Room temperature efficacious synthesis of diphenylmethane over Fe/Al-MCM-41 catalysts

Fe3+‐Exchanged Titanate Nanotubes: A New Kind of Highly Active Heterogeneous Catalyst for Friedel‐Crafts Type Benzylation

“…In recent years, mesoporous silica materials emerged as ideal catalyst supports because of their high surface area, which have been considered to be favorable for the dispersion of Fe-containing sites [2,9,11,[18][19][20][21][22][23][24][25][26]. As expected, these Fe-containing mesoporous silica materials are very active for Friedel-Crafts type benzylation.…”

“…For example, it takes less than 10 min to reach complete BC conversion at 80 ∘ C, while it will cost about 30 min if the reaction temperature is 70 ∘ C. The lowered temperature not only results in the slow reaction rate but also produces obvious induction period, so that Fe-TNTs cannot provide any detectable BC conversion until the reaction is carried out over 5 min, 10 min, 20 min, and 25 min for 75 ∘ C, 70 ∘ C, 65 ∘ C, and 60 ∘ C, respectively. The phenomenon of induction period, which commonly exists in the heterogeneous catalysis of benzylation of benzene [7,17,21,22,[48][49][50][51], has been attributed to the moisture adsorbed on the catalytic sites that could delay the diffusion and activation of reaction substrates [16,52]. Ferric sites in Fe-TNTs are highly dispersed; thus it is not difficult to understand that these active sites are occupied by some moisture due to the hydrophilicity of Fe 3+ ions.…”

“…Even we increase [Fe 3+ ] to 3.36 mM; the benzylation of benzene still cannot be induced, which directly confirms that the catalytic activity indeed comes from heterogeneous catalytic sites rather than the leaching Fe 3+ . In previous literatures on heterogeneous catalysis for the benzylation of benzene, the decreased catalytic activity accompanied with the leaching of active sites was a general phenomenon, because HCl as the main by-product could facilitate the leaching process [2,[20][21][22]. Some reported catalysts seem to survive the leaching of active sites, where only several recycles were applied [9,11,54].…”

“…Vinu et al developed a method for the direct synthesis of Fe-containing SBA-15 that was rich in tetrahedrally coordinated Fe 3+ ions under weak acidic condition (pH ≈ 2.2), and the obtained catalysts showed superior catalytic performance and recyclability as compared to the Al-SBA-15 catalysts in the benzylation of benzene [18]; Sun et al and Lei et al loaded small Fe 2 O 3 nanoparticles into SBA-15 with the assistance of surfactants and chemical vapor infiltration, respectively, and these Fe 2 O 3 /SBA-15 catalysts could trigger the reaction between benzene and benzyl chloride even at relatively low temperature (60 ∘ C) [19,20]; Li et al reported a simple incipient wetness coimpregnation route to produce highly dispersed Fe(III) centers in SBA-15 by casting furfuryl alcohol solution of iron acetylacetonate, and the catalysts displayed extraordinarily high catalytic performance with a 100% yield of monoalkylated product even in 1.5 min at 60 ∘ C [2]; our group also fabricated a series of novel Fe-containing mesoporous materials (Fe-JLU-15s) by using semifluorinated surfactant as template, which were generally active for the benzylation of various aromatic compounds [11]. Although the significant enhancement has been achieved in these Fe-containing mesoporous silica materials, it is not easy to maintain their catalytic activities during the processes of recycling and regeneration, since amorphous nature of mesoporous silica will result in the collapse of structure and leaching of active sites [2,[20][21][22]. Therefore, it still remains a challenge to find new supports that can possess stable structure and anchor Fe-containing active sites.…”

A highly efficient catalyst for Suzuki–Miyaura coupling reaction of benzyl chloride under mild conditions

“…Diarylmethane derivatives are fundamental building blocks in organic synthesis and their preparation is an important industrial goal. They have been exploited to produce biologically active compounds, 1,2 polybenzyls 3,4 as well as building blocks in organic synthesis, [5][6][7] and usually can be obtained through the traditional electrophilic substitution reaction, i.e., Friedel-Cras reaction. But the weak reactivity of the aromatic compounds containing electron-withdrawing groups and the tendency of alkyl/aryl halides to rearrange seriously limit industrial applications.…”