1,2-Ethanedithiol

Ethylene Dithiol · EDT · 1,2-Dimercaptoethane · Dithioglycol

CAS Number: 540-63-6 · Molecular Formula: C₂H₆S₂ · MW: 94.19

Abstract

1,2-Ethanedithiol (EDT), C₂H₆S₂, is a bifunctional organosulfur compound whose two thiol groups (HSCH₂CH₂SH) are attached to adjacent carbon atoms. It presents as a colourless to pale yellow liquid with a characteristically strong odour. EDT is widely employed as a building block in organic synthesis and serves as an effective bidentate chelating ligand for transition metals. In materials science it is applied to quantum dot surface passivation, nanomaterial engineering and as a scavenger in solid-phase peptide synthesis.

Full monograph

Skeletal structural formula of 1,2-ethanedithiol showing the two terminal thiol groups — Figure 1. Molecular structure of 1,2-ethanedithiol (skeletal formula).Adapted from NIST Chemistry WebBook.

Table 1. Selected physical properties of 1,2-ethanedithiol.

Property	Value	Unit	Source
Melting Point	−41	°C	lit.
Boiling Point	144–146	°C	lit.
Density (25 °C)	1.123	g/mL	lit.
Refractive Index	n²⁰/D 1.558	—	lit.
Vapor Pressure	4.8	mmHg	at 20 °C
Flash Point	44–50	°C	closed cup, reported range

Source: NIST Chemistry WebBook; literature values (lit.).

Complete property data

Applications

EDT serves as a versatile reagent across multiple disciplines of chemistry and materials science:

Preparation

Two principal synthetic routes to 1,2-ethanedithiol are employed:

ClCH₂CH₂Cl + 2 NaSH → HSCH₂CH₂SH + 2 NaCl

Reaction 1. Industrial route via 1,2-dichloroethane.Conditions: Aqueous/alcoholic NaSH at elevated temperature.

BrCH₂CH₂Br + 2 (H₂N)₂C=S → (H₂N)₂C⁺–S–CH₂CH₂–S–C⁺(NH₂)₂ · 2 Br⁻

+ 4 NaOH → NaS–CH₂CH₂–SNa + 2 (H₂N)₂C=O + 2 H₂O + 2 NaBr

+ 2 H₃O⁺ → HSCH₂CH₂SH + 2 H₂O + 2 Na⁺

Reaction 2. Laboratory thiourea method.Conditions: Salt formation, alkaline hydrolysis and controlled acidification.

Detailed synthetic procedures

Safety Summary

Signal Word: DANGER

H226Flammable liquid and vapour
H301Toxic if swallowed
H310Fatal in contact with skin
H330Fatal if inhaled

LD₅₀: 143.88 mg/kg (oral, rat)

Full safety data

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