2-Fluoro-5-bromopyridine

2-% E6% B0% 9F - 5-%E6%BA%B4%E5%90%A1%E5%95%B6%E7%9A%84%E4%B8%BB%E8%A6%81%E7%94%A8%E9%80%94%E5%8D%B3%E4%B8%BA%E6%96%BD%E6%B0%B4%E4%B8%8E%E9%9B%86%E6%B0%B4%E4%B9%8B%E7%94%A8%E3%80%82
"Tiangong Kaiwu" has the saying: "Where water is treated anywhere, it will benefit the disease and harvest it at the same time." 2 - Canal and 5 - weir are set up for this purpose.
2 - Canal, to dredge as the main. At a higher point in the terrain, cut channels to divert water upwards, so that it can meander and stretch, irrigate the fields. When drought rages, the canal water can relieve the thirst of the seedlings, so that the crops can be protected. And the water flows through the canal, can initialize silt, make the land fertile, and benefit farming.
5 - Weir, to block storage for use. In the place where the water flow is rapid, build a weir to cut across, slow down its flow, and gather water into an abyss. In this way, it not only prevents floods from flooding and destroying the fields; but also accumulates water sources. When water is needed, the gate is opened to release water to moisten the fields below. The weir setting also makes fish and turtles multiply in the water and adds livelihood to the people.
The ancients set up 2-canal and 5-weir, using wisdom to make use of the situation to maximize the benefits of water conservancy. Make the flow of water conform to nature and be used by people. Not only to maintain the foundation of agricultural production, but also to maintain the tranquility of one side of the water and soil. In fact, it is a good strategy for improving water conservancy and removing water disasters. Later generations have also learned from it, and it has continued endlessly, laying a solid foundation for the prosperity of Huaxia's agricultural civilization.

To make dihydroxypentaldehyde, there are three methods.
First, formaldehyde and acetaldehyde are used as the starting point, and hydroxyaldehyde is condensed. First, formaldehyde and acetaldehyde are condensed with hydroxyaldehyde under the catalysis of alkali. Bases such as sodium hydroxide can take alpha-hydrogen from acetaldehyde to generate anion, which nucleophilically attacks the carbonyl group of formaldehyde to obtain beta-hydroxyaldehyde. This product is dehydrated and then reduced to obtain dihydroxypentaldehyde.
Second, choose an appropriate unsaturated aldehyde and use the method of hydrogenation and hydroxylation. For example, find an aldehyde containing a suitable number of carbon and an unsaturated bond. First, under the action of appropriate catalysts such as platinum and palladium, the unsaturated bond is hydrogenated, and then a special hydroxylation reagent, such as osmium tetroxide, is used for hydroxylation reaction to obtain dihydroxypentaldehyde.
Third, starting from carbohydrates. Some carbohydrates, under specific conditions, can be oxidized and cleaved into dihydroxypentaldehyde. Take glucose as an example, first oxidize it to gluconic acid, followed by a specific cracking method, so that the carbon chain is broken at a suitable position, and then modified and adjusted to obtain the target product dihydroxypentaldehyde.
Various production methods have their own advantages and disadvantages. The method of hydroxyaldehyde condensation requires accurate temperature control and alkali content control, while the reaction steps are slightly complicated. The hydrogenation of unsaturated aldose requires high catalyst requirements, and the hydroxylation reagents may be highly toxic. The method of sugar conversion, although the raw materials are naturally easy to obtain, the reaction conditions are harsh, and the product separation and purification are also challenging. To choose the best method, consider the actual situation and weigh the cost of raw materials, the difficulty of reaction, and the purity of the product.

The price of a restaurant in Guanfu City is related to the change in supply and demand, as well as the quality of materials and the quality of skills. As for the "2-Jiang-5-Caoxiang" item, it has not been investigated in detail, but if you want to push the price of a restaurant in the market, you need to consider various factors in detail.
The place where the cover is located has a huge impact on the supply and demand situation, depending on the price. If this item is in the market, there are many people who want it, but there are few people who supply it, the price will rise; on the contrary, if the supply exceeds the demand, the price will drop.
Material is also the key. If it is made of exquisite materials, with tough texture, warm color, and durability, the price will be high; if the material is ordinary, it is fragile and easy to decay, and the price will not be high.
Furthermore, the craftsmanship also affects the price. If it is made by a skilled craftsman, with exquisite craftsmanship, unique shape, and exquisite decoration, every knife and every stroke shows ingenuity, the price will be high; if the production is rough and the craftsmanship is simple, the price will be low.
However, because I don't know what "2-Jiang-5-Caoxiang" is, it is difficult to determine the price of its market. Or it is a rare treasure, priced at more than a thousand gold; or it is an ordinary product, priced at only a few words. Only by specifying the characteristics of the goods and the supply and demand at the time can we obtain a more accurate market price.

