Well-Dispersed Trifluoromethanesulfonic Acid-Treated Metal Oxide Nanoparticles Immobilized on Nitrogen-Doped Carbon as Catalysts for Friedel窶鼎rafts Acylation
Well-Dispersed Trifluoromethanesulfonic Acid-Treated Metal Oxide Nanoparticles Immobilized on Nitrogen-Doped Carbon as Catalysts for Friedel窶鼎rafts Acylation
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分散良好的三氟甲磺酸处理的金属氧化物纳米粒子固定在氮掺杂碳上作为弗里德尔筏酰化催化剂
DOI：
10.1002/asia.202001274
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
S.
中科院分区：
文献类型：
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作者：
Yang;X.;Yasukawa;T.;Maki;T.;Yamashita;Y.;Kobayashi;S.
尽管强酸处理的金属氧化物是用于各种有机转化的有用的非均相超强酸催化剂，但由于其表面积低，它们通常具有有限的酸性位点密度。在此，开发了非均相三氟甲磺酸固定氮掺杂碳包埋钛纳米颗粒（NP）催化剂，该催化剂由分散良好的小Ti NP（约7纳米）组成，而使用酸处理的金属氧化物很难实现这种催化剂。该催化剂在低钛负载量（2 mol%，对于 1 mmol 底物，<1 mg 金属）下表现出高弗里德尔-克来福特酰化活性。一系列微观、光谱和物理化学研究表明，氮掺杂碳固定了三氟甲磺酸，并且金属的添加进一步改变了酸性物质的性质并增强了催化活性。
Although strong acid‐treated metal oxides are useful heterogeneous superacid catalysts for various organic transformations, they usually have a limited density of acidic sites due to their low surface areas. Herein, heterogeneous trifluoromethanesulfonic acid immobilized nitrogen‐doped carbon‐incarcerated titanium nanoparticle (NP) catalysts have been developed that are composed of well‐dispersed, small Ti NPs (ca 7 nm) that are otherwise difficult to achieve using acid‐treated metal oxides. The catalysts showed high activity for Friedel–Crafts acylation with low titanium loading (2 mol%, <1 mg of metal for 1 mmol of substrate). A range of microscopic, spectroscopic and physicochemical studies revealed that the nitrogen‐doped carbon immobilized the trifluoromethanesulfonic acid and that the addition of metals further changed the nature of the acidic species and enhanced catalytic activity.