1,2-Ethanedithiol

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1,2-Ethanedithiol
1,2-Ethanedithiol
Ball-and-stick model of ethane-1,2-dithiol
Space-filling model of ethane-1,2-dithiol
Identifiers
CAS number 540-63-6 YesY
ChemSpider 13865015 YesY
UNII 92T634FLAR YesY
RTECS number KI3325000
Jmol-3D images Image 1
Properties
Molecular formula C2H6S2
Molar mass 94.20 g mol−1
Appearance Colorless liquid
Density 1.123 g/cm³
Melting point −41 °C (−42 °F; 232 K)
Boiling point 146 °C (295 °F; 419 K) 46 mmHg
Solubility in water Slightly sol
Solubility in other solvents Good solubility in
most organic solvents
Acidity (pKa) ~11
Refractive index (nD) 1.5589 (D-line, 25 °C)
Hazards
EU classification Toxic (T)
R-phrases R10 R22
S-phrases S16
NFPA 704
Flammability code 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g., diesel fuel Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity (yellow): no hazard code Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 50 °C (122 °F; 323 K)
Related compounds
Related thiols Ethanethiol; 1,3-Propanedithiol; 1,2-Benzenedithiol; Thiophenol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

1,2-Ethanedithiol is a colorless liquid with the formula C2H4(SH)2. It has a very characteristic odor which is compared by many people to rotten cabbage. It is a common building block in organic synthesis and an excellent ligand for metal ions.

Preparation[edit]

1,2-Ethanedithiol is prepared commercially by the reaction of 1,2-dichloroethane with aqueous sodium bisulfide. In the laboratory, it can also be prepared by the action of 1,2-dibromoethane on thiourea followed by hydrolysis.[1]

Applications[edit]

This compound is widely used in organic chemistry because it reacts with aldehydes and ketones to give 1,3-dithiolanes, which are useful intermediates. [2]

C2H4(SH)2 + RR'CO → C2H4S2CRR' + H2O
Protecting a carbonyl group by converting it to a 1,3-dithiolane, using 1,2-ethanedithiol

Other 1,2- and 1,3-dithiols undergo this reaction to give related 1,3-dithiolanes and 1,3-dithianes (six-membered rings). Diols such as ethylene glycol undergo analogous reactions to 1,3-dioxalanes and 1,3-dioxanes. One distinguishing feature of the dithiolanes and dithianes derived from aldehydes is that the methyne group can be deprotonated and the resulting carbanion alkylated.

References[edit]

  1. ^ Speziale, A. J. (1963), "Ethanedithiol", Org. Synth. ; Coll. Vol. 4: 401 
  2. ^ R. E. Conrow "Ethanedithiol" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289