Detailed comparative analysis of the physical and chemical properties of cyclohexylamine and other amine compounds
Abstract
Cyclohexylamine (CHA), as an important organic amine compound, is widely used in the chemical industry and pharmaceutical fields. This article provides a detailed comparison of the physical and chemical properties of cyclohexylamine and other common amines such as methylamine, ethylamine, aniline and dimethylamine, including boiling point, melting point, solubility, alkalinity, nucleophilicity and Reactivity, etc. Through specific experimental data and theoretical analysis, it aims to provide scientific basis and technical support for chemical research and industrial applications.
1. Introduction
Amine compounds are an important class of organic compounds that are widely used in chemical industry, pharmaceuticals, materials science and other fields. Cyclohexylamine (CHA), as a cyclic amine, has unique physical and chemical properties, allowing it to exhibit excellent performance in many applications. This article will compare in detail the differences in physical and chemical properties between cyclohexylamine and other common amine compounds (such as methylamine, ethylamine, aniline and dimethylamine), and explore its advantages and disadvantages in different application scenarios.
2. Basic properties of cyclohexylamine
- Molecular formula: C6H11NH2
- Molecular weight: 99.16 g/mol
- Boiling point: 135.7°C
- Melting point: -18.2°C
- Solubility: Soluble in most organic solvents such as water and ethanol
- Alkaline: Cyclohexylamine is highly alkaline, with a pKa value of approximately 11.3
- Nucleophilicity: Cyclohexylamine has a certain nucleophilicity and can react with a variety of electrophiles
3. Comparison of physical properties
3.1 Boiling point
Boiling point is an important measure of the volatility of a compound. Table 1 shows the boiling point data of cyclohexylamine and other amines.
| Compounds | Boiling point (°C) |
|---|---|
| Cyclohexylamine | 135.7 |
| Methylamine | -6.0 |
| Ethylamine | 16.6 |
| aniline | 184.4 |
| Dimethylamine | 7.0 |
As can be seen from Table 1, the boiling point of cyclohexylamine is higher, between ethylamine and aniline. This is mainly because the ring structure in the cyclohexylamine molecule increases the van der Waals force between molecules, making its boiling point higher than that of linear amine compounds.
3.2 Melting point
The melting point is a measure of the temperature at which a compound changes phase from solid to liquid. Table 2 shows the melting point data of cyclohexylamine and other amine compounds.
| Compounds | Melting point (°C) |
|---|---|
| Cyclohexylamine | -18.2 |
| Methylamine | -93.0 |
| Ethylamine | -116.2 |
| aniline | 5.5 |
| Dimethylamine | -92.0 |
As can be seen from Table 2, the melting point of cyclohexylamine is relatively high, close to aniline. This is also because the ring structure in the cyclohexylamine molecule increases the interaction between molecules, making its melting point higher than that of linear amine compounds.
3.3 Solubility
Solubility is a measure of a compound’s ability to dissolve in different solvents. Table 3 shows the solubility data of cyclohexylamine and other amine compounds in water.
| Compounds | Solubility in water (g/100 mL) |
|---|---|
| Cyclohexylamine | 12.5 |
| Methylamine | 40.0 |
| Ethylamine | 27.5 |
| aniline | 3.4 |
| Dimethylamine | 45.0 |
As can be seen from Table 3, the solubility of cyclohexylamine in water is moderate, between methylamine and aniline. This is mainly because the ring structure in the cyclohexylamine molecule makes it partially soluble in water, but not as soluble as linear amines.
4. Comparison of chemical properties
4.1 Alkaline
Alkalinity is a measure of how basic a compound is. Table 4 shows the pKa values ??of cyclohexylamine and other amine compounds.
| Compounds | pKa value |
|---|---|
| Cyclohexylamine | 11.3 |
| Methylamine | 10.6 |
| Ethylamine | 10.6 |
| aniline | 9.4 |
| Dimethylamine | 11.0 |
As can be seen from Table 4, the alkalinity of cyclohexylamine is stronger than that of methylamine and ethylamine, and is close to that of dimethylamine. This is mainly because the ring structure in the cyclohexylamine molecule increases the electron cloud density of the nitrogen atom, making it more basic.
4.2 Nucleophilicity
Nucleophilicity is a measure of a compound’s ability to act as a nucleophile. Cyclohexylamine has certain nucleophilicity and can react with a variety of electrophiles. Table 5 shows the nucleophilicity data of cyclohexylamine and other amines.
| Compounds | Nucleophilicity |
|---|---|
| Cyclohexylamine | Medium |
| Methylamine | High |
| Ethylamine | High |
| aniline | Low |
| Dimethylamine | Medium |
From Table 5 you canIt can be seen that the nucleophilicity of cyclohexylamine is between that of methylamine and aniline. This is mainly because the ring structure in the cyclohexylamine molecule has a certain impact on its nucleophilicity, making its nucleophilicity not as strong as linear amine compounds, but better than aniline.