Water is the most gentle and good thing. Rivers and rivers are formed by the convergence of water. In today's "2-river-5-estuary", its physical and chemical properties are particularly important, and it is related to all ecological things and cannot be ignored.
Its physical properties, the first word temperature. Due to the different topography, seasons and sunshine, the water temperature often changes. Summer is warm, winter is cold. This change affects the growth and reproduction of aquatic organisms, and if the cold temperature is inappropriate, organisms may become sick or die. The speed of water flow is also key. At the intersection of rivers, the water flow is turbulent, or swirls, or turbulence. Where it is fast, it is difficult to store sediment; where it is slow, sediment gradually accumulates. Therefore, the water flow rate is related to the shape of the river and the transport of substances. Furthermore, the density of water varies with salt content and temperature. In the estuary, fresh water and seawater meet, density is mixed, and stratification is common. This has a great impact on the mixing and material exchange of water bodies.
As for chemical properties, pH is the first. The water of rivers is mostly neutral, but it also varies due to the influence of geology and human activities in the basin. If acidic substances flow in, the water will be acidic, corroding river bottoms and banks, and endangering organisms. And if the alkalinity is too strong, it is not conducive to biological survival. Dissolved oxygen in water is crucial and depends on aquatic life to breathe. Rivers and rivers meet, water bodies mix, and dissolved oxygen is complex. The photosynthesis of aquatic plants and the respiration of organisms both affect the amount of dissolved oxygen. In addition, the nutrients in the water, such as nitrogen and phosphorus, are related to the growth of algae and aquatic plants. In moderation, the ecology is lush, and in excess, it will lead to eutrophication, algae will grow wildly, and water quality will deteriorate.
There are trace elements, although the content is very small, but the effect is huge. Iron, manganese, zinc and other elements are necessary for biological growth, but if the content exceeds the standard, it will also become toxic. Therefore, the physical and chemical properties of the "2-river-5-river estuary" are intertwined to maintain ecological balance. Our generation should study it carefully and take care of it carefully, so as to ensure the stability of the river and the prosperity of all things.

The storage conditions of 2-% E6% B0% 9F and 5-% E6% BA% B4 are related to many factors such as geographical shape and water flow situation.
The situation of Guanfu mountains and rivers is quite important for storage. Around 2-% E6% B0% 9F, if mountains are surrounded, they can form a barrier, which can slow down the water potential and help it deposit. At this point, the flow speed gradually decreases, and the sediment and other materials carried are easy to settle, accumulating over time, and then forming a reservoir. Furthermore, if the river channel is wide and smooth, the kinetic energy loss of water is also large, and the material is easier to retain.
As for 5-% E6% BA% B4, its storage conditions are also closely related to the topography. If the topography in the upper reaches of the river is more undulating and the water flow is turbulent, and the topography in the lower reaches a flat place, the water flow will be slow, and a large amount of sediment will be deposited with the situation. And if the topography on both sides is surrounded, it can collect water and sediment, creating favorable conditions for storage.
The water flow situation is also left and right storage. If the 2-% E6% B0% 9F water volume is abundant and stable, it will continue to carry sediment, and it will be deposited in suitable places, and the storage amount will be considerable. In case of abnormal water conditions such as floods, although the amount of sediment carried by the water flow will increase sharply in the short term, after the flood, the return of the water flow will also reshape the storage pattern. 5-% E6% BA% B4 If there are tributaries entering, it will bring additional sediment and water. At the intersection, due to the interaction of water flow, it will also affect the storage distribution.
Soil texture and vegetation status cannot be ignored. If the soil in the basin is loose, it is easy to be carried away by water flow erosion, providing a rich source of materials for storage. On the contrary, if the vegetation is lush, it can fix soil and retain water, reduce sediment entering the river, and the storage amount may be affected. The differences in soil and vegetation in the areas where 2-% E6% B0% 9F and 5-% E6% BA% B4 are located will be reflected in the storage conditions.
Overall, the storage conditions of 2% E6% B0% 9F and 5-% E6% BA% B4 are the result of the interaction of various factors such as mountain and river topography, water flow situation, soil and vegetation, and each factor is related to each other to create a unique storage situation.