2-Mercaptoethanol

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2-Mercaptoethanol
Structural formula of 2-mercaptoethanol
Ball and stick model of 2-mercaptoethanol
Names
Preferred IUPAC name
2-Sulfanylethan-1-ol[1]
Other names
2-Mercaptoethan-1-ol
2-Hydroxy-1-ethanethiol
β-Mercaptoethanol
Thioglycol
Beta-merc
Identifiers
3D model (
JSmol
)
3DMet
773648
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard
 100.000.422 Edit this at Wikidata
EC Number
  • 200-464-6
1368
KEGG
MeSH Mercaptoethanol
RTECS number
  • KL5600000
UNII
UN number 2966
  • InChI=1S/C2H6OS/c3-1-2-4/h3-4H,1-2H2 checkY
    Key: DGVVWUTYPXICAM-UHFFFAOYSA-N checkY
  • OCCS
Properties
C2H6OS
Molar mass 78.13 g·mol−1
Odor Disagreeable, distinctive
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 0.76 hPa (at 20 °C);
4.67 hPa (at 40 °C)
Acidity (pKa) 9.643
Basicity (pKb) 4.354
1.4996
Hazards
GHS labelling:
GHS05: Corrosive GHS06: Toxic GHS09: Environmental hazard
Danger
H301, H310, H315, H317, H318, H330, H410
P260, P273, P280, P284, P301+P310, P302+P350
Flash point 68 °C (154 °F; 341 K)
Explosive limits
 18%
Lethal dose or concentration (LD, LC):
244 mg/kg (oral, rat)[2]
150 mg/kg (skin, rabbit)[2]
Related compounds
Related compounds
1,2-Ethanedithiol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

2-Mercaptoethanol (also β-mercaptoethanol, BME, 2BME, 2-ME or β-met) is the

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
.

Production

2-Mercaptoethanol is manufactured industrially by the reaction of ethylene oxide with hydrogen sulfide. Thiodiglycol and various zeolites catalyze the reaction.[3]

Reaction of ethylene oxide with hydrogen sulfide to form 2-mercaptoethanol in the presence of thiodiglycol as solvent and catalyst.

Reactions

2-Mercaptoethanol reacts with

oxathiolanes.[4] This makes 2-mercaptoethanol useful as a protecting group, giving a derivative whose stability is between that of a dioxolane and a dithiolane.[5]

Reaction scheme for the formation of oxathiolanes by reaction of 2-mercaptoethanol with aldehydes or ketones.

Applications

Reducing proteins

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:

RS–SR + 2 HOCH2CH2SH ⇌ 2 RSH + HOCH2CH2S–SCH2CH2OH
Reaction scheme for the cleavage of disulfide bonds by 2-mercaptoethanol

By breaking the S-S bonds, both the

redox potential (at pH 7) of −0.33 V, compared to −0.26 V for 2-mercaptoethanol.[7]

2-Mercaptoethanol is often used interchangeably with dithiothreitol (DTT) or the odorless tris(2-carboxyethyl)phosphine (TCEP) in biological applications.

Although 2-mercaptoethanol has a higher volatility than DTT, it is more stable: 2-mercaptoethanol's half-life is more than 100 hours at pH 6.5 and 4 hours at pH 8.5; DTT's half-life is 40 hours at pH 6.5 and 1.5 hours at pH 8.5.[8][9]

Preventing protein oxidation

2-Mercaptoethanol and related reducing agents (e.g., DTT) are often included in enzymatic reactions to inhibit the oxidation of free sulfhydryl residues, and hence maintain protein activity. It is often used in enzyme assays as a standard buffer component.[10]

Denaturing ribonucleases

2-Mercaptoethanol is used in some RNA isolation procedures to eliminate

disulfide bonds make ribonucleases very stable enzymes, so 2-mercaptoethanol is used to reduce these disulfide bonds and irreversibly denature the proteins. This prevents them from digesting the RNA during its extraction procedure.[11]

Deprotecting carbamates

Some

carboxybenzyl (Cbz) or allyloxycarbonyl (alloc) can be deprotected using 2-mercaptoethanol in the presence of potassium phosphate in dimethylacetamide.[12]

Safety

2-Mercaptoethanol is considered toxic, causing irritation to the nasal passageways and respiratory tract upon inhalation, irritation to the skin, vomiting and stomach pain through ingestion, and potentially death if severe exposure occurs.[13]

See also

References

  1. ISBN 978-0-85404-182-4
    . The prefixes 'mercapto' (–SH), and 'hydroseleno' or selenyl (–SeH), etc. are no longer recommended.
  2. ^ a b 2-Mercaptoethanol
  3. ISBN 978-3527306732
    .
  4. ^ "1,3-Dithiolanes, 1,3-Dithianes". Organic Chemistry Portal. Archived from the original on 17 May 2008. Retrieved 27 May 2008.
  5. PMID 14719975
    .
  6. ^ "2-Mercaptoethanol". Chemicalland21.com. Archived from the original on 2006-10-05. Retrieved 8 October 2006.
  7. PMID 17921203
    .
  8. ISBN 978-0-9720774-4-6
    .
  9. doi:10.1016/0307-4412(83)90048-1
    .
  10. PMID 3921014
    .
  11. ISBN 0-7167-4339-6
    .
  12. S2CID 248776636
    .
  13. ^ "Material Safety Data Sheet". Merck. Retrieved 24 September 2023.
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