The main uses of 1-mercury, 2,3-dibromo, and 5-pyridyl groups in the era covered by Tiangong Kaiwu are not as diverse and in-depth as in modern times, but there are also signs of their related applications.
Mercury, known as "mercury" in ancient times, was used for alchemy in ancient times. Taoist alchemists believed that through the refining of mercury and other substances, longevity elixirs could be obtained. In the era of Tiangong Kaiwu, although the wind of alchemy was not as prosperous as it was in the previous era, there were still magicians engaged in it. Second, mercury was used in the gilding process. That is, mercury and gold were made into gold amalgam, which was applied to the surface of the utensils, heated to evaporate the mercury, and the gold was attached to the utensils for the purpose of decoration and protection. This process was widely used in the production of ancient gold and silver utensils and the decoration of bronze ut
Dibromine related content, in the era of "Tiangong Kaiwu", bromine has not been systematically recognized and extracted, but bromine-containing compounds may exist in some natural substances, ancient people or inadvertently contact, such as some marine organisms containing bromine, coastal residents may be exposed to bromine-containing ingredients when eating or using related organisms, but there is no clear conscious use record.
Pyridyl, although there was no concept of pyridyl at that time, but pyridyl alkaloids were widely found in natural plants. Some plants have medicinal value because they contain such ingredients. In long-term medical practice, the ancients used pyridine-containing alkaloids to treat diseases, such as some plants that can repel insects, relieve pain, and treat gastrointestinal diseases. Although their pyridyl-containing structures are unknown, their medicinal effects can be used empirically.

1. ** Preparation of 1-bromo-2,3-diene-5-carbonyl indoles **:
- ** Selection of starting materials **: Indole compounds are often used as starting materials, because of their indole parent structure, which is an important basis for constructing target molecules. If indoles with suitable substituents are selected, their substituents on the benzene ring or pyrrole ring can affect the check point and selectivity of subsequent reactions.
- ** Bromination reaction **: Introduction of bromine atoms into indole derivatives. Liquid bromine can be used in the presence of suitable solvents and catalysts for the reaction. For example, in dichloromethane solvent, iron powder is used as a catalyst to control the reaction temperature at low temperature (such as 0-5 ° C), and liquid bromine is slowly added dropwise to selectively replace bromine atoms at the target position to form bromine-containing indole intermediates. This step requires attention to control the amount of bromine and the reaction temperature to avoid excessive bromination.
- ** Construction of diene structure **: For the construction of 2,3-diene structure, the Wittig reaction or the Horner-Wadsworth-Emmons reaction can be used. Taking the Wittig reaction as an example, a suitable phosphorus ylide reagent is prepared first, and a phosphorus-containing compound is reacted with a strong base (such as butyl lithium, etc.) at low temperature to form phosphorus ylide. Then it reacts with a carbonyl-containing indole intermediate in a suitable solvent (such as tetrahydrofuran), and under heated reflux conditions, a product with a 2,3-diene structure is formed. In this process, the preparation of phosphorus ylide and the control of reaction conditions are crucial for the formation of diene structures.
- ** Introduction of carbonyl **: The introduction of 5-carbonyl can be achieved by various methods. If an acylation reaction is used, select a suitable acylation reagent (such as acyl chloride or acid anhydride), react with the previously obtained indole intermediates containing diene and bromine in the presence of bases (such as pyridine, triethylamine, etc.), and introduce a carbonyl group at the 5 position of the indole to obtain 1-bromo-2,3-diene-5-carbonyl indole. In the reaction, the appropriate base and reaction temperature should be selected according to the activity of the acylation reagent and the reactivity of the substrate. The entire preparation process requires strict monitoring of each step of the reaction. The reaction process and product purity are determined by means of thin-layer chromatography (TLC) and nuclear magnetic resonance (NMR), and the products in each step are separated and purified, such as column chromatography, to obtain high-purity target products.

