1 Iodo 2 Methyl 4 Nitrobenzene

Adenine, guanine, cytosine, and thymine are the four bases of the Fujia gene. These four play a crucial role in the inheritance and expression of life and other biochemical processes.
Adenine, which is sexually active, is often connected to thymine by hydrogen bonds, and plays an important role in the maintenance of DNA double-stranded structure. In gene transcription and translation, it is also an element of codon formation, participating in the sequencing of protein coding, and is related to the execution of basic functions of life.
Guanine, its structure is stable, and it is complementary to cytosine to form a base pair, which is very powerful in the stability of DNA helical structure. Moreover, guanine also occasionally participates in the process of cell signaling, energy metabolism, etc., which affects the regulation of cell physiological activities.
Cytosine has relatively peaceful chemical properties. In addition to pairing with guanine to maintain DNA structure, its methylation modification can regulate gene expression, or silence genes, or promote their activation. It is crucial for the temporal and spatial regulation of genes in embryonic development, cell differentiation and other life processes.
Thymine, which is mainly present in DNA molecules, is complementary to adenine to ensure the accurate replication and transmission of genetic information. It is of great significance for the stable inheritance of genetic material. < Br >
These four bases cooperate with each other, such as musicians playing the piano according to the score, playing the splendid chapter of life inheritance and expression in the microscopic world of cells, and building the cornerstone of biodiversity and complex life processes.

"Tiangong Kaiwu" has a saying: "Hemp is a cheap product, but non-woven solitary furs cannot keep out the cold." The power of hemp, ramie and the like is very important for those who keep warm from the cold.
The genus of hemp is mostly born in the ground, and its quality is tough. The ancients observed its properties and took it for weaving. Weaving hemp for cloth can make clothes and quilts, and it can withstand the cold of winter. And the nature of hemp is more durable than other things. Although it has passed through the years, it is not easy to damage.
Ramie is the best among hemp. Its fibers are slender, white and shiny, and the woven cloth is not only warm, but also has a good texture. In midsummer, the ancients also used ramie cloth to make clothes, because it is breathable and sweaty, so it is refreshing.
The solitary fur refers not only to the fur made of fox fur, but also to the clothing made of all kinds of fur. The fur of fur is warm and gentle, and in the cold winter, people can wear it to withstand the cold wind. However, if there is no linen cloth as a lining or as a bottom, it is difficult to rely on the fur alone. The warmth of covering hemp lies in its fiber structure, which can hide air and prevent the invasion of cold evils.
Therefore, hemp and solitary fur were important for keeping out the cold in the life of the ancients. Although linen cloth is not precious, it is necessary for people's livelihood and is indispensable; although solitary fur is warm, it depends on hemp for its use. The two are combined to ensure that people are warm and at ease in the cold sky. This is the great righteousness of the ancients using hemp and solitary fur to keep warm from the cold.

To prepare 1-bromo-2-methyl-4-nitrobenzene, there are various methods.
First, toluene can be used as the starting material. Under the condition of co-heating of concentrated sulfuric acid and concentrated nitric acid, the main mixture of o-nitrotoluene and p-nitrotoluene can be obtained because the methyl group is an o-para-position group, and then the p-nitrotoluene can be separated and purified. Then, p-nitrotoluene is substituted with bromine under the catalysis of iron bromide. Because nitro is the meta-locator and methyl is the ortho-para-locator, bromine atoms can be introduced into the ortho-locator of methyl to obtain 1-bromo-2-methyl-4-nitrobenzene.
Second, p-methylaniline can also be used as a starting material. P-methylaniline is first reacted with acetyl chloride, and the amino group is protected by acetylation to form p-methylacetaniline. Next, the nitration reaction is carried out under the action of concentrated sulfuric acid and concentrated nitric acid. Due to the localization effect of acetamide group, the nitro group mainly enters its para-site. Subsequently, the product is hydrolyzed under acidic conditions to restore the amino group. Then through the diazotization reaction, the amino group is converted into a diazonium salt, and then the Sandmeier reaction occurs with cuprous bromide and hydrobromic acid, the diazonium group is replaced by the bromine atom, and then 1-bromo-2-methyl-4-nitrobenzene is obtained.
Third, m-nitrotoluene is used as a raw material. Under the action of an appropriate catalyst, m-nitrotoluene undergoes a substitution reaction with bromine. Because methyl is an ortho-site group, bromine atoms can be introduced at the ortho-site of methyl, and the target product 1-bromo-2-methyl-4-nitrobenzene is successfully prepared. The above methods have their own advantages and disadvantages. It is necessary to consider the availability of raw materials, the difficulty of reaction conditions, the high and low yield and other factors according to the actual situation, and choose the appropriate method.

