pyridine, 3-chloro-2,5-difluoro-

"Mercury, commonly known as mercury, has properties like water and flows like silver. Mercury bisvalent compounds have different properties.
Mercury, the normal state is liquid metal, silver light flickers and does not flow. It is like smart water, but has a metallic luster, which is its unique physical properties. Its melting point is extremely low, only -38.87 ° C, so it is a flowing liquid at room temperature, easy to pour and transfer. And the density of mercury is quite high, about 13.59 g/cm ³, much higher than that of common liquids, and it feels heavy.
As for mercury bisvalent compounds, take mercury chloride as an example, mercury chloride, white crystalline powder, highly toxic. It has a certain solubility in water, and its aqueous solution is corrosive. This compound is chemically active and can react with many metals to replace other metals from its salt solution, highlighting the oxidizing properties of mercury ions.
It also has mercury oxide, red or yellow powder. When heated, mercury oxide is easy to decompose, releasing oxygen, and reducing itself to mercury elemental substance, which is one of the important ways to obtain mercury. Its chemical properties are also active, and it can participate in a variety of chemical reactions. It is widely used in the field of chemical preparation.
Mercury and its divalent compounds have been used in ancient alchemy, medicine and industry due to their unique physical and chemical properties. However, mercury and its compounds are many toxic. When using them, it should be used with extreme caution and must not be negligent, causing harm to be invisible.

Mercury is one of the chemical elements, with the symbol Hg. It has many unique chemical properties.
Mercury is liquid at room temperature, and it is the only liquid metal. This property is particularly strange. Its chemical properties are relatively stable. Under normal conditions, it is not easy to react with oxygen. However, when heated, mercury will combine with oxygen to form mercury oxide.
In addition, mercury can react with sulfur. Once the two come into contact, they quickly combine to form mercury sulfide. This reaction is very useful when dealing with mercury leaks. It can be used to cover mercury droplets with sulfur powder to convert mercury into relatively stable mercury sulfide to avoid mercury volatilization and harm to the environment and people.
Mercury can also react with nitric acid. When mercury meets concentrated nitric acid, it will react violently to form mercury nitrate, nitrogen dioxide and water; if it reacts with dilute nitric acid, it will form mercury nitrate, nitric oxide and water.
In the order of metal activity, mercury is located after hydrogen, so it cannot replace hydrogen from the acid solution. However, mercury can react with some metal salt solutions, such as with silver nitrate solution, mercury can replace silver from the silver nitrate solution and convert itself into a mercury nitrate solution.
Mercury was often used in ancient times in fields such as alchemy due to its special chemical properties, but its toxicity should not be underestimated. When using and handling, extreme caution is required.

"Tiangong Kaiwu" is a scientific and technological masterpiece written by Song Yingxing in the Ming Dynasty, in which mercury (mercury) and mercury disulfide (cinnabar) are described. Mercury, often called mercury, is a liquid metal with unique properties. Mercury disulfide, or cinnabar, is a common sulfide mineral.
In ancient times, mercury and mercury disulfide were mainly used in the following places:
First, the field of alchemy. Ancient alchemists were keen on alchemy and hoped to use it to refine elixirs of immortality. Mercury and mercury disulfide are both commonly used in alchemy. For example, Ge Hong's "Baopuzi" records that during the process of alchemy, cinnabar can be converted into mercury through a series of chemical reactions, and mercury can be combined with other substances. The alchemists believed that these medicinal pills had magical effects, which could help people prolong life and become immortals. Although this concept had no scientific basis, it reflected the exploration of the chemical properties of mercury and mercury disulfide at that time.
Second, medical use. Traditional Chinese medicine also uses mercury and mercury disulfide as medicine. Mercury disulfide (cinnabar) has a calming effect and can treat insomnia, heart palpitations and other diseases. However, due to the strong toxicity of mercury, the use of mercury-containing drugs is extremely cautious today. In ancient times, it was limited by cognition and did not fully understand the toxicity of mercury, and there were risks when using it.
Third, pigment production. Cinnabar has a bright color and is an important source of red pigment. Ancient paintings, lacquer ware, ceramics and other crafts often use cinnabar pigments. After grinding and processing, cinnabar can be made into red pigments of different shades, making the artwork colorful. Many ancient paintings and cultural relics can see traces of cinnabar, and the colors are still bright after years.

To prepare 3-hydroxy-2,5-dienone, the synthesis method is as follows:
You can first take a suitable starting material and start with a nucleophilic addition reaction. Find a compound containing active hydrogen and let it react with a carbonyl group. This reaction requires an appropriate catalyst to make the reaction proceed smoothly. The choice of catalyst is related to the reaction rate and yield, and it should be done with caution.
Then, the intermediate product needs to undergo an elimination reaction. This step aims to form the desired bisene structure. The control of reaction conditions is crucial, and temperature and solvent have a great influence on the reaction. If the temperature is too high, it may cause side reactions to breed; if the temperature is too low, the reaction will be delayed.
When eliminating the reaction, a suitable base can be selected. The strength and dosage of the base will affect the direction of the reaction. At the same time, the polarity of the solvent will also affect the mechanism and rate of the elimination reaction. Choosing a solvent with the right polarity can make the reaction develop in the expected direction.
In addition, during the synthesis process, monitoring the reaction process is indispensable. By means of thin layer chromatography, nuclear magnetic resonance, etc., the progress of the reaction can be known in real time to determine the follow-up operation.
Also, the purity of the raw material is also related to the success or failure of the synthesis. Impure raw materials are easy to introduce impurities and interfere with the reaction, so the raw materials need to be purified to reach a certain purity standard.
Synthesis of 3-hydroxy-2,5-dienone requires careful design of the reaction route, strict control of the reaction conditions at each step, and close monitoring of the reaction process. In this way, it is expected to obtain products with high yield and purity.

As far as carbon dioxide is concerned, there are many things that should be paid attention to.
As far as carbon dioxide is concerned, first, because of its high flammability and high flammability, fire prevention and explosion prevention are the most important factors in the storage and storage. It is necessary to check the factors that may cause ignition and explosion, such as the fire source and temperature, and the pipes of the storage container are well grounded to dissipate the explosion. Second, the molecules are small and easy to penetrate, which requires the storage container and the pipeline to have a high degree of sealing to prevent leakage. Commonly used storage methods include high temperature, low temperature, etc., each of which has its own characteristics. High temperature requires high temperature containers, and liquid temperature requires low temperature systems, all of which are carefully designed.
As for carbon dioxide, first, because it is often stored in the form of high temperature, the resistance performance requirements of storage containers and pipelines are high. Regularly improve the tightness of containers and pipelines to prevent leakage accidents due to normal force. Second, carbon dioxide is usually non-flammable, but a large number of leaks will suffocate people. For storage and storage, it is necessary to maintain good communication and alarm to prevent leakage. Third, under certain conditions, carbon dioxide will react to certain substances, such as water reacting to form carbonic acid, so the materials for storage containers and pipes can resist this corrosion.
In addition, carbon dioxide is stored and processed, and each has different attention requirements due to its characteristics. Only by following the rules and considering all factors can we ensure the safety and reliability of the whole process.