White Crystal 99.5% 1 MmHg Salicylic Crystal CAS No 69-72-7

White crystalline powder, odorless, slightly bitter before spicy. It exists in willow bark, white pearl leaves and sweet birch in nature. The chemical formula C6H4 (OH) (COOH), melting point 157-159 ℃, gradually changes color under light. Relative density 1.44. The boiling point is about 211 ℃ / 2.67kpa. Sublimation at 76 ℃. Under atmospheric pressure, it is rapidly heated and decomposed into phenol and carbon dioxide. Soluble in ethanol, ether, chloroform, benzene, acetone and turpentine chemicalbook oil, not soluble in water. 1g salicylic acid can be dissolved in 460ml water, 15ml boiling water, 2.7ml ethanol, 3ml acetone, 3ml ether, 42ml chloroform, 135ml benzene, 52ml turpentine, about 60ml glycerol and 80ml petroleum ether respectively. Adding sodium phosphate and borax can increase the solubility of salicylic acid in water. The pH value of salicylic acid aqueous solution is 2.4. Salicylic acid and ferric chloride aqueous solution form a special purple.

Salicylic acid is an important raw material for fine chemicals such as medicine, perfume, dye and rubber additives. In the pharmaceutical industry, salicylic acid itself is used as a disinfectant and antiseptic for local keratin hyperplasia and skin fungal infection. As a pharmaceutical intermediate, it is used for Zhitongling, diuretic urea Acetylsalicylic acid (aspirin), sodium salicylate, salicylamide, glibenclamide, niclosamide, phenyl salicylate, ethyl p-hydroxybenzoate, bismuth subsalicylate, sulfasalazine and other drugs. In the dye industry, it is used to produce chemicalbook to produce dyes such as direct yellow GR, direct sun resistant gray BL, direct sun resistant Brown RT, acid mordant Brown g and acid mordant Yellow GG. Various esters of salicylic acid They can be used as spices, such as methyl salicylate, oral spices for toothpaste, other spices and food spices. In the rubber industry, it is used in the production of anti coking agent, ultraviolet absorber and foaming additives. Salicylic acid can also be used as curing agent for phenolic resin, sizing preservative for textile printing and dyeing, expansion agent (dye promoter) for synthetic fiber dyeing, etc. 

The preparation method is obtained by carboxylation of phenol sodium salt with carbon dioxide and acidification. Phenol sodium salt solution is prepared from phenol and liquid caustic soda, dried in vacuum, and then dried carbon dioxide is slowly introduced at 100 ℃, when the pressure reaches 0.7 ~ 0.5 ℃ When the chemical pressure is 8Mpa, stop carbon dioxide and raise the temperature to 140 ~ 180 ℃. After the reaction, add clean water to dissolve the sodium salicylate, decolorize and filter, and then add sulfuric acid to acidify, that is, separate out the salicylic acid, and obtain the finished product after filtration, washing and drying.