3-Chloro-2-methylbenzenethiol (CAS Number: 53249-76-6) is an important organosulfur compound featuring both halogen and thiol functional groups on a substituted aromatic ring. This molecule finds relevance in organic synthesis, agrochemical research, pharmaceutical intermediates, and material science due to its reactive thiol group and substituted benzene ring.
In this article, we explore the chemical structure, physical and chemical properties, synthesis routes, applications, and handling precautions of this versatile compound.
IUPAC Name: 3-Chloro-2-methylbenzenethiol
CAS Number: 53249-76-6
Molecular Formula: C7H7ClS
Molecular Weight: 158.65 g/mol
Synonyms:
3-Chloro-o-toluenethiol
2-Methyl-3-chlorothiophenol
o-Toluenethiol, 3-chloro-
The structure of 3-Chloro-2-methylbenzenethiol consists of a benzene ring substituted with three groups:
A thiol group (-SH) at position 1
A methyl group (-CH₃) at position 2
A chlorine atom (Cl) at position 3
Positioning (Ortho-Substitution):
The methyl and thiol groups are in adjacent positions, and the chlorine occupies the next adjacent position, giving rise to regioselective reactivity in organic transformations.
Property |
Value |
|---|---|
Appearance |
Pale yellow to amber liquid |
Odor |
Characteristic sulfurous smell |
Melting Point |
~ Not well-documented |
Boiling Point |
~230–250°C (estimated) |
Solubility |
Slightly soluble in water; soluble in organic solvents like ethanol, diethyl ether |
Density |
~1.25 g/cm³ (approx.) |
Refractive Index |
~1.58–1.60 |
Stability |
Stable under recommended storage; sensitive to oxidation |
One common route to synthesize 3-chloro-2-methylbenzenethiol involves:
Halogenation of o-toluenethiol to introduce a chlorine atom at the meta position.
Selective thiolation of 3-chlorotoluene derivatives using thiourea or other sulfur-transfer reagents.
These processes usually require controlled conditions due to the reactivity of thiol compounds.
Due to the presence of both lipophilic (methyl, aromatic ring) and polar (thiol, chloro) groups, 3-chloro-2-methylbenzenethiol serves as a valuable intermediate in the synthesis of bioactive molecules, especially those requiring sulfur-containing moieties.
Its functional groups allow for incorporation into herbicide, pesticide, or fungicide development, offering structural flexibility in designing active compounds.
This compound can participate in:
Thiol–ene reactions
Coupling reactions via the –SH group
Nucleophilic substitution at the aromatic ring (under proper conditions)
The thiol group facilitates bonding with metal surfaces, making it suitable for preparing self-assembled monolayers (SAMs) or functionalizing nanoparticles.
As with most thiol-containing chemicals, 3-chloro-2-methylbenzenethiol requires careful handling:
Odor Control: Thiol compounds have strong, unpleasant odors even at trace levels.
Storage: Store in cool, dry conditions away from oxidizing agents.
Protective Measures: Use gloves, eye protection, and fume hoods when handling.
First Aid: In case of skin contact, wash immediately. If inhaled, seek fresh air and medical attention if symptoms persist.
Always consult the Material Safety Data Sheet (MSDS) for detailed hazard and precautionary statements.
3-Chloro-2-methylbenzenethiol (CAS: 53249-76-6) is a unique aromatic thiol compound combining the reactivity of a thiol with the structural variability of substituted aromatics. Its dual functionality opens avenues in synthetic chemistry, pharmaceuticals, and materials science. While its potential is vast, it should be handled with care due to its reactive nature and strong odor.
