Pyridine, 2-iodo-3-hydroxy-

Alumite has unique chemical properties. Alumite contains mostly metal cations and sulfate ions, such as alum, that is, potassium aluminum sulfate dodecahydrate.
It is active and can undergo many chemical changes in aqueous solutions. Take alum as an example. In water, alum will ionize aluminum ions, potassium ions and sulfate ions. Aluminum ions will undergo hydrolysis reactions to form aluminum hydroxide colloids. This colloid has adsorption properties and can absorb suspended impurities in water to make them settle, so it is often used in water purification.
Alumite can also chemically react with many substances. When exposed to alkali, aluminum ions will react with hydroxide ions. Depending on the amount of hydroxide ions, aluminum hydroxide will form a precipitate. If there is an excess of hydroxide ions, the precipitate will dissolve and form metaaluminate ions. When interacting with acids, sulfate ions are generally more stable, but metal cations may undergo corresponding chemical reactions due to different types and concentrations of acids.
In addition, alumite will also change when heated. Alumite of crystalline hydrate will gradually lose its crystalline water when heated, accompanied by changes in color and morphology. If some alumite loses its crystalline water, it will change from crystal clear to white powder. Its chemical properties vary depending on the metal cations it contains. Different aluminite has unique uses in many fields such as industry, medicine, and daily life. It is actually one of the most unique chemical substances.

The flint is also a fire-making tool, and its physical properties are quite wonderful.
The flint is made of gold, which is strong and strong. Its texture is dense, resistant to knocking and not easy to crack, which is the foundation for using sky fire. When flint strikes, Mars can be born, because of the friction between the two, it instantly generates heat, and energy accumulates and bursts out. Although Mars is small, it has the ability to burn things. When encountering flammable things, such as moxa velvet and hemp flocculent, it can cause fire.
And the color of flint, whether blue or gray, is simple and unadorned, and its appearance is not impressive but contains magic. Its thermal conductivity is also considerable. When heated but not dissipated, it can be at the moment of attack, so that Mars can gather heat and not dissipate, so as to form a fire.
Furthermore, the weight of flint is moderate and appropriate. It is held in the hand, convenient to handle, and easy to hit, and people can control it at will to obtain the source of fire. This is the wisdom of ancient times. He observed the nature of things in heaven and earth, and used the energy of things to invent flintlock fire, so that human beings can leave the realm of raw hair and drink blood, and start the path of civilization and progress. Although its physical nature is simple, it has a great contribution to human development, which cannot be ignored.

For silylalkynes, there are many common synthesis methods.
First, the reaction between halogenated hydrocarbons and alkynes. When halogenated hydrocarbons encounter alkynyl lithium, sodium alkynyl and other reagents, the two can react to form silylalkynes. This reaction condition is relatively mild, but halogenated hydrocarbons need to be selected as active ones, and the preparation of alkynes should also be cautious to prevent them from reacting with impurities, resulting in low yield.
Second, the coupling reaction catalyzed by transition metals. With transition metals such as palladium and copper as catalysts, silicon-based halides and alkynes can be coupled in the presence of ligands and bases. Such as palladium-catalyzed Sonogashira coupling reaction, alkynes and silyl halides can be efficiently synthesized into silylalkynes under the action of palladium catalysts, ligands and bases. This method has good selectivity and is suitable for a wide range of substrates. However, the cost of the catalyst is high, and the post-reaction treatment is slightly complicated. It is necessary to remove the catalyst to avoid affecting the purity of the product.
Third, the method of adding alkynes to hydrosilylsilane. Under the action of a suitable catalyst, the addition of hydrosilica compounds and alkynes can obtain silylalkynes. This reaction has high atomic economy and is easy to operate. However, the activity and selectivity of the catalyst have a great impact on the reaction. It is necessary to find a suitable catalyst to control the reaction check point and < Br >
Fourth, the substitution reaction of alkynes with silylating reagents. Some silylating reagents, such as silyl halide, silyl sulfonate, etc., can be substituted with alkynes under alkali catalysis to form silylalkynes. This reaction condition is easy to control, and the raw materials are relatively easy to obtain. However, the reaction rate may vary depending on the structure of the substrate. Some substrates need to increase the temperature or prolong the reaction time to achieve the ideal yield.
All these methods have advantages and disadvantages. In the actual synthesis, it is necessary to choose carefully according to the availability of raw materials, product requirements and reaction conditions to achieve the best synthesis effect.

