Isobutyl-2-methylimidazole: Background and current research status
Isobutyl-2-methylimidazole (1-Isobutyl-2-methylimidazole, referred to as IBMI) is an organic compound with unique structure and properties, belonging to the imidazole compound family. Due to its excellent chemical stability and unique physical properties, imidazole compounds have shown wide application prospects in many fields. However, due to its complex synthesis, high cost and potential environmental impact, research on its alternatives has gradually become a hot topic in recent years.
First, let's understand the basic structure of IBM. The molecular formula of IBMI is C9H14N2 and the molecular weight is 150.22 g/mol. It consists of an imidazole ring and two substituents: one isobutyl and the other is methyl. This structure imparts good solubility, thermal stability and chemical inertia to IBM, making it outstanding in areas such as catalysis, separation and materials science.
However, while IBM has many advantages, it also has some problems. For example, its synthesis process involves multiple steps, resulting in higher production costs; in addition, IBM may have adverse environmental impacts in some applications, such as poor biodegradability and may be toxic to aquatic organisms. Therefore, finding an alternative that can maintain IBM's excellent performance and overcome its shortcomings has become the focus of scientific researchers.
In recent years, domestic and foreign scholars have made significant progress in research on IBM alternatives. These studies focus not only on the development of new compounds, but also on improving the synthesis of existing compounds, optimizing their performance, and evaluating their environmental friendliness. Next, we will detail several potential IBMI alternatives and explore their potential applications in the environmental protection field.
Substitute 1: 1-ethyl-3-methylimidazole tetrafluoroborate
Chemical structure and physical properties
1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF4 for short) is a common ionic liquid with an imidazole ring structure similar to IBMI. Its molecular formula is C6H11BF4N2 and its molecular weight is 191.07 g/mol. The big feature of EMIM-BF4 is its ionic conductivity in liquid state, which makes it perform well in many applications.
| parameters | 1-ethyl-3-methylimidazole tetrafluoroborate (EMIM-BF4) |
|---|---|
| Molecular formula | C6H11BF4N2 |
| Molecular weight | 191.07 g/mol |
| Density | 1.38 g/cm³ |
| Melting point | -78°C |
| Boiling point | >300°C |
| Viscosity | 40 mPa·s (25°C) |
| Conductivity | 7.2 mS/cm (25°C) |
As can be seen from the table, EMIM-BF4 has a lower melting point and a higher boiling point, which means it remains liquid over a wide temperature range and is suitable for a variety of industrial processes. In addition, its viscosity is moderate and its conductivity is high, making it potentially useful in electrolytes, catalyst support, etc.
Synthetic method and process flow
The synthesis of EMIM-BF4 is relatively simple and is usually carried out by a two-step method. The first step is to synthesize 1-ethyl-3-methylimidazole chloride (EMIM-Cl), and the second step is to replace the chloride ions with tetrafluoroborate ions (BF4-) through ion exchange reaction. The specific steps are as follows:
- Synthetic EMIM-Cl: 1-methylimidazole and 1-bromoethane were mixed under anhydrous conditions, heated to reflux, and EMIM-Cl was obtained after several hours of reaction.
- Ion Exchange: EMIM-Cl and sodium tetrafluoroborate (NaBF4) were mixed in water, stirred and filtered to obtain pure EMIM-BF4.
The advantages of this synthesis method are that the raw materials are easy to obtain, the reaction conditions are mild, the yield is high, and the by-products are easy to handle, which is suitable for large-scale industrial production.
Performance Advantages and Disadvantages
EMIM-BF4, as a replacement for IBM, has the following significant advantages:
- Excellent thermal stability: The decomposition temperature of EMIM-BF4 is much higher than that of IBM, and can remain stable in a high-temperature environment. It is suitable for high-temperature reaction systems.
- Good solubility: EMIM-BF4 can dissolve a variety of organic and inorganic substances, especially insoluble polar compounds, which makes it excellent in extraction, separation and catalytic reactions.
- Low Volatility: EMI compared to traditional organic solventsM-BF4 is almost non-volatile, reducing safety hazards and environmental pollution during operation.
