Aluminium phenoxide, catalyst

A complication in the preparation of compounds having sec- and tert-alkyl groups in the 2- and in the 4-positions is their vulnerability to thermal dealkylation with acidic catalysts, particularly with 1% oleum in the range 160-200°C, and, as has been mentioned, to aluminium phenoxide when this is used at high temperature (ref.12). Indeed above 250°C all sec- and tert- groups are eliminated from alkylated phenols. The role of thermal dealkylation has been mentioned for the preparation of nonylphenol from dinonylphenol. In the case of 5-methyl-2,4-di-tert-butylphenol and 4-methyl-2,6-di-tert-butylphenol resulting from the tert-butylation of 3-methyl and 4-methylphenol mixtures, the former... 

Related mononuclear aluminium monophenoxides with a morpholine instead of a benzotriazole substituent were investigated by the group of Kerton, as shown in Scheme 18.48. With PPNCl as cocatalyst and styrene oxide as test substrate, the aluminium phenoxide produced styrene carbonate in 37% yield (24 h, 60 °C, 40 bar carbon dioxide, 0.2 mol% catalyst/ cocatalyst). 

Scheme 18.10 Aluminium (sulfonylamido)phenoxides as Lewis-acid catalysts.

---