2,5-Dibromopyrazine

2% 2C5-dihydroxybenzoic acid has a wide range of main uses. In the field of medicine, it can be used as a raw material for drug synthesis. For example, in the development of some anti-inflammatory and antibacterial drugs, due to its special chemical structure, it can participate in key reaction steps, help to construct a molecular structure with specific pharmacological activity, and then improve the efficacy of drugs.
In the chemical industry, it is an important organic synthesis intermediate. It can be used to synthesize various fine chemicals, such as high-quality dyes. Using its structural characteristics and specific chemical reactions, it can produce dyes with bright color and good stability to meet the needs of textile, printing and dyeing industries.
In the food industry, 2% 2C5-dihydroxybenzoic acid has potential applications. It has certain antioxidant properties and can be used as a food antioxidant to delay the oxidative deterioration of food, prolong the shelf life, and ensure food quality and safety.
In agriculture, it can be used to synthesize plant growth regulators. With its regulation effect on plant physiological activities, it affects plant growth, development, flowering, fruit and other processes, and improves crop yield and quality.
Although "Tiangong Kaiwu" does not directly mention 2% 2C5-dihydroxybenzoic acid, the use of such substances is related to the needs of people's livelihood. Medicine is related to people's health, chemical products facilitate life, food additives protect the quality of food, and agricultural regulators increase the production of grains. All are used in the world to benefit the livelihood of all people.

2% 2C5-dibromohexane, an organic compound. Its physical properties are as follows:
It is a colorless to light yellow transparent liquid with a special odor. This odor originates from the presence of bromine atoms in its molecular structure, which stimulates the olfactory nerve. At room temperature and pressure, its state is liquid. Due to the moderate intermolecular force, it is not enough to solidify it into a solid state, nor can it be vaporized.
Its density is greater than that of water, about 1.68 g/cm ³. When mixed with water, it will sink to the bottom. This is due to the relatively large weight of dibromohexane molecules, which are closely arranged and have a higher mass per unit volume than water.
Dibromohexane is insoluble in water because it is a non-polar molecule, while water is a polar molecule. According to the principle of "similarity and miscibility", the polarity difference between the two is large, and the force on each other is weak, so it is difficult to dissolve. However, it is soluble in a variety of organic solvents, such as ethanol, ether, chloroform, etc. Because these organic solvents are mostly non-polar or weakly polar, they match the intermolecular force of dibromohexane and can be miscible. The boiling point of
dibromohexane is about 218-220 ° C. Due to the existence of van der Waals forces between molecules, and the bromine atom enhances the polarity of the molecule. The van der Waals force increases, and a higher temperature is required to provide energy to overcome the intermolecular force and The melting point is about -55 degrees Celsius, and the thermal motion of the molecules weakens at low temperatures. When the temperature drops below the melting point, the molecules are arranged in an orderly manner and solidify into a solid state.

2% 2C5-dibromo-p-xylene is an organic compound. It has unique properties and is widely used in the chemical industry.
In terms of physical properties, 2% 2C5-dibromo-p-xylene is mostly white to pale yellow crystalline at room temperature, with a fixed melting point of about 86-88 degrees Celsius. This substance is insoluble in water, but easily soluble in common organic solvents such as ethanol, ether, and chloroform. This solubility characteristic is closely related to its molecular structure. Because its molecule contains hydrophobic benzene ring and methyl group, it is insoluble in polar solvent water, but easily soluble in non-polar or weakly polar organic solvents.
In terms of chemical properties, the bromine atoms in 2% 2C5-dibromo-p-xylene are extremely active. First, nucleophilic substitution reactions can occur. When encountering nucleophilic reagents, bromine atoms are easily replaced by nucleophilic reagents, such as co-heating with sodium hydroxide aqueous solution, bromine atoms can be replaced by hydroxyl groups to generate corresponding alcohol compounds; when reacting with ammonia or amine substances, nitrogen-containing derivatives can be formed. Second, this substance can also participate in the elimination reaction. Under the action of strong bases, bromine atoms and hydrogen atoms on adjacent carbon atoms can debrominate hydrogen, forming carbon-carbon double bonds, and then forming unsaturated compounds. Third, due to the presence of the benzene ring, 2% 2C5-dibromo-p-xylene can undergo a substitution reaction on the benzene ring. For example, under the action of a catalyst, halogenation reactions on the benzene ring can occur with halogens such as bromine and chlorine, and nitrification and sulfuric acid can also occur.
2% 2C5-dibromo-p-xylene has active chemical properties and is often used as an intermediate in organic synthesis for the preparation of fine chemicals such as drugs, pesticides, and dyes. However, it should be noted that it contains bromine atoms, and some reactions may produce toxic and harmful by-products. When operating, norms should be followed to ensure safety.

There are several common methods for the synthesis of 2% 2C5-dibromohexane:
First, hexene is used as a raw material to obtain it by addition reaction with bromine. Hexene has a carbon-carbon double bond and is chemically active. The bromine atom in bromine can undergo electrophilic addition with the double bond. The chemical reaction formula is: $CH_3CH_2CH = CHCH_2CH_3 + Br_2\ longrightarrow CH_3CH_2CHBrCHBrCH_2CH_3 $. The reaction conditions are mild. Under normal temperature and pressure, an organic solvent such as carbon tetrachloride can be used as a medium to proceed smoothly, and the yield is quite high.
Second, starting from hexanol, hexanol is first converted into halohexane, and then hexene is obtained by elimination reaction, and finally added with bromine. Specifically, hexanol and hydrobromic acid under the catalysis of sulfuric acid underwent a substitution reaction to generate halogenated hexane, such as $CH_3 (CH_2) _4CH_2OH + HBr\ stackrel {H_2SO_4} {\ longrightarrow} CH_3 (CH_2) _4CH_2Br + H_2O $. The obtained halogenated hexane was eliminated under the action of a strong base (such as potassium hydroxide ethanol solution) to form hexene, $CH_3 (CH_2) _4CH_2Br + KOH\ stackrel {C_2H_5OH} {\ longrightarrow CH_3CH_2CH} = CHCH_2CH_3 + KBr + H_2O $. Finally, hexene and bromine were added to obtain 2% 2C5-dibromohexane. There are more steps in this pathway, but the raw material hexanol is more common and easy to obtain.
Third, take 1% 2C5-dibromopentane as the starting material, make Grignard reagent with metal magnesium, then react with halomethane to grow the carbon chain, and finally obtain the target product through reduction and other steps. 1% 2C5-dibromopentane reacts with magnesium in anhydrous ether to form Grignard reagent $Br (CH_2) _5MgBr $, and then reacts with halomethane (such as iodomethane), $Br (CH_2) _5MgBr + CH_3I\ longrightarrow CH_3 (CH_2) _5Br + MgBrI $. Subsequent by appropriate reduction means, 2% 2C5-dibromopentane can be prepared. Although this method is more complicated, it is also an effective synthesis path under specific conditions.

The price of 2% 2C5-dihydroxybenzoic acid in the market often varies depending on quality, quantity, supply and demand.
The price is slightly lower if it is of high quality and wide quantity. If it is an ordinary commercial product, the price per gram may be between a few corners and a few yuan. If you want a fine and high-purity sample, the price will be high, or tens of yuan per gram, or even more than a hundred.
Common in the city, according to its purity and packaging, the price is also poor. Simple packaging, those with a little less purity, the price is more affordable; sealed fine packaging, high purity goods, the price will jump.
Also, the purchase quantity also depends on the price. If you buy in bulk, you can often get a good price, and the cost will be diluted due to the increase in quantity. If you only take a little trial, the price may be higher.
And the trend of supply and demand is greatly affected by the price. There are many applicants and few suppliers, and the price will rise; if supply exceeds demand, the price will be reduced. Therefore, the price is not fixed, and it often fluctuates between a few cents per gram and a hundred yuan per gram. If you want to know the exact price, you need to carefully observe the market conditions and the actual situation of the goods.