3-Bromo-4-chloropyridine

3-3-4-4-4. Its main use is for food, cooking, and other things.
In the process of serving food, it is essential to taste the most important things. "Shang Xiao · Under the Order" said: "If you make a soup, it is only plum." Yan Hua and the soup, it is a must-use flavor for plum. When people eat, the taste is chewed together, and the dishes lose their delicious taste. And it can be improved, so that the essence of the ingredients is more obvious. It can also be used for food, such as meat and vegetables, to help food to be stored for a long time without spoilage.
When it is used for food, it also has a similar effect. " "Divine Materia Medica", "The main ghost is evil and poisonous, the lower part hides the body, and the muscles and bones". It can be used in the field for a long time. Gargle with water, it can clear the mouth, prevent the body, and relieve the pain of the throat. External application can eliminate the blood stasis and dissipate blood stasis, and it is also effective in some skin diseases.
In terms of workmanship, the use is good. In the manufacture of ceramics, it can be used as a melting aid, reducing the degree of ceramic formation, making the billet denser and harder, and the glaze surface is smooth. In tanning, soaking the raw skin in water can prevent corrosion and facilitate the tanning process. Dyeing can be used as a dye promoter, and the dye can be better adsorbed on the material, so that the dyeing is firm.
Therefore, 3 - 4 - is essential for food, food, and labor, all of which are essential for people's livelihood.

There are several common methods for the synthesis of 3-bromo-4-fluorotoluene:
One is the nucleophilic substitution of halogenated aromatics. Using p-fluorobromobenzene as the starting material, in the presence of suitable bases and catalysts, nucleophilic substitution reactions occur with methylating reagents such as iodomethane. This reaction condition needs to be precisely controlled. The strength of the base, the type and dosage of the catalyst will affect the process and yield of the reaction. If the strength of the base is too strong, it may initiate side reactions and reduce the purity of the product; if the amount of catalyst is not appropriate, the reaction rate will be slowed down or the yield will be poor. < Br >
The second is to take aromatic hydrocarbons as the starting material and undergo selective halogenation and methylation steps. First, toluene is selectively brominated and fluorinated. During bromination, suitable brominating reagents and catalysts can be selected to selectively replace hydrogen atoms at specific positions on the toluene-benzene ring under specific reaction conditions. Then a fluorination reaction is carried out to introduce fluorine atoms. The key to this process is to control the selectivity of the halogenation reaction. Due to the different activities of hydrogen atoms at different positions on the toluene-benzene ring, it is necessary to select suitable reaction conditions and reagents to promote the main substitution of halogen atoms in the target position.
The third is through the Grignard reagent method. Grignard reagents containing bromine or fluorine halogenated aromatics are prepared first. For example, Grignard reagents are prepared by reacting p-bromofluorobenzene with magnesium in anhydrous ether or tetrahydrofuran solvents. After that, the Grignard reagent reacts with suitable methylating reagents, such as methyl halide or methyl borate, to form a carbon-carbon bond and achieve the synthesis of 3-bromo-4-fluorotoluene. In this method, the preparation of Grignard reagents needs to be carried out in an anhydrous and oxygen-free environment, otherwise the Grignard reagents are prone to react with water or oxygen, resulting in the failure of the reaction. And the choice and dosage of methylating reagents also have a significant impact on the formation and purity of the product.

3-C-4-C is a common metal, and its materiality has its own characteristics.
It has excellent performance. Since ancient times, people have observed these characteristics, so it is used in manufacturing. Because it can make the flow flow and reduce the consumption of energy, it is an indispensable thing in today's power system and children. And its performance is also good, it is often used in manufacturing tools, which can make all tools be used, so that food can be cooked properly. There is also a beautiful golden light, which is purple in color, and has been placed in the air for a long time. This is also one of its characteristics. In addition, the malleability is very good, and it can be easily drawn into thin sheets or thin sheets, which is easy to be used as various fine utensils.
, the density is low, and the density is low. This characteristic makes it widely used in the aerospace field, which can effectively reduce the weight of the mobile device and improve the performance of the mobile device. It also has good corrosion resistance, and its surface is easy to form a dense oxide film, which can prevent the first step of the mobile device from being oxidized and rotted, so it is often used for windows, building materials, etc., which can be durable. The performance of the mobile phone is a little bit low, but it is also good, and the cost is low. Therefore, for some combinations with high cost requirements, it is also often replaced by mobile phones, such as high cost. In addition, its ductility is also excellent, and it can be used as a foil for food packaging, etc., which is both convenient and raw.
Of course, 3-4-4-3 physical reasons are different, and they play an important role in different fields, which is a great convenience for people's life.

There are three or four kinds of tools today, and what is the market value of them? This is a matter that the world does not care about. The three kinds of tools are clever, while the four kinds of products are slightly heavier.
And the market value depends on a number of factors. First, the materials used are of paramount importance. If it is made with fine gold, and the work of the moulding is exquisite, it will be high. If it is made of red, it will be of good quality, and it will be of good quality.
Second, the work of its work also affects the quality. If it is made, the flowers are exquisite, the characters are clear, and the shape is exquisite. If it is engraved with auspicious and rui, and the seal is printed with exquisite characters, the person who can be introduced will be green, and the price will also be high.
Third, the supply and demand of the market cannot be ignored. If it is low, the world needs three kinds of tools, and there are few makers, the supply will not be high, and the price will rise; on the contrary, if the four kinds of tools are made too much, but the number of seekers is small, the price will fall.
Furthermore, the difference in region also has an impact. For a certain type of product, the three kinds of tools are used by the people, and the price is high; for others, the four kinds of tools are more respected, and the price will be high.
Therefore, the three-to-four-to-one tool market cannot be generalized, and it is necessary to consider material, work, supply and demand, and regional factors in order to know the general situation.

3 - 4 - In the process of storage and storage, there are many things to be paid attention to. The first thing to be noticed is the high flammability of the gas. Air mixing can form explosive mixtures, which are easy to ignite and explode in case of open fire and high temperature. Therefore, if there is no storage space, it must be prohibited from burning, and it needs to be equipped with perfect fire fighting equipment and emergency equipment.
Furthermore, the density of the gas is less than that of the air, and it is easy to escape. Therefore, the storage containers and pipes have good tightness to prevent leakage. It is very important to conduct regular close inspections of containers and pipes to check for possible leakage problems such as breakage and cracking.
In addition, due to the chemical activity, it is necessary to avoid the connection of incompatible substances such as oxidation. If not, it may cause the reaction of the strong, and it will become dangerous.
In terms of the storage environment, the storage environment is good and difficult. Avoid direct light exposure and high temperature, because high temperature may cause the pressure of the container to rise, increasing the explosion. During the process, it is also necessary to prevent the container from being shocked and hit, so as not to cause the container to break.
The same angle, the operator needs to be well-trained, familiar with the dangerous characteristics and emergency measures of the container. In the whole storage and storage process, the grid follows the safety operation procedures, and must not be negligent, so as to ensure the safety of storage.