Introduction: The rise and importance of green solvents
In the context of increasing global environmental awareness today, organic solvents used in the traditional chemical industry are gradually being replaced by more environmentally friendly and sustainable alternatives. Although traditional organic solvents such as methane and dichloromethane have excellent properties in many chemical reactions and industrial processes, they often have disadvantages such as high toxicity, volatileness, and harmful to the environment and human health. With people's emphasis on environmental protection and sustainable development, the development of new green solvents has become a common pursuit in the chemical and industrial circles.
Green solvents refer to those that are environmentally friendly, harmless to the human body, biodegradable or easy to recycle. They not only reduce environmental pollution, but also improve the safety and economic benefits of the production process. In recent years, with the popularization of green chemistry concepts, more and more researchers and enterprises have begun to pay attention to the research and development and application of green solvents. Among them, the green solvent system based on 2-propyliimidazole (2-PIM) has gradually become a research hotspot due to its unique physical and chemical properties and extensive industrial application prospects.
2-propylimidazole, as an organic compound, has good solubility and thermal stability, and its derivatives can be modified by simple chemical reactions, thereby giving it more functional properties. A green solvent system based on 2-propylimidazole can not only replace traditional organic solvents, but also exhibit superior performance in certain specific industrial fields. This article will introduce in detail the design principles, preparation methods, performance characteristics and their applications in multiple industrial fields of 2-propylimidazole green solvent system, aiming to provide readers with a comprehensive and in-depth understanding.
2-Basic Structure and Characteristics of Propyliimidazole
2-Propylimidazole (2-PIM, referred to as 2-PIM) is an organic compound containing imidazole ring and propyl side chain, and its molecular formula is C7H11N2. The imidazole ring is a five-membered heterocycle containing two nitrogen atoms, and this structure imparts the unique physicochemical properties of 2-propyliimidazole. Specifically, the nitrogen atoms in the imidazole ring have certain basicity and hydrophilicity, while the propyl side chain imparts certain hydrophobicity to the compound. This amphiphilic characteristic makes 2-propylimidazole have good solubility in various solvents, which can be dissolved in polar solvents or exhibit a certain solubility in non-polar solvents.
2-Physical Properties of Propylimidazole
| Physical Properties | parameters |
|---|---|
| Molecular Weight | 123.18 g/mol |
| Density | 0.95 g/cm³ (20°C) |
| Melting point | -45°C |
| Boiling point | 168°C (760 mmHg) |
| Refractive index | 1.48 (20°C) |
| Flashpoint | 61°C |
| Water-soluble | Sluble in water, solubility is about 10 g/L (25°C) |
From the table above, it can be seen that 2-propylimidazole has a low melting point and a moderate boiling point, which is suitable for use at room temperature. Its density is slightly smaller than water, so a stratification phenomenon can be formed in the mixture. In addition, the high flash point of 2-propylimidazole indicates that it is relatively safe during storage and transportation and is not prone to fire. These physical properties make 2-propylimidazole have high stability and safety in industrial applications.
Chemical properties of 2-propylimidazole
The chemical properties of 2-propyliimidazole are mainly determined by the imidazole ring and the propyl side chain. The two nitrogen atoms in the imidazole ring make it have a certain alkalinity and can undergo a protonation reaction under acidic conditions. In addition, imidazole rings can also form complexes with metal ions as ligands, a property that is widely used in catalytic reactions and materials science. The propyl side chain imparts a certain hydrophobicity of 2-propylimidazole, making it show good selectivity during organic synthesis and separation.
Another important feature of 2-propylimidazole is its thermal stability. Studies have shown that 2-propylimidazole can maintain a stable chemical structure at high temperatures and will not undergo decomposition or polymerization. This characteristic makes it have a wide range of application prospects in high-temperature reaction systems, especially in industrial processes that require high-temperature operation, such as petroleum refining, chemical synthesis, etc.
In addition, 2-propylimidazole also has good oxidation resistance and corrosion resistance. It can remain stable in acidic, alkaline and neutral environments and is not easily oxidized or corroded. This characteristic makes 2-propylimidazole also has potential application value in some special environments (such as marine engineering, aerospace, etc.).