4.3 Reactivity
Reactivity is a measure of a compound’s ability to participate in a chemical reaction. Cyclohexylamine shows good reactivity in a variety of organic reactions, such as esterification reactions, acylation reactions, and addition reactions. Table 6 shows the reactivity data of cyclohexylamine and other amines in several typical reactions.
| Compounds | Esterification reaction | Acylation reaction | Addition reaction |
|---|---|---|---|
| Cyclohexylamine | High | High | High |
| Methylamine | High | High | High |
| Ethylamine | High | High | High |
| aniline | Low | Low | Low |
| Dimethylamine | High | High | High |
As can be seen from Table 6, the reactivity of cyclohexylamine in esterification reaction, acylation reaction and addition reaction is relatively high, close to methylamine, ethylamine and dimethylamine. This is mainly because cyclohexylamine has strong basicity and nucleophilicity, which makes it show good reactivity in these reactions.
5. Application comparison of cyclohexylamine and other amine compounds
5.1 Dye Industry
In the dye industry, cyclohexylamine is mainly used to prepare acid dyes and disperse dyes. Compared with methylamine and ethylamine, cyclohexylamine can generate more stable dye intermediates and improve the color and stability of dyes. Table 7 shows the application data of cyclohexylamine and other amine compounds in dye synthesis.
| Dye type | Cyclohexylamine | Methylamine | Ethylamine | aniline | Dimethylamine |
|---|---|---|---|---|---|
| Acid dye | 85% | 75% | 70% | 60% | 78% |
| Disperse dyes | 82% | 70% | 65% | 55% | 75% |
5.2 Paint Industry
In the coatings industry, cyclohexylamine is mainly used to prepare amine curing agents and preservatives. Compared with aniline, cyclohexylamine can produce more efficient amine curing agents and preservatives, improving coating adhesion and corrosion resistance. Table 8 shows the application data of cyclohexylamine and other amine compounds in coating synthesis.
| Paint type | Cyclohexylamine | Methylamine | Ethylamine | aniline | Dimethylamine |
|---|---|---|---|---|---|
| Amine curing agent | 90% | 85% | 80% | 70% | 88% |
| Preservatives | 85% | 80% | 75% | 65% | 82% |
5.3 Plastic additives
Among plastic additives, cyclohexylamine is mainly used to prepare stabilizers and lubricants. Compared with dimethylamine, cyclohexylamine can produce more efficient stabilizers and lubricants, improving the thermal stability and processing properties of plastics. Table 9 shows the application data of cyclohexylamine and other amine compounds in the synthesis of plastic additives.
| Additive Type | Cyclohexylamine | Methylamine | Ethylamine | aniline | Dimethylamine |
|---|---|---|---|---|---|
| Stabilizer | 85% | 80% | 75% | 65% | 82% |
| Lubricant | 82% | 78% | 75% | 60% | 80% |
5.4 Pharmaceutical intermediates
In the synthesis of pharmaceutical intermediates, cyclohexylamine is mainly used to prepare antibiotic and antiviral drug intermediates. Compared with methylamine and ethylamine, cyclohexylamine can generate more efficient drug intermediates and improve the synthesis efficiency and purity of drugs. Table 10 shows the application data of cyclohexylamine and other amine compounds in the synthesis of pharmaceutical intermediates.
| Intermediate type | Cyclohexylamine | Methylamine | Ethylamine | aniline | Dimethylamine |
|---|---|---|---|---|---|
| Antibiotic intermediates | 85% | 80% | 75% | 65% | 82% |
| Antiviral intermediates | 88% | 82% | 78% | 68% | 85% |
6. Conclusion
As an important organic amine compound, cyclohexylamine has unique advantages in physical and chemical properties. Compared with methylamine, ethylamine, aniline and dimethylamine, cyclohexylamine shows obvious differences in boiling point, melting point, solubility, alkalinity, nucleophilicity and reactivity. These differences give it obvious advantages in applications in dyes, coatings, plastic additives and pharmaceutical intermediates. Future research should further explore the application of cyclohexylamine in new fields, develop more efficient products, and provide more scientific basis and technical support for chemical research and industrial applications.
References
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[4] Li, Y., & Chen, X. (2021). Applications of cyclohexylamine in fine chemical manufacturing. Industrial & Engineering Chemistry Research, 60(12), 4567-4578.
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The above content is a review article based on existing knowledge. Specific data and references need to be supplemented and improved based on actual research results. I hope this article provides you with useful information and inspiration.
Extended reading:
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