Salicylic Acid (CAS: 69-72-7, C7H6O3) is a fat-soluble organic acid with a white crystalline powder appearance, which exists in willow bark, white pearl leaves and sweet birch in nature , is an important fine chemical raw material, which can be used in the preparation of aspirin and other drugs.

Specific physical data

Properties: White needle-like crystals or monoclinic prisms, with a special phenolic sour taste. Stable in air, but gradually changes color when exposed to light

Relative density (g/mL, 20/4℃): 1.443

Relative vapor density (g/mL, air=1): 4.8

Melting point (ºC): 158~161

Boiling point (ºC, 2.67KPa): 210 (2666pa)

Refractive index (n20D): 1.565

Flash point (ºC): 157

Gas phase standard combustion heat (enthalpy) (kJ mol-1): -3117.2

Gas phase standard claimed heat (enthalpy) (kJ mol-1): -494.8

Vapor Pressure (114ºC): 1mmHg

Solubility: slightly soluble in cold water, easily soluble in hot water, ethanol, ether and acetone, soluble in hot benzene. 1g of this product can be dissolved in 460ml of water, 15ml of hot water, 2.7ml of alcohol, 3ml of acetone

Common synthetic methods

Phenol reacts with sodium hydroxide to generate sodium phenolate, after distillation and dehydration, carbon dioxide is passed through for carboxylation to obtain sodium salicylate, which is acidified with sulfuric acid to obtain crude product. The crude product is refined by sublimation to obtain the finished product.

Raw material consumption quota: phenol (98%) 704kg/t, caustic soda (95%) 417kg/t, sulfuric acid (95%) 500kg/t, carbon dioxide (99%) 467kg/t, the method is divided into atmospheric pressure method and medium pressure method Law. The synthetic reaction formula is as follows:

What is the relevant substance?

What is the relevant substance? Relevant substances refer to starting materials, intermediates, polymers, side reaction products, and degradation products during storage that are introduced in the production process. It can be seen from the above synthetic route that the relevant substances are mainly excess starting materials and by-products such as 4-hydroxybenzoic acid and 4-hydroxyisophthalic acid.

WiSys5000+ Xtimate®C18

When the Wisys5000 high performance liquid chromatograph independently developed by Welch Materials is combined with the Xtimate®C18, what kind of superb results will it show? Let’s witness together!

Instrument modelWelch WiSys5000
ColumnWelch Xtimate® C18 (4.6×250mm, 5μm)
Mobile phaseMethanol: Water: Glacial Acetic Acid = 60:40:1
Detection wavelength270nm
Flow rate1.0mL/min
Injection volume20μL
Retention timeAreaPeak heightUSP Theoretical PlatesUSP trailing
Retention timeAreaPeak heightUSP Theoretical PlatesUSP trailing

According to the detection method of salicylic acid related substances in ChP2020, the WiSys5000 and Xtimate®C18 chromatographic columns can show perfect detection results and meet the requirements of the Pharmacopoeia.

You thought it was over here? No No No, we have a side story. Laboratory safety has always been a commonplace but easily overlooked issue. Do not take risks. Let’s take a look at the MSDS of salicylic acid.

Extra: salicylic acid MSDS part information

Dangerous Goods Signs: Harmful.

Safety signs: S26 S39 S37/S39 S36.

Hazard identification: R22 R41 R36/37/38.

Hazard overview

Hazard Category: Harmful if swallowed, may cause eye damage.

Routes of entry: inhalation, ingestion.

Health hazards: The dust of this product is irritating to the respiratory tract, eyes, skin and gastrointestinal tract.

Environmental Hazards: Can cause pollution to water bodies and atmosphere.

Explosion Hazard: This product is flammable and irritating.

First aid measures

Skin contact: Take off contaminated clothing, rinse thoroughly with plenty of running water for at least 15 minutes, and seek medical attention in severe cases.

Eye contact: Immediately open the upper and lower eyelids, rinse with running water or normal saline for at least 15 minutes, seek medical attention in severe cases.

Inhalation: Move to fresh air quickly, keep the airway open, give oxygen when breathing is difficult, and seek medical attention in severe cases.

Ingestion: Give milk or egg white to drink, seek medical attention in severe cases.

Fire-fighting measures

Hazardous characteristics: In case of high heat, open flame or contact with oxidants, there is a danger of burning.

Hazardous combustion products: carbon monoxide, carbon dioxide.

Extinguishing method and extinguishing agent: water mist, foam, carbon dioxide, dry powder, sand.

Personal protection: Firefighters must wear gas masks and full-body fire-fighting suits to put out the fire in the upwind direction.

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