From Conventional Lewis Acids to Heterogeneous Montmorillonite K10: Eco‐Friendly Plant‐Based Catalysts Used as Green Lewis Acids

Abstract

The concept of green chemistry began in the USA in the 1990s. Since the publication of the 12 principles of this concept, many reactions in organic chemistry have been developed, and chemical products have been synthesized under environmentally friendly conditions. Lewis acid mediated synthetic transformations are by far the most numerous and best studied. However, the use of certain Lewis acids may cause risks to environmental and human health. This Review discusses the evolution of Lewis acid catalyzed reactions from a homogeneous liquid phase to the solid phase to yield the expected organic molecules under green, safe conditions. In particular, recent developments and applications of biosourced catalysts from plants are highlighted.

Direct Alkylation of Benzene at Lower Temperatures in the Liquid Phase: Catalysis by Montmorillonites as Noble‐Metal‐Free Solid Acids

“…Montmorillonite, a layered acidic clay, has recently received much attention as a solid acid catalyst for liquid‐phase organic syntheses . The unique acidity of montmorillonite affords much higher efficiencies for acid‐catalyzed carbon‐carbon/heteroatom bond‐forming reactions such as hydroalkylation and allylsilylation compared with other zeolites and inorganic/organic homogeneous acids at 100–180 °C . In this study, the direct alkylation of benzene using alkanes at 150 °C was carried out using cation‐exchanged montmorillonites as solid acid catalysts.…”

“…[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] The unique acidity of montmorillonite affords much higher efficiencies for acid-catalyzed carbon-carbon/ heteroatom bond-forming reactions such as hydroalkylation and allylsilylation compared with other zeolites and inorganic/ organic homogeneous acids at 100-180°C. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] In this study, the direct alkylation of benzene using alkanes at 150°C was carried out using cation-exchanged montmorillonites as solid acid catalysts. The layered structure of the proton-exchanged montmorillonite (H-mont) enabled control of the product selectivity by choosing alkylation of benzene or cracking of alkanes.…”

A Highly Effective Route to Si−O−Si Moieties through O‐Silylation of Silanols and Polyhedral Oligomeric Silsesquioxane Silanols with Disilazanes

“…[59] Therefore, it is highly desirable to reduce the amount of catalyst (or avoid its use), and to minimize waste generatedd uring the reaction. [60][61][62] Consequently,t he development of catalyst-free synthetic procedures has received significant interesti nr ecent times. [63][64][65][66][67][68][69][70][71][72] Important advantages of many of thesem ethods are their simplicity and efficiency.I np articular,r oom-temperature (RT) reactions are very attractive for potential further application.G iven all this, we focusedo nd eveloping the synthesis of organosilicon compoundsi nagreen chemistry manner.…”

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“…It used to be made from benzene using sulfuric acid and sodium hydroxide in a multi-stage process with 78% yield; the reaction can be expressed as: Sodium sulfite is the by-product, can be used in other processes. However, if it is not in demand, that would mean this may not be the most suitable reaction for manufacturing phenol 12,13 .…”