N-Ethylaniline: Properties, Uses & Lab Guide

N-Ethylaniline is a secondary aromatic amine widely employed as a versatile intermediate in organic synthesis, dye chemistry, and pharmaceutical research.

Chemical Name

N-Ethylaniline

CAS Number

103-69-5

Molecular Formula

C₈H₁₁N

Molecular Weight

121.18 g/mol

Appearance

Colorless to pale yellow liquid

Aladdin SKU

N661252

Compound Class

Secondary aromatic amine (N-alkylaniline)

Chemical Identity and Physical Properties

N-Ethylaniline (CAS 103-69-5) is a secondary aromatic amine with the molecular formula C₈H₁₁N and a molecular weight of approximately 121.18 g/mol. Structurally, it consists of an aniline backbone in which one N–H hydrogen has been replaced by an ethyl group, yielding the motif PhNHCH₂CH₃. At ambient conditions it presents as a colorless to pale yellow liquid with a characteristic amine odor. Key physical parameters reported in standard chemical references include a boiling point near 204–205 °C and a density of approximately 0.96 g/mL. The compound is sparingly soluble in water but miscible with common organic solvents such as ethanol, diethyl ether, and acetone. Its pKaH (conjugate acid) is approximately 5.12, reflecting reduced basicity compared with aliphatic secondary amines owing to delocalization of the nitrogen lone pair into the aromatic ring.

Synthesis and Laboratory Preparation

N-Ethylaniline is most commonly prepared by the N-alkylation of aniline with an ethylating agent. Classical routes include reductive amination of aniline with acetaldehyde in the presence of a reducing agent such as sodium cyanoborohydride, or direct alkylation using diethyl sulfate or ethyl halides under controlled conditions to minimize over-alkylation to the tertiary amine (N,N-diethylaniline). Catalytic hydrogenation approaches employing ethanol over supported metal catalysts (e.g., Raney nickel) also afford good selectivity for the monoethylated product.

In the research laboratory, careful control of stoichiometry and temperature is critical to suppress diethylation. Thin-layer chromatography or GC analysis is recommended to monitor reaction progress and confirm product identity prior to purification by fractional distillation under reduced pressure.

Applications in Research and Industry

N-Ethylaniline serves as a multifunctional building block across several domains:

• Dye and pigment synthesis: It is a classical intermediate in the manufacture of azo dyes, triarylmethane dyes, and reactive dyes for textile applications, where N-alkyl substituents modulate color strength and solubility.
• Pharmaceutical and agrochemical intermediates: The compound acts as a nitrogen-containing scaffold for synthesizing active pharmaceutical ingredients (APIs) and crop-protection chemicals. Its secondary amine functionality participates in amide bond formation, reductive amination, and condensation reactions.
• Organic synthesis reagent: N-Ethylaniline is used as a mild base or nucleophile in a range of transformations, including the synthesis of Schiff bases, enamine formation, and as a ligand precursor in coordination chemistry.
• Reference standard and analytical chemistry: High-purity N-Ethylaniline is used as a reference compound in method development for HPLC, GC, and mass spectrometry, particularly in environmental and food-safety analysis of aromatic amine contaminants.

Safe Handling, Storage, and Regulatory Considerations

Hazard profile: N-Ethylaniline is a combustible liquid and a health hazard. Aromatic amines as a class are associated with potential carcinogenicity; users should consult the current Safety Data Sheet (SDS) before handling. The compound may cause skin and eye irritation, and absorption through skin is a recognized exposure route.

Personal protective equipment (PPE): Use chemical-resistant gloves (nitrile or neoprene), lab coat, and safety goggles. Work in a well-ventilated fume hood to minimize inhalation of vapors.

Storage: Store in a tightly sealed container away from heat sources, oxidizing agents, and strong acids. Recommended storage temperature is room temperature in a cool, well-ventilated area protected from light. Check for container integrity periodically, as prolonged exposure to air may cause gradual discoloration.

Disposal: Dispose of waste in accordance with local, national, and institutional regulations for hazardous aromatic amine waste. Do not pour into drains or waterways.

Regulatory status: Users are responsible for verifying the regulatory status of N-Ethylaniline under applicable local chemical inventories (e.g., REACH, TSCA) prior to import or use.

Frequently asked questions

What is N-Ethylaniline used for in organic synthesis?

N-Ethylaniline functions as a versatile secondary amine building block. It is commonly employed in dye intermediate synthesis, reductive amination reactions, Schiff base formation, enamine chemistry, and as a nitrogen nucleophile in condensation and acylation reactions relevant to pharmaceutical and agrochemical research.

How should N-Ethylaniline be stored to maintain purity?

Store N-Ethylaniline in a tightly sealed container at room temperature in a cool, dry, well-ventilated location, protected from light and away from oxidizing agents and strong acids. Prolonged exposure to air and light can cause gradual oxidative discoloration; minimize headspace in the container to reduce contact with atmospheric oxygen.

What safety precautions are required when handling N-Ethylaniline?

Always handle N-Ethylaniline in a well-ventilated fume hood while wearing chemical-resistant gloves, a lab coat, and safety goggles. Aromatic amines carry potential health hazards including skin sensitization and possible carcinogenicity risks; consult the current SDS for specific first-aid measures, exposure limits, and emergency procedures before use.

What is the difference between N-Ethylaniline and N,N-diethylaniline?

N-Ethylaniline is a secondary amine bearing one ethyl group on the nitrogen (PhNHEt), retaining one N–H bond and acting as a nucleophile or mild base. N,N-Diethylaniline is the corresponding tertiary amine (PhNEt₂) with no N–H bond, which alters its reactivity profile significantly—it cannot participate in reactions requiring an N–H group such as Schiff base or simple amide formation.

Is N-Ethylaniline available in small volumes for screening purposes?

Yes. Aladdin Scientific offers N-Ethylaniline (SKU: N661252) as part of its molecular library in 1 mL format, making it suitable for high-throughput screening, method development, and small-scale feasibility studies in research laboratories.

References

1. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 4th ed.; Wiley-Interscience: New York, 1992.
2. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012.
3. PubChem Compound Summary for CID 7215, N-Ethylaniline. National Center for Biotechnology Information.
4. Sigma-Aldrich / Merck product SDS for N-Ethylaniline, CAS 103-69-5 (consulted as general reference for physical data).

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.