However, EMIM-BF4 also has some shortcomings:
- High cost: Although the synthesis method is relatively simple, the price of tetrafluoroborate is relatively high, resulting in the production cost of EMIM-BF4.
- Poor biodegradability: Studies have shown that EMIM-BF4 is difficult to be degraded by microorganisms in the natural environment, which may have long-term impact on the ecosystem.
Substitute 2: 1-hexyl-3-methylimidazole hexafluorophosphate
Chemical structure and physical properties
1-Hexyl-3-methylimidazolium hexafluorophosphate (HMIM-PF6 for short) is another ionic liquid with an imidazole ring structure. Its molecular formula is C9H16PF6N2 and its molecular weight is 289.24 g/mol. Similar to EMIM-BF4, HMIM-PF6 also has excellent thermal stability and chemical inertness, but performs better in some aspects.
| parameters | 1-hexyl-3-methylimidazole hexafluorophosphate (HMIM-PF6) |
|---|---|
| Molecular formula | C9H16PF6N2 |
| Molecular Weight | 289.24 g/mol |
| Density | 1.42 g/cm³ |
| Melting point | -60°C |
| Boiling point | >300°C |
| Viscosity | 55 mPa·s (25°C) |
| Conductivity | 5.8 mS/cm (25°C) |
As can be seen from the table, the melting point of HMIM-PF6 is slightly lower than that of EMIM-BF4, but has a slightly higher viscosity and a lower conductivity. This suggests that HMIM-PF6 may require higher temperatures or longer to achieve optimal results in certain applications.
Synthetic method and process flow
The synthesis method of HMIM-PF6 is similar to EMIM-BF4, and is also carried out through a two-step method. The first step is to synthesize 1-hexyl-3-methylimidazole chloride (HMIM-Cl), and the second step is to replace the chloride ions with hexafluorophosphate ions (PF6-) through ion exchange reaction. The specific steps are as follows:
- Synthetic of HMIM-Cl: 1-methylimidazole and 1-bromohexane were mixed under anhydrous conditions, heated to reflux, and after several hours of reaction, HMIM-Cl was obtained.
- ion exchange: HMIM-Cl and potassium hexafluorophosphate (KPF6) were mixed in water, stirred and filtered to obtain pure HMIM-PF6.
The advantages of this synthesis method are that the raw materials are easy to obtain, the reaction conditions are mild, the yield is high, and the by-products are easy to handle, which is suitable for large-scale industrial production.
Performance Advantages and Disadvantages
HMIM-PF6, as a replacement for IBM, has the following significant advantages:
- Higher thermal stability: The decomposition temperature of HMIM-PF6 is higher than that of EMIM-BF4, and can remain stable in extreme high temperature environments, suitable for a wider range of industrial applications.
- Best solubility: HMIM-PF6 is able to dissolve more organic and inorganic substances, especially non-polar compounds, which makes it excellent in extraction, separation and catalytic reactions.
- Lower toxicity: Studies have shown that HMIM-PF6 is less toxic and has less harm to the human body and the environment.
However, HMIM-PF6 also has some shortcomings:
- Higher cost: The price of hexafluorophosphate is higher than that of tetrafluoroborate, resulting in a further increase in the production cost of HMIM-PF6.
- Biodegradability still needs to be improved: Although HMIM-PF6 is low in toxicity, its biodegradability is still poor, which may have long-term impact on the ecosystem.
Substitute 3: 1-butyl-3-methylimidazole chloride
Chemical structure and physical properties
1-Butyl-3-methylimidazolium chloride (BMIM-Cl for short) is a common ionic liquid with an imidazolium ring structure similar to IBMI. Its molecular formula is C8H15ClN2 and its molecular weight is 182.67 g/mol. The big feature of BMIM-Cl is its low cost and synthesisability, which makes it economical advantage in many applications.
| parameters | 1-butyl-3-methylimidazole chloride (BMIM-Cl) |
|---|---|
| Molecular formula | C8H15ClN2 |
| Molecular Weight | 182.67 g/mol |
| Density | 1.36 g/cm³ |
| Melting point | -21°C |
| Boiling point | >300°C |
| Viscosity | 35 mPa·s (25°C) |
| Conductivity | 6.5 mS/cm (25°C) |
It can be seen from the table that BMIM-Cl has a low melting point, moderate viscosity and high conductivity, and is suitable for a variety of industrial processes. In addition, BMIM-Cl has a low cost and is suitable for large-scale industrial production.
