Vinyl alcohol

Vinyl alcohol
Names
IUPAC name
Ethenol
Other names
Hydroxyethene
Hydroxyethylene
Identifiers
557-75-5 YesY
ChEMBL ChEMBL76101 YesY
ChemSpider 10726 YesY
Jmol interactive 3D Image
PubChem 11199
Properties
C2H4O
Molar mass 44.053 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Vinyl alcohol, also called ethen-1-ol (IUPAC name), is an alcohol. It is not to be confused with the drinking alcohol, ethanol. With the formula CH2CHOH, vinyl alcohol is an isomer of acetaldehyde and ethylene oxide. Under normal conditions, it converts (tautomerizes) to acetaldehyde:

Tautomerization of acetaldehyde to vinyl alcohol

At room temperature, acetaldehyde (H3CC(O)H) is more stable than vinyl alcohol (H2C=CHOH) by 42.7 kJ/mol:[1]

H2C=CHOH → H3CC(O)H                 ∆H298,g = –42.7 kJ/mol

This keto-enol tautomerization has a high barrier and does therefore not occur near room temperature. This tautomerization can be catalyzed via photochemical process. These findings suggest that the keto-enol tautomerization is a viable route under atmospheric and stratospheric conditions, relevant to a role for vinyl alcohol in the production of organic acids in the atmosphere.[2][3]

Relationship to polyvinylalcohol

Because of the instability of vinyl alcohol, the thermoplastic polyvinyl alcohol (PVA or PVOH) is made indirectly by polymerization of vinyl acetate followed by hydrolysis of the ester bonds (Ac = acetyl, HOAc = acetic acid):

n CH2=CHOAc → (CH2-CHOAc)n
(CH2-CHOAc)n + n H2O → (CH2-CHOH)n + n HOAc

As a ligand

Several metal complexes are known that contain vinyl alcohol as a ligand. One example is Pt(acac)(η2-C2H3OH)Cl.[4]

Occurrence in interstellar medium

Vinyl alcohol was discovered in the molecular cloud Sagittarius B using the 12-meter radio telescope at the Kitt Peak National Observatory.[5] This vinyl alcohol being stable in the (dilute) interstellar medium shows that its tautomerization is not unimolecular.

See also

References

  1. ↑ R.D. Johnson III. "CCCBDB NIST Standard Reference Database.". Retrieved 2014-08-30.
  2. ↑ Heazlewood, B. R.; Maccarone, A. T.; Andrews, D. U.; Osborn, D. L.; Harding, L. B.; Klippenstein, S. J.; Jordan, M. J. T.; Kable, S. H. "Near-threshold H/D exchange in CD3CHO photodissociation." Nat. Chem. 2011, 3, 443−448. doi:10.1038/nchem.1052
  3. ↑ Andrews, D. U.; Heazlewood, B. R.; Maccarone, A. T.; Conroy, T.; Payne, R. J.; Jordan, M. J. T.; Kable, S. H. "Photo-tautomerization of acetaldehyde to vinyl alcohol: A potential route to tropospheric acids." Science 2012, 337, 1203−1206. doi:10.1126/science.1220712
  4. ↑ F. A. Cotton, J. N. Francis, B. A. Frenz, M. Tsutsui "Structure of a dihapto(vinyl alcohol) complex of platinum(II)" Journal of the American Chemical Society, 1973, volume 95, p. 2483-6. doi:10.1021/ja00789a011
  5. ↑ "Scientists Toast the Discovery of Vinyl Alcohol in Interstellar Space". National Radio Astronomy Observatory. 2001-10-01. Retrieved 2006-12-20.
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