4 Bromo 2 Iodopyridine

The method of 4-alkali-2-alum-1-salt described in "Tiangong Kaiwu" is mainly used in the preparation of glazes in ceramic production.
In terms of ceramic technology, glaze is crucial, it not only gives ceramics a smooth and bright appearance, but also enhances their wear resistance and chemical stability. The alkali, alum, salt and other substances involved in this formula each play a unique role in the formation of glaze.
Alkali in it can reduce the melting point of the glaze, causing it to melt at a relatively low temperature, thereby forming a uniform and continuous vitreous glaze layer. Different kinds of alkalis, due to differences in chemical properties, will affect the melting point, fluidity and color of the glaze layer. For example, certain alkaline substances can enhance the transparency and gloss of the glaze, making the ceramic surface more crystal clear.
Alum substances play a key role in adjusting the chemical composition and properties of the glaze. Metal ions in alum can participate in the chemical reaction of the glaze, changing the color, hardness and corrosion resistance of the glaze. For example, copper-containing alum may give the glaze a unique green tone, while iron-containing alum may give the glaze a different shade of brown.
Salt in this formula helps to control the melting rate and viscosity of the glaze, ensuring that the glaze layer is evenly distributed on the surface of the ceramic body. Appropriate salt addition can avoid undesirable phenomena such as flow glaze and shrinkage glaze in the firing process of the glaze, thereby ensuring the quality and integrity of the glaze surface of the finished ceramic.
This formula has been verified and perfected by long-term practice and is the crystallization of the wisdom of ancient craftsmen. It laid a solid foundation for the development of China's ceramic industry, making ancient Chinese ceramics famous for their exquisite glaze decoration and excellent quality. It was widely spread all over the world and had a profound impact on the development of global ceramic technology.

4 - - 2 - There are various ways to make horns. In "Tiangong Kaiwu", the horns are a good material for making glue, and the method of making them is also exquisite.
When you take the horns, you first need to clean them. Choose the horns of high quality and no rot, which is the basis. If you cover the rotten ones, there are many impurities, which affects the quality of the glue. After cleaning, wash the horns, remove their dirt, and make them clean and stain-free.
Next, soak them in water. Soak them in water for a few hours to make the horns full of water, and the texture is slightly soft, which is convenient for subsequent treatment. The clarity of the water is related to the purity of the glue, so you must use water.
After soaking, put it in a kettle and boil it. Add water to the kettle and boil it over slow heat. The size of the fire is very critical. If the fire is fierce, the horns will be easy to burn and the colloid will be damaged; if the fire is slow, it will take a long time. When cooking, someone needs to watch and stir in a timely manner to make the horns evenly heated. After a long time of cooking, the horns will gradually melt, and the colloid will dissolve into the water.
When the horns are almost completely melted, take the soup. Filter it with a fine filter screen to remove the residue and obtain a pure glue. This glue needs to be refined again to evaporate excess water and make it thick. When refining, the heat should still be properly controlled and thick and suitable.
Finally, wait for the glue to cool and condense into pieces. Place it in a ventilated place to dry in the shade, do not expose it to the sun, and the glue will be brittle if exposed to the sun. In this way, the method of synthesizing glue with horns has been completed, and the glue made can be used for many purposes and is important in craftsmen's skills.

4% of the total, 2% of the total, especially. Its physical rationality can be determined by both the quantity and the form.
Let's talk about its quantity first. 4% of the total, weighing 4%; 2% of the total, weighing 2%. The weight of the ancient, twenty-four% of the total, 4% of the total, 2% of the total, such as the five% of the total system, the amount of the total. The amount of the total, affecting the value of its circulation. It is easy to use, or to cause private problems to prevail, and the method is used to break the normal order.
The shape of the second time. The shape of the system, the regular shape of the square hole. 4, 2, and the shape of the square hole is also often used, but because of its size, straightness, thickness, or normal size, it is slightly smaller. The small size of the shape also reflects the quality of the model, technology and other factors. If the performance is not good, the shape of the model may be uneven, rough, and the text is blurred. This is also used for the beauty of the shadow.
4, 2, in order to improve the materiality of the problem, the politics of the problem, the security of the problem. The cost of the problem, or the suitability of the problem, but the number of reasons, also reflects the wisdom of the ruler.

4-Ether-2-pyridine is an organic compound with unique chemical properties. Its properties are as follows:
First, it is basic. The pyridine ring nitrogen atom has lone pairs of electrons, can accept protons, and is basic. In acidic environments, it can react with acids to form salts. This property makes it useful in many acid-base related chemical reactions and catalytic reactions. It is often used as a base in organic synthesis to participate in the reaction, help regulate the pH of the reaction environment, and promote the reaction process.
Second, nucleophilic substitution reaction activity. The electron cloud of the pyridine ring is unevenly distributed, and the density of the electron cloud at a specific location is low, which is conducive to the attack of nucleophiles and the occurrence of nucleophilic substitution reactions. For example, under suitable conditions, leaving groups such as halogen atoms can be replaced by nucleophiles, whereby the structure of 4-ether-2-pyridine can be modified, different functional groups can be introduced, and its applications in drug synthesis, material preparation and other fields can be expanded.
Third, redox properties. 4-ether-2-pyridine can participate in redox reactions. It can be oxidized under the action of specific oxidants, and the pyridine ring or ether bond changes to form products containing different oxidation states; in the presence of certain reducing agents, it can be reduced to achieve specific structural transformation, providing a way for the synthesis of complex organic compounds.
Fourth, coordination ability. Pyridine nitrogen atoms can be used as ligands to coordinate with metal ions to form metal complexes. Such complexes have excellent performance in the field of catalysis, can catalyze a variety of organic reactions, improve reaction efficiency and selectivity; in materials science, they are also used to prepare functional materials with special properties.

As for the price of this 4-2 utensil, its scope in the market should be carefully studied before it becomes clear.
The price of this utensil depends first on the material. If the material used in this utensil is rare, its price must be high. If it is an ordinary and easy material, the price is average. And the workmanship of the production is also the main reason. If the craftsman is exquisite, the carving is delicate, the process is complicated, and the labor time is expended, the price of this utensil should be high. On the contrary, if the production is crude and the craftsmanship is simple, the price is also difficult to be high.
And the supply and demand of the market has a great impact on the price. If this device is liked by everyone, and there are many people who want it, but the supply in the market is limited, the price will definitely rise. If there is no one to ask for it, the supply will exceed the demand, and the price may drop. Furthermore, the world's chaos and the abundance of time are also related to prices. When peace is prosperous, commerce is smooth, and the price of goods may be stable or slightly reduced; if in troubled times and barren years, business travel is blocked, and the circulation of goods is not smooth, the price will often rise.
By extension, if the material of this 4-2 device is ordinary, the craftsmanship is not too exquisite, and the market demand is not exuberant, its price may be in the realm of Zhongping, and each device may be worth between tens of dollars and hundreds of dollars. If the material is high-quality, the craftsmanship is outstanding, and the world is competing to buy, the price can reach thousands of dollars or even higher. However, the market is impermanent, the price is uncertain, or changes over time, it is difficult to say for sure that it must be within a certain range.