3-pyridinecarboxaldehyde, 6-chloro-5-fluoro-

3-pentyne, 6-bromo-5-hexene, are all organic compounds with unique physical properties.
3-pentyne, belongs to the alkyne class, and the molecule contains carbon and carbon triple bonds. Under normal conditions, it is mostly colorless liquid, with a certain volatility, unique smell, not very strong. Its density is smaller than that of water, and it will float on the water surface when mixed with water. It is difficult to dissolve in water, because water is a polar molecule, and 3-pentyne is a non-polar molecule. According to the principle of "similar compatibility", the two are insoluble. However, it is soluble in a variety of organic solvents, such as ethanol, ether, benzene, etc. These organic solvents are mostly non-polar or weakly polar, similar in structure to 3-pentyne. The boiling point is about 56 ° C, which is relatively low. It is mainly due to the van der Waals force between molecules, which is weak. When heating up, it is easy to overcome this force and boil.
6-Bromo-5-hexene, the molecule contains carbon double bonds and bromine atoms. The appearance is often colorless to light yellow liquid, with a special odor. The density is greater than that of water, and it will sink to the bottom when mixed with water. It is also difficult to dissolve in water. The reason is similar to 3-pentyne, and its molecular polarity is not strong. Soluble in common organic solvents. The boiling point is affected by the molecular structure. The double bond and bromine atom change the intermolecular force. The specific boiling point varies depending on the precise measurement conditions, and is roughly in a certain temperature range. In addition, due to the carbon-carbon double bond, it is sensitive to light, heat and other conditions, so it should be paid attention to when storing. At the same time, bromine atoms make the substance chemically active and can participate in a variety of chemical reactions.

The chemical properties of 3-pentyne and 6-bromo-5-hexene are as follows:
###3-pentyne
1. ** Addition reaction **:
- ** Addition to halogen **: Addition reaction can occur with bromine water or chlorine gas. If reacted with bromine elemental, the carbon-carbon triple bond in the alkyne is opened, and two bromine atoms are added to the two carbon atoms connected to the triple bond to form the corresponding dibromine substitute. The reaction equation is:\ (CH_ {3} C ≡ CCH_ {2} CH_ {3} + 2Br_ {2}\ longrightarrow CH_ {3} CBr_ {2} CBr_ {2} CH_ {2} CH_ {3}\). This reaction is often used to test for the presence of carbon-carbon triple bonds, and the reaction phenomenon is that the reddish-brown color of bromine water fades.
- ** Addition to hydrogen halide **: Following the Markov rule, when added with hydrogen halide (e.g.\ (HCl\)), hydrogen atoms are added to unsaturated carbon atoms with more hydrogen, and halogen atoms are added to unsaturated carbon atoms with less hydrogen. The first step is to generate 3-chloro-3-pentene. If the amount of hydrogen halide is sufficient, the addition can continue to generate 3,3-dichloropentane. < Br > - ** Addition to hydrogen **: Under the action of a catalyst (such as\ (Pd\),\ (Pt\) or\ (Ni\)), an addition reaction can occur with hydrogen. If the amount of hydrogen is insufficient, the triple bond can be partially hydrogenated to form 3-pentene; if the amount of hydrogen is sufficient, the final formation of pentane.
2. ** Oxidation reaction **:
- ** Oxidation by potassium permanganate **: Under basic or neutral conditions, 3-pentyne is oxidized by potassium permanganate, and the carbon-carbon triple bond is broken to form potassium propionate and potassium acetate. Under acidic conditions, propionic acid and acetic acid are formed, and the purple-red color of the potassium permanganate solution fades away. This reaction can also be used to identify alkynes.
3. ** Polymerization **: Under certain conditions, 3-pentyne can be polymerized, but due to the particularity of its structure, the polymerization reaction is relatively difficult to occur, and the polymer structure formed is more complicated.
##6-bromo-5-hexene
1. ** Addition reaction **:
- ** Addition of carbon-carbon double bonds **:
- Addition reaction occurs with hydrogen under the action of catalyst, the double bond is opened, and hydrogen atoms are added to the carbon atoms at both ends of the double bond to generate 6-bromohexane.
- Addition to halogen elements (such as bromine), bromine atoms are added to the two carbon atoms of the double bond to generate 1,2-dibromo-6-bromohexane, which can fade bromine water and is used to test carbon-carbon double bonds. < Br > - Addition to hydrogen halide, following the Markov rule, hydrogen atoms are added to double-bonded carbon atoms containing more hydrogen, and halogen atoms are added to double-bonded carbon atoms containing less hydrogen, such as addition to\ (HBr\) to generate 1,6-dibromohexane.
2. ** Substitution reaction **:
- ** Substitution of halogen atoms **: The bromine atoms in the molecule can undergo a substitution reaction. Heating in an aqueous solution of sodium hydroxide, the bromine atoms are replaced by hydroxyl groups to generate 6-hydroxy-5-hexene. < Br > - ** Allyl position substitution **: Since the bromine atom is in the allyl position, under light or high temperature conditions, it reacts with halogen elemental substances (such as chlorine), and the hydrogen atom at the allyl position can be replaced by chlorine atoms to generate a variety of chlorine-containing substitution products.
3. ** Oxidation reaction **:
- ** Oxidation of carbon-carbon double bonds **: It can be oxidized by oxidizing agents such as potassium permanganate, and the carbon-carbon double bond is broken. Different oxidation products are generated according to different reaction conditions. For example, alters or ketones may be generated under mild conditions, and carboxylic acids may be generated under strong oxidation conditions. At the same time, the color of the potassium permanganate solution changes, which can be used to identify the structure of olefin

