1,2-Ethanedithiol
[CAS# 540-63-6]

Identification

• Classification: Flavors and spices >> Synthetic spice >> Thiol perfume
• Name: 1,2-Ethanedithiol
• Synonyms: 1,2-Dimercaptoethane; Dithioethyleneglycol; Ethylene mercaptan
• Molecular Formula: C₂H₆S₂
• Molecular Weight: 94.19
• CAS Registry Number: 540-63-6
• EC Number: 208-752-3
• FEMA: 3484
• SMILES: C(CS)S

Properties

• Density: 1.123 g/mL (Expl.)
• Melting point: -41 °C (Expl.)
• Boiling point: 144-146 °C (Expl.)
• Refractive index: 1.558 (Expl.)
• Flash point: 44 °C (Expl.)
• Water solubility: insoluble (Expl.)

Safety Data

• Hazard Symbols: GHS02;GHS06;GHS07 Danger
• Risk Statements: H226-H301-H302-H310-H313-H319-H330
• Safety Statements: P210-P233-P240-P241-P242-P243-P260-P262-P264-P264+P265-P270-P271-P280-P284-P301+P316-P301+P317-P302+P352-P303+P361+P353-P304+P340-P305+P351+P338-P316-P317-P320-P321-P330-P337+P317-P361+P364-P362+P364-P370+P378-P403+P233-P403+P235-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Flammable liquids	Flam. Liq.	3	H226
Acute toxicity	Acute Tox.	4	H302
Acute toxicity	Acute Tox.	3	H301
Acute toxicity	Acute Tox.	2	H330
Acute toxicity	Acute Tox.	2	H310
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	4	H312
Acute toxicity	Acute Tox.	3	H331
Specific target organ toxicity - single exposure	STOT SE	3	H336
Acute toxicity	Acute Tox.	4	H332
Specific target organ toxicity - single exposure	STOT SE	3	H335
Aspiration hazard	Asp. Tox.	1	H304
Skin irritation	Skin Irrit.	2	H315

• Transport Information: UN 3071

Discovery and Applications

1,2-Ethanedithiol, also known as EDT or ethylene dithiol, is a bifunctional organosulfur compound characterized by its two thiol (-SH) groups attached to adjacent carbon atoms. It has the molecular formula C(_2)H(_6)S(_2) and appears as a colorless to pale-yellow liquid with a pungent odor typical of thiol compounds. This compound is widely utilized in synthetic chemistry and industrial applications due to its unique reactivity.

The discovery and initial characterization of 1,2-ethanedithiol emerged during the exploration of thiol chemistry in the 20th century, particularly as chemists sought efficient methods for sulfur incorporation into organic molecules. Advances in thiol synthesis enabled its production through reactions such as the reaction of ethylene dibromide with thiourea, followed by hydrolysis. This method provides high yields and has been a reliable industrial route for its synthesis.

In synthetic organic chemistry, 1,2-ethanedithiol serves as a versatile reagent for the protection of carbonyl groups. It reacts with aldehydes or ketones to form cyclic dithioacetals or dithiolanes, which are stable intermediates that safeguard carbonyl groups during multi-step syntheses. These protecting groups can be removed under specific conditions, making EDT essential in the preparation of complex molecules, including pharmaceuticals and natural products.

1,2-Ethanedithiol is also pivotal in the field of material science. Its thiol groups readily bind to metal surfaces, facilitating the formation of self-assembled monolayers (SAMs) on gold and other metals. These SAMs are used to modify surface properties for applications ranging from sensors and catalysts to nanotechnology.

Additionally, EDT is employed as a curing agent in polymer chemistry, particularly in the vulcanization of rubber. Its bifunctionality allows it to crosslink polymer chains, enhancing the mechanical properties of the material. This has found use in producing specialized rubber materials for industrial applications.

Despite its wide utility, 1,2-ethanedithiol must be handled with care due to its strong odor and potential toxicity. Exposure can cause irritation to the respiratory system and skin, necessitating proper safety precautions during its use.

Research into the development of EDT alternatives or derivatives with improved safety and environmental profiles continues to advance, reflecting the ongoing innovation in thiol chemistry. However, 1,2-ethanedithiol remains a cornerstone reagent in various fields, demonstrating its enduring importance.

References

2024. Synthetic access to thiols: A review. Journal of Chemical Sciences, 136(9).
DOI: 10.1007/s12039-024-02300-7

2024. Characterization of 1,1- and 1,2-ethenedithiol, elusive compounds of potential astrochemical interest. Journal of Molecular Modeling, 30(9).
DOI: 10.1007/s00894-024-06149-y