One-pot synthesis of Pd-promoted Ce–Ni mixed oxides as efficient catalysts for imine production from the direct <i>N</i>-alkylation of amine with alcohol

Zhang, Mengyuan; Wu, Shipeng; Bian, Longchun; Cao, Qiue; Fang, Wenhao

doi:10.1039/c8cy01857j

Cited by 61 publications

(31 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As reported in Table 2 (entries 4, 7, and 8), decreasing the ratio from 1.5/1 to 1/1 brings about a decline in both the conversion of benzyl alcohol (from 99 to 85 %) and imine selectivity (from 99 to 91 %), while benzaldehyde selectivity increases (from 1 to 9 %). This shows that an appropriate excess of aniline is necessary to promote the oxidative coupling reaction, as has been observed on other CeO 2 ‐based catalysts and may be related to the weak basicity of aniline for facilitating selective oxidation of benzyl alcohol to benzaldehyde [14c, 21] . Interestingly, the hsm CeO 2 catalyst can work at 30 °C (Table 2, entry 9).…”

Section: Resultssupporting

confidence: 59%

Efficient Imine Formation by Oxidative Coupling at Low Temperature Catalyzed by High‐Surface‐Area Mesoporous CeO₂ with Exceptional Redox Property

Wang

Cao

et al. 2020

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

High‐surface‐area mesoporous CeO2 (hsmCeO2) was prepared by a facile organic‐template‐induced homogeneous precipitation process and showed excellent catalytic activity in imine synthesis in the absence of base from primary alcohols and amines in air atmosphere at low temperature. For comparison, ordinary CeO2 and hsmCeO2 after different thermal treatments were also investigated. XRD, N2 physisorption, UV‐Raman, H2 temperature‐programmed reduction, O2 temperature‐programmed desorption, EPR spectroscopy, and X‐ray photoelectron spectroscopy were used to unravel the structural and redox properties. The hsmCeO2 calcined at 400 °C shows the highest specific surface area (158 m2 g−1), the highest fraction of surface coordinatively unsaturated Ce3+ ions (18.2 %), and the highest concentration of reactive oxygen vacancies (2.4×1015 spins g−1). In the model reaction of oxidative coupling of benzyl alcohol and aniline, such an exceptional redox property of the hsmCeO2 catalyst can boost benzylideneaniline formation (2.75 and 5.55 mmol gceria-1 h−1 based on >99 % yield at 60 and 80 °C, respectively) in air with no base additives. It can also work effectively at a temperature of 30 °C and in gram‐scale synthesis. These are among the best results for all benchmark ceria catalysts in the literature. Moreover, the hsmCeO2 catalyst shows a wide scope towards primary alcohols and amines with good to excellent yield of imines. The influence of reaction parameters, the reusability of the catalyst, and the reaction mechanism were investigated.

show abstract

Section: Resultssupporting

confidence: 59%

Efficient Imine Formation by Oxidative Coupling at Low Temperature Catalyzed by High‐Surface‐Area Mesoporous CeO₂ with Exceptional Redox Property

Wang

Cao

et al. 2020

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

show abstract

“…[ 17 ] It is commonly accepted oxygen vacancies benefit the adsorption and activation of O 2 or H 2 O molecules, which subsequently turn into surface oxygen species. [ 6a,18 ] These very oxygen species generally play vital roles in oxidation or dehydrogenations reactions, [ 19 ] and thus may facilitate the oxidation of benzyl alcohol in our reaction system.…”

Section: Resultsmentioning

confidence: 99%

Insight into Ce Doping Induced Oxygen Vacancies over Ce‐Doped Mno₂ Catalysts for Imine Synthesis

Shen

Wang

et al. 2020

Chin. J. Chem.

