| 摘要 |
<p>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) Q3 PMomW12-mO40 or ii) Q3+v PMnVvO40, 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.</p> |
