Water → Salicylic Acid

Participants

Reaction Conditions

Reaction Steps

In a reactor equipped with a thermometer and a stirrer, 913 parts of methyl salicylate were charged, followed by heating to 100-110° C. At the same temperature, 525 parts of α,α'-dichloro-p-xylene were charged in portions over 5 hours. The resulting mixture was subjected to aging at 150° C. for 2 hours. The pressure of the reactor was reduced to 10 mmHg by a pump and unreacted methyl salicylate was separated for reuse at 150-180° C. After allowed to cool down to 100° C., 350 ml of toluene were added to the residue, whereby a toluene solution of a salicylic acid ester resin was obtained. In a reactor equipped with a thermometer and a stirrer, 160 parts of caustic soda and 907 parts of water were charged, followed by the dropwise addition of the above-obtained toluene solution at 85-90° C. over 4 hours. The temperature was raised to 100° C. so that the toluene was distilled off. After removal of insoluble matter, the residue was neutralized with 2,250 parts of an 8% aqueous solution of hydrochloric acid. The solid so precipitated was collected by filtration, washed with water and dried, whereby a salicylic acid resin was obtained in a yield of 705 parts. In a reactor equipped with a thermometer and a stirrer, 100 parts of the salicylic acid resin obtained above [composition (area %) according to a GPC analysis: 51.1% l=0, 22.3% l=1, 20.3% l=2, 4.3% l≥3, 1.0% others; number-average molecular weight: 543], 33.5 parts of benzyl chloride, 400 parts of 1,1,2-trichloroethane and 0.4 part of zinc chloride were charged, followed by reaction at 110° C. for 3 hours. After completion of the reaction, 1,000 parts of water were added and the 1,1,2-trichloroethane was azeotropically distilled off. The solid so precipitated was collected by filtration and dried, whereby 121 parts of an aralkylated salicylic acid resin were obtained. The resin was found to have a number-average molecular weight of 641 and a carboxylic acid equivalent of 251 g/eq.

Provenance & Evidence