Study On Synthesis Of M-Aminophenol

As an important intermediate of medicine and organic material, m-aminophenol is widely used in the petrochemical industry, pesticide, medicine, printing and dyeing industry. Nevertheless, the synthesis processes of m-aminophenol have some disadvantages with harsh reaction condition and large discharge of waste, and high cost. Therefore, it is of significant practical significance to explore a synthesis process with mild condition, low discharge of waste and low cost.The use and market situation and many synthesis methods were summarized in this dissertation. A process route called selective diazotization of m-phenylenediamine was put forward, with mild condition, low discharge of waste and low cost. M-phenylenediamine was used as the regent. Firstly,3'-aminoacetanilide hydrochloride was prepared with the yield 92.5%, via salt formation of one amino of m-phenylenediamine and acetylation reaction of the other. And then m-aminophenol was prepared with the yield 70.5% via diazotization reaction and hydrolysis of diazonium salt.The optimum reaction conditions of synthesizing m-aminophenol via acetylation reaction, diazotization reaction and hydrolysis of diazonium salt were researched in the experiment. The optimum reaction conditions in the synthesis of 3'-aminoacetanilide hydrochloride are as following:The molar ratio of acetic anhydride and m-phenylenediamine is 1:1.1, the concentration of hydrochloride acid is 30%, and the temperature of the reaction is 40℃. In this step, 3'-aminoacetanilide hydrochloride is gained in the yield of 92.5%. The optimum reaction conditions of diazotization reaction are as following:the molar ratio of 3'-aminoacetanilide hydrochloride, sodium nitrite, and sulfuric acid is 1:1.1:3, and the diazotization reaction was carried out in 20% sulfuric acid at-10℃. The diazonium salt synthesized at this condition gave the highest yield (70.5%) of m-aminophenol in the following hydrolysis reaction, the total yield of the whole process is 65.2%, with the purity of 99.9%.