1 Bromo 5 Iodo 2 Methylbenzene

Ethanol, commonly known as alcohol, is a common organic compound. Its chemical properties are unique and valuable for investigation.
First, ethanol is flammable. In sufficient oxygen, ethanol can burn violently, turning into carbon dioxide and water, and releasing a lot of heat energy. This property makes it often used as a fuel, such as ethanol gasoline, in motor vehicles and other fields. The chemical equation for its combustion is: $C_ {2} H_ {5} OH + 3O_ {2}\ stackrel {ignited }{=\!=\!=} 2CO_ {2} + 3H_ {2} O $.
Second, ethanol can undergo catalytic oxidation reactions. Under the condition of copper or silver catalyst and heating, ethanol can be oxidized by oxygen to acetaldehyde. In this reaction, the hydroxyl group in the ethanol molecule and the hydrogen atom on the connected carbon atom are removed to form acetaldehyde containing aldehyde groups. The chemical equation is: $2C_ {2} H_ {5} OH + O_ {2}\ stackrel {Cu or Ag} {\ underset {\ Delta }{=\!=\!=}} 2CH_ {3} CHO + 2H_ {2} O $.
Third, ethanol can be replaced with active metals such as sodium metal. The hydrogen atom of the hydroxyl group in ethanol has a certain activity and can be replaced by sodium to generate sodium ethanol and hydrogen gas. This reaction is relatively mild and different from the violent reaction of water and sodium. The chemical equation is: $2C_ {2} H_ {5} OH + 2Na = 2C_ {2} H_ {5} ONa + H_ {2}\ uparrow $.
Fourth, ethanol can be esterified with carboxylic acid. Under the condition of concentrated sulfuric acid as a catalyst and heating, ethanol reacts with acetic acid to form ethyl acetate and water. This reaction is a reversible reaction. Concentrated sulfuric acid not only acts as a catalyst, but also acts as a water-absorbing agent to promote the reaction in the direction of ester formation. Its chemical equation is: $CH_ {3} COOH + C_ {2} H_ {5} OH\ underset {\ Delta} {\ overset {concentrated sulfuric acid} {\ rightleftharpoons}} CH_ {3} COOC_ {2} H_ {5} + H_ {2} O $.
The many chemical properties of ethanol make it widely used in many fields such as chemical industry, medicine, food, etc. It is of great significance to human life and industrial production.

To produce ethylamine, there are many common synthesis methods. One is the method of ammonolysis of halogenated hydrocarbons. Taking ethylene halides as an example, they react with ammonia under suitable conditions. The halogen atoms in ethylene halides can be replaced by the amino groups in ammonia to form ethylamine. In this reaction, ammonia needs to be excessive, because halogenated hydrocarbons will continue to react with the generated ethylamine, resulting in the formation of multiple substitution products. The reaction is roughly as follows: When ethylene halides encounter ammonia, the halogen atoms leave, and the nitrogen atoms of ammonia attack the carbon atoms of ethylene halides with their lone pair electrons to form ethylamine and hydrogen halides.
The second is the method of nitrile reduction. Ethylamine can be prepared by reducing cyanoethane. Commonly used reducing Lithium aluminum hydride has strong reducing properties, and can gradually reduce the carbon and nitrogen three bonds in the cyanyl group to obtain ethylamine. In this process, cyanoethane reacts with lithium aluminum hydride in an appropriate solvent, and through a series of electron transfer and bond cleavage and formation, the cyanyl group is converted into an amino group to obtain ethylamine.
The third is the reductive amination method of aldehyde or ketone. Taking acetaldehyde as an example, it first condenses with ammonia to produce imine, and then reduces to obtain ethylamine. In the reduction step, a suitable reducing agent, such as sodium borohydride, can be selected. Acetaldehyde reacts with ammonia, the carbonyl oxygen in the aldehyde combines with the hydrogen of ammonia, dehydrates to form imine, and sodium borohydride provides hydrogen negative ions, which hydrogenates and reduces the carbon and nitrogen double bonds in the imine to form ethylamine. These various methods have their own advantages and disadvantages and applicable scenarios, which need to be selected according to the actual situation.

