3,4,5-Trihydroxyflavone, also known as baicalein, is one of the flavonoids, which is mostly found in plants such as skullcap in nature. Its physical properties are as follows:
1. ** Appearance **: Under normal conditions, 3,4,5-trihydroxyflavone is yellow crystalline. The appearance of this color is derived from the conjugated system in its molecular structure, which absorbs and reflects light of specific wavelengths, resulting in its yellow appearance. This feature is often an important basis for identifying the compound.
2. ** Melting point **: about 264-265 ° C. As an inherent physical property of a substance, the melting point depends on intermolecular forces and lattice structure. There are hydrogen bonds and van der Waals forces between the molecules of 3,4,5-trihydroxyflavone. At a specific temperature, these forces are overcome, and the substance changes from solid to liquid. This temperature is the melting point. The melting point data can provide a reference for its purity identification and separation and purification.
3. ** Solubility **: Slightly soluble in water, soluble in organic solvents such as ethanol and acetone. Because the molecules of 3,4,5-trihydroxyflavone contain multiple hydroxyl groups and have a certain polarity, the whole molecule is still dominated by hydrophobic benzene rings and pyrone rings. Water is a strong polar solvent, so the solubility of this compound in water is limited; while organic solvents such as ethanol and acetone have moderate polarity, and can form hydrogen bonds or van der Waals forces between molecules of 3,4,5-trihydroxyflavone, so that it can be better dissolved. This solubility property is of great significance in the processes of extraction, separation and preparation.

3,4,5-Trihydroxybenzoic acid, also known as gallic acid, is a very important organic compound. It has the following chemical properties:
Looking at its acidity, this compound is acidic because it contains carboxyl groups and multiple hydroxyl groups. The carboxyl group can be dissociated from hydrogen ions in water, resulting in its acidic properties. In many chemical reactions, this acidity can be neutralized with bases to form corresponding salts and water. If reacted with sodium hydroxide, it can form sodium gallate and water.
The reactivity of its hydroxyl groups, the presence of multiple hydroxyl groups, allows the compound to participate in a variety of reactions. One is the esterification reaction, the hydroxyl group can be esterified with an alcohol under the catalysis of acid to form an ester compound. This reaction is often used in organic synthesis to prepare esters with specific functions, and has a wide range of uses in the fields of fragrance and drug synthesis. Second, the hydroxyl group is easily oxidized. Under the action of appropriate oxidizing agents, it can be converted into functional groups with higher oxidation states such as carbonyl or carboxyl groups. This oxidation reaction is of great significance in organic synthesis and the biosynthesis of some natural products.
As far as the characteristics of phenolic hydroxyl groups are concerned, the hydroxyl groups directly connected to the phenolic ring have the typical properties of phenolic hydroxyl groups. The hydrogen of phenolic hydroxyl groups has a certain acidity and can react with ferric chloride solution to produce a characteristic purple color. This reaction is often used as an important method for testing phenolic compounds. In addition, phenolic hydroxyl groups increase the electron cloud density of the benzene ring, making the benzene ring more prone to electrophilic substitution reactions, such as halogenation, nitration, etc. In the halogenation reaction, halogen atoms are easily introduced into the phenolic hydroxyl group ortho and para-position.
In addition, 3,4,5-trihydroxybenzoic acid can still dehydrate. Under appropriate conditions, intramolecular or intermolecular hydroxyl and carboxyl groups can be dehydrated to form compounds such as acid anhydrides or esters. This reaction is also an important means to construct specific structures in organic synthesis. In short, the diverse chemical properties of 3,4,5-trihydroxybenzoic acid make it widely used in many fields such as chemical industry, medicine, food, etc.

3,4,5-Trihydroxyflavone, that is, quercetin, its main uses are as follows:
First, in the field of medicine, it has significant pharmacological activity. Although the name of quercetin is not directly mentioned in many ancient books such as "Compendium of Materia Medica", many medicinal plants contain this ingredient. It has anti-inflammatory effects, can reduce the body's inflammatory response, just like a good doctor applying medicine, relieving the body's pain. It also has antioxidant functions, can remove free radicals in the body, such as guarding, protecting cells from oxidative damage, preventing aging and various diseases. It can also regulate cardiovascular function, lower blood pressure, blood lipids, stabilize heart rhythm, and maintain cardiovascular safety.
Second, in the food industry, it can be used as a natural antioxidant. Although there is no modern food industry in ancient times, it is known that certain antioxidants can keep food from being bad. Quercetin can prolong the shelf life of food, prevent oil rancidity, pigment oxidation, and protect the color, aroma, taste and nutrition of food. And it has a certain antibacterial effect, can inhibit the growth of harmful microorganisms in food, and increase food safety.
Third, in the field of cosmetics, it is favored for its antioxidant and anti-inflammatory properties. It can be added to skin care products to resist skin aging, reduce wrinkles and pigmentation, and make skin smooth and delicate. It can also slow down skin inflammation, suitable for sensitive skin, and protect skin health.
Fourth, in the field of scientific research, it is an important research object. Scholars study its pharmacological mechanism and physiological activity to explore more potential uses. Such as studying its action pathway on specific diseases to find clues for new drug development.