View full text Add to dashboard Cite

of main observation and conclusion The pursuit of modern sustainable chemistry has stimulated the development of innovative catalytic processes that enable chemical transformations to be performed under mild and clean conditions with high efficiency. Here, an amorphous sheet-like MnO2 (Ce-doped MnO2: CMBO) was obtained after Ce doping, which exhibits excellent catalytic performance for the oxidation coupling of alcohol and aniline. Conversion of 99% and a selectivity of 99% could be achieved within 6 h at 60 o C under air atmosphere, and the formation rate of target product was up to 30.2 μmol•h-1 •m-2. Based on a series of characterizations, it was found that the doping of Ce into the MnO2 could increase the concentration of the oxygen vacancies, thus forming abundant active surface oxygen species and favoring the mobility of lattice oxygen, which are the main reasons for the greatly enhanced catalytic performance of CMBO. This work indicates that increasing oxygen vacancy by element doping may serve as a facile and efficient way to enhance catalytic performance of transition metal oxide.

show abstract

“…Imines are one of the most versatile functional groups in synthesis. Numerous studies have focused on their preparation [ 1 , 2 , 3 , 4 , 5 ], chemical structure and tautomeric or transimination equilibrium [ 6 , 7 , 8 ], and use as a precursor for the construction of more complex structures [ 9 , 10 , 11 , 12 ]. Due to their versatility, they play an important role in medicinal chemistry, serving as urease and protease inhibitors [ 13 ] as well as antimalarial, antibacterial, and antifungal agents [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

Regioselective Mercury(I)/Palladium(II)-Catalyzed Single-Step Approach for the Synthesis of Imines and 2-Substituted Indoles

et al. 2021

View full text Add to dashboard Cite

An efficient synthesis of ketimines was achieved through a regioselective Hg(I)-catalyzed hydroamination of terminal acetylenes in the presence of anilines. The Pd(II)-catalyzed cyclization of these imines into the 2-substituted indoles was satisfactorily carried out by a C-H activation. In a single-step approach, a variety of 2-substituted indoles were also generated via a Hg(I)/Pd(II)-catalyzed, one-pot, two-step process, starting from anilines and terminal acetylenes. The arylacetylenes proved to be more effective than the alkyl derivatives.

show abstract

One-pot synthesis of Pd-promoted Ce–Ni mixed oxides as efficient catalysts for imine production from the direct N-alkylation of amine with alcohol

Abstract: Pd-promoted CeNiXOY mixed oxides showed high production of imines through the oxidative coupling of amines with alcohols due to the synergistic effect between Pd0 species and redox properties of CeNiXOY.

Cited by 61 publications

References 54 publications

Efficient Imine Formation by Oxidative Coupling at Low Temperature Catalyzed by High‐Surface‐Area Mesoporous CeO₂ with Exceptional Redox Property

Efficient Imine Formation by Oxidative Coupling at Low Temperature Catalyzed by High‐Surface‐Area Mesoporous CeO₂ with Exceptional Redox Property

Insight into Ce Doping Induced Oxygen Vacancies over Ce‐Doped Mno₂ Catalysts for Imine Synthesis

Regioselective Mercury(I)/Palladium(II)-Catalyzed Single-Step Approach for the Synthesis of Imines and 2-Substituted Indoles

Contact Info

Product

Resources

About

One-pot synthesis of Pd-promoted Ce–Ni mixed oxides as efficient catalysts for imine production from the direct N-alkylation of amine with alcohol

Abstract: Pd-promoted CeNiXOY mixed oxides showed high production of imines through the oxidative coupling of amines with alcohols due to the synergistic effect between Pd0 species and redox properties of CeNiXOY.

Cited by 61 publications

References 54 publications

Efficient Imine Formation by Oxidative Coupling at Low Temperature Catalyzed by High‐Surface‐Area Mesoporous CeO2 with Exceptional Redox Property

Efficient Imine Formation by Oxidative Coupling at Low Temperature Catalyzed by High‐Surface‐Area Mesoporous CeO2 with Exceptional Redox Property

Insight into Ce Doping Induced Oxygen Vacancies over Ce‐Doped Mno2 Catalysts for Imine Synthesis

Regioselective Mercury(I)/Palladium(II)-Catalyzed Single-Step Approach for the Synthesis of Imines and 2-Substituted Indoles

Contact Info

Product

Resources

About

Efficient Imine Formation by Oxidative Coupling at Low Temperature Catalyzed by High‐Surface‐Area Mesoporous CeO₂ with Exceptional Redox Property

Efficient Imine Formation by Oxidative Coupling at Low Temperature Catalyzed by High‐Surface‐Area Mesoporous CeO₂ with Exceptional Redox Property

Insight into Ce Doping Induced Oxygen Vacancies over Ce‐Doped Mno₂ Catalysts for Imine Synthesis