In the world of chemical synthesis and industrial formulations, 3-Chloro-2-Methylbenzenethiol (CAS 53249-76-6) stands out as a valuable intermediate compound. Known for its distinct reactivity and sulfur-containing structure, this compound plays an essential role in the production of advanced materials, agrochemicals, and pharmaceuticals.
This article offers a comprehensive overview of CAS No. 53249-76-6, exploring its chemical structure, properties, uses, and safety guidelines in research and industrial applications.
3-Chloro-2-Methylbenzenethiol, also known as 3-Chloro-o-toluenethiol, belongs to the family of aromatic thiols, compounds characterized by the presence of a sulfur-hydrogen (-SH) functional group attached to an aromatic ring.
Its structure offers a unique combination of aromatic stability and thiol reactivity, making it an important precursor for various chemical transformations, including substitution, oxidation, and coupling reactions.
Chemical Name: 3-Chloro-2-Methylbenzenethiol
CAS Number: 53249-76-6
Molecular Formula: C₇H₇ClS
Molecular Weight: 158.65 g/mol
IUPAC Name: 3-Chloro-2-methylbenzenethiol
The structure of 3-Chloro-2-Methylbenzenethiol features a benzene ring substituted with a chlorine atom (Cl) at position 3 and a methyl group (CH₃) at position 2, along with a thiol (-SH) group.
This substitution pattern influences both its physical properties and reactivity, especially in nucleophilic substitution and oxidation reactions.
Property |
Details |
|---|---|
Molecular Formula |
C₇H₇ClS |
Molecular Weight |
158.65 g/mol |
Appearance |
Pale yellow to colorless liquid |
Boiling Point |
~216–220°C |
Density |
~1.25 g/cm³ |
Odor |
Strong sulfurous odor |
Solubility |
Insoluble in water; soluble in organic solvents (e.g., ethanol, ether, benzene) |
3-Chloro-2-Methylbenzenethiol is typically synthesized through thiolation reactions, where a chlorinated aromatic precursor reacts with a sulfur donor, such as sodium hydrosulfide or thiourea, under controlled conditions.
A common synthesis route includes:
Starting material: 3-Chloro-2-methylbenzyl chloride or 3-chloro-o-toluidine.
Reaction: Nucleophilic substitution or reduction to introduce the thiol group (-SH).
Purification: Distillation or crystallization to obtain high-purity 3-Chloro-2-Methylbenzenethiol.
The reaction parameters—temperature, solvent, and catalyst—are carefully optimized to maximize yield and purity.
The presence of both chlorine and thiol substituents enhances the compound’s reactivity, making it suitable for various coupling and oxidation reactions.
The -SH group acts as a nucleophile and can form disulfides upon oxidation.
The chlorine atom facilitates further substitution reactions, enabling synthesis of more complex derivatives.
The methyl substituent provides slight electron-donating effects, affecting the overall aromatic ring reactivity.
This combination makes CAS 53249-76-6 a highly adaptable building block in fine chemical and pharmaceutical synthesis.
3-Chloro-2-Methylbenzenethiol serves as a key intermediate in the synthesis of therapeutic molecules, especially those containing sulfur-based pharmacophores. It is often used to prepare sulfur-containing heterocycles and benzothiazoles, which are prevalent in antimicrobial and anti-inflammatory drug classes.
In the agricultural sector, this compound is used to produce fungicides, herbicides, and insecticides, where the thiol moiety enhances biological activity and binding efficiency.
Due to its reactive thiol group, it acts as a chain transfer agent in polymerization processes, controlling molecular weight and polymer structure.
It is widely employed in academic and industrial R&D for developing organosulfur compounds, catalysts, and other specialized materials.
While 3-Chloro-2-Methylbenzenethiol is a valuable chemical, it requires strict safety measures due to its strong odor, potential irritancy, and reactivity.
Causes skin and eye irritation.
Inhalation of vapors may cause respiratory discomfort.
Harmful if swallowed.
Flammable in vapor form when exposed to ignition sources.
Use in a well-ventilated fume hood.
Wear protective gloves, goggles, and lab coat.
Avoid exposure to heat and open flames.
Store in tightly sealed containers under dry, cool conditions.
Keep away from oxidizing agents and sources of moisture.
Recommended storage temperature: below 25°C.
Due to its sulfur content, improper disposal of 3-Chloro-2-Methylbenzenethiol can contribute to odor pollution and potential aquatic toxicity.
Best practices include:
Neutralization before disposal.
Adhering to local environmental and chemical waste regulations.
Avoiding release into soil or water systems.
The demand for CAS 53249-76-6 has increased with the growing use of organosulfur intermediates in specialty chemicals and pharmaceuticals. Manufacturers ensure high purity (≥98%) for consistency in downstream applications.
Its global market presence is strongest in Asia-Pacific and Europe, where it is used in chemical research and agrochemical production.
As industries continue shifting toward green and sustainable chemistry, researchers are exploring eco-friendly synthesis routes for thiol-containing compounds.
Future advancements may include:
Catalytic, solvent-free production methods.
Improved odor-control during handling.
Integration into biobased chemical processes.
3-Chloro-2-Methylbenzenethiol’s versatility ensures its continued importance in fine chemical development and industrial innovation.
3-Chloro-2-Methylbenzenethiol (CAS No. 53249-76-6) is more than just a chemical intermediate—it’s a cornerstone compound in modern synthetic chemistry. With its distinctive thiol functionality, aromatic structure, and reactive chlorine substituent, it supports diverse applications across pharma, agro, and material science sectors.
However, due to its strong odor and reactive nature, careful handling and responsible storage are essential. As sustainable chemistry advances, the compound’s synthesis and use will continue evolving toward safer and more environmentally friendly practices.
