Alkylation of Phenol: A Mechanistic View

DFT study of phenol alkylation with propylene on H-BEA in the absence and presence of water

Water reduces the activation barrier of the rate-limiting step of phenol alkylation with propylene in H-BEA. This, in turn, increases the transition-state theory rate coefficient by two orders-of-magnitude, suggesting much faster alkylation.

6,6′-{[Ethane-1,2-diylbis(azaneylylidene)]bis(methaneylylidene)}bis[2-(hexyloxy)phenolato] Nickel(II)

Polymeric nickel complexes of salen ligands meet a wide range of applications in catalysis and electrochemistry. Because these polymers usually form very rigid films, the introduction of the conformationally flexible fragments in the corresponding monomers favors the amorphization and, thus, the mass transport. Herein we report a preparation of the hexyloxy-substituted monomeric NiSalen complex by the direct alkylation of the hydroxy-substituted complex. The resulting product was characterized by the 1H and 13C nuclear magnetic resonance (NMR), ESI-high resolution mass spectrometry (ESI-HRMS, and Fourier-transform infrared spectroscopy (FTIR). The crystal structure of the product was examined by an XRD, indicating the formation of the solvate with dichloromethane. The obtained product was found to be highly soluble in non-polar solvents, in contrast to typical NiSalens.

Characterization of Sulfated SnO2-ZrO2 Catalysts and Their Catalytic Performance on the Tert-Butylation of Phenol

Understanding the catalytic behavior of sulfated metal oxides has been the topic of several research studies in the past few decades. Their apparent super-acidic behavior has been correlated with the molecular structure of the surface sulfate species. Herein, we couple FTIR and Raman spectroscopies to study the molecular structural evolution of surface sulfate species on mixed metal hydroxides as well as calcined oxides. We show that on the surface of hydroxides, monodentate and possibly bidentate species are dominant, while for SnO2-rich samples, clusters of polymeric sulfate species may also be present. After calcination, sulfate species bind strongly on the surface of mixed oxides, and different configurations can be seen with a range of S=O functionalities of varying strength. Through comparison of the catalytic performance of all sulfate oxides in the tert-butylation of phenol, it was found that SnO2-rich samples show high TBA conversion, with monoalkylated phenols as the primary product.