2-Fluoropyridine-5-carbaldehyde

"Tiangong Kaiwu" says: "There are two kinds of rice, japonica and waxy, which are soaked in water for several days. When they germinate, they are sprinkled in the field, and they give birth to inches. Their name is seedlings. Thirty days after the seedlings are born, they are pulled up and planted." This is a common method of rice farming. As for the varieties of rice, japonica rice is strong in nature, and the rice is hard in quality; glutinous rice is soft in nature, and is mostly used for brewing wine and making cakes.
As for "2-Yanjiang-5 turtle", turtle is also commonly known as turtle. Turtle meat is delicious and nutritious, and it is valued by the world. Its main use is to eat it first. Turtle meat is rich in protein, a variety of vitamins and minerals, and has a good nourishing effect. " The Compendium of Materia Medica contains: "Turtle meat has a sweet taste and a flat nature, and has the effect of nourishing yin and tonifying the kidney and clearing away virtual heat." In the field of diet and health care, turtle meat is often used to nourish people who are weak and have internal heat due to yin deficiency.
Furthermore, the shell of the turtle, that is, turtle armor, is an important Chinese medicinal material. "Shennong Materia Medica Classic" lists turtle armor as a middle product, saying that it is "the main heart and abdomen, with strong accumulation of problems, cold and heat, removal of ruffians, polyps, yin erosion, hemorrhoids (nuclei), and evil meat". After being processed, turtle armor can be used as medicine for the treatment of yin deficiency fever, bone steaming and heat, yin deficiency and yang hyperactivity, dizziness and many other diseases. It is
And turtle meat in cooking, can be stewed, can be burned, can be stewed, and the taste of the dish is mellow, such as the classic "Farewell My Concubine", with turtle meat and chicken cooked together, complementing each other, not only has the taste of food, but also has the effect of health, so turtle has important value in diet and medicine.

2-%E6%B0%9F%E5%90%A1%E5%95%B6, 5-%E7%94%B2%E9%86%9B, the most spiritual thing between heaven and earth. It has all kinds of physical properties, which I will describe in detail today.
First of all, its quality is often liquid, warm and flowing. If the water of the river flows endlessly, follows the trend, and has no shape, it can change with the device, entering the square is square, and entering the circle is round. However, it can also become gaseous, transpiring up, turning into clouds, floating in the sky; it can also be condensed into a solid state, turning into ice in case of cold, hard as stone, clear and crystal clear.
In terms of its density, under normal temperature and pressure, it is about one gram per cubic centimeter, which is suitable for many constituent elements of life. This density makes all things rise and fall differently in it, or float on the surface of the water, or sink to the bottom of the water, and everything in the world has its place.
Furthermore, its solubility is quite strong, which can be called "universal solvent". Many substances can be dissolved in it, such as salt and sugar, which melt when they enter water, and are invisible, but change the nature of water. This property is of great importance to the survival of life and the transmission of substances. Many chemical reactions in the body of life depend on the dissolution of water to occur, and the transportation of nutrients and the discharge of metabolic wastes also use water as a carrier.
The boiling point and freezing point of water are also unique. Under standard atmospheric pressure, the boiling point is one hundred degrees. At this time, water vaporizes violently, turning into steam, and energy overflows; the freezing point is zero degrees. At this temperature, water turns from liquid to solid, and it is ice and jade clean. These two temperatures have a profound impact on the growth and change of all things in the world. Because of the three-state change of water, it is nourished and experiences cold and summer, and the cycle repeats, endless.
Water has hot topic compatibility, absorbs or releases a lot of heat, but its own temperature changes relatively slowly. It can adjust the climate, making the earth cold and hot, warm and pleasant. The seaside, the summer is cool, the winter is mild, all because of the hot topic of water.
2-%E6%B0%9F%E5%90%A1%E5%95%B6, the physical properties of 5-%E7%94%B2%E9%86%9B, complex and delicate, in the creation of heaven and earth, all creatures, are fundamental, is the treasure of nature, indispensable.

