6291-84-5Relevant articles and documents
A Nanocrystal Catalyst Incorporating a Surface Bound Transition Metal to Induce Photocatalytic Sequential Electron Transfer Events
Beard, Matthew C.,Chen, Xihan,Han, Chuang,Lin, Yixiong,Martin, Jovan San,Miller, Collin,Wang, Xiaoming,Yamamoto, Nobuyuki,Yan, Yanfa,Yan, Yong,Yazdi, Sadegh,Zeng, Xianghua
supporting information, p. 11361 - 11369 (2021/08/16)
Heterogeneous photocatalysis is less common but can provide unique avenues for inducing novel chemical transformations and can also be utilized for energy transductions, i.e., the energy in the photons can be captured in chemical bonds. Here, we developed a novel heterogeneous photocatalytic system that employs a lead-halide perovskite nanocrystal (NC) to capture photons and direct photogenerated holes to a surface bound transition metal Cu-site, resulting in a N-N heterocyclization reaction. The reaction starts from surface coordinated diamine substrates and requires two subsequent photo-oxidation events per reaction cycle. We establish a photocatalytic pathway that incorporates sequential inner sphere electron transfer events, photons absorbed by the NC generate holes that are sequentially funneled to the Cu-surface site to perform the reaction. The photocatalyst is readily prepared via a controlled cation-exchange reaction and provides new opportunities in photodriven heterogeneous catalysis.
Continuous chemoselective methylation of functionalized amines and diols with supercritical methanol over solid acid and acid-base bifunctional catalysts
Oku, Tomoharu,Arita, Yoshitaka,Tsuneki, Hideaki,Ikariya, Takao
, p. 7368 - 7377 (2007/10/03)
The selective N-methylation of bifunctionalized amines with supercritical methanol (scCH3OH) promoted by the conventional solid acids (H-mordenite, β-zeolite, amorphous silica-alumina) and acid-base bifunctional catalysts (Cs-P-Si mixed oxide and γ-alumina) was investigated in a continuous-flow, fixed-bed reactor. The use of scCH 3OH in the reaction of 2-aminoethanol with methanol (amine/CH 3OH = 1/10.8) over the solid catalysts led to a significant improvement in the chemoselectivity of the N-methylation. Among the catalysts examined, the Cs-P-Si mixed oxide provided the most efficient catalyst performance in terms of selectivity and reactivity at 300 °C and 8.2 MPa; the N-methylation selectivity in the products reaching up to 94% at 86% conversion. The present selective methylation was successfully applied to the synthesis of N-methylated amino alcohols and diamines as well as O-methylated ethylene glycol. Noticeably, ethoxyethylamine was less reactive, suggesting that the hydroxy group of the amino alcohols is a crucial structural factor in determining high reactivity and selectivity, possibly because of the tethering effect of another terminus, a hydroxo group, to the catalyst surface. The magic-angle-spinning NMR spectroscopy and X-ray diffraction analysis of the Cs-P-Si mixed oxide catalyst revealed that the acidic and basic sites originate from P2O5/SiO2 and Cs/SiO2, respectively, and the weak acid-base paired sites are attributed to three kinds of cesium phosphates on SiO2. The weak acid-base sites on the catalyst surface might be responsible for the selective dehydrative methylation.
Poly-bis-triazinylimides, their preparation
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, (2008/06/13)
Poly-bis-triazinylimides of the formula STR1 are prepared from bis-(2,4-dichloro-1,3,5-triazin-6-yl)imides and polyalkylpiperidylamines. They are used as light stabilizers for polymers.
