2-Mercaptoethanol
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| Names | |||
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Preferred IUPAC name
2-Sulfanylethan-1-ol
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| Other names
2-Mercaptoethan-1-ol (no longer recommended)
2-Hydroxy-1-ethanethiol β-Mercaptoethanol Thioglycol |
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| Identifiers | |||
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3D model (Jmol)
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| 3DMet | B00201 | ||
| 773648 | |||
| ChEBI | |||
| ChemSpider | |||
| DrugBank | |||
| ECHA InfoCard | 100.000.422 | ||
| EC Number | 200-464-6 | ||
| 1368 | |||
| KEGG | |||
| MeSH | Mercaptoethanol | ||
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PubChem CID
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| RTECS number | KL5600000 | ||
| UN number | 2966 | ||
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| Properties | |||
| C2H6OS | |||
| Molar mass | 78.13 g·mol−1 | ||
| Density | 1.114 g/cm3 | ||
| Melting point | −100 °C (−148 °F; 173 K) | ||
| Boiling point | 157 °C; 314 °F; 430 K | ||
| log P | -0.23 | ||
| Vapor pressure | 100 Pa (at 20 °C) | ||
| Acidity (pKa) | 9.643 | ||
| Basicity (pKb) | 4.354 | ||
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Refractive index (nD)
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1.4996 | ||
| Hazards | |||
| Safety data sheet | msds.chem.ox.ac.uk | ||
| GHS pictograms |
  
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| GHS signal word | DANGER | ||
| H301, H310, H315, H317, H318, H330, H410 | |||
| P260, P273, P280, P284, P301+310, P302+350 | |||
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EU classification (DSD)
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 T  N
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| R-phrases | R20/22, R24, R34, R51/53 | ||
| S-phrases | S26, S36/37/39, S45, S61 | ||
| Flash point | 68 °C (154 °F; 341 K) | ||
| Explosive limits | 18% | ||
| Lethal dose or concentration (LD, LC): | |||
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LD50 (median dose)
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244 mg/Kg (oral, rat) 150 mg/kg (skin, rabbit) |
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| Related compounds | |||
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Related compounds
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Ethylene glycol |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is   ?) |
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| Infobox references | |||
2-Mercaptoethanol (also β-mercaptoethanol, BME, 2BME, 2-ME or β-met) is the chemical compound with the formula HOCH2CH2SH. ME or βME, as it is commonly abbreviated, is used to reduce disulfide bonds and can act as a biological antioxidant by scavenging hydroxyl radicals (amongst others). It is widely used because the hydroxyl group confers solubility in water and lowers the volatility. Due to its diminished vapor pressure, its odor, while unpleasant, is less objectionable than related thiols.
2-Mercaptoethanol may be prepared by the action of hydrogen sulfide on ethylene oxide:
2-Mercaptoethanol reacts with aldehydes and ketones to give the corresponding oxathiolanes. This makes 2-mercaptoethanol useful as a protecting group.
Some proteins can be denatured by 2-mercaptoethanol, which cleaves the disulfide bonds that may form between thiol groups of cysteine residues. In the case of excess 2-mercaptoethanol, the following equilibrium is shifted to the right:
By breaking the S-S bonds, both the tertiary structure and the quaternary structure of some proteins can be disrupted. Because of its ability to disrupt the structure of proteins, it was used in the analysis of proteins, for instance, to ensure that a protein solution contains monomeric protein molecules, instead of disulfide linked dimers or higher order oligomers. However, since 2-mercaptoethanol forms adducts with free cysteines and is somewhat more toxic, dithiothreitol (DTT) is generally more used especially in SDS-PAGE. DTT is also a more powerful reducing agent with a redox potential (at pH 7) of −0.33 V, compared to −0.26 V for 2-mercaptoethanol.
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