3,4-dihydroxybenzoic acid is not only a kind of phenolic acids, but also a metabolite of polyphenols, which is widely used in medicine, health care products, cosmetics and other industries.
3,4-dihydroxybenzoic acid can be extracted in a variety of ways, such as from the leaves of syringa. The method is divided into raw material pretreatment and extraction. It is necessary to dry syringa first, remove seeds and other impurities after selective selection, and crush the remaining part to get fine powder.
The above-mentioned fine powder is crushed to 70 mesh sieve, 2 grams as raw material, under certain technological conditions, anhydrous ethanol is used as the extraction agent for extraction, the extraction solution is obtained, after filtration, the residue is removed, and then ethanol is recycled, 3,4-dihydroxybenzoic acid can be obtained.
To refine 3,4-dihydroxybenzoic acid, a few more operations are required. Add 50mL ethanol and 3ml 0.1mol/L hydrochloric acid to crude protocatechuic acid, gently shake them to dissolve together, then put them into a clean separating funnel, extract with 0.1mol/L sodium hydroxide solution, operate 3 times, extract 50mL each time, and extract with 10ml ether, then wash with sodium hydroxide solution. After the ether solution is combined, the pH value is adjusted to 6, and then evaporative drying is carried out to obtain white powder crystal — refined 3,4-dihydroxybenzoic acid.