Synthetic method and process flow
The synthesis method of BMIM-Cl is very simple and is usually carried out in one-step method. The specific steps are as follows:
- Synthetic of BMIM-Cl: 1-methylimidazole and 1-bromobutane were mixed under anhydrous conditions, heated to reflux, and BMIM-Cl was directly obtained after several hours of reaction.
The advantages of this synthesis method are that the raw materials are easy to obtain, the reaction conditions are mild, the yield is high, and there is no need for complicated post-treatment steps, which is suitable for large-scale industrial production.
Performance Advantages and Disadvantages
BMIM-Cl, as a replacement for IBM, has the following significant advantages:
- Low Cost: The synthetic raw materials of BMIM-Cl are cheap, the synthesis method is simple, and the production cost is much lower than that of other ionic liquids. They are suitable for large-scale applications.
- Good solubility: BMIM-Cl is able to dissolve a variety of organic and inorganic substances, especially in the extraction and separation of polar compounds.
- Higher Conductivity: BMIM-Cl has a high conductivity and is suitable for electrolytes, catalyst carriers and other applications.
However, BMIM-Cl also has some shortcomings:
- Poor thermal stability: The decomposition temperature of BMIM-Cl is low and is not suitable for use in high temperature environments.
- Poor biodegradability: Studies have shown that BMIM-Cl is difficult to be degraded by microorganisms in the natural environment, which may have long-term impact on the ecosystem.
Substitute 4: 1-propyl-3-methylimidazole acetate
Chemical structure and physical properties
1-Propyl-3-methylimidazolium acetate (PMIM-Ac for short) is an ionic liquid with an imidazole ring structure. Its molecular formula is C8H15O2N2 and its molecular weight is 183.22 g/mol. The major feature of PMIM-Ac is its good biodegradability, which makes its application in the field of environmental protection great potential.
| parameters | 1-Propyl-3-methylimidazole acetate (PMIM-Ac) |
|---|---|
| Molecular formula | C8H15O2N2 |
| Molecular Weight | 183.22 g/mol |
| Density | 1.18 g/cm³ |
| Melting point | -25°C |
| Boiling point | >300°C |
| Viscosity | 30 mPa·s (25°C) |
| Conductivity | 4.2 mS/cm (25°C) |
It can be seen from the table that PMIM-Ac has a low melting point, moderate viscosity and low conductivity, and is suitable for a variety of industrial processes. In addition, PMIM-Ac has good biodegradability and is suitable for use in the environmental protection field.
Synthetic method and process flow
The synthesis method of PMIM-Ac is relatively simple and is usually carried out by a two-step method. The first step is to synthesize 1-propyl-3-methylimidazole chloride (PMIM-Cl), the second step isIt is to replace chloride ions with acetate ions (Ac-) through ion exchange reaction. The specific steps are as follows:
- Synthetic PMIM-Cl: 1-methylimidazole and 1-bromopropane were mixed under anhydrous conditions, heated to reflux, and PMIM-Cl was obtained after several hours of reaction.
- ion exchange: PMIM-Cl and sodium acetate (NaAc) were mixed in water, stirred and filtered to obtain pure PMIM-Ac.
The advantages of this synthesis method are that the raw materials are easy to obtain, the reaction conditions are mild, the yield is high, and the by-products are easy to handle, which is suitable for large-scale industrial production.
Performance Advantages and Disadvantages
PMIM-Ac, as a replacement for IBM, has the following significant advantages:
- Good biodegradability: Studies have shown that PMIM-Ac can be rapidly degraded by microorganisms in the natural environment and will not have a long-term impact on the ecosystem.
- Lower toxicity: PMIM-Ac has lower toxicity and is less harmful to the human body and the environment.
- Good solubility: PMIM-Ac can dissolve a variety of organic and inorganic substances, especially in the extraction and separation of polar compounds.
However, PMIM-Ac also has some shortcomings:
- Low conductivity: PMIM-Ac has a lower conductivity, limiting its performance in electrolytes, catalyst carriers and other applications.
