclear [Fe(kNN O-HL)Cl(µ-OMe)] 2 (3), have also been synthesized using the same ligand as reported earlier [41]. The three complexes (1-3) were screened as catalytic precursors to assess their catalytic performances in the oxidation of alcohols. In the present investigation, we chose primary or secondary benzyl alcohols (benzyl alcohol, 1-phenyl alcohol) and secondary aliphatic alcohols (cyclohexanol) as model substrates and tert-butyl hydroperoxide (TBHP) as oxidising agent under microwave irradiation. MW irradiation acts as an alternative technique due to its simplicity and energy saving characteristics [6], usually leading to higher product yields and selectivities. In this investigation, the best catalytic conditions were optimized by comparing several cofactors like temperature, reaction time, influence of the presence of additives, etc. Results and Discussion Synthesis and CharacterizationsThe pro-ligand N-acetylpyrazine-2-carbohydrazide (H 2 L) was used to synthesize the mononuclear Cu(II) complex [Cu(kNN O-HL)(H 2 O) 2 ] (1) (Scheme 1). The Fe(III) complexes [Fe(kNN O-HL)Cl 2 ] (2) and [Fe(kNN O-HL)Cl(µ-OMe)] 2 (3) derived from the same pro-ligand were obtained by a method from the literature [41]. As previously observed, in this case, the N-acetylpyrazine-2-carbohydrazide also acts as a mononegative tridentate N,N,O donor (HL − ) towards the metal centre [41] and shows different coordination behaviour from a relate...

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“…These transition metal complexes have shown greater biological potential than the proligands. In addition, transition metal complexes of AHs are known to act as efficient and selective catalysts towards various chemical reactions …”

Section: Introductionmentioning

confidence: 99%

“…Hydrazones containing di‐ tert ‐butyl phenol moiety as a key structural feature are of conspicuous interest, due to their diverse antioxidant, anticancer, antifungal, antibacterial and dual COX/LOX inhibitory activities . An array of metal complexes of di‐ tert ‐butyl phenylhydrazones has been described in the literature . Many of them did not divulge a biological relevance.…”

Section: Introductionmentioning

confidence: 99%

Mononuclear Co(III), Ni(II) and Cu(II) complexes of 2‐(2,4‐dichlorobenzamido)‐N'‐(3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)benzohydrazide: Structural insight and biological assay

Chimmalagi

Kendur

Patil

et al. 2018

Applied Organom Chemis

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A series of mononuclear metal complexes of Co(III), Ni(II) and Cu(II) with 2-(2,4-dichlorobenzamido)-N′-(3,5-di-tert-butyl-2-hydroxybenzylidene)benzohydrazide (LH 3 ) have been synthesized and characterized using various physico-chemical, spectroscopic and single crystal X-ray diffraction techniques. Structural studies of [Co(LH)(LH 2 )]·H 2 O (4) revealed the presence of both amido and imidol tautomeric forms of LH 3 , resulting in a distorted octahedral geometry around the Co(III) ion. [Ni(LH)(H 2 O)]·H 2 O (5) and [Cu(LH)(H 2 O)]·H 2 O (6) are isomorphous structures and crystallize in the monoclinic P2 1 /c space group. The crystal structures of 4, 5 and 6 are stabilized by hydrogen bonds formed by the enclathrated water molecules, C-H···π and π···π interactions. Complexes along with the ligand (LH 3 ) were screened for their in vivo anti-inflammatory activity (carrageenan-induced rat paw edema method) and in vitro antioxidant activity (DPPH free radical scavenging assay). Metal complexes have shown significant anti-inflammatory and antioxidant potential.KEYWORDS anti-inflammatory activity, antioxidant activity, crystal structure, di-tert-butyl phenylhydrazone, isomorphous metal complexes

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Microwave-assisted peroxidative oxidation of toluene and 1-phenylethanol with monomeric keto and polymeric enol aroylhydrazone Cu(II) complexes

Cited by 41 publications

References 54 publications

Supported Gold Nanoparticles as Catalysts in Peroxidative and Aerobic Oxidation of 1-Phenylethanol under Mild Conditions

Supported Gold Nanoparticles as Catalysts in Peroxidative and Aerobic Oxidation of 1-Phenylethanol under Mild Conditions

Cu(II) and Fe(III) Complexes Derived from N-Acetylpyrazine-2-Carbohydrazide as Efficient Catalysts Towards Neat Microwave Assisted Oxidation of Alcohols

Mononuclear Co(III), Ni(II) and Cu(II) complexes of 2‐(2,4‐dichlorobenzamido)‐N'‐(3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)benzohydrazide: Structural insight and biological assay

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