Design of green solvent system based on 2-propyliimidazole
The design of green solvent system based on 2-propyliimidazole is an important research direction in the field of green chemistry in recent years. 2-propylimidazole itself has good solubility and thermal stability, but to further improve its performance in industrial applications, the researchers have developed a variety of 2-propylene based on 2-propylene by introducing different functional groups or combining with other compounds. Green solvent system for kimidazole. These solvent systems not only retain the advantages of 2-propylimidazole, but also show significant advantages in solubility, selectivity, and recyclability.
1. Modification strategies for introducing functional groups
By modifying the functional group of 2-propyliimidazole, its physicochemical properties can be changed, thereby optimizing its properties as a solvent. Common functional groups include hydroxyl groups, carboxyl groups, sulfonic acid groups, amino groups, etc. The introduction of these functional groups can enhance the polarity or hydrophilicity of 2-propylimidazole, thereby improving its solubility in polar solvents. For example, by introducing hydroxyl groups on the propyl side chain of 2-propyliimidazole, its solubility in water can be significantly improved, making it suitable for aqueous phase reaction systems.
| Featured Group | Modified characteristics | Application Fields |
|---|---|---|
| Hydroxy (-OH) | Improve polarity and hydrophilicity, enhance water solubility | Aqueous phase reaction, biochemistry |
| Carboxylic (-COOH) | Enhance acidity and chelation abilities | Metal extraction, catalyst support |
| Sulphonic acid group (-SO₃H) | Improving ion exchange capability and conductivity | Electrolyte and membrane separation |
| Amino (-NH₂) | Enhance alkalinity and coordination capabilities | Complex synthesis, drug delivery |
2. Combination with ionic liquid
Ionic Liquids (ILs) are a type of liquid composed entirely of cations and anions, with the advantages of low volatility, wide liquid range, good thermal stability and adjustable solubility. In recent years, ionic liquids have received widespread attention in the field of green solvents due to their unique properties. By combining 2-propylimidazole with ionic liquid, a new green solvent system with both advantages can be developed.
Taking 1-ethyl-3-methylimidazole tetrafluoroborate ([EMIM][BF₄]) as an example, after mixing it with 2-propyliimidazole, the composite solvent system formed not only retains 2 -The solubility and thermal stability of -propylimidazole also inherit the low volatility and wide liquid range characteristics of ionic liquids. This composite solvent system has excellent performance in the fields of organic synthesis, catalytic reactions and material processing, especially under high temperature and high pressure conditions, which can effectively reduce the reaction temperature and improve the reaction efficiency.
3. Combination with deep eutectic solvent
Deep Eutectic Solvents (DESs) are composed of two or more components through hydrogen bonds or other weak interactionsThe eutectic mixture formed. Similar to ionic liquids, deep eutectic solvents also have low volatility, good solubility and adjustable physicochemical properties. By combining 2-propylimidazole with common deep eutectic solvent components (such as choline chloride, urea, etc.), a green solvent system with unique properties can be developed.
For example, after mixing 2-propylimidazole with choline chloride in a certain proportion, the deep eutectic solvent system formed is liquid at room temperature, with low viscosity and high conductivity. This solvent system exhibits excellent properties in electrochemical reactions, battery electrolytes and catalytic reactions, and is especially suitable for situations where high conductivity and low viscosity are required.
4. Synergistic effects with other green solvents
In addition to combining with ionic liquids and deep eutectic solvents, 2-propylimidazole can also be mixed with other green solvents (such as glycerol, ethylene glycol, etc.) to form a solvent system with synergistic effects. By reasonably selecting the proportion of different solvents, the solubility, selectivity and recyclability of the solvent system can be optimized. For example, after mixing 2-propylimidazole with a certain proportion, the formed solvent system exhibits good solubility in both polar solvents and non-polar solvents, and is suitable for a variety of organic synthesis reactions.
Method for preparing 2-propyliimidazole green solvent system
The preparation method of 2-propyliimidazole green solvent system can be adjusted according to different application scenarios and requirements. The following are several common preparation methods, covering a variety of technical means from simple mixing to complex synthesis.
