The process of direct synthesis of salicylic acid from phenol catalyzed by K2CO3 in supercritical CO2 was studied. CO2 could act not only as a reagent but also as a solvent in this process. The conventional two-step synthesizing process of organic phenolic acid by Kolbe Schmitt reaction was improved, and the salicylic acid was synthesized by only one step. The influences of temperature (from 160 to 220℃), pressure (from 4 to 14 MPa), reaction time, amount of catalyst used were investigated. The highest salicylic acid yield could reach 54％, by-product is p-hydroxybenzoic acid of a very small amount, and selectivity is higher than 99％. The obtained optimum conditions of the reaction are as following: reaction temperature 190℃, reaction pressure 8 MPa, reaction time 3～5 h, amount of catalyst 10 mmol(n K2CO3/n phenol=l).%在超临界CO2中以K2CO3为催化剂,由苯酚一步直接合成了水杨酸.改进了传统的有机酚酸(Kolbe-Schmitt 反应)的两步法合成工艺.在CO2压力4～14 MPa、温度160～220℃,考察温度、压力、反应时间、催化剂用量等条件对水杨酸收率的影响.水杨酸最高得率接近54%,产物的选择性在99%以上,副产物有极少量对羟基苯甲酸.较为理想的反应条件为:反应温度190℃,反应压力8 MPa,反应时间3～5 h,催化剂用量10 mmol(nk2co3/n phenol=1).
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