4 Iodo 4 Methylbiphenyl

What are the main uses of 4-methylbiphenyl?
Although "4-methylbiphenyl" is not directly recorded in "Tiangong Kaiwu", it can be answered in ancient form from common knowledge in the chemical industry and related fields.
4-methylbiphenyl is widely used in the chemical industry in this world. First, in the field of organic synthesis, it is often a key raw material. Many fine chemicals can be prepared through various chemical reactions. For example, by reacting with specific reagents, through a series of complex condensation and substitution steps, organic compounds with special structures and properties can be generated and used in pharmaceutical synthesis.
Second, in the field of materials science, 4-methyl biphenyl also has extraordinary uses. Can participate in the preparation of high-performance polymers. In the polymerization reaction, as one of the monomers, polymerized with other monomers, the resulting polymer has unique physical and chemical properties. For example, the polymer material made from it may have excellent thermal stability and mechanical properties, and can be used to make parts of high-end electronic devices. Because it can withstand certain heat and has good mechanical strength, it can ensure stable operation of electronic devices.
Furthermore, in the field of liquid crystal materials, 4-methyl biphenyl also occupies a place. Liquid crystal materials are widely used in display technology. The special molecular structure of 4-methyl biphenyl, which can be properly modified and blended, can become an important component of liquid crystal compositions, affecting the phase transition temperature, optical anisotropy and other key properties of liquid crystal, helping to improve the display effect of liquid crystal displays, such as enhancing contrast and response speed, so as to bring people a clearer and smoother visual experience.

"Tiangong Kaiwu" has a saying: "Where silver comes from China, there are old pits in Zhejiang and Fujian, which may have been mined or closed at the beginning of the country. In Rao, Xin and Rui counties in Jiangxi, there are pits that have never been opened. Huguang is out of Chenzhou, Guizhou is out of Tongren, Henan is out of Yiyang, Zhao Baoshan, Yongning Qiushupo, Lu's Gaozuoer, Songxian Mangshan, and Sichuan Huichuan Mile Mountain, Gansu Dahuangshan, etc., are all called beautiful mines. The natives all live in tunnels, more than ten meters across, with different depths. They all abandon the soil, wash for a few days, and then get it." However, what I answer today is not about silver mines, but the physical properties of 4-question 4 '-methylbiphenyl.
Methylbiphenyl, colorless crystal, has a special aromatic odor. Its melting point is quite low, about 20-22 ° C. Under this temperature, it is in the shape of a solid state, with a regular crystal shape and a solid texture. When the temperature rises to about 280 ° C, it turns into a gaseous state. The boiling point makes it possible to realize the transformation of solid, liquid and gas in a specific temperature range.
Its density is less than that of water, about 0.996 g/cm ³, so if it is mixed with water, it will float on the water surface. And it is insoluble in water, because of the characteristics of its molecular structure, it is difficult to form an effective force with water molecules. However, in organic solvents, such as ethanol, ether, etc., it exhibits good solubility, due to the similar chemical structure and force between organic solvent molecules.
Methylbiphenyl is relatively stable in chemical properties, and it is not easy to react violently with common substances at room temperature and pressure. However, under certain conditions, such as high temperature and the presence of catalysts, the methyl groups on its benzene ring can undergo substitution reactions, such as halogenation reactions, etc., which can introduce other functional groups, resulting in the derivation of many compounds with different properties, which are widely used in the field of organic synthesis.
Furthermore, methyl biphenyl is flammable, and can be burned in the event of an open flame or hot topic. When burned, a bright flame will be produced, accompanied by black smoke, which is caused by the failure of carbon to oxidize completely during the combustion process.
The physical properties of methyl biphenyl are important factors in many industrial production, scientific research and other fields. Only by in-depth understanding of it can we get the best use of it.