- Poor thermal stability: The decomposition temperature of PMIM-Ac is low and is not suitable for use in high temperature environments.
Potential Application of Alternatives in the Field of Environmental Protection
As the global focus on environmental protection is increasing, it has become an inevitable trend to find green and sustainable chemicals to replace traditional chemicals. IBM and its alternatives have broad application prospects in the field of environmental protection, especially in wastewater treatment, waste gas purification, soil restoration, etc.
1. Wastewater treatment
Ionic liquids, as a new type of green solvent, have been widely used in the field of wastewater treatment. Due to its excellent solubility and selectivity, ionic liquids can effectively remove harmful substances such as heavy metal ions, organic pollutants and dyes in wastewater. For example, EMIM-BF4 and HMIM-PF6 can convert heavy metal ions (such as copper, zinc, lead, etc.) in wastewater into stable complexes through complexing reactions, thereby achieving high efficiencyRemove. In addition, PMIM-Ac can reduce the risk of secondary contamination during wastewater treatment due to its good biodegradability.
2. Waste gas purification
In the industrial production process, exhaust gas emissions are an important environmental issue. Ionic liquids can be used as absorbers or catalysts to capture and convert harmful gases in waste gases, such as carbon dioxide, sulfur dioxide, nitrogen oxides, etc. Studies have shown that BMIM-Cl and PMIM-Ac have a high absorption capacity for carbon dioxide, and can effectively capture carbon dioxide at room temperature and convert it into stable carbonates. In addition, EMIM-BF4 and HMIM-PF6 can act as catalysts to promote the reduction reaction of nitrogen oxides in the exhaust gas, thereby reducing nitrogen oxide emissions.
3. Soil Repair
Soil pollution is one of the major environmental problems facing the world, especially heavy metal pollution and the accumulation of organic pollutants. Ionic liquids can extract harmful substances in the soil through leaching, rinsing, etc., thereby realizing soil repair. For example, EMIM-BF4 and HMIM-PF6 can effectively leaching heavy metal ions in the soil, while PMIM-Ac can be used to remove organic pollutants in the soil. In addition, ionic liquids can also act as an auxiliary agent for phytorepair, promoting the absorption and accumulation of heavy metals by plants, thereby accelerating the soil repair process.
4. Biofuel Production
As fossil fuel resources gradually deplete, biofuels have attracted widespread attention as a renewable energy source. Ionic liquids can be used as catalysts or solvents for pretreatment and conversion of biomass, thereby increasing the yield and quality of biofuels. For example, BMIM-Cl and PMIM-Ac can effectively dissolve lignocellulose, promote its hydrolysis and fermentation, and produce bio or biodiesel for the duration of life. In addition, EMIM-BF4 and HMIM-PF6 can serve as catalysts to promote the reaction of biomass gasification, generate syngas (CO and H2), and then be used to produce biofuels.
Conclusion and Outlook
By analyzing the research progress of several IBMI alternatives and their potential applications in the field of environmental protection, we can draw the following conclusions:
- Ionic liquids have broad prospects as alternatives to IBM: EMIM-BF4, HMIM-PF6, BMIM-Cl and PMIM-Ac plasma liquids have thermal stability, solubility, electrical conductivity, etc. Excellent performance in terms of aspects, able to meet the needs of a variety of industrial applications.
- Environmental performance is a key factor in choosing alternatives: While ionic liquids perform well in many ways, their biodegradability and toxicity are still issues that need attention. Future research should focus more on the development of ionic liquids with better environmental protection properties to reduce the impact on the environment..
- Multi-disciplinary cross-cooperation is the key to promoting research: The research of ionic liquids involves multiple fields such as chemistry, materials science, and environmental science. Future breakthroughs require interdisciplinary cooperation and innovation. Researchers should strengthen exchanges and cooperation with other disciplines to jointly promote the application and development of ionic liquids in the field of environmental protection.
In short, with the continuous advancement of technology and the increase in environmental awareness, ionic liquids as alternatives to IBM will play an increasingly important role in the future. We look forward to more scientists and engineers participating in research in this field and contributing wisdom and strength to achieve green and sustainable development goals.
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