ACS Catalysis
·
2024
·
IF 11.3
Xiaohui Leng,Xin Zhou,Lu Ma,Yonghua Du,Ouwen Peng,Zhongxin Chen,Jinhui Pan,Ming-Yu Qi,Jian-Hui Zheng,Yi-Jun Xu,Kian Ping Loh
Visible light induced oxidative C–C and C–N coupling provides a milder alternative to the current synthetic strategies. However, the photochemical C–C coupling of benzylamine and chromoselective C–C/C–N conversion are not widely reported. Herein, we demonstrate that the introduction of indium vacancies in ZnIn2S4 improves the catalytic activity for C–C coupling of benzylamine and imparts a strong chromoselectivity for C–C or C–N coupled products. A high C–C selectivity of ∼80% is achieved with a benzylamine conversion of ∼80%. Mechanistic studies unveil the switchable reaction routes between kinetically favored C–C coupling and thermodynamically favored C–N coupling under specific illumination conditions.
研究领域:
化学
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材料科学
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光催化
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2015
·Vol. 5
·期 117
·96372-96376
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IF 3.84
Zheng-Jun Wang,Peng-Hui Wang,Jing-Jing Lv,Jiu-Ju Feng,Xinhua Xu,Ai-Jun Wang,Chak-Tong Au,Renhua Qiu
Commercial copolymer Luviset clear (L1), an environmentally benign and efficient ligand, was used to facilitate the catalytic performance of Cu(NO3)2 for homo-coupling of terminal alkynes. A series of substituted aromatic and aliphatic terminal alkynes were investigated. It was found that Cu(NO3)2@L1 can catalyze the C–C coupling reactions without any other base, and the corresponding diynes are generated in good to excellent yield. X-ray photoelectron spectroscopy was used to study the reaction mechanism, and the results evidence a Cu(II)/Cu(I) catalytic system. Additionally, the catalyst can be easily separated and reused without showing significant loss of catalytic activity.
研究领域:
化学
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催化科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Catalysis
·
2016
·
IF 9.307
Jie Sun,Qiuxia Cai,Yan Wan,Shaolong Wan,Li Wang,Jingdong Lin,Donghai Mei,Yong Wang
The promotional effects of a cesium promoter on higher alcohol (C2+OH) synthesis from syngas over Cs2O-Cu/ZnO/Al2O3 catalysts were investigated using a combined experimental and density functional theory (DFT) calculation method. In the presence of a cesium promoter, the C2+OH productivity increases from 77.1 to 157.3 g kgcat–1 h–1 at 583 K due to the enhancement of the initial C–C bond formation. A detailed analysis of chain growth probabilities (CGPs) confirms that initial C–C bond formation is the rate-determining step in the temperature range of 543–583 K. Addition of a cesium promoter significantly increases the productivities of 2-methyl-1-propanol, while the CGP values (C3* to 2-methyl-C3*) are almost unaffected. With the assistance of a cesium promoter, the CGPs of the initial C–C bond formation step (C1* to C2*) increase from 0.13 to 0.25 at 583 K. DFT calculations indicate that the initial C–C bond formation during syngas synthesis over the ZnCu(211) model surface is mainly due to the HCO + HCO coupling. In the presence of Cs2O, the stabilities of key intermediates such as HCO and H2CO are enhanced, which facilitates both HCO + HCO and HCO + H2CO coupling steps with lower activation barriers. In addition, Bader charge analysis suggests that the presence of cesium ions could facilitate nucleophilic coupling between HCO and H2CO for the initial C–C bond formation.
研究领域:
催化化学
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能源化学
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理论化学
✓ 已验证
产品关联
DOI
高影响因子
MACROMOLECULES
·
2024
·
IF 5.1
Ranran Qi,Mengli Gao,Ziwen Gan,Mingyi Liao
This study focuses on the synthesizing of liquid-terminated carboxyl fluoropolymers (LTCFs) from poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) through microwave (MW)-assisted oxidative degradation. An in-depth analysis was conducted on the preparation process, the duration of MW irradiation, and the resulting changes in LTCFs. Chemical titration and gel permeation chromatography (GPC) revealed that the MW-assisted oxidative degradation was achieved in 150–240 s, which is several orders of magnitude shorter than heat (CH) oxidative degradation. The modifications in the structure of C═C and C═O bonds within LTCFs were investigated over a time range of 0 to 900 s using Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectrophotometry (UV–vis), and 19F nuclear magnetic resonance (19F-NMR). The analysis reveals that the dehydrofluorination reaction primarily occurs on the HFP-VDF-HFP sequence, resulting in two sequence structures: C═CZaitsev and C═CHofmann. The dehydrofluorination of the P(VDF-HFP) copolymer followed Zaitsev’s rule mainly and Hofmann’s rule slightly. Furthermore, it was observed that the processes of C═C bond formation (KHF reaction) and conversion (KC–C reaction) are in competition. When H2O2 is enough, the degradation of the P(VDF-HFP) copolymer predominantly follows the KC–C reaction and partially the KHF reaction. The opposite is true for low H2O2 concentrations. To conclude, this study suggests a mechanism for the synthesis of LTCFs using MW-assisted oxidative degradation of P(VDF-HFP). Under MW, the C atom adjacent to a C═C bond readily undergoes autocatalytic KHF reactions, creating conjugated polyene sequences of certain lengths. Meanwhile, the rapid degradation of H2O2 expedites C═C oxidative breaking, producing the COOH functional groups.
研究领域:
材料科学
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化学工程
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高分子化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
·
2020
·Vol. 36
·期 6
·1013-1016
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IF 1.063
Yu Qiuying,Lin Xiu,Li Xinhao,Chen Jiesheng
Heterogeneous catalysts have been developed for C-C coupling reactions, but stand low activity and always proceed under harsh conditions. Photocatalytic Stille cross-coupling reaction as a green catalytic method for C-C bond formation is of great interest for a wide range of scientists but still lacks stable and highly efficient catalysts. Herein, we have designed an Au nanoparticle-graphitic carbon nitride heterojunction as an outstanding photo-catalyst for artificial photosynthesis in Stille cross-coupling reaction. The interface effect between metal and semiconductor makes electron rectify and prevents the recombination of electron-hole pairs. Moreover, the efficiency of Au nanoparticle catalysts could be adjusted by gold contents. Thus the turnover frequency(TOF) value reached the highest level of 788 h −1 over the optimal heterojunction catalyst. Most importantly, the C-C bond formation reaction has been proved to be carried out well under visible light irradiation, indicating the low-cost organic synthesis process. Further analysis confirmed the stability and general application of our heterogeneous Au nano-heterojunction catalyst.
研究领域:
化学
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材料科学
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催化
·
光化学
✓ 已验证
DOI
高影响因子
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