To prepare 4-yl-4 '-methyl biphenyl, the following method can be followed.
First take the appropriate halogenated aromatic hydrocarbon, such as p-halogenated toluene, and take the p-halogenated benzene, supplemented by a suitable metal catalyst, such as palladium catalyst, and alkali substances. In a suitable reaction solvent, such as ether or aromatic hydrocarbon solvent, the two are coupled to react. This reaction needs to be carried out at a specific temperature and reaction time. With the action of metal catalysts, a carbon-carbon bond is formed between the halogen atom of the halogenated aromatic hydrocarbon and the carbon atom of another aromatic hydrocarbon, and then the skeleton structure of the biphenyl is gradually constructed. For example, p-bromotoluene and p-bromobenzene are used as starting materials, and the reaction is heated and stirred in toluene or dioxane solvent in the presence of potassium carbonate and other bases catalyzed by palladium catalysts such as tetra (triphenylphosphine). During the reaction, the bromine atom of p-bromotoluene is acted by a palladium catalyst to form an active intermediate with palladium. This intermediate undergoes nucleophilic substitution with the benzene ring of p-bromobenzene, and then goes through a series of electron transfer and elimination steps to generate 4-yl-4 '-methylbiphenyl.
After the reaction is completed, the mixture is separated and purified. First, the method of extraction is used to make use of the difference in solubility between the product, the reaction by-product and the unreacted raw materials in different solvents to preliminarily separate. Then, by column chromatography, the appropriate stationary phase and mobile phase are selected to further purify the product, remove impurities, and finally obtain pure 4-yl-4 '-methyl biphenyl.

4-4 '-Methylaniline should be paid attention to in the process of storage and storage. This is because of the special properties of methylaniline. If it is not controlled, it may cause more damage to the environment.
The first time it is stored, it is the first time to be dry in the environment. In the trendy environment, it is easy to cause damage to the environment, causing it to change its properties, and it will be used in the future. And in the place of, avoid direct light. High light, can be transformed and reversed, so that its components decompose or disappear.
In addition, the place where it is stored is good. Methylaniline may produce harmful substances. If it is empty, it will not harm the health of the survivors, and it may lead to safety accidents.
The safety of the container is also very important. It is necessary to use a corrosion-resistant and well-sealed container to prevent leakage. If the leakage does not cause waves, it will pollute the environment, and it is more likely to cause poison to the people who come in contact.
If it is not necessary, the package must be firm. Depending on the phase, the use of packaging materials is required to ensure that there is no shock or collision on the way. In addition, people are familiar with the dangerous characteristics and emergency treatment methods of methylaniline.
In addition, the documentation must be complete, including the name, quantity, and performance of the product, so that the relevant people can grasp it, and it may be released.
Therefore, methylaniline should be paid attention to in many aspects, such as storage, environment, containers, packaging, etc., and must not be ignored in order to ensure the safety of the process.

The theory of "Tiangong Kaiwu": "4% Question - 4 '-Effect of Methylbiphenyl on Environment and Human Health"
Phloromethylbiphenyl is widely used in the industrial field, but its impact on the environment and human health cannot be ignored.
First talk about its disturbance to the environment. Methylbiphenyl has a certain stability and is not easy to rapidly degrade in the natural environment. If released in water, it can persist in water for a long time, and is easily ingested by aquatic organisms. It is transmitted and enriched through the food chain, endangering many aquatic organisms. In the soil, it may cause changes in the physical and chemical properties of the soil, hindering the absorption of nutrients by plant roots, causing plant growth to be hindered, or even withered.
As for the atmosphere, after the volatilization of methyl biphenyl, it can interact with other pollutants in the atmosphere, affect the chemical composition of the atmosphere, or participate in photochemical reactions, generating even more harmful secondary pollutants, which can deteriorate air quality, and cause bad weather such as haze and acid rain.
Then look at its harm to human health. If the human body ingests methyl biphenyl through breathing, diet or skin contact, it can accumulate in the body. Or interfere with the human body's endocrine system, cause hormone imbalance, and affect growth and development and reproductive function. Studies have shown that long-term exposure to methylbiphenyl-containing environments may damage reproductive cells, reduce fertility, and increase the risk of fetal malformations.
And methylbiphenyl may be potentially carcinogenic. Although more research is needed to confirm the relevant, animal experiments have shown that high-dose exposure to methylbiphenyl can cause tumors in the body. In addition, it also has adverse effects on the nervous system, which can cause symptoms such as dizziness, fatigue, memory loss, etc. In the long run, or impair the normal function of the nervous system.
Therefore, methylbiphenyl poses a risk to both the environment and personal health. People should treat it with caution, develop better alternatives, and strengthen the control of its emissions to protect the environment and human well-being.