"Tiangong Kaiwu" is a scientific and technological masterpiece written by Song Yingxing in the Ming Dynasty, and it is widely used in many fields.
In the field of agriculture, the book describes many agricultural techniques in detail. As for rice farming, from soaking seeds, raising seedlings, to transplanting seedlings, and field management, there are detailed records. This knowledge helps farmers master the correct agricultural time and planting methods to improve rice yield. When it comes to wheat planting, it also explains the key points such as seed selection, sowing density, and fertilization timing, which are of great significance to northern wheat production. In terms of sericulture, the key links such as silkworm seed selection, mulberry leaf picking, and silkworm room temperature and humidity control are explained in detail, which effectively promotes the stability and quality improvement of raw material supply in the silk weaving industry.
In the field of handicraft industry, the chapter of ceramic production has made remarkable contributions. From clay selection and washing, to billet shaping, decorative painting, and even kiln firing and atmosphere control, there are detailed explanations, providing important technical guidance for craftsmen in ceramic production areas such as Jingdezhen, and promoting China's ceramic technology to reach a very high standard. The products are sold well at home and abroad. In the metal smelting part, the metal smelting process of gold, silver, copper, iron, lead, zinc and other metals is described in detail, including ore mining, mineral processing, smelting equipment structure and operation, as well as alloy ratio, etc., to promote the development of metal casting industry and provide high-quality metal materials for tool manufacturing, weapon building, etc.
In addition, in the papermaking, salt making, oil pressing and other industries, "Tiangong Kaiwu" also has many practical records. In terms of papermaking, the steps from raw material processing, pulping, papermaking to paper drying were complete, which laid the foundation for the technological inheritance and innovation of the papermaking industry at that time. The salt making method introduces the production methods of sea salt, well salt, pool salt, etc., which improved the yield and quality of salt. The oil pressing process records the pressing methods and oil yield of various oil crops, providing a technical basis for the production of edible oil. All these, "Tiangong Kaiwu" has immeasurable application value in the fields of agriculture and industry, injecting strong impetus into the social and economic development at that time.

Those who look to the city of Gun-ji today, and look at the world today, covered with all kinds of scenes.
At this moment, the world is bustling and prosperous, all for profit; the world is bustling, all for profit. The city of Gun-ji is no exception. The merchants converge, and the merchants and soldiers come and go between them. There are general merchandise listed, and there are many categories. There are pearls and jade treasures, which dazzle people's eyes; there are cloth, beans and millet, which are needed for people's livelihood. And the people in the city have their own thoughts, or they want to pursue profits and get rich, or they want goods to use.
However, the scene of the city is not perfect. During this period, there are many people who deceive and deceive the hypocrites, who shirk the shoddy, and deceive the customers. There are also people who buy and sell, bully the weak, and disturb the order of the city. In addition to the management of the city, there may be negligence, resulting in congestion and chaos in the city, and poor hygiene.
Of course, there are also people who can be called good. People with skills in the city show their abilities, and the equipment is exquisite, which is admirable. And there are honest businesspeople, children and old people are not deceived, winning with quality, and their reputation is far-reaching, adding a lot to the city. The prosperity of the city also drives the surrounding land, so that the common people can get employment and their lives are gradually prosperous.
The city of Guanfu Guangji, although there is chaos, there is also a sign of prosperity. In time, if we can rectify the management, remove evil and promote good, the city will be more prosperous, seek more well-being for the people, and become a grand scene for one side.