547-64-8Relevant articles and documents
Two-Step Continuous-Flow Synthesis of Fungicide Metalaxyl through Catalytic C?N Bond-Formation Processes
Ishitani, Haruro,Yu, Zhibo,Ichitsuka, Tomohiro,Koumura, Nagatoshi,Onozawa, Shun-ya,Sato, Kazuhiko,Kobayashi, Shū
supporting information, p. 18 - 23 (2021/09/02)
Metalaxyl, an acylalanine fungicide, was synthesized through catalytic continuous sequential-flow reactions. Commonly used syntheses of this compound use batch systems and suffer from problems such as coproduction of halogen-containing by-products derived from acyl and alkyl halides in the substitution reactions of 2,6-dimethylaniline. To minimize waste and enhance efficiency, a halide-free approach including two continuous-flow catalytic processes, heterogeneous Pt-catalyzed reductive alkylation and homogeneous acid-catalyzed amidation with an acid anhydride, was developed. Systematic examination of the two reactions in flow mode enabled a high-yielding, two-step sequential continuous-flow process to be achieved. (Figure presented.).
Enhancing Effect of Residual Capping Agents in Heterogeneous Enantioselective Hydrogenation of α-keto Esters over Polymer-Capped Pt/Al2O3
Chung, Iljun,Song, Byeongju,Kim, Jeongmyeong,Yun, Yongju
, p. 31 - 42 (2021/01/11)
Heterogeneous enantioselective catalysis is considered a promising strategy for the large-scale production of enantiopure chemicals. In this work, polymer-capped Pt nanocatalysts having a uniform size were synthesized using poly(vinyl pyrrolidone) (PVP) and poly(vinyl alcohol) and supported on γ-Al2O3. After a facile heat treatment process, their catalytic performance for enantioselective hydrogenation of α-keto esters, a structure-sensitive reaction, was investigated. The presence of residual capping agents on the Pt surface often perturbs the adsorption of reacting species and reduces performance in structure-sensitive reactions. However, the 1 wt % PVP-Pt/Al2O3 catalyst exhibited an enhancement in both activity and enantioselectivity compared to a reference Pt/Al2O3 catalyst prepared by wet impregnation. Under optimized reaction conditions, the cinchonidine-modified PVP-Pt/Al2O3 gave an enantiomeric excess of 95% for the enantioselective hydrogenation of methyl pyruvate despite the low Pt loading. We demonstrate that depending on the type of polymers, the residual capping agents can lead to site-selective blockage of the Pt surface, that is, defects or terraces. Quantitative and qualitative analyses also show that the noticeable improvement in enantioselectivity is attributed to the stable adsorption of chiral modifiers on selectively exposed Pt terrace sites. The findings of this work provide a promising strategy to prepare metal nanoparticles having selectively exposed sites and offer insights into the enhancing effect of residual capping agents on the catalytic properties in structure-sensitive reactions.
Conversion of sugars to methyl lactate with exfoliated layered stannosilicate UZAR-S4
Murillo, Beatriz,de la Iglesia, óscar,Rubio, César,Coronas, Joaquín,Téllez, Carlos
, p. 90 - 96 (2020/04/27)
Biomass has been shown as an alternative to fossil fuels for obtaining chemicals. In this work, the transformation of sugars into methyl lactate (ML) at 160 °C was carried out using the layered stannosilicate UZAR-S3 (University of Zaragoza-solid number 3) and the delaminated material UZAR-S4 (University of Zaragoza-solid number 4) obtained from its exfoliation. The exfoliation of UZAR-S3 to UZAR-S4 increased the accessibility of the compounds to the catalytic sites and the medium-strength acidity. Thus, the yield to ML for sucrose transformation increased from 8% for UZAR-S3 to 49.9 % for UZAR-S4. In the reusability tests, the UZAR-S4 catalyst was characterized before and after reaction by several techniques such as X-ray diffraction, thermogravimetry analysis, scanning electronic microscopy, energy dispersive X-ray spectroscopy and nitrogen adsorption. A deactivation of the catalyst was observed, which was related to carbonaceous deposits that decreased the specific surface area and the pore volume of the catalyst.