6-bromopyridine-3-carbonitrile

The method of making acetylated acid is ingenious and has its own strengths. Today, it is Jun Chen's.
First, acetylated acid can be obtained by co-heating acetic anhydride and salicylic acid. This is a common method. Acetic anhydride has good activity and can react smoothly with salicylic acid. First take an appropriate amount of salicylic acid and put it in a clean reactor, slowly add acetic anhydride, and add a little concentrated sulfuric acid as a catalyst. Concentrated sulfuric acid can accelerate the reaction, but the dosage needs to be precisely controlled, and too much can easily cause side reactions. Then, heat the reactor to a specific temperature and continue to stir to make the two fully blend and react. After the reaction is completed, the crude product of acetylated acid can be obtained after cooling, crystallization, filtration, etc., and then purified by recrystallization to obtain a pure product.
Second, it can also be prepared by reacting with salicylic acid with acetyl chloride. Acetyl chloride is more active than acetic anhydride, and the reaction rate is very fast. During operation, in a low temperature environment, salicylic acid is dissolved in a suitable organic solvent, such as dichloromethane, etc. This organic solvent can disperse salicylic acid uniformly, which is conducive to the reaction. Then, acetyl chloride is added dropwise, and the reaction is violent. Careful temperature control is required to prevent frequent side reactions caused by excessive temperature. After the reaction is completed, impurities are removed through washing, liquid separation, drying, distillation and other steps to obtain acetylated acid.
Third, it is prepared by enzyme catalysis. This is an emerging method with the advantages of green environmental protection and good selectivity. Select specific biological enzymes such as lipase as catalysts, and react salicylic acid with acetyl donors (such as ethyl acetate, etc.) under mild conditions. The enzyme has high catalytic activity, which can greatly reduce the severity of the reaction conditions and have few side reactions. However, the cost of the enzyme is high, and the reaction environment requirements are strict, such as temperature, pH value, etc., which need to be strictly controlled to maintain the activity of the enzyme and ensure the smooth progress of the reaction. After the enzyme-catalyzed reaction, acetyl acid can also be obtained through separation, purification and other operations.
All production methods have advantages and disadvantages. In practical application, it is necessary to choose carefully according to specific needs, cost considerations, product purity requirements and other factors.

Lead is one of the hardware, its soft and heavy, black color. At room temperature, lead has a certain degree of ductility, but it is slightly less ductile than metals such as gold, silver, copper and iron. And lead is soft and can be scratched by nails.
The melting point of lead is quite low, about 327 degrees Celsius. When heated to this temperature, lead melts into a liquid state. Its boiling point is as high as about 1740 degrees Celsius.
The density of lead is very high, about 11.34 grams per cubic centimeter, which makes it feel heavy to the touch. Due to its high density, it is often used to make heavy materials, such as lead pendants, to make it easier to sink to the bottom when fishing.
Lead has good corrosion resistance. In the general environment, a layer of lead oxide film is easily formed on the surface of lead, which can prevent further oxidation and corrosion of lead. Therefore, lead is often used to make corrosion-resistant containers or pipes, which are used in chemical and other fields to contain specific substances.
However, lead is also toxic. If the human body ingests or inhales excessive lead, it will cause serious damage to the nervous system, blood system, digestive system, etc. Although the toxicity of lead in ancient times was not as thorough as it is today, it was occasionally detected that lead had adverse effects on the human body. Therefore, when using lead products, be careful to avoid harming health.