The synthesis method of 3,4,5-tribromobenzoic acid, although the ancient book "Tiangong Kaiwu" does not describe the synthesis of this substance in detail, it can be inferred by its ideas and ancient chemical wisdom.
First, it can be started from benzoic acid. In ancient methods, halogenated substances were often reacted with substrates in order to obtain halogenated substances. To produce 3,4,5-tribromobenzoic acid, benzoic acid can be placed in an appropriate solvent, such as oil refined from natural oils as a solvent, because natural oils can dissolve some organic matter and are relatively stable. Slowly adding bromine, however, bromine is active and the reaction is easy to get out of control. In ancient times, there was no modern accurate temperature control, and it could react slowly in a cool and ventilated place, using the temperature difference between day and night. At the same time, in order to precisely replace bromine at the 3, 4, and 5 positions, an appropriate amount of catalyst can be added. Ancient alum may be tried, and alum substances may be able to guide the substitution position of bromine.
Second, or start from its precursor compounds. If a suitable benzene ring derivative can be found, which has a group that can be converted into a carboxyl group, and other positions on the benzene ring are easier to introduce bromine atoms, it is also a method. For example, a benzene derivative with an alkyl group can be found first. The alkyl group can be oxidized by ancient methods, such as strong oxidizing substances such as saltpeter, under appropriate conditions. At the same time, using the positioning effect of alkyl groups, bromine atoms are first introduced into the appropriate position. After the introduction of bromine atoms is completed, the alkyl group can be oxidized to a carboxyl group. However, the oxidation process of saltpeter needs to be cautious, because the reaction is violent, easy to cause fire or explosion, the operation needs to be in an open place, and the dosage and reaction conditions are strictly controlled.
Or you can refer to the reaction of alkaline substances such as plant ash water in the ancient method. If a suitable intermediate can be found, it can react with bromide in an alkaline environment, or it can guide bromine atoms into the designated position, and then synthesize 3,4,5-tribromobenzoic acid. However, after the reaction, it needs to be purified by ancient methods such as recrystallization, assisted by some ingredients in plant ash water or natural mineral water, and crystallize many times to obtain a pure product.

3,4,5-Trihydroxyflavonoids are an important member of flavonoids. During storage and transportation, there are many things to pay attention to, as detailed below:
First, when storing, choose a dry, cool and well-ventilated place. This is because the substance is afraid of moisture. If the environment is humid, it is easy to absorb moisture, which in turn affects its quality and stability. If there is too much moisture absorption, it may cause chemical reactions, resulting in structural changes and reduced activity.
Second, temperature is also crucial. It should be avoided at high temperatures and should be stored in a low temperature environment. Under high temperatures, 3,4,5-trihydroxyflavonoids may accelerate decomposition, and their chemical properties are active. High temperatures can easily promote them to react with surrounding substances, resulting in a decrease in purity. Therefore, in general, refrigeration is appropriate, but care should be taken to avoid freezing and damage to its structure due to low temperature.
Third, light is also a factor that cannot be ignored. This substance is sensitive to light, and light may cause its photochemical reaction to change its chemical structure. Therefore, when storing, use opaque containers, such as brown glass bottles, or add light-shielding materials to the packaging to avoid direct light exposure.
Fourth, during transportation, shock resistance and collision resistance are extremely important. Because it is mostly solid powder or crystalline, if it is subject to violent vibration, collision, or changes in the degree of crushing, it will affect subsequent use. And the packaging needs to be firm to prevent damage to the packaging during transportation, contact with the external environment, and damage to quality.
Fifth, isolation from other substances should not be ignored. 3,4,5-trihydroxyflavones have special chemical properties or react with certain substances. When transporting and storing, do not mix with oxidants, acids, bases and other substances to avoid chemical reactions and damage to their quality.