Alas! Trimethoprim is widely used in organic synthesis. It can be used to prepare antibacterial drugs. Trimethoprim has antibacterial properties and is often used in combination with sulfonamides to increase antibacterial effects. The two are compatible and are widely used in the field of medicine.
In addition, trimethoprim can also be a key intermediate in organic synthesis. Through specific chemical reaction steps, chemists can use its structural characteristics to introduce specific functional groups, and then build more complex organic molecular structures, providing a raw material basis for new drug development, materials science and other fields.
In the chemical synthesis industry, trimethoprim can participate in many reaction pathways due to its unique chemical properties, contributing to the synthesis of compounds with specific properties. In organic synthesis, it is like a delicate tool in the hands of skilled craftsmen, playing a unique role in different scenarios, contributing to the development of various related fields, and promoting technological innovation and product optimization.

Methyl ether is an organic compound. Its molecular formula is $C_2H_6O $, and its structural formula is $CH_3OCH_3 $. The physical properties of methyl ether are quite characteristic.
Looking at its physical state, under room temperature and pressure, methyl ether is gaseous, colorless and has a unique ether odor, with a slightly aromatic taste. Its boiling point is very low, about $-24.9 ^ {\ circ} C $, which makes methyl ether volatile at room temperature and easy to gasify. Compared with the boiling point of water of 100 dollars ^ {\ circ} C $, the boiling point of methyl ether is very different, and the difference is obvious.
In terms of solubility, methyl ether is soluble in water, but its solubility is limited. Although methyl ether contains oxygen atoms, it can form hydrogen bonds with water, but its hydrocarbon group part is large, resulting in its non-strong hydrophilicity. However, methyl ether can be miscible with many organic solvents, such as ethanol and ether, in any ratio. Because methyl ether has a similar structure to this type of organic solvent, according to the principle of "similar miscibility", the two are well miscible.
As for the density, the density of methyl ether in the gaseous state is slightly higher than that of air, about $1.977kg/m ^ 3 $, because the relative molecular mass of methyl ether is greater than the average relative molecular mass of air. The density of methyl ether in the liquid state is about $0.661g/cm ^ 3 $, which is less than the density of water $1g/cm ^ 3 $. If methyl ether coexists with water, methyl ether will float on water.
In addition, methyl ether is flammable, generating a light blue flame when burning, generating carbon dioxide and water. This combustion characteristic makes methyl ether can be used as a fuel and has certain application potential in the energy field. And methyl ether has certain toxicity. Although the toxicity is not high, if inhaled in excess, it can still cause damage to human health, such as irritating the respiratory tract, causing dizziness, fatigue and other symptoms. Therefore, when using methyl ether, it is necessary to pay attention to safety protection, ensure good ventilation, and prevent the accumulation of methyl ether from causing harm.

In "Tiangong Kaiwu", the storage conditions of species B ramie are quite exquisite. After the hemp plant is harvested, it needs to be treated in time. Ramie likes to be cool and moist, and should not be exposed to the hot sun. Therefore, the storage place should be selected in a well-ventilated and cool place to avoid direct sunlight from causing the quality of hemp to deteriorate.
The storage place should be dry and moisture-free. If it is in a humid environment, the ramie is prone to mildew and rot, which will damage its quality. Therefore, it should be selected in a dry place, or in a warehouse, and wooden boards should be laid to keep the ramie off the ground to prevent it from being invaded by moisture.
Furthermore, the storage of ramie also needs to be protected from pests. Common silverfish like to eat ramie, so they can be placed in the ramie with natural insect repellents such as prickly ash and mugwort leaves to repel insects. Or before storage, soak the ramie in lime water and then dry it to prevent insects.
And the ramie should be neatly stacked and not disorderly. In this way, one is easy to ventilate, and the other is easy to check. If there is a change in the quality of the hemp, it can be detected and processed in time.
When storing, you should also pay attention to the change of temperature and humidity. In the hot summer, it is necessary to strengthen ventilation and heat dissipation; in the cold winter, although it is not necessary to deliberately keep warm, it is also necessary to prevent it from being damaged by ice and snow moisture. Such careful storage can obtain high-quality ramie for subsequent textile and other purposes.