Resorcinol is a colorless crystal in appearance, which turns red under the action of light and moist air. Specific gravity 1.28. Melting point 109 ~ 111 ℃. Boiling point 280 ~ 281 ℃. Soluble in water, ethanol and ether, slightly soluble in benzene, almost insoluble in chloroform. There are many synthetic routes for resorcinol products, and there are only two industrialized ones, namely benzene sulfonation alkali fusion method and m-dicumene oxidation method.
Resorcinol is an important organic chemical raw material, widely used in rubber adhesives, synthetic resins, dyes, preservatives, pharmaceuticals and analytical chemical reagents and photosensitive materials. Resorcinol products and formaldehyde form polycondensates, which are used in the manufacture of viscose yarns and tire cord adhesives; preparation of adhesives RS, RL, RE, RH, etc., used as sandpaper, gauze and wood processing adhesives, etc. . Resorcinol has a bactericidal effect and can be used as a preservative for cosmetics and dermatological drug adhesives and ointments. Resorcinol is also an intermediate of many dyes and medicines, such as important dye intermediates such as m-aminophenol, etc.; Resorcinol is also used in the production of benzophenone UV absorbers, such as UV-0, UV-531, UV-9 etc. In addition, resorcinol is often used as an additive in chemical plating of plastics such as ABS.
(1) Sulfonated alkali fusion method
Using benzene and fuming sulfuric acid as raw materials to react to generate isophthalic acid, neutralize it with sodium hydroxide to form sodium isophthalate, and then eutectic with sodium hydroxide to generate sodium resorcinate, which is finally acidified by hydrochloric acid to form isophthalate. Hydroquinone.
The benzene sulfonation method is a traditional method for the production of resorcinol, which is currently used in China, the United States and India. The production of resorcinol in this process requires a large amount of oleum, hydrochloric acid, and caustic soda, and produces a large amount of inorganic salts Na2SO3 and Na2SO4. The waste liquid treatment cost is high, and the pollution is relatively serious; at the same time, the yield of the benzene sulfonation alkali fusion method is low, The yield of manufacturers is usually only 60%-70%. In the aspect of benzene sulfonation process, some researchers have carried out a lot of research, and have carried out fruitful improvements to multiple unit operations, and some have been industrialized and achieved good results.
(2) m-dicumene oxidation method
Meta-dicumene is oxidized to dicumyl dihydroperoxide, which is then decomposed under acidic conditions to generate resorcinol and by-product acetone. This method is a new process developed abroad in the mid-1980s. It is similar to the process of preparing phenol and acetone by oxidation of cumene. It has little environmental pollution, compact process, and is convenient for continuous production. It represents the development direction of resorcinol synthesis technology.
At present, the production capacity of the sulfonated alkali fusion method and the m-dicumene oxidation method is similar. From the perspective of environmental protection and development prospects, the m-dicumene oxidation method has obvious advantages. The sulfonation method has a lengthy process flow, many three wastes, and the yield is only about 60%-70%; while the m-dicumyl benzene oxidation method has a high yield, a good degree of automatic control, and is easy to continuous large-scale production. The discharge of the three wastes is very small. According to reports, the oxidation method is compared with the sulfonation method to produce 1t of resorcinol, and the oxidation method reduces the discharge amount compared with the sulfonation method. Moreover, on the premise that the raw materials and technology are guaranteed, the production cost of the oxidation method is also significantly lower than that of the traditional sulfonation method.
