METHOD OF COMBINED SYNTHESIS OF PYROCATECHOL AND HYDROQUINONE Russian patent published in 1995 - IPC

FIELD: chemical technology. SUBSTANCE: pyrocatechol and hydroquinone were synthesized by interaction of phenol with hydrogen peroxide aqueous solution in the presence of catalyst at 40-102 C in packed apparatus of column type. Reagent direct flow is carried out in freely draining film of reaction mass and countercurrent of aqueous-phenolic vapors with complete condensation of vapors and their recovery into column in the form of phlegm. Molar ratio of phenol:hydrogen peroxide:ferrous (II) sulfate = 1:(0.4-1.5): (2.7 x 10^-4-2.8 x 10^-3). Catalyst is prepared preliminary by mixing of ferrous sulfate, phenol, pyrocatechol, hydroquinone and water at 20-40 C for 10-90 min at the molar ratio of ferrous sulfate:phenol:pyrocatechol:hydroquinone: water = 1:(1-5):(0.02-1.0):(0.01-1):(500-1500). Process is carried out in atmosphere of carbon dioxide at the molar ratio phenol:CO₂ = 1: (0.1-1.0). EFFECT: improved method of synthesis. 2 tbl