1. Direct mixing method
Direct mixing method is a simple and commonly used preparation method. This method forms a uniform solvent system by physically mixing 2-propylimidazole with other solvents or additives in a certain proportion. The advantage of this method is that it is easy to operate, low cost, and is suitable for large-scale industrial production. However, the limitation of the direct mixing method is that the properties of the resulting solvent system may be affected by the interactions between the components and it is difficult to achieve precise regulation.
Step:
- Select solvent components: Select appropriate solvents or additives according to the target application, such as ionic liquids, deep eutectic solvents, etc.
- Determine the ratio: Determine the optimal mixing ratio of each component based on experimental or literature data.
- Mixing and stirring: Add each component to the reaction vessel in turn, and mix it thoroughly with a magnetic stirrer or a mechanical stirrer to ensure that the components are evenly dispersed.
- Detection Performance: Evaluate the performance of the solvent system through physical and chemical analysis (such as density, viscosity, solubility tests) and adjust it as needed.
2. Chemical synthesis method
Chemical synthesis method refers to combining 2-propylimidazole with other compounds through chemical reactions to generate a green solvent with a specific structure and function. This method can accurately control the chemical composition and physical properties of the solvent and is suitable for application scenarios where customized solvents are required. Common chemical synthesis methods include esterification reaction, amidation reaction, sulfonation reaction, etc.
Step:
- Select reaction substrate: Select appropriate reaction substrates according to the properties of the target solvent, such as carboxylic acids, sulfonic acids, amino acids, etc.
- Design reaction routes: Design a reasonable reaction route according to the properties of the reaction substrate to ensure mild reaction conditions and high product purity.
- Processing the reaction: Carry out the reaction under appropriate temperature, pressure and catalyst conditions to ensure that the reaction is carried out completely.
- Separation and purification: Separation and purification of the product by distillation, crystallization, column chromatography and other methods to ensure the purity and stability of the solvent.
- Property Test: Perform physical and chemical performance tests on the synthetic solvents to evaluate their solubility, thermal stability, selectivity and other key indicators.
3. Preparation of deep eutectic solvents
The preparation of deep eutectic solvents is usually prepared by low-temperature melting or blending. Low temperature melting method refers to mixing two or more components at low temperatures to form a low eutectic mixture. The blending method is to mix each component at room temperature or heating conditions to form a uniform solvent system. The preparation method of deep eutectic solvent is relatively simple, but attention is needed to be paid to the interaction between the components to ensure that the resulting solvent system has good physical and chemical properties.
Step:
- Select components: Select appropriate deep eutectic solvent components according to the target application, such as choline chloride, urea, lactic acid, etc.
- Determine the ratio: Determine the best molar ratio of each component based on literature data or experimental results.
- Mixed and melted: Add the components to the reaction vessel in proportion, heat to the appropriate temperature (usually below 100°C), and stir until a uniform liquid is formed.
- Cooling and Curing: The melted solvent system is slowly cooled to room temperature to form a stable deep eutectic solvent.
- Performance Test: Physical and chemical properties of the prepared deep eutectic solvent are tested to evaluate its solubility, conductivity, thermal stability and other key indicators.
4. Preparation of ionic liquids
The preparation of ionic liquids usually uses ion exchange method or direct synthesis method. Ion exchange method refers to converting one ionic liquid into another ionic liquid through an ionic exchange resin. The direct synthesis rule is to react cations and anionic precursors under appropriate conditions to generate target ionic liquid. The preparation method of ionic liquids is relatively complex, but it can accurately control its chemical composition and physical properties, and is suitable for application scenarios where high-performance solvents are needed.
Step:
- Select precursor: Select appropriate cationic and anionic precursors according to the properties of the target ionic liquid, such as imidazole, quaternary ammonium salt, tetrafluoroborate, etc.
- Design reaction routes: Design a reasonable reaction route according to the properties of the precursor to ensure mild reaction conditions and high product purity.
- Processing the reaction: Carry out the reaction under appropriate temperature, pressure and catalyst conditions to ensure that the reaction is carried out completely.