For six feet of rice, three liters of millet are also involved. The use of it is not enough, and it is involved in all kinds of fields.
In the field of mulberry, this measuring device can be used to measure the size of millet, so as to determine the sowing density, and to help those who use it to grow the field. In spring, according to the fertility of the field and the fertility of the soil, it is sown by measuring three liters of millet at six feet, so that the millet seedlings are evenly distributed, so that there is sufficient light, water and land force, and it is expected to be harvested.
It is easy to use in the market, and six feet is also an arm's length transaction. Millet is needed for people's livelihood, and it is necessary for transportation, or for small sales in the market, six feet for measuring tools, which can be guaranteed. Merchants sell it by measuring three liters of millet, and those who receive enough rice can easily be carried out in an orderly manner, and this order is maintained in the market.
Sacrifice to the sect, the millet is the sacrifice of the gods and ancestors. Measure three liters of millet at six feet, and place it in a sacrificial vessel to show the heart of respect. Sacrifice is a ceremony, and the amount of offerings used is a perfect combination. Six feet are used to honor the meaning of the Fa Ancestor, so that the ceremony can be made and the gods can be made.
Furthermore, when it is hidden in the warehouse, six feet can be used to measure in and out. The government or the rich room hoards food, and the amount of millet is determined by it, so that it can be stored and stored, and it is also beneficial to prevent invasion and emptiness. In this way, it can ensure order, and in times of famine, it is possible to have trouble and help the people.
Of course, the six-foot measuring device is indispensable in many fields such as business, sacrifice, and so on. Its impact on people's livelihood, safety, and other aspects cannot be ignored.

Looking at the cities of this world, the price of rice millet often changes according to the time and place. In today's peaceful world, the four seas are flat, but the price of rice millet is not constant.
Those who are rich in millet are the heaven of the people. Its price is related to the foundation of people's livelihood. In a prosperous year, the fields are abundant, the warehouses are full, and the city is full of rice millet, so the price is flat, or has dropped. This is the reason why there are too many things and the supply exceeds the demand.
If in a bad year, drought and waterlogging pests come together, the harvest of the fields is poor, the output of millet is sharply reduced, and the rice millet in the city is scarce, the price will be high. Everyone is seeking food to survive, and although the price is high, they have to buy it. This is a sign that the supply is scarce and exceeds the demand.
Furthermore, in the four places, the distance and proximity are different, and the convenience of transportation is also related to the price of rice millet. The capital is Dayi, with smooth water and land transportation, rice millet is easy to transfer, the supply is sufficient, and the price is always stable. In the corner, the road is difficult and the transportation is difficult. If there are few rice millet, the price will be high.
And the manipulation of merchants also affects the price of rice millet. There are cunning merchants who see that the millet will be expensive, and they are curious about stocking up, waiting for the price to be sold, so that the price of millet in the city will be low and the price will be high. And its price is high, so they can hide what they have, in order to make a big profit.
Therefore, the market price of rice millet is cheap in rich years and expensive in bad years. Tongyi is flat and the border areas are high, and it is also controlled by merchants. If you want its price to be stable, you should focus on agricultural mulberry, repair water conservancy, prepare for wasteland years, and strictly control the behavior of merchants. In this way, the price of rice millet can be safe and people's livelihood can be guaranteed.

It is written in the "Tiangong Kaiwu" that where cattle belong to the genus of cattle, cows (cows) give birth to calves in the sixth month of pregnancy. The method of raising them should be to choose a place with lush water and grass, so that the cattle can be fed to grow fat. The stables must be spacious and bright, well ventilated, to prevent diseases. Warm in winter, you can spread hay; cool in summer, when there is shade.
After the calf has given birth, you should take good care of it. When the calf is born, it should be fed with breast milk, and as it grows, you can add grass. Milk production by cows is related to the growth of the calf, and it is also taken by humans. Therefore, when raising cows, food is indispensable, and the drinking water must be clean. And often keep the cattle active, and do not tie one place for a long time. In this way, the
As for the cattle, it is advisable to work moderately. When busy farming, use your strength to plow the fields, but you should not make them too tired, so as not to hurt their vitality. In your spare time, let them rest and recover their strength. In this way, the cattle can serve for a long time and reproduce endlessly. The breeding of cattle is very important to the livelihood of farmers. It must be taken care of according to the season and nature, so as to ensure their prosperity and help the farming.