Propiolic acid

Propiolic acid is the organic compound with the formula HC2CO2H. It is the simplest acetylenic carboxylic acid. It is a colourless liquid that crystallises to give silky crystals. Near its boiling point, it decomposes.

Propiolic acid
Names
Preferred IUPAC name
Prop-2-ynoic acid[1]
Other names
Propiolic acid
Acetylene carboxylic acid
Propargylic acid
Acetylene mono-carboxylic acid
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.006.763
EC Number
  • 207-437-8
KEGG
MeSH C011537
UNII
Properties
C3H2O2
Molar mass 70.047 g·mol−1
Density 1.1325 g/cm3
Melting point 9 °C (48 °F; 282 K)
Boiling point 144 °C (291 °F; 417 K) (decomposes)
Acidity (pKa) pka = 1.89 [2]
Hazards
Safety data sheet External MSDS
T+
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

It is soluble in water and possesses an odor like that of acetic acid.[3][4]

Preparation

It is prepared commercially by oxidizing propargyl alcohol at a lead electrode.[5] It can also be prepared by decarboxylation of acetylenedicarboxylic acid.

Reactions and applications

Exposure to sunlight converts it into trimesic acid (benzene-1,3,5-tricarboxylic acid).[4] It undergoes bromination to give dibromoacrylic acid. With hydrogen chloride it forms chloroacrylic acid. Its ethyl ester condenses with hydrazine to form pyrazolone.[4]

It forms a characteristic explosive solid upon treatment to its aqueous solution with ammoniacal silver nitrate.[4] An amorphous explosive precipitate forms with ammoniacal cuprous chloride.

Propiolates

Propiolates are esters or salts of propiolic acid. Common examples include methyl propiolate and ethyl propiolate.

See also

References
  1. Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 748. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
  2. https://pubchem.ncbi.nlm.nih.gov/compound/propiolic_acid
  3. ed, Susan Budavari (1990). The Merck index an encyclopedia of chemicals, drugs, and biologicals (11. ed., 2. print. ed.). Rahway, NJ: Merck. pp. 7833, 1911. ISBN 9780911910285.
  4. Chisholm, Hugh, ed. (1911). "Propiolic Acid" . Encyclopædia Britannica. 22 (11th ed.). Cambridge University Press. p. 449.
  5. Wilhelm Riemenschneider (2002). "Carboxylic Acids, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a05_235. ISBN 3527306730.
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