- Separation and purification: Separation and purification of the product by distillation, recrystallization, column chromatography and other methods to ensure the purity and stability of the ionic liquid.
- Property Test: Perform physical and chemical performance tests on the synthetic ionic liquid to evaluate its solubility, thermal stability, electrical conductivity and other key indicators.
Property characteristics of 2-Propylimidazole green solvent system
The reason why the 2-propylimidazole green solvent system has received widespread attention is mainly because of its excellent performance in solubility, selectivity, thermal stability and recyclability. These performance characteristics not only make them perform well in a variety of industrial applications, but also provide new ideas and directions for the development of green chemistry.
1. Solubility
2-propylimidazole green solvent system has wide solubility and can dissolve a variety of organic compounds, inorganic salts and polymers. This is due to the amphiphilic structure of the 2-propylimidazole itself and the special chemical environment formed by modification or combination with other solvents. Specifically, the imidazole ring of 2-propylimidazole imidates it with certain polarity, allowing it to dissolve in polar solvents; while the propyl side chain imidates it with certain hydrophobicity, giving it with certain non-polarity It can also show good dissolution ability in the solvent.
| Dissolved objects | Solution |
|---|---|
| Organic compounds (such as aromatic hydrocarbons, aliphatic hydrocarbons, ketones, esters, etc.) | Good |
| Inorganic salts (such as sodium chloride, copper sulfate, silver nitrate, etc.) | Medium |
| Polymers (such as polyethylene, polypropylene, polyurethane, etc.) | Limited |
| Bio macromolecules (such as proteins, nucleic acids, etc.) | Poor |
Study shows that the solubility of the 2-propyliimidazole green solvent system can be significantly improved by introducing different functional groups or combining with other solvents. For example, after combining 2-propylimidazole with ionic liquid or deep eutectic solvent, the resulting solvent system exhibits good dissolution ability in both polar solvents and non-polar solvents, and is suitable for a variety of organic synthesis reactions and materials Processing process.
2. Selectivity
2-propylimidazole green solvent system performs excellent in selectivity and is able to preferentially dissolve or extract specific compounds in complex reaction systems. This is due to its unique chemical structure and physical properties. Specifically, the imidazole ring of 2-propylimidazole has a certain basicity and coordination ability, and can form a stable complex with acidic compounds or metal ions; while the propyl side chain imparts a certain hydrophobicity, Hydrophilic compounds can be dissolved preferentially.
| Selective Object | Selective |
|---|---|
| Acidic compounds (such as carboxylic acids, phenols, etc.) | High |
| Metal ions (such as iron, copper, zinc, etc.) | Medium |
| Hyperophobic compounds (such as aliphatic hydrocarbons, aromatic hydrocarbons, etc.) | High |
| Polar compounds (such as alcohols, amines, etc.) | Limited |
Selectivity is of great significance in industrial applications, especially during isolation and purification. For example, during petroleum refining, the 2-propylimidazole green solvent system can selectively extract light hydrocarbons to improve the purity and quality of the product; during metal extraction, the 2-propylimidazole green solvent system can selectively extract light hydrocarbons to improve the purity and quality of the product; during metal extraction, the 2-propylimidazole green solvent system can selectively Extract specific metal ions, reduce production costs and improve resource utilization.
3. Thermal Stability
2-propylimidazole green solvent system has good thermal stability and can maintain a stable chemical structure under high temperature conditions andPhysical properties. This is due to the thermal stability of the 2-propylimidazole itself and the special chemical environment formed by modification or combination with other solvents. Specifically, the imidazole ring of 2-propylimidazole has high thermal stability and can maintain a complete ring structure at high temperature; while the propyl side chain gives it a certain flexibility and can resist it at high temperature. Thermal decomposition and polymerization reaction.
Study shows that the thermal stability of the 2-propyliimidazole green solvent system at high temperature is closely related to its chemical structure. For example, by introducing functional groups such as carboxyl or sulfonic acid groups, their thermal stability can be further improved and they remain stable at higher temperatures. In addition, after combining 2-propylimidazole with ionic liquid or deep eutectic solvent, the thermal stability of the resulting solvent system at high temperature has also been significantly improved, and is suitable for high-temperature reaction systems and high-temperature processing processes.
4. Recyclability
2-propylimidazole green solvent system has good recyclability and can maintain high performance after multiple uses. This is due to its unique chemical structure and physical properties. Specifically, the imidazole ring of 2-propylimidazole has high chemical stability and corrosion resistance, and can maintain a stable chemical structure in various environments; while the propyl side chain gives it a certain hydrophobicity. It can effectively prevent the solvent from being contaminated or degraded during use.
Study shows that the recyclability of the 2-propyliimidazole green solvent system is closely related to its chemical structure and use conditions. For example, in the organic synthesis process, the 2-propylimidazole green solvent system can be recovered by simple distillation or filtration, and the recovery rate can reach more than 90%; in electrochemical reactions, the 2-propylimidazole green solvent system can be recovered by simple distillation or filtration method, and the recovery rate can be up to more than 90%. In electrochemical reactions, the 2-propylimidazole green solvent system can be Recovery by electrolysis or adsorption method can reach more than 80%. In addition, after combining 2-propylimidazole with ionic liquid or deep eutectic solvent, the recoverability of the resulting solvent system has also been significantly improved and is suitable for industrial processes that require multiple uses.
2-Industrial Application of Propyliimidazole Green Solvent System
2-propylimidazole green solvent system has shown wide application prospects in many industrial fields due to its excellent solubility, selectivity, thermal stability and recyclability. The following will introduce its specific applications in the fields of organic synthesis, catalytic reactions, material processing, energy storage and environmental restoration.
1. Organic synthesis
In the field of organic synthesis, the 2-propylimidazole green solvent system has become an ideal solvent for many reactions due to its good solubility and selectivity. Although traditional organic solvents such as methane and dichloromethane show excellent properties in some reactions, they often have the disadvantages of being highly toxic, volatile, and harmful to the environment. In contrast, the 2-propylimidazole green solvent system can not only replace these traditional solvents, but also exhibit superior performance in certain specific reactions.
For example, in Friedel-Crafts alkylation reaction, 2-Propylimidazole green solvent system can selectively dissolve aromatic hydrocarbons and alkyl halides, promote the progress of the reaction, and avoid environmental pollution problems caused by traditional solvents. In addition, in the Diels-Alder reaction, the 2-propylimidazole green solvent system can effectively dissolve the conjugated diene and dienophile, improving the selectivity and yield of the reaction. Studies have shown that using 2-propyliimidazole green solvent system for organic synthesis can not only improve the reaction efficiency, but also significantly reduce the generation of by-products and reduce production costs.
2. Catalytic reaction
2-propylimidazole green solvent system also performs well in catalytic reactions, especially in the fields of homogeneous and heterogeneous catalysis. The nitrogen atoms in the imidazole ring have a certain basicity and coordination ability, and can form stable complexes with metal ions as catalyst support or cocatalysts. In addition, the solubility and selectivity of the 2-propyliimidazole green solvent system also help to improve the activity and selectivity of the catalyst and promote the progress of the reaction.
For example, in a palladium-catalyzed cross-coupling reaction, the 2-propylimidazole green solvent system can selectively dissolve substrates and catalysts to facilitate the progress of the reaction while avoiding the toxicity and volatility brought by traditional solvents. question. In addition, in the gold-catalyzed alkyne addition reaction, the 2-propylimidazole green solvent system can effectively dissolve gold nanoparticles, improve the activity and stability of the catalyst, and extend the service life of the catalyst. Studies have shown that using 2-propylimidazole green solvent system for catalytic reactions can not only improve the reaction efficiency, but also significantly reduce the amount of catalyst and reduce production costs.
3. Material processing
2-propylimidazole green solvent system is also widely used in the field of material processing, especially in polymer processing, coating and film preparation. Due to its good solubility and selectivity, the 2-propyliimidazole green solvent system can effectively dissolve a variety of polymers and form a uniform solution or suspension, which facilitates subsequent processing and molding. In addition, the thermal stability and recyclability of the 2-propylimidazole green solvent system also help improve the quality and performance of the material and reduce production costs.
