What Is N-Ethylpiperazine (CAS 5308-25-8)?
N-Ethylpiperazine, also written as 1-ethylpiperazine, CAS 5308-25-8, is a saturated six-membered heterocyclic amine carrying an ethyl substituent on one of its two nitrogen atoms. Its molecular formula is C6H14N2 and its molecular weight is 114.19 g/mol. The technical product is a colourless to pale yellow liquid with a distinct amine odour; it is fully miscible with water and with alcohols, ketones, esters and aromatic solvents. Because the ring contains one secondary and one tertiary nitrogen, the molecule offers two different reactivity sites, which is exactly what makes it valuable as a synthetic building block rather than as an end product. Commercial material is normally supplied at 98 % to 99 % purity with water, colour and residual starting amine controlled to suit downstream reactions.
Typical Physical and Chemical Properties
| Property | Typical value |
|---|---|
| Chemical name | N-Ethylpiperazine (1-ethylpiperazine) |
| Chemical formula | C6H14N2 |
| CAS number | 5308-25-8 |
| Molecular weight | 114.19 g/mol |
| Appearance | Colourless to pale yellow liquid |
| Odour | Characteristic amine odour |
| Boiling point | Approximately 157 °C at 101.3 kPa |
| Density at 20 °C | Approximately 0.90 g/cm3 |
| Refractive index at 20 °C | Approximately 1.469 |
| Flash point (closed cup) | Approximately 47 °C |
| Water solubility | Fully miscible |
| Technical grade assay | 98.0 % minimum |
Pharmaceutical and Fine Chemical Applications
The tertiary nitrogen of N-ethylpiperazine alkylates readily, so the compound is widely used to install the piperazine ring into active pharmaceutical ingredients. Piperazine and N-ethylpiperazine fragments appear in antihistamines, antipsychotics, antidepressants, anti-infective agents and analgesics, where they adjust the basicity, solubility and binding profile of the final molecule. The secondary nitrogen can be acylated or reacted with chloroalkyl and epoxy intermediates, allowing chemists to extend the scaffold in a controlled way. Because even a small change in the amine substituent shifts solubility, metabolic stability and receptor affinity, manufacturers keep close control over isomeric purity and residual starting amine, and the intermediate is normally characterised by gas chromatography before release. The same reactivity supports the synthesis of agrochemical intermediates, dyes, pigments and specialty fine chemicals.
Surfactants, Corrosion Inhibitors and Catalysis
In industrial chemistry N-Ethylpiperazine is used to build cationic and amphoteric surfactants, emulsifiers and wetting agents that lower surface tension in cleaning and emulsifying systems. As a corrosion inhibitor or as the amine core of inhibitor derivatives, it adsorbs on metal surfaces and forms a protective film that shields steel and copper equipment from acidic and oxygen-bearing environments in water treatment and oilfield service. Piperazine-type amines are also fast epoxy curing agents and chain extenders, and N-ethylpiperazine serves as a tertiary amine catalyst and acid scavenger in polyurethane and other polymerisation systems. Additional outlets include rubber chemicals, chelating agents, photographic processing chemicals and gas treating formulations.
Packaging, Handling and Safety
N-Ethylpiperazine is shipped in drums, intermediate bulk containers and ISO tank containers. Stainless steel or lined carbon steel is the normal material of construction for tanks, pumps and lines; copper and copper alloys are not recommended for wetted parts, and aluminium should be evaluated before use. Containers must be kept closed and, where colour stability is important, blanketed with dry nitrogen, because amines absorb carbon dioxide and moisture from air and darken. Store in a cool, dry, well ventilated place below about 30 °C, away from acids, acid chlorides, oxidising agents and sources of ignition. The liquid is combustible with a closed-cup flash point near 47 °C, and it is corrosive to skin, eyes and the respiratory tract, so goggles, chemical-resistant gloves, protective clothing and local exhaust ventilation are required during sampling, decanting and cleaning operations.
Frequently Asked Questions
Q: What is N-Ethylpiperazine used for?
It is mainly a pharmaceutical and fine chemical building block, and is also used to make cationic and amphoteric surfactants, corrosion inhibitors, epoxy curing agents and polyurethane catalysts.
Q: What is the CAS number of N-Ethylpiperazine?
CAS 5308-25-8. The compound is also named 1-ethylpiperazine and has the formula C6H14N2.
Q: Is N-Ethylpiperazine soluble in water?
Yes. It is fully miscible with water and also dissolves readily in alcohols, ketones, esters and aromatic solvents.
Q: What is the difference between piperazine and N-Ethylpiperazine?
Piperazine is the unsubstituted parent ring with two secondary nitrogens. N-Ethylpiperazine has an ethyl group on one nitrogen, leaving one tertiary and one secondary nitrogen, which changes both reactivity and the physical properties.
Q: How should N-Ethylpiperazine be stored?
In closed stainless steel or lined carbon steel containers, below about 30 °C, protected from moisture, carbon dioxide, acids and ignition sources, with nitrogen blanketing where colour stability matters.
Q: What safety precautions are needed when handling N-Ethylpiperazine?
It is corrosive and has a low flash point, so use eye protection, chemical-resistant gloves and protective clothing, work under local exhaust ventilation, and keep ignition sources away from the handling area.
Q: Why does N-Ethylpiperazine discolour in storage?
Amines react with carbon dioxide and oxygen in air, forming carbamates and oxidation products that darken the liquid. Closed containers, dry nitrogen blanketing and short storage cycles keep colour within specification.