Efficient imine synthesis from oxidative coupling of alcohols and amines under air atmosphere catalysed by Zn-doped Al2O3 supported Au nanoparticles

Wu, Shipeng; Sun, Weixiao; Chen, Junjie; Zhao, Jinghan; Cao, Qiue; Fang, Wenhao; Zhao, Qi‐Hua

doi:10.1016/j.jcat.2019.07.027

Cited by 60 publications

(26 citation statements)

References 58 publications

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“…The preparation of Schiff bases can proceed by the condensation reaction of carbonyl compounds with primary amines. Apart from the condensation reaction commonly used in the synthesis of Schiff bases, other synthetic methods have been reported, such as the reductive imination of nitro compounds [3], rebound hydrolysis [4], hydroamination of alkynes with anilines [5], oxidative coupling of alcohols and amines [6] and cross-coupling of amines [7,8].…”

Section: Introductionmentioning

confidence: 99%

Ag(I) Complexes of Imine Derivatives of Unexpected 2-Thiophenemethylamine Homo-Coupling and Bis-(E)-N-(furan-2-ylmethyl)-1-(quinolin-2-yl)methanimine

Adeleke

Zamisa

Omondi

2021

Molbank

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Imines are fundamental organic compounds used as synthetic intermediates and as ligands in coordination chemistry. They are also found to be important pharmacophores in various bioactive compounds. In this report, two Schiff bases were prepared using the traditional condensation of 4-pyridinecarboxaldehyde with 2-thiophenemethylamine and 2-quinolinecarboxaldehyde with furfurylamine to form (E)-1-(pyridin-4-yl)-N-(thiophen-2-ylmethyl)methanimine (L1) and (E)-N-(furan-2-ylmethyl)-1-(quinolin-2-yl)methanimine (L2) respectively. L1 and L2 were complexed with silver perchlorate in 2:1 [M:L] stoichiometry to obtain complexes 1 and 2, respectively. The crystal structures of 1 and 2 were unequivocally determined by single-crystal X-ray diffraction analysis. The resulting structures revealed 2 to be a four-coordinate as expected. In contrast, an unexpected chemoselective hydrolytic cleavage of one mole of the (CH=N) imine ligands occurred in complex 2 and, further, the amines (thiophenemethylamine) homo-coupled to form a new imine ligand derivative in situ (L1a) before coordinating to the Ag(I) center along with L1. This observation described an alternative synthetic route to be explored to synthesize a diverse range of imine derivatives, which involves the Ag(I)-promoted homo-coupling of amines. Herein, the crystal structures of Ag(I) complexes of pyridinyl [Ag(L1)(L1a)]ClO4 (1) and quinolinyl [Ag(L2)2]ClO4 (2) Schiff bases are presented.

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Section: Introductionmentioning

confidence: 99%

Ag(I) Complexes of Imine Derivatives of Unexpected 2-Thiophenemethylamine Homo-Coupling and Bis-(E)-N-(furan-2-ylmethyl)-1-(quinolin-2-yl)methanimine

Adeleke

Zamisa

Omondi

2021

Molbank

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“…Selective oxidation of alcohols into aldehydes or ketones stands out as a class of essential and important transformations in organic synthesis and the fine-chemical industry. , Specifically, oxidation of bioalcohols derived from lignocellulose would benefit the utilization of renewable organic carbon feedstocks parallel to fossil fuels. − This plays a crucial role in sustainable development and long-term economic stability. Vanillin (4-hydroxy-3-methoxybenzaldehyde) is most often used as a simplified model for the study of lignin conversion, because it features the characteristic structural unit of lignin but offers an easier analytical methodology in comparison to the complexity of the lignin moiety. − Moreover, the production of high-value vanillin for a rapidly growing demand is very important to the food, pharmaceutical, cosmetic, and fine-chemical industries.…”

Section: Introductionmentioning

confidence: 99%

Effective Control of Particle Size and Electron Density of Pd/C and Sn-Pd/C Nanocatalysts for Vanillin Production via Base-Free Oxidation

Sun

et al. 2020

ACS Catal.

