Methylation of phenol to 2,6-dimethylphenol on a manganese oxide catalyst

Kinetics of the alkylation of phenol with methanol over catalysts derived from hydrotalcite-like anionic clays

“…Ea for phenol conversion calculated in the present study varies in the same range (30-130 kJ tool ~) as those reported over manganese oxide (115.0 kJ mol "~) [8], anion loaded A1PO4 (20-60 kJ mol -l) [9] and H-ZSM 5 zeolite (50-70 kJ mol "1) [10], indicating the validity of the model assumed for the evaluation of kinetic data. It has been shown by several authors that a good correlation exists between Ea and In A for a single reaction taking place over different catalysts or different reactions taking place over one catalyst [11][12][13].…”

The transformations involving methanol in the acid- and base-catalyzed gas-phase methylation of phenol

“…Various solutions have been proposed to minimize this side reaction (see, for example, [48]), amongst which the cofeeding of water seems to be the most effective [45,49]. This aspect, however, is often forgotten in scientific literature, and only few papers take into consideration the methanol decomposition [19,34,[51][52][53] and the transformations that occur on the alkylating alcohol. On the other hand, a wide literature demonstrates that methanol undergoes different transformations on metal oxides, depending on the catalyst surface properties [13,54,55].…”

A cascade mechanism for a simple reaction: The gas-phase methylation of phenol with methanol

“…The gas-phase methylation of phenol with methanol is one of the first examples of a "green reaction" applied to industry, in which an electrophilic substitution on an aromatic ring was carried out by using an alcohol. In fact, these types of reaction are typically triggered using reactants which co-produce inorganic salts, such as dimethylsulphate or methylchloride [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Even though this reaction is described in encyclopaedias as a classical SEAr alkylating Friedel-Crafts reaction in which the reactive species is a CH3 + species, formed by the protonation of methanol by the H + released from phenol [16], we demonstrated in several previous papers that the true reactive species is formaldehyde, generated by the in-situ dehydrogenation of methanol [17][18][19][20][21][22][23].…”