| 摘要 |
PCT No. PCT/GB92/00258 Sec. 371 Date Aug. 3, 1993 Sec. 102(e) Date Aug. 3, 1993 PCT Filed Feb. 13, 1992.Hydroxylation of phenol is prone to the production of tarry by-products. Selective hydroxylation of phenol can be obtained by reacting a limited amount of hydrogen peroxide with phenol in solution in a compatible organic solvent and in the presence of a catalyst that is at least partly soluble in the reaction medium and is the salt of a heteropolyacid of general formula: i) Q3PMomW12-mO40 or ii) Q3+vPMnVvO40, in which Q represents a compatible organic cation, m is zero or an integer less than 6, M represents molybdenum or tungsten, v is an integer which is up to 3, and n is an integer such that n+v=12. A preferred organic cation comprises cetyl pyridinium. Selectivity towards catechol is particularly observed employing heteropolyacid salts in which m=0 in formula i) and when n=11 and M=tungsten in formula ii) and towards hydroquinone when n=11 and M=molybdenum in formula ii). Preferably the reaction medium comprises acetonitrile. |
