METHOD FOR COMBINED PRODUCTION OF PYROCATECHIN, HYDROQUINONE AND CONCRETE PLASTICIZER Russian patent published in 1995 - IPC

FIELD: phenol hydroxylation. SUBSTANCE: method includes reaction of aqueous solutions of phenol, hydrogen peroxide in the presence of catalytic system consisting of water-soluble oxybenzene of formula 1 or dioxybenzene of formula 2, where R is H, NO₂, Cl, Br, SO₃H, SO₂ONa, alkyl C_nH_2n+1 with n= 1-5 or of their mixtures in combination with water-soluble salt of iron or metal taken from the series of Cu, Co, Os, Ru or their mixtures at mole of phenol-to-iron salt (or said metal of their mixtures-to-oxybenzene (or dioxybenzene or their mixtures) ratio of 1:2˙( 10^-5 ÷ 10^-3):3˙(10^-5÷ 10^-3). Process is conducted in packed column with supply of reagents and catalyst to column top. Phenol vapors and steam are returned in form of reflux to column at specific consumption of initial phenol 0.3-12 moles per square meter of column cross-section per hour and time of staying of reaction mass in column of 2-8 min. Reaction mass is withdrawn from the column bottom through hydroseal and mixed with filler selected from the definite group of compounds and with initial phenol-to-filler mass ratio of (30-50):1. Then, extraction is effected by organic solvent selected from the definite group. Aqueous layer after extraction in form of suspension is used as concrete plasticizer and organic layer is subjected to distillation with separation of solvent, phenol, pyrocatechin and hydrocatechin and hydroquinone and resin and compounds of formulas 1 and 2. EFFECT: higher efficiency. 5 cl, 5 tbl