3,4-dibromopyridine (98%)

The main use of carbon disulfide (98%) is recorded in "Tiangong Kaiwu", and it involves various processes.
First, in the ink industry, carbon disulfide is quite crucial. In ancient ink work, to obtain good ink, high-quality carbon black is required as the base. Carbon disulfide can be used to extract impurities in carbon black raw materials such as pine smoke and oil fume, which increases the purity of carbon black and improves the texture. Pure carbon black ink is used to make ink, which is black and shiny, smooth writing, and does not fade for a long time. It is valued by scholars and writers.
Second, in the extraction of fragrances, carbon disulfide is also very useful. Many natural fragrances are hidden in plant roots, flowers and leaves. Carbon disulfide can be extracted efficiently because of its good solubility. The ancient incense road prevailed, and nobles and scholars often smoked their clothes and smoked rooms with spices to create an elegant atmosphere. The fragrance extracted by carbon disulfide is pure and rich, which adds a lot to the fragrance.
Third, in the embryonic stage of the rubber industry, carbon disulfide also played an important role. Although the rubber industry in ancient times was not as developed as it is today, it has been initially explored. Carbon disulfide can be used as a vulcanizing agent to react with rubber, which improves the properties of rubber, enhances its strength, elasticity and wear resistance, and lays the foundation for the early application of rubber products.
Fourth, in the pharmaceutical field, carbon disulfide can participate in some drug synthesis processes. In ancient medicine, it was necessary to precisely extract the active ingredients. The solubility of carbon disulfide could help them obtain specific ingredients from herbs and other raw materials. After formulation, they could be made into a good medicine for treating patients and relieving their suffering.

There are many methods for the synthesis of 3,4-dibromoethane (98%), and the common ones are as follows:
First, the addition reaction of ethylene and bromine. This is a classical preparation method. Under suitable reaction conditions, ethylene gas is introduced into the carbon tetrachloride solution of bromine. The double bond of ethylene molecules is attacked by bromine atoms, and an electrophilic addition reaction occurs to generate 3,4-dibromoethane. The reaction equation is: $CH_2 = CH_2 + Br_2\ rightarrow CH_2BrCH_2Br $. This method has milder reaction conditions, high yield and good product purity. Due to the high selectivity of the reaction between ethylene and bromine, only the target product is basically formed.
Second, it is prepared from ethanol. Ethanol is first dehydrated to form ethylene. The commonly used dehydrating agent is concentrated sulfuric acid, etc. The reaction needs to be controlled at a suitable temperature, generally about 170 ° C. The reaction formula is: $C_2H_5OH\ xrightarrow [170 ° C] {concentrated sulfuric acid} CH_2 = CH_2\ uparrow + H_2O $. Then the obtained ethylene is then added to bromine to obtain 3,4-dibromoethane. Although this approach is slightly complicated, ethanol comes from a wide range of sources and has relatively low cost. It also has certain application value in industrial production.
Third, acetylene is used as a raw material. Acetylene is added to an appropriate amount of bromine. Acetylene has a carbon-carbon triple bond and can be gradually added to bromine. First add a molecule of bromine to form 1,2-dibromoethylene, and continue to react with bromine to obtain 3,4-dibromoethane. The reaction equations are: $CH\ equiv CH + Br_2\ rightarrow CHBr = CHBr $, $CHBr = CHBr + Br_2\ rightarrow CHBr_2CHBr_2 $. This method is easy to carry out due to the active nature of acetylene, but the amount of bromine needs to be precisely controlled to prevent excessive addition to form polybrominates and affect the purity of the product.

3% 2C4 + - + yttrium disulfide (98%) during storage and transportation, when paying attention to everything, it can be kept safe.
When storing, the first environment is dry. Yttrium disulfide is susceptible to water vapor intrusion, causing its properties to vary. Therefore, when placed in a dry place, and the container used must be well airtight to prevent moisture penetration. If placed in a humid place, or the container is not well sealed, the water vapor will interact with yttrium disulfide, or cause it to decompose, or cause it to form impurities, which will damage its purity and quality.
Temperature control is also key. This substance should be stored in a normal temperature environment, avoid high temperature hot topic. Under high temperature, the internal structure of yttrium disulfide may change, causing chemical reactions and causing damage to its quality. It should be stored in a place protected from direct sunlight and well ventilated to keep the temperature constant.
As for transportation, the packaging must be solid. Wrap it with suitable packaging materials to prevent it from being damaged by collision and vibration during transportation. Buffers, such as foam and sponge, can be placed in the packaging to reduce external impact.
The cleanliness of the means of transportation should not be ignored. The compartment or cabin must be clean and free of other chemical residues. If impurities are mixed in, contact with yttrium disulfide, or cause adverse reactions, affecting its quality.
Transport personnel should also be familiar with the characteristics of yttrium disulfide. In case of emergencies, such as packaging damage, leakage, etc., we can quickly take appropriate measures according to its characteristics to reduce the harm. In this way, when storing and transporting yttrium disulfide (98%), pay attention to the above things to ensure its safety, stability and quality.

What is the market price of 3% 2C4 sulfur dioxide (98%) today?
I try to estimate it for you. The price of sulfur dioxide (98%) in the market often varies according to many reasons, such as origin, season, supply and demand conditions, etc. However, based on the common market view nowadays, its price per ton may be between [X1] yuan and [X2] yuan.
If the origin is abundant and when the supply and demand are relatively balanced, the price may tend to be low, close to [X1] yuan per ton. This is due to the large supply and stable demand. Businesses compete for the market or reduce their prices.
On the contrary, if there is a reason for the origin, the supply is tight, and the demand is strong, the price may rise, close to [X2] yuan per ton.
The change of seasons also has an impact. For example, in some peak industrial production seasons, there are many people who need sulfur dioxide, and the price may be slightly higher; while in the off-season, the demand is small, and the price may be slightly lower.
However, this is only a rough estimate. The market conditions are constantly changing. To know the exact price, you need to carefully observe the real-time market conditions, consult the industry merchants, and check the transaction data.

"Tiangong Essential Materials", the amount of 3% 2C4-diethyl ether (98%) is not accurate, and it has been studied. Outside, it is not clear that the color is not good. Smell, taste has the inherent taste of the substance, and the taste is not a good product.
In terms of accuracy, it is 98%, and it needs to be analyzed by a precise analysis method. Commonly used methods such as phase chromatography can determine the content of diethyl ether in it. If the deviation is large, it is not suitable. The moisture content is also low, and the multi-moisture will affect the efficiency of its chemical properties. Generally, there is a water filter, and the water does not meet the requirements.
It should not be ignored. Or influence its reaction activity, characterization, etc. Using various optical and chemical analysis methods, there is no quality and content. If there is any unknown quality or the amount exceeds the limit, it cannot be qualified.
Boiling is also an important indicator. Diethyl ether has a specific boiling temperature, and the boiling temperature deviation is large, suggesting that the degree is low, and it may be mixed with other things with different boiling temperatures. Set it with precision boiling temperature, and if the boiling temperature does not match, it can be passed. In addition, such multiple temperatures need to be tested to obtain a qualified 3% 2C4-diethyl ether (98%).