Anisole diphenylmethane

Monodirectional 12 membered ring zeolites (offretite, L, mordenite and 0) are very inefficient as catalysts for formaldehyde benzene condensation to give diphenylmethane, esterification of phenylacetio acid with equimolar amounts of ethanol, Friedel-Crafts acylation of 3-phenylpropanoyl chloride with anisole and Claisen-Schmidt condensation of acetophenone with benzaldehyde. This fact has been attributed to diffusional constraints of organic compounds inside the channels. By contrast, the behaviour of the tridireotional f zeolite is very similar to that of dealuminated HY zeolites, inoreasing the turnover of the acid sites with the framework Si-to-Al ratio. 

Formylation of the less reactive phenol and anisole with CO in HF-BF3 was found to require at least stoichiometric amount of the acid for effective transformation (50 equiv. of HF, 2 equiv. of BF3, 50 bar CO, 45°C).445 Conversion increases with increasing reaction time but results in decreasing paralortho ratios suggesting a change from kinetic control to thermodynamic control and the reversibility of formylation. Furthermore, the amount of byproducts (mainly diphenylmethane derivatives) originating from reactions between substrates and products also increases. Additional studies in ionic liquids showed that imidazolium cations with increased chain lengths—for example, l-octyl-3-methylimidazolium salts—are effective in the formylation process. This was attributed to the enhanced solubility of CO in the ionic liquid medium. Tris(dichloromethyl)amine, triformamide, and tris (diformylamino)methane have recently been applied in the formylation of activated aromatic compounds in the presence of triflic acid at low temperature (— 10 to 20°C) albeit yields are moderate.446... 

Reductive Friedel-Crafts reaction Reaction of anisole with Ga2Cl4 (2 equiv.) and an aromatic aldehyde in CS2 at room temperature results in diphenylmethanes. Similar results obtain with ketones and aliphatic aldehydes. This reaction involves the reducing ability of GaCl and the Lewis acid activity of GaClj. 

Further support for this mechanism came from the results of studies in other solvents. Carrying out the cyclization in toluene led to the formation of diphenylmethane 4 as the major product, while in carbon tetrachloride, the formation of 1,4-dichlorobenzene 5 was observed. In methanol, benzene and some benzyl alcohol 6 were formed but, notably, no anisole was detected. These results could only be explained by the intermediacy of a free radical species 2a and clearly ruled out the possibility of a charged (polar) intermediate. ... 

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