2-%E6%B0%9F%E5%90%A1%E5%95%B6, 5-%E7%94%B2%E9%86%9B, both of these are wonderful things in the world. As for 5-%E7%94%B2%E9%86%9B, its chemical properties are quite stable.
The structure of the 5-%E7%94%B2%E9%86%9B is composed of specific atoms arranged in a delicate order. This structure gives it unique properties. In common environments, 5-%E7%94%B2%E9%86%9B is not easy to chemically react with others. Just like the calm person, it is not easily moved by the outside world.
And 5-%E7%94%B2%E9%86%9B encounter ordinary temperature and pressure, it can maintain its own state, not easily deformed, and does not interact with the surrounding air, water vapor and other common substances. This stability makes it useful in many fields. Or used to build strong materials, because of its chemical stability, it can resist the erosion of external chemicals and maintain its own characteristics for a long time; or used in special chemical reaction environments, as a stable medium, providing a stable basis for other reactions.
Compared with many active chemicals, 5-%E7%94%B2%E9%86%9B such as quiet lake water, calm. Even if it encounters some external disturbances, it can quickly return to its original state by virtue of its stable chemical properties.
However, everything in the world is not absolute. If placed under extreme conditions, such as extremely high temperature, extreme pressure, or coexistence with specific strong chemically active substances, 5-%E7%94%B2%E9%86%9B stability may also be challenged, and its chemical properties may change. But in the usual situation, its stable chemical properties are indeed its outstanding characteristics, which are used by people and benefit the world.

To prepare diethyl ether and pentamethyl ether, there are three methods.
One is the alcohol dehydration method. Take an appropriate amount of ethanol, use concentrated sulfuric acid as a catalyst, heat it to 140 degrees Celsius, and dehydrate the ethanol molecules, then obtain diethyl ether. The reaction formula is:\ (2C_ {2} H_ {5} OH\ xrightarrow [140 ^ {\ circ} C] {concentrated H_ {2} SO_ {4}} C_ {2} H_ {5} OC_ {2} H_ {5} + H_ {2} O\). If you make pentamethyl ether, you can take methanol. In the same way, catalyze with concentrated sulfuric acid, and heat to dehydrate the methanol molecules to obtain pentamethyl ether.
The second is the Williamson synthesis method. First take the halogenated hydrocarbon and react with sodium alcohol. To obtain diethyl ether, bromoethane can be mixed with sodium ethyl alcohol, and a nucleophilic substitution reaction occurs. The bromine ion leaves, and the ethoxy group replaces it to form diethyl ether. The reaction formula is:\ (C_ {2} H_ {5} Br + C_ {2} H_ {5} ONa\ longrightarrow C_ {2} H_ {5} OC_ {2} H_ {5} + NaBr\). For the preparation of pentamethyl ether, iodomethane can be reacted with sodium methoxide. According to this principle, pentamethyl ether can be obtained.
The third is the addition method of olefins and alcohols. Taking diethyl ether as an example, ethylene and ethanol undergo an addition reaction under the action of an acidic catalyst, the ethylene double bond is opened, the ethoxy group of ethanol is added to one end of ethylene, and hydrogen is added to the other end to form diethyl ether. Similarly, if isopentene and methanol are reacted under suitable acidic conditions, pentamethyl ether can be prepared. These three methods have their own advantages and disadvantages, and they need to be chosen according to the actual situation, such as raw material cost, difficulty of reaction conditions, product purity and other factors, in order to achieve the purpose of efficient synthesis of diethyl ether and pentamethyl ether.

Today, 20% flow to the fifth, and the price range of nail crabs in the market is a matter of concern to everyone. To understand it in detail, you need to look at various factors.
The supply and demand of the husband's market is also the key to controlling the price. If the production of nail crabs is abundant, but there are few seekers, the price may decline; on the contrary, if the production is thin and the crowd is sought, the price will rise. The change of qi has a great impact on the growth and reproduction of nail crabs. Tianshun is when the crabs are strong and abundant, and the price may be stable and decline; if there is a disaster, there will be few crabs, and the price will rise.
Furthermore, the difficulty and distance of transportation are also related to the price. If the place of origin is remote, it is difficult to transport to the city, and the cost is quite huge, the price must be high; if the place of origin is close to the city and the transportation is convenient, the price may be slightly lower. And the people are good, which is also a major reason. At present, there are many people who like crabs, and there are many people who ask for them, and the price cannot be suppressed; if there are changes in the future, and the number of people who ask for them decreases, the price will also drop accordingly.
Looking back at the past, the nail crab was in the city, and in ordinary times, the price per catty was between tens of dollars and hundreds of dollars. However, during the festive event, those who ask for it are like a tide, and the price is often doubled. As for the old desolate crab, the price can be as high as a It is based on the price range of the crab in the market, which often varies with various factors, and it is difficult to determine the number. Usually, tens to hundreds of dollars per catty are common; in special cases, it may be low or high, and the fluctuation is quite large.