The main uses of 3-pentyne, 6-bromo-5-hexene, are related to many fields.
In the field of organic synthesis, it can be called a key intermediate. Taking 3-pentyne as an example, the unique activity of alkynyl groups makes it possible to participate in various reactions. For example, nucleophilic addition reactions, the π electron cloud density of alkynyl groups is quite high, making it vulnerable to attack by nucleophiles, whereby various functional groups can be introduced to construct complex organic molecules. Chemists can use 3-pentyne to add compounds containing active hydrogen, such as alcohols and amines, to derive new substances with specific properties and functions, which is of great significance in the field of medicinal chemistry. Drug developers often use such reactions to modify the structure of lead compounds to optimize their pharmacological activity and pharmacokinetic properties.
In 6-bromo-5-hexene, bromine atoms coexist with carbon-carbon double bonds, giving them special reactivity. The double bond can be used for addition, polymerization and other reactions, while the bromine atom can be used as a leaving group to participate in nucleophilic substitution. In the field of materials science, this compound may be used to prepare functional polymer materials. Through the polymerization of double bonds, it can be constructed in the main chain or side chain of the polymer, and the bromine atom can be reacted later to introduce other functional groups, giving the material special properties such as fluorescence and conductivity.
In the fine chemical industry, the two also play an important role. They can be used to synthesize fine chemicals such as fragrances and dyes. Taking synthetic fragrances as an example, using the active groups of 3-pentyne and 6-bromo-5-hexene, through multi-step reactions, molecular structures with unique aromas can be constructed to meet the market demand for various characteristic fragrances.
In the field of chemical research, the two are also important research objects. By studying the reaction mechanism and reaction conditions optimization they participate in, researchers can deepen their understanding of the basic theory of organic chemistry, and provide theoretical support and practical experience for the development of new reactions and new synthesis methods.

To prepare 3-pentyne and 6-bromo-5-hexene, the synthesis method is as follows:
Pre-prepare 3-pentyne, which can be obtained by reacting 1-bromopropane with sodium acetylene. Take an appropriate amount of acetylene, use liquid ammonia as a solvent, add sodium amide to obtain sodium acetylene. Then 1-bromopropane is slowly added to this solution, and 3-pentyne can be obtained through nucleophilic substitution reaction. The reaction formula is: HC ≡ CNa + BrCH < unk > CH < unk > CH < unk > HC ≡ C CH < unk > CH < unk > + NaBr.
As for the synthesis of 6-bromo-5-hexene, the conjugate addition reaction of 1,3-butadiene with hydrogen bromide can be performed first. Under appropriate conditions, 1,3-butadiene is added to hydrogen bromide, and 1-bromo-2-butene is mainly obtained. The reaction formula is: CH - CH = CH - CH = CH - + HBr → CH - CH = CH - CHBr - CH.
Then 1-bromo-2-butene and 3-butene-1-ol under alkaline conditions, through nucleophilic substitution reaction, produce 6-bromo-5-hexene. The specific operation is to mix 1-bromo-2-butene and 3-butene-1-ol in alkaline solution, and the target product can be obtained through reaction. The reaction formula is: CH ³ = CH - CHBr - CH
The above synthesis methods can be reasonably designed and operated to obtain the required 3-pentyne and 6-bromo-5-hexene. During operation, attention should be paid to the control of reaction conditions, such as temperature, solvent, and ratio of reactants, to ensure the smooth progress of the reaction and improve the yield and purity of the product.

With three-dimensional, six-dimensional-five-dimensional-water, there is no need to pay attention to it when it is stored.
The first important thing is the environment of existence. Such things are sensitive to the degree and degree of the environment. Three-dimensional should be placed in a dry and refreshing place. If the environment is humid, it is easy to cause oxidation and formation, and it is difficult to cause it. Six-dimensional-five-water should avoid high temperatures. Under high temperatures, its chemical properties or activities, and even there are problems and decomposition, so it should be stored in the common environment, and the building materials of the house should also be corrosion-resistant to prevent the intrusion and leakage of six-dimensional-five-water.
Second, the package is also essential. For the three-year-old package, if you want to buy it, you can use a resistant gold or plastic container, and cover it with a moisture-proof package to prevent the outside world from entering. The six-year-five-water package should not be well sealed, and the container should have a high degree of resistance. Due to the corrosion of the six-year-five-water package, if the package is slightly broken, it must be outside, and it will cause damage to the environment.
On the way, you should not slack off. The three-year-old package should be kept flat, to avoid strong shocks, so as not to be damaged. And there is a moisture-proof and rain-proof package to prevent rain and moisture during the package. Six-five-water, must be used in tanks and tanks, and should be equipped with perfect leakage and emergency equipment, such as adsorption materials, neutralization, etc. It is also subject to environmental protection, familiar with the dangerous characteristics and emergency management methods of six-five-water, and ensure its safety during transportation.

Therefore, it is necessary to store or three-three-three, six-five-water, and be careful, and there should be no negligence in the environment, packaging, and transportation to ensure the safety of these materials.