Tetrolic acid

Tetrolic acid (2-butynoic acid) is a short-chain unsaturated carboxylic acid, described by the formula CH3-C≡C-CO2H. Salts and esters of tetrolic acid are known as tetrolates.

Tetrolic acid
Names
Preferred IUPAC name
But-2-ynoic acid
Other names
2-Butynoic acid
But-2-ynoic acid
Butynoic acid
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.008.815
Properties
C4H4O2
Molar mass 84.074 g·mol−1
Density 0.9641 g/cm3[1]
Melting point 78 °C (172 °F; 351 K)[1]
Boiling point 203 °C (397 °F; 476 K)[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

History

The first reported synthesis[2] of tetrolic acid is believed to be by German chemist Johann Georg Anton Geuther in 1871 as part of his work investigating the derivatives of ethyl acetoacetate.

Production

Tetrolic acid is manufactured[3] on a commercial scale by treatment of propyne with a strong base (to form an acetylide), followed by carbon dioxide:

Scheme2

Strong bases such as n-BuLi[4] and NaNH2[5] can be used.

Properties

Tetrolic acid is highly soluble in polar solvents (water, ethanol) and may be recrystallized from non polar solvents (such as heptane, toluene). The compound is a white crystalline solid which can exist in two polymorphous crystalline forms.[6]

The proton nuclear magnetic resonance (1H-NMR) spectrum in deuterated dimethyl sulfoxide shows a characteristic singlet peak at 1.99 ppm corresponding to the -CH3 protons.

Tