O-Xylene → 2(3H)-Benzofuranone

Beteiligte Stoffe

Reaktionsschritte

To a solution of 262.3 g (1.00 mol) of 5,7-di-tert-butyl-3-hydroxy-3H-benzofuran-2-one (compound (201), Table 2, Example la) in 500 ml (4.05 mol) of o-xylene are added 40 g of Fulcat 22B and the mixture is refluxed for 1.5 hours on a water separator. The Fulcat 22B catalyst is then removed by filtration and excess p-xylene is removed by distillation on a vacuum rotary evaporator. Crystallisation of the residue from 500 ml of methanol yields 244 g (69%) of 3-(3,4-dimethylphenyl)-5,7-di-tert-butyl)-3H-benzofuran-2-one, m.p. 130-132° C. (compound (103), Table 1), which additionally contains c. 1.3% of the structural isomer [3-(2,3-dimethylphenyl)-5,7-di-tert-butyl-3H-benzofuran-2-one, compound (103A)]. The mother liquor yields a further 42.4 g of product which, according to GC-MS analysis, consists of 12.3% of the compound (103) and 87.7% of the isomeric compound (103A).

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