Design of high-performance heterogeneous catalysts using hydrotalcite for selective organic transformations

• Published in: Green chemistry : an international journal and green chemistry resource : GC Vol. 21; no. 6; pp. 1361 - 1389
• Main Authors: Kaneda, Kiyotomi, Mizugaki, Tomoo
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2019
• Subjects: Anion exchanging; Anions; Basicity; Brucite; Catalysis; Catalysts; Cation exchanging; Economic conditions; Green chemistry; Interlayers; Learning; Liquid phases; Magnesium hydroxide; Phase transitions; Reagents; Solid surfaces; Substrates
• ISSN: 1463-9262; 1463-9270
• DOI: 10.1039/C8GC03391A

Hydrotalcite (HT) is an anionic layered double hydroxide clay, consisting of positively charged Brucite-like layers. To compensate for the positive charges, various inorganic and organic anions are located within the interlayer along with water. Hydrotalcite exhibits the characteristic cation-exchange features of the Brucite-like layer, the anion exchangeability of the interlayer, a memory effect, and tunable basicity and adsorption capacity. Based on these features, nanostructured metal species on HTs were prepared in a much simpler way than those previously reported; this provides a strong protocol for the preparation of catalytically active species with uniform composition that are evenly distributed on the solid surface. This review focuses on the design of high-performance heterogeneous catalysts using HT and HT-like compounds for selective molecular transformations under liquid-phase conditions. Catalytic systems that use HT offer significant benefits for achieving green organic syntheses because of the following: (i) they use nonpolluting reagents, (ii) they exhibit high catalytic activities and selectivities, (iii) they tolerate a wide range of substrates, and (iv) a simple work-up procedure facilitates easy catalyst recovery and reuse. Furthermore, highly atom-economical catalytic reactions, such as multiple reactions in a single pot, can be realized by using the novel HT-based catalysts.