-
Categories
-
Pharmaceutical Intermediates
-
Active Pharmaceutical Ingredients
-
Food Additives
- Industrial Coatings
- Agrochemicals
- Dyes and Pigments
- Surfactant
- Flavors and Fragrances
- Chemical Reagents
- Catalyst and Auxiliary
- Natural Products
- Inorganic Chemistry
-
Organic Chemistry
-
Biochemical Engineering
- Analytical Chemistry
- Cosmetic Ingredient
-
Pharmaceutical Intermediates
Promotion
ECHEMI Mall
Wholesale
Weekly Price
Exhibition
News
-
Trade Service
Salicylic acid (salicylic acid), also known as 2-hydroxybenzoic acid (2-hydroxyl benzoic acid), salicylic acid , salicylic acid , Shali Xi acid, sprinkle acid, of the formula C .
7 H .
6 O .
3 , a molecular weight of 138.
1 , The structural formula is
1.
Product performance
White needle-like crystal or crystalline powder, with a spicy taste; melting point 158～161℃, boiling point 211℃ (2.
6664kPa), sublimation at 76℃; relative density (d 4 20 ) 1.
443; flammable; low toxicity; in air It is stable in medium, but gradually changes color when exposed to light; slightly soluble in water, soluble in acetone, turpentine, ethanol , ether , benzene and chloroform, its aqueous solution is acidic; it produces a special purple color with aqueous ferric chloride solution
.
2.
Production principle
After phenol and caustic soda form a salt, it undergoes carboxylation reaction with carbon dioxide , and then acidifies to obtain salicylic acid
.
3.
Process flow
4.
Technical formula (kg/t)
5.
Main equipment
Salt carboxylated gold, water separator, acid precipitation pot, sublimation kettle, condenser, cooling tower, centrifuge, refining kettle (stainless steel)
.
6.
Production process
(1) Salt formation and carboxylation
.
Put 100kg of phenol (98%) into the cast iron reactor and stir, add 86kg of 50% sodium hydroxide solution, and take samples after 0.
(2) Acid precipitation
.
Under stirring, add about 1000 kg of 7% to 8% sulfuric acid solution to the 50% sodium salicylate solution generated above to make the pH 1-2
(3) Sublimation
.
The crude salicylic acid is added to the sublimation tank, and the sublimation is carried out at 150～170℃/20×133.
(4) Refined
.
Put 60kg of sublimated salicylic acid, 360L of water, and 0.
36kg of phosphoric acid into a stainless steel refining tank in turn, stir and raise the temperature to 90°C, keep it for 1h, lower the temperature to 35°C, filter, and vacuum dry to obtain 58kg of salicylic acid
.
7.
Laboratory preparation method
Dissolve 47 g of phenol in 20.
5 g of NaOH and 30 mL of water in a nickel evaporating dish, and heat on an asbestos net to prepare powdered sodium phenate
.
Add the powdered sodium phenate to a 250mL three-necked bottle, heat the oil bath to 110°C, and start to pass in the CO 2 after being washed by the sulfuric acid bottle and the silica gel column .
The CO 2 tube should be directly connected to the surface of the sodium phenate
.
After ventilation for 1 hour, the temperature was gradually increased, and the temperature rose to 190°C within 4 hours
.
Heat at 200°C for another 2h
.
After the reaction product is cooled, it is dissolved by adding water, and then 1 g of activated carbon is added
.
Heat at 60°C for 15 min and then hot filter
.
Concentrated hydrochloric acid was added to the filtrate to precipitate salicylic acid
.
Crystallize in an ice-salt bath and filter with suction to obtain a crude product
.
Then recrystallize with water
.
The pure product has a melting point of 156°C
.