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The effective control of particle size and electron density of metal active sites is challenging yet important for supported nanoparticles, as size effects and promoter effects play vital roles in heterogeneous catalysis on the nanoscale. In this work, we report Pd/C and Sn-Pd/C nanocatalysts for the base-free aerobic oxidation of vanillyl alcohol to vanillin, a challenging reaction not only in the fundamental research of selective oxidation of alcohols but also for the practical transformation of bio-based alcohols to value-added chemicals. We effectively tuned the mean size of Pd nanoparticles from 1.8 to 6.7 nm by varying the temperature used for catalyst preparation and further modified the electron density of the Pd/C catalyst by adding a SnO2 promoter with different loadings. TEM, HAADF-STEM, XPS, CO chemisorption, and in situ DRIFT-IR of CO adsorption characterizations allowed us to get insight into the unique catalytic properties of Pd nanocatalysts. It was conjectured that the base-free aerobic oxidation of vanillyl alcohol to vanillin over the Pd/C catalyst can be a structure-sensitive reaction and the Pd particle size was decisive for the dispersion of Pd, the proportion of catalytically active Pd0 sites, and the intrinsic turnover frequency (iTOF). The 1 wt % Pd/C (1.8 nm) catalyst showed an iTOF value of 268 h–1 and 100% yield to vanillin at 120 °C, 5 bar of O2, and 20 mg of the catalyst within 9 h. We further demonstrated that Sn4+ ions in SnO2 as an electronic promoter can promote Pd/C activity by the formation of highly active, electron-sufficient Pd0 sites which significantly lowered the apparent activation energy of reaction. The 0.1Sn-Pd/C catalyst showed a higher iTOF value of 458 h–1 and a yield of 100% to vanillin at 120 °C, 3 bar of O2 and 15 mg of the catalyst within 6 h. Moreover, we verified a satisfying reusability and an adequate substrate scope over the 0.1Sn-Pd/C catalyst.

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“…), reactive surface-adsorbed oxygen species (O 2– , O 2 2– , and/or O – , O ads. ), and oxygen species in OH groups (O OH ). − The BE values of Ru and Co species are found to vary upon Ru loading (Table S2). On the Ru 4 CoO y (OH) catalyst, the BE of Ru 0 species shifts to the highest value whereas those of Co ions shift to the lowest.…”

Section: Resultsmentioning

confidence: 99%

Base-Free Aerobic Oxidation of 5-Hydroxymethylfurfural on a Ru(0) Center in Cooperation with a Co(II)/Co(III) Redox Pair over the One-Pot Synthesized Ru–Co Composites

Gao

Zhang

et al. 2020

Ind. Eng. Chem. Res.

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A novel Ru x CoO y (OH) composite catalyst was prepared by the simple one-pot hydrolysis of Ru and Co salts at room temperature in the presence of NaBH4. This catalyst showed promise for aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) under environmentally benign conditions, i.e., using water as the solvent, O2 as the oxidant, and no soluble base additives. Various physicochemical techniques, including ICP-MS, PXRD, DRIFT, TEM, H2-TPR, O2-TPD, XPS, and CO2-TPD, were used to study the catalytic properties that depend on the Ru load. The influence of reaction parameters (i.e., HMF/Ru ratio, O2 pressure, reaction temperature, and time) and the reaction pathway was investigated. HMF oxidation was initiated mainly from the OH group on metallic Ru0 active sites, and the cooperation of the Co(II)/Co(III) redox pair allowed the effective transformation of O2 to reactive lattice oxygen and the regeneration of Ru0 sites. It was shown that the Ru4CoO y (OH) catalyst with an enhanced Ru–Co metal interaction was the most active in giving a 99.9% yield of FDCA at 140 °C and 10 bar of O2 after 18 h, corresponding to a high productivity (3.3 molFDCA molRu –1 h–1) compared to those of Ru-based benchmark catalysts in the literature. Moreover, this catalyst was considerably stable during seven reuses.

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Efficient imine synthesis from oxidative coupling of alcohols and amines under air atmosphere catalysed by Zn-doped Al2O3 supported Au nanoparticles

Cited by 60 publications

References 58 publications

Ag(I) Complexes of Imine Derivatives of Unexpected 2-Thiophenemethylamine Homo-Coupling and Bis-(E)-N-(furan-2-ylmethyl)-1-(quinolin-2-yl)methanimine

Ag(I) Complexes of Imine Derivatives of Unexpected 2-Thiophenemethylamine Homo-Coupling and Bis-(E)-N-(furan-2-ylmethyl)-1-(quinolin-2-yl)methanimine

Effective Control of Particle Size and Electron Density of Pd/C and Sn-Pd/C Nanocatalysts for Vanillin Production via Base-Free Oxidation

Base-Free Aerobic Oxidation of 5-Hydroxymethylfurfural on a Ru(0) Center in Cooperation with a Co(II)/Co(III) Redox Pair over the One-Pot Synthesized Ru–Co Composites

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