Explanation of an unusual substituent effect in the benzylation of anisole and identification of the origin of the active site in Clayzic.

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

“…Although Friedel–Crafts reactions have been well studied and documented, Friedel–Crafts alkylation in the presence of MK10 impregnated with ZnCl 2 was of great interest for the scientific community because experimental results combined theoretical studies with clear practical applicability. From this perspective, some results obtained from clayzic‐catalyzed Friedel–Crafts alkylation were somewhat at odds with theory, such as 1) benzene is a catalyst in the benzylation of toluene, mesitylene, and p ‐xylene; 2) inversion of the relative reactivities of mesitylene and toluene, 3) benzyl alcohol is more reactive than benzyl chloride if they are mixed together, and results in inversion of the reactivities in the benzylation of anisole with mesitylene or toluene, respectively; and 4) inversion of the relative selectivities and reactivities of aryl halides . Interestingly, some studies have revealed important and significant characteristics of clayzic, which is obtained by MK10 modification through exchange of the interlamellar cations or through impregnation of metals.…”

Heterogeneous catalysis of organic reactions

“…19 Besides Brønsted acidic sites that pre-exist in the highly acidic K10 clay, impregnation supplies additional Lewis acidic sites (Zn II ) to the Fe III sites pre-existing also in the clay: a study belabored and confirmed this obvious fact. 34 This new catalyst, 'clayzic', was surprisingly efficient, as indicated above, in Friedel-Crafts alkylations. Thus it became of industrial interest as an environment friendly catalyst because it could be used in catalytic rather than stoichiometric amounts.…”

“…However, the existence of such porosity in the structure does not guarantee that it be relevant to reactivity, and the logical link has failed to be established. 34,39,45,46 Leaders and followers Breakthroughs are aptly named; they become quickly avenues of 'research.' Perhaps the greatest problem in science nowadays, tightly coupled with the bureaucratization of research funding and management (an activity that tends to be performed more and more by science dropouts without enough experience in many years of research at the leading edge), is the crowding out of creative research by imitative research.…”

Mg‐Fe‐hydrotalcite as catalyst for the benzylation of benzene and other aromatics by benzyl chloride reactions

“…[1 -3] The new environmental legislation pushes for the replacement of all liquid acids by solid acid catalysts which are environmentally more friendly catalysts and which lead to minimal pollution and waste. [4,5] Indeed, several solid acid catalysts have already been proposed which are efficient catalysts such as: Fe-modified ZSM-5 and H-β zeolites; Fe 2 O 3 or FeCl 3 deposited on micro-, meso-and macroporous [6] ; Fe-containing mesoporous molecular sieves materials [7,8] ; Fe-, Zn-, Ga-and In-modified ZSM-5 type zeolite catalysts [9] ; Ga-SBA-15 [10] ; InCl 3 , GaCl 3 , FeCl 3 and ZnCl 2 supported on clays and Si-MCM-41 [11] ; transition metal chloride-supported mesoporous SBA-15 [12] ; Sb supporting K10 [13] ; solid superacid and silica-supported polytrifluoro-methanesulfosil oxane [14] ; H 2 SO 4 , HNO 3 and HClO 4 /metakaolinite [15] ; alkali metal salts and ammonium salts of keggin-type heteropolyacids [16] ; ionexchanged clays [17] ; clayzic [18] ; solid superacids based on sulfated ZrO 2 [19] ; HY [20] ; Fe, Ce, W-modified Hβ zeolites [21] ; H-ZSM-5 [22] and FeCl 3 , MnCl 2 , CoCl 2 , NiCl 2 , CuCl 2 , ZnCl 2 supported on acidic alumina [23] for the benzylation of benzene and other aromatic compounds. However, the reports on the use of basic catalysts for the benzylation reactions are scarce.…”