Mercury, commonly known as mercury, is a liquid metal, flowing silver at room temperature, with a metallic luster and a heavy weight. Its density is quite large, heavier than that of common things. It is volatile and can gradually turn into mercury vapor in the air. This gas is toxic. If people inhale too much, it may be harmful to health. Mercury can dissolve many metals and form amalgams. This property is useful in metallurgy and other techniques.
Dialum, that is, alum and alum. Alum, white in color, crystalline, astringent in nature. In the matter of purifying water, impurities in the water can settle and make the water clear. Green alum, green in color, also crystalline, used in dyeing and weaving. It is often used as a mordant to help dyes adhere to fabrics.
Naphthalene benzene, a chemical substance of later times, may not have been heard of in ancient times. However, in terms of physical properties, it must have specific chemical activities and physical properties. It may be a solid, with a certain melting point and boiling point. Or it has specific solubility, soluble in some organic solvents, or insoluble in polar solvents such as water. Its molecular structure may be aromatic, or it may have a special smell due to the presence of benzene rings and naphthalene groups. And because of its structure, or it has certain stability, and because of the existence of functional groups, or it can occur specific chemical reactions, such as substitution, addition, etc., it is useful in organic synthesis and other fields.

Mercury, carbon dioxide, acetylene, and cyanobenzene need to pay attention to many key matters during storage and transportation. The following are the key points for you:
Mercury is a liquid metal at room temperature, which is highly volatile and highly toxic. When storing, when placed in a sealed container to prevent the volatilization of mercury from escaping, the container should be strong and airtight to prevent leakage. The storage environment must be cool, dry and well ventilated, away from heat and fire sources, because mercury vapor is at risk of combustion and explosion when exposed to open flames and hot topics. When transporting, it is necessary to strictly follow the relevant regulations on the transportation of hazardous chemicals, use professional transportation vehicles, the vehicles should be equipped with leakage emergency treatment equipment, and the transportation personnel should also have professional knowledge and emergency treatment capabilities.
Carbon dioxide, although non-toxic, is a suffocating gas. When storing, cylinders must be placed in a cool and ventilated place, away from fire and heat sources, protected from direct sunlight, and stored separately from flammable and combustible materials. During transportation, ensure that the cylinder valve is tightly closed to prevent gas leakage, and at the same time pay attention to avoid cylinder collision and damage, resulting in a large number of gas leakage and danger.
Acetylene is a very flammable gas. Fireworks should be strictly prohibited in storage places, obvious safety warning signs should be set up, and fire-fighting equipment of the corresponding variety and quantity should be equipped. Storage containers must be grounded to prevent the accumulation of static electricity from causing fires. When transporting, vehicles should meet explosion-proof requirements, install fire arresters and other safety devices, and must not be mixed with oxidants, acids, etc.
Cyanobenzene is a toxic and harmful chemical. Storage should be placed in a cool and ventilated warehouse, away from fire and heat sources, and keep the container sealed. Do not mix with oxidants and edible chemicals. When transporting, the packaging should be intact and sealed to ensure that there is no leakage. Transportation vehicles should hang dangerous goods signs, be equipped with emergency rescue equipment and protective supplies. Transportation personnel should be familiar with the hazardous characteristics of cyanobenzene and emergency treatment methods.
During storage and transportation, these items need to be operated in strict accordance with regulations and pay attention to details to ensure safety.

There is a question today, what is the big problem in the market of 1-1,2,3-dihydrate and 5-aminobenzene? This is a matter of business and life. If you want to know how it works, you need to look at many reasons.
A person who is a husband, or a special thing that is used in a certain place, is determined by various factors. If the land is narrow, the amount is scarce, and the world needs it, it will be high. On the contrary, if the amount is abundant, and the need is few, it will be high.
As for 2,3-dihydrate, if this material is required for engineering and production, and it can be obtained by means of technical methods, or by means of special land benefits, it will also be expensive. If it is easy to provide, and the source is wide, it will be easy to produce.
5-aminobenzene may be of great use in the industrial and chemical industry. If the demand for research and development is surging, and the supply is fast, the price must be high. And if the chemical industry is prosperous, the need for this raw material can also make the grid wave.
However, if you want to know the best, you need to go to the market, find business and experts, and find their nearest market. Or take the test of business cooperation in various places, in order to obtain its approximation. In this way, the city is often floating, and it is often covered by a word, and it must be covered by the feelings below. Only by adding the school can we know the truth of 1-1, 2,3-dihydrate, and 5-aminobenzene.