3-Bromopropane, also known as 3-bromopropanol, is a colorless to pale yellow liquid. Although it did not have a fine chemical concept like modern times in ancient times, it may have unique uses in traditional crafts and formulas according to its chemical properties. Although it is not detailed in "Tiangong Kaiwu", it can be deduced from its possible uses according to the principles of ancient crafts.
In the field of ancient alchemy and pharmaceutical processing, 3-bromopropane may have applications. Alchemists want to "turn a stone into gold" and often react with various chemical agents. 3-bromopropane has active halogen atoms and can participate in a variety of chemical reactions. If it reacts with certain metal salts, it can change the properties of metal compounds and help alchemists achieve their goals. In pharmaceutical processing, it may be extracted from medicinal materials. Because 3-bromopropane has good solubility to some organic components, it can be used to treat medicinal materials, or to extract active ingredients and increase drug efficacy.
Ancient dyeing processes may also be used. Natural dyes are used in traditional dyeing, and some dyes need to be chemically treated to firmly combine with fabrics. 3-bromopropane may be used as a mordant to assist dyeing. It reacts with dye molecules and fabric fibers to form complexes on the surface of the fibers, making dyeing more uniform, long-lasting, and brighter in color.
Furthermore, in handicrafts such as leather processing, 3-bromopropane may be used as an auxiliary agent. Leather tanning requires chemical treatment to increase leather durability and softness. 3-Bromopropane may participate in the tanning reaction, improve the properties of leather, and make leather more suitable for clothing, shoemaking, etc. Although its name is rarely seen in ancient literature, it is deduced from chemical principles and traditional processes. 3-bromopropane may play an important role in the production and life of the ancients.

3-Bromopropene, also known as allyl bromide, is a commonly used raw material in organic synthesis. Its physical properties are quite unique and are described as follows:
- ** Physical state and color **: Under normal temperature and pressure, 3-bromopropene appears as a colorless to light yellow transparent liquid with a clear appearance and is quite recognizable.
- ** Odor **: This substance emits a relatively strong and pungent smell, which is very obvious and can produce significant stimulation to the olfactory system.
- ** Boiling point **: Its boiling point is about 70-71 ° C. At this temperature, 3-bromopropylene changes from a liquid state to a gaseous state, a property of great significance in the separation and purification process.
- ** Melting point **: The melting point is about -119 ° C, the lower melting point indicates that it is stable in a liquid state at room temperature, and only solidifies at extremely low temperatures.
- ** Density **: The density is greater than that of water, about 1.398g/cm ³. When mixed with water, it will settle at the bottom of the water, a property that is crucial in operations involving liquid-liquid separation.
- ** Solubility **: 3-bromopropene is slightly soluble in water, but can be miscible with most organic solvents, such as ethanol, ether, chloroform, etc. in any ratio. This solubility characteristic allows it to choose a suitable solvent system according to the reaction requirements in organic synthesis to ensure the smooth progress of the reaction.
- ** Volatility **: The substance has a certain degree of volatility and will gradually evaporate into the air in an open environment. Therefore, during storage and use, proper sealing measures need to be taken to prevent its volatilization and dissipation.

3-Bromopropene is an organic compound, and its chemical properties are not stable.
In terms of structure, the carbon atom connected to the bromine atom in 3-bromopropene is allyl carbon. The allyl structure has unique electronic delocalization characteristics, which makes the carbon-bromine bond show a certain activity.
In terms of nucleophilic substitution, 3-bromopropene is prone to nucleophilic substitution because its allyl positive ion intermediate is stable due to electron delocalization. For example, in sodium hydroxide aqueous solution, the hydroxyl negative ion acts as a nucleophilic reagent, which will attack the carbon atom connected to the bromine, and the bromine ion will leave, thus generating 3-hydroxy propene.
In terms of elimination reactions, 3-bromopropene is prone to elimination reactions under the action of strong bases, eliminating hydrogen bromide and generating acrylonne. This is due to the allyl structure that promotes the acidity of beta-hydrogen atoms and is more susceptible to alkali capture.
In addition, 3-bromopropene molecules have carbon-carbon double bonds, which can undergo addition reactions. For example, it can be added to bromine elementals, the double bond is opened, and two bromine atoms are added to the carbon atoms at both ends of the double bond, generating 1,2,3-tribromopropane.
Since 3-bromopropene can undergo both nucleophilic substitution and elimination and addition reactions, it is sufficient to show that its chemical properties are not stable and it exhibits high activity in many chemical reactions.

3-Bromopropene is a commonly used raw material in organic synthesis. During the production process, many key matters need to be carefully paid attention to:
First, safety protection must be comprehensive. 3-Bromopropene is irritating and toxic, and can cause damage to the eyes, respiratory tract and skin. Therefore, during production, operators must strictly follow safety procedures and wear appropriate protective equipment, such as gas masks, protective glasses, chemical-resistant gloves and protective clothing, to prevent contact and inhalation.
Second, precisely control the reaction conditions. The reaction of synthesizing 3-bromopropene is sensitive to conditions such as temperature, pressure, reactant ratio and reaction time. If the temperature is too high or the reaction time is too long, it is easy to cause side reactions to occur and reduce the purity of the product; if the temperature is too low or the reaction time is too short, the reaction will be incomplete and the yield will be affected. Therefore, it is necessary to borrow experimental and production experience to precisely adjust the reaction conditions to achieve the best reaction effect.
Third, pay attention to the quality of raw materials. The purity of raw materials and the content of impurities have a significant impact on the production of 3-bromopropylene. Impurities or abnormal reactions reduce the quality and yield of products. Therefore, when selecting raw materials, it is necessary to strictly control the quality to ensure that it meets the production standards.
Fourth, properly dispose of waste. Waste generated in the production process, such as wastewater, waste gas and waste residue, contains toxic and harmful substances. If not disposed of properly, it will seriously pollute the environment Should be in accordance with environmental requirements, the use of appropriate treatment technology, proper disposal of waste, up to emission standards before discharge.
Fifth, strengthen equipment maintenance and management. The normal operation of production equipment, for the protection of product quality and production safety. Regular inspection, maintenance and maintenance of equipment, timely detection and repair of potential problems, to prevent equipment failure caused by safety accidents and quality problems.
In short, 3-bromopropylene production process, safety, quality, environmental protection and other aspects can not be ignored, need to be strictly controlled in all directions, in order to ensure the smooth progress of production, the output of high-quality products.

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