2-Ethylaniline
[CAS 578-54-1]

Identification

• Classification: Organic raw materials >> Amino compound >> Cycloalkylamines, aromatic monoamines, aromatic polyamines and derivatives and salts
• Name: 2-Ethylaniline
• Synonyms: o-Amino ethylbenzene; 2-Ethylbenzenamine
• Molecular Formula: C₈H₁₁N
• Molecular Weight: 121.18
• CAS Registry Number: 578-54-1
• EC Number: 209-424-2
• SMILES: CCC1=CC=CC=C1N

Properties

• Density: 1.0±0.1 g/cm³ Calc.^*, 0.983 g/mL (Expl.)
• Melting point: -44 °C (Expl.)
• Boiling point: 212.3±9.0 °C 760 mmHg (Calc.)^*, 210 °C (Expl.)
• Flash point: 91.1 °C (Calc.)^*, 93 °C (Expl.)
• Solubility: water: insoluble (Expl.)
• Index of refraction: 1.556 (Calc.)^*, 1.559 (Expl.)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS06;GHS07;GHS08 Danger
• Risk Statements: H302-H311+H331-H311-H315-H319-H331-H373
• Safety Statements: P260-P261-P262-P264-P264+P265-P270-P271-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P316-P319-P321-P330-P332+P317-P337+P317-P361+P364-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	3	H311
Acute toxicity	Acute Tox.	3	H331
Acute toxicity	Acute Tox.	4	H302
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - repeated exposure	STOT RE	2	H373
Skin irritation	Skin Irrit.	2	H315
Acute toxicity	Acute Tox.	3	H301
Acute toxicity	Acute Tox.	2	H330
Specific target organ toxicity - single exposure	STOT SE	2	H371
Acute toxicity	Acute Tox.	4	H312
Carcinogenicity	Carc.	2	H351
Skin sensitization	Skin Sens.	1	H317

• Transport Information: UN 2273

chemBlink Chemical Story

2-Ethylaniline is an alkyl-substituted aromatic amine belonging to the class of substituted anilines. The compound consists of an aniline structure in which an ethyl group is attached to the benzene ring adjacent to the amino group. This simple structural modification of aniline changes its physical and chemical properties and makes it useful as an intermediate in organic synthesis and industrial chemical production.

Aniline and its derivatives have played an important role in the development of modern organic chemistry. Aniline was one of the earliest aromatic amines studied and became an important industrial chemical because of its applications in dye manufacturing, polymer chemistry, and chemical synthesis. As research expanded into substituted aromatic compounds, alkyl-substituted anilines such as 2-ethylaniline were developed to provide modified aromatic amine structures with different reactivity and physical properties.

The molecular structure of 2-ethylaniline consists of a benzene ring bearing an amino group and an ethyl substituent at the 2-position. The amino group is directly attached to the aromatic ring, making the compound an aniline derivative. The ethyl group is located next to the amino group, creating an ortho-substituted aromatic amine.

The benzene ring provides a stable aromatic framework through delocalization of pi electrons. The amino group contains a nitrogen atom with a lone pair of electrons that can interact with the aromatic ring through resonance. This interaction influences the electronic properties of the molecule and distinguishes anilines from aliphatic amines.

The amino group is the main reactive functional group in 2-ethylaniline. It can undergo protonation reactions with acids to form corresponding ammonium salts. It can also participate in common amine transformations, including acylation, alkylation, and diazotization reactions. These reactions make substituted anilines valuable intermediates for preparing other organic compounds.

The ethyl substituent influences the properties of the aromatic amine through both electronic and steric effects. As an alkyl group, it donates electron density to the aromatic ring through hyperconjugation, making the ring more electron-rich compared with unsubstituted aniline. Because the ethyl group is positioned next to the amino group, it also affects the spatial environment around the nitrogen atom.

The ortho relationship between the ethyl group and the amino group can influence molecular geometry and intermolecular interactions. Steric effects from the neighboring ethyl group may affect the orientation of the amino group relative to the aromatic ring and can modify the accessibility of the nitrogen lone pair during chemical reactions.

2-Ethylaniline has been used primarily as a chemical intermediate. Substituted anilines are important starting materials in the production of dyes, pigments, agrochemicals, pharmaceuticals, and specialty chemicals. The amino group provides a convenient site for further functionalization, while the substituted aromatic ring contributes specific structural characteristics required in synthetic applications.

In the field of dye and pigment chemistry, aromatic amines have historically served as precursors for the preparation of colored compounds. Their ability to undergo diazotization and coupling reactions allows the formation of azo compounds and related structures. Alkyl substitution can be used to modify the properties of these aromatic intermediates.

In pharmaceutical and agrochemical research, substituted anilines are commonly used as building blocks because their aromatic amino structure can be incorporated into more complex molecules. The ethyl substituent provides additional structural variation that can influence the properties of derivatives produced from the compound.

The physical properties of 2-ethylaniline are determined by the combination of the aromatic ring, amino group, and ethyl substituent. The molecule contains both polar and nonpolar regions. The amino group contributes hydrogen-bonding ability, while the hydrocarbon portions provide hydrophobic character. This balance influences its solubility and behavior in organic and aqueous environments.

Overall, 2-ethylaniline is a simple but important substituted aromatic amine whose significance comes from its role as an intermediate in chemical synthesis. Its combination of an aniline amino group and an ortho ethyl substituent provides a useful framework for preparing a wide range of aromatic derivatives used in industrial and research chemistry.