Cyanide is also a highly toxic thing. When storing and transporting cyanide, many precautions must be taken into account.
When storing cyanide, choose the first heavy container. A special container must be used, which is made of strong material and tightly sealed to prevent it from leaking. Once cyanide leaks, the toxic gas overflows, which is very harmful to the surrounding people and animals. And it needs to be placed in a cool, dry and well-ventilated place, away from fire and heat sources. Because cyanide is easily decomposed when heated, it releases highly toxic hydrogen cyanide gas, so the control of temperature and humidity is crucial.
Furthermore, the storage place should be isolated from acids, alkalis, oxidants, etc. When cyanide meets acid, it reacts quickly, producing highly toxic hydrogen cyanide gas; when mixed with oxidants, it may also cause violent chemical reactions, causing explosions and other serious consequences.
As for the transportation of cyanide, the process is dangerous, and special caution is required. Transport vehicles must have professional protective facilities to ensure that the carriages are well sealed and have eye-catching signs, clearly indicating that the contents are highly toxic substances. Escort personnel must undergo professional training and be familiar with the characteristics of cyanide and emergency treatment methods. During transportation, they should not stop at will, and should follow the established route to avoid densely populated areas and important places.
Once a leak occurs during transportation, the escort personnel make an immediate decision, quickly evacuate the surrounding people, set up a warning area, and strictly prohibit unrelated personnel from approaching. At the same time, immediately report to the superior and take effective measures to block the leakage source. If the leakage is small, it can be adsorbed with inert materials such as sand and vermiculite; if the leakage is large, professional rescue teams need to carry professional equipment to deal with it, and must not act rashly.
The storage and transportation of cyanide is related to human life and environmental safety, and must not be sloppy at all. Practitioners must strictly abide by norms and be cautious in order to ensure the safety of one party.

Cyanyl groups, amino groups, carboxyl groups, etc., have their own effects on the environment and human health, and cannot be ignored.
Cyanyl groups are strong in nature. In the environment, if cyanide is leaked into the water and soil, it can cause malignant changes in the water quality and soil. Aquatic genera, such as fish and shrimp, are difficult to survive in case of it, and the ecological chain is messed up because of it. It is also stained in the air. If people absorb it, it can cause dizziness, nausea, and life-threatening. In the past, there were industrial places, where cyanide management was improper, and the surrounding residents were sick.
Amino groups are essential in living organisms. The structure of proteins, the ginseng of lysine groups. However, in the environment, if an excess of amino compounds accumulate, or cause water enrichment. For example, in rivers, lakes and marshes, there is too much nitrogen (amino-related), algae grow wildly, the water color turns green, the dissolved oxygen in the water body drops suddenly, and organisms such as fish and shrimp die because of it. And some compounds of amino groups may have peculiar smell, pollute the air, and affect the sense of human habitation.
Carboxyl groups have their own states in the environment and human health. In biological metabolism, they are common groups. In the environment, organic acids containing carboxyl groups may affect the degree of soil acid and alkali. Moderate is beneficial to soil fertility, and excessive is caused to soil acidification, harming crops. In the human body, carboxyl groups often exist in food ingredients, such as acetic acid, etc., which can help digestion and be healthy when ingested in moderation. However, if you accidentally eat harmful substances containing carboxyl groups, or cause gastrointestinal discomfort.
As for carbonyl groups, their environmental impact is often associated with organic reactions. Some carbonyl compounds, under conditions such as light, can participate in photochemical reactions, causing air quality to deteriorate, such as the formation of photochemical smog. In the human body, if carbonyl compounds are inhaled or exposed to too much, or irritate the skin and mucous membranes, causing allergies and other diseases.
All these groups are of mixed interest to the environment and human health. When treated with caution, scientific control can ensure the beauty of the environment and the safety of the person.