2-ethyl-4-methylimidazole: a comprehensive analysis from chemical structure to industrial applications

Introduction

In the broad field of chemistry, various organic compounds play a crucial role, among which 2-ethyl-4-methylimidazole (CAS number: 931-36-2) as an important intermediate plays an irreplaceable role in epoxy resin curing, the electronics industry, and many industrial fields. In this paper, the chemical structure, synthetic methods, properties, uses, and safety of the chemical compounds are discussed in depth to provide readers with a comprehensive understanding and reference.

Chemical structure of 2-ethyl-4-methylimidazole

Basic information

2-ethyl-4-methylimidazole, also known as EMI-2,4, 4-methyl-2-ethyl-imidazole or 2-ethyl-4-methyl-1H-imidazole, is an organic compound with the formula C6H10N2 and a molecular weight of 110.157. This compound is a yellowish viscous liquid at room temperature and has a very good compatibility with epoxy resin. It is a key raw material for the preparation of high-performance curing agents.¹

Structural characteristics

Chemically, 2-ethyl-4-methylimidazole contains two nitrogen atoms, which are located at different locations in the imidazole ring, forming a stable five-membered heterocyclic structure. Ethyl (C₂H₅-) and methyl (CH₃-) are attached to the 2nd and 4th positions of the imidazole ring as substituents, which gives them unique chemical properties and wide application potential.

The synthesis method

Traditional synthesis methods

At present, there are two main methods for preparing 2-ethyl-4-methylimidazole abroad: one is cyclization and dehydrogenation of binary amine and acylating agent in the presence of a catalyst; The second is the cyclic reaction of diamine and nitrile in the presence of sulfur, after sulfur removal and dehydrogenation, imidazoline is obtained and then dehydrogenated under nickel catalyst. However, these methods have some problems, such as low yield, many by-products, and difficult purification, which limit their large-scale industrial application.²

New synthesis method

In order to overcome the shortcomings of traditional methods, the researchers developed a new step method to prepare 2-ethyl-4-methylimidazole. The method mainly includes the following steps:

Cyclic reaction: In the presence of a catalyst, propanitrile, sulfur dichloride, and 1, 2-propylenediamine are added to the reaction vessel for a warming reaction. By precisely controlling the reaction temperature and pressure, the ring reaction can be carried out smoothly. After the reaction, the initial product was obtained by vacuum distillation.

Dehydrogenation: The initial product is heated with a Raney nickel composite catalyst for dehydrogenation. At high temperatures, the catalyst promoted the dehydrogenation reaction and further converted the product to 2-ethyl-4-methylimidazole. After the reaction, the same vacuum distillation was carried out to obtain high-purity 2-ethyl-4-methylimidazole.³

Refining: In order to further improve the purity of the product, the obtained 2-ethyl-4-methylimidazole is heated with sodium hydroxide solution for refining. By removing impurities and unreacted raw materials, the final product meets industry standards.

This new synthesis method not only reduces the process cost, and optimizes the reaction process, but also simplifies the operation steps, reduces pollution, and improves the reaction yield and product purity.

Nature and use

Physical properties

2-ethyl-4-methylimidazole is a yellowish thick liquid at room temperature with a boiling point of 292°C and a similarly high active temperature. The compound is soluble in water and most organic solvents and is alkaline. The appearance color will become darker under long-term light, but it will not affect the properties of the cured material.

Chemical properties

As a member of imidazole compounds, 2-ethyl-4-methylimidazole has strong reactivity. It can react with a variety of compounds to produce derivatives with specific functions. At the same time, its alkaline properties also make it show a unique advantage in some acid-base reactions.

 Used in epoxy resin curing agent

The most widespread use of 2-ethyl-4-methylimidazole is as a curing agent for epoxy resins. It can improve the curing speed and curing degree of epoxy resin so that the cured epoxy resin has higher mechanical strength, heat resistance, and chemical medium resistance. Therefore, 2-ethyl-4-methylimidazole is widely used in bonding, coating, pouring, encapsulation, impregnation, and recharging of epoxy resins in electronic and electrical appliances, aerospace, automotive manufacturing, and other fields.⁴

Used in electronics industry

2-ethyl-4-methylimidazole is also widely used in the electronics industry because of its good electrical insulation properties and resistance to chemical media. For example, in semiconductor packaging materials, 2-ethyl-4-methylimidazole can be used as a curing agent to improve the stability and reliability of packaging materials.5

Other uses

In addition, 2-ethyl-4-methylimidazole can also be used to prepare other organic compounds and intermediates, such as key raw materials in drug synthesis. With the continuous development of science and technology, its application field will continue to expand.

References

[1].Bravo, C.; Leis, J. R.; Pena, M. E., Effect of alcohols on catalysis by dodecyl sulfate micelles. The Journal of Physical Chemistry 1992,96(4), 1957-1961.

[2].Patist, A.; Axelberd, T.; Shah, D. O., Effect of long chain alcohols on micellar relaxation time and foaming properties of sodium dodecyl sulfate solutions. Journal of colloid and interface science 1998,208(1), 259-265.

[3].Caponetti, E.; Martino, D. C.; Floriano, M.; Triolo, R., Localization of n-alcohols and structural effects in aqueous solutions of sodium dodecyl sulfate. Langmuir 1997,13(13), 3277-3283.

[4].F?rland, G. M.; Samseth, J.; Gjerde, M. I.; H?iland, H.; Jensen, A. ?.; Mortensen, K., Influence of alcohol on the behavior of sodium dodecylsulfate micelles. Journal of colloid and interface science 1998,203(2), 328-334.

[5].Méndez-Bermúdez, J. G.; Dominguez, H., Structural changes of a sodium dodecyl sulfate (SDS) micelle induced by alcohol molecules. Journal of molecular modeling 2016,22,1-9.