Ethylbenzene → 5,7-di-tert-butyl-3-(3-ethylphenyl)-3H-benzofuran-2-one

Participants

Reaction Steps

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 1a) in 500 ml (4.08 mol) of ethyl benzene 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 ethyl benzene is removed by distillation on a vacuum rotary evaporator. GC-MS analysis shows the residue to consist of a mixture of 59.2% of the para-isomer (compound (105). Table 1), 10.8% of the meta-isomer (compound (105A) and 21.1% of the ortho-isomer(compound (105B). Crystallisation of the residue from 400 ml of methanol yields 163.8 g (47%) of 5,7-di-tert-butyl)-3-(4-ethylphenyl)-3H-benzofuran-2-one (compound (105), Table 1) (para-isomer), which additionally contains 5.6% of the meta-isomer 5,7-di-tert-butyl-3-(3-ethylphenyl)-3H-benzofuran-2-one (compound (105A) and 1.3% of the ortho-isomer 5,7-di-tert-butyl-3-(2-ethylphenyl)3H-benzofuran-2-one (compound (105B). Further crystallisation from methanol yields the almost pure para-isomer (compound (105), Table 1), m.p. 127-132° C.

Provenance & Evidence