For example, in the preparation of polyurethane foam, the 2-propylimidazole green solvent system can effectively dissolve the polyurethane prepolymer, promote the dispersion of the foaming agent and the formation of bubbles, and improve the uniformity and porosity of the foam. In addition, during the coating and film preparation process, the 2-propylimidazole green solvent system can effectively dissolve the coating or film material, form a uniform coating or film, and improve the adhesion and durability of the material. Research shows that using 2-propyliimidazole green solvent system for material processing can not only improve the quality and performance of the material, but also significantly reduce the use of solvents and reduce environmental pollution.
4. Energy Storage
2-propylimidazole green solvent system also has important applications in the field of energy storage, especially in battery electrolytes and supercapacitor electrolytes.Due to its good solubility and conductivity, the 2-propylimidazole green solvent system can effectively dissolve the electrolyte salt, form a stable electrolyte solution or electrolyte, and promote the transport of ions and charges. In addition, the thermal stability and recyclability of the 2-propylimidazole green solvent system also help improve the performance and life of batteries and supercapacitors and reduce production costs.
For example, in lithium-ion batteries, the 2-propylimidazole green solvent system can effectively dissolve lithium salts, form a stable electrolyte, promote the transfer of lithium ions and charge, and improve the charging and discharging efficiency and circulation of the battery. life. In addition, in supercapacitors, the 2-propylimidazole green solvent system can effectively dissolve the electrolyte salt, form a stable electrolyte, promote the transfer of ions and charges, and improve the energy density and power density of the supercapacitor. Research shows that using 2-propylimidazole green solvent system for energy storage can not only improve the performance and life of batteries and supercapacitors, but also significantly reduce the use of electrolyte and reduce environmental pollution.
5. Environmental Repair
2-propylimidazole green solvent system also has important applications in the field of environmental restoration, especially in the restoration of heavy metal-contaminated soil and water bodies. Due to its good solubility and selectivity, the 2-propylimidazole green solvent system can effectively extract and remove heavy metal ions in soil and water, reducing environmental pollution. In addition, the thermal stability and recyclability of the 2-propylimidazole green solvent system also help improve the repair effect and reduce the repair cost.
For example, during the repair process of heavy metal contaminated soil, the 2-propylimidazole green solvent system can effectively extract heavy metal ions in the soil, such as lead, cadmium, mercury, etc., reduce the heavy metal content of the soil, and restore the soil ecology Function. In addition, during the repair of heavy metal contaminated water bodies, the 2-propylimidazole green solvent system can effectively remove heavy metal ions in the water body, reduce the heavy metal content of the water body, and protect the aquatic ecosystem. Research shows that using 2-propylimidazole green solvent system for environmental restoration can not only improve the repair effect, but also significantly reduce the repair cost and reduce environmental pollution.
Conclusion and Outlook
To sum up, the green solvent system based on 2-propylimidazole has shown wide application prospects in many industrial fields due to its excellent solubility, selectivity, thermal stability and recyclability. Whether it is organic synthesis, catalytic reaction, material processing, energy storage and environmental restoration, the 2-propylimidazole green solvent system has performed well, which can effectively replace traditional organic solvents, reduce environmental pollution, improve production efficiency and economic benefits.
However, although significant progress has been made in the 2-propylimidazole green solvent system, there are still some challenges and room for improvement. First of all, how to further optimize its solubility and selectivity to adapt to more complex industrial application scenarios is still an urgent problem. Secondly, how to reduce costs and increase its large scaleThe feasibility of industrial production is also the focus of future research. In addition, with the continuous improvement of environmental protection requirements, how to further improve its recyclability and biodegradability will also become an important direction for future research.
Looking forward, with the continuous deepening of green chemistry concepts and technological advancements, green solvent systems based on 2-propylimidazole are expected to be widely used in more fields. We look forward to more scientific researchers and enterprises being able to invest in research and development in this field, jointly promote the development of green chemistry, and contribute to the realization of sustainable development.
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