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)
878176
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.006.763 Edit this at Wikidata
EC Number
  • 207-437-8
81893
KEGG
MeSH C011537
UNII
  • InChI=1S/C3H2O2/c1-2-3(4)5/h1H,(H,4,5) ☒N
    Key: UORVCLMRJXCDCP-UHFFFAOYSA-N ☒N
  • InChI=1/C3H2O2/c1-2-3(4)5/h1H,(H,4,5)
    Key: UORVCLMRJXCDCP-UHFFFAOYAX
  • C#CC(=O)O
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
GHS labelling:[3]
GHS02: FlammableGHS06: ToxicGHS07: Exclamation mark
Danger
H226, H301, H310, H315, H335
P210, P233, P240, P241, P242, P243, P261, P262, P264, P270, P271, P280, P301+P310, P302+P350, P302+P352, P303+P361+P353, P304+P340, P310, P312, P321, P322, P330, P332+P313, P361, P362, P363, P370+P378, P403+P233, P403+P235, P405, P501
Safety data sheet (SDS) External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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It is soluble in water and possesses an odor like that of acetic acid.[4][5]

Preparation

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It is prepared commercially by oxidizing propargyl alcohol at a lead electrode.[6] It can also be prepared by decarboxylation of acetylenedicarboxylic acid.

 

Reactions and applications

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

It forms a characteristic explosive solid upon treatment to its aqueous solution with ammoniacal silver nitrate.[5] An amorphous explosive precipitate forms with ammoniacal cuprous chloride.

Propiolates

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

See also

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References

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  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. ^ "Propiolic acid".
  3. ^ "Propiolic acid". pubchem.ncbi.nlm.nih.gov. Retrieved 16 December 2021.
  4. ^ 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.
  5. ^ a b c d Chisholm, Hugh, ed. (1911). "Propiolic Acid" . Encyclopædia Britannica. Vol. 22 (11th ed.). Cambridge University Press. p. 449.
  6. ^ Wilhelm Riemenschneider (2002). "Carboxylic Acids, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a05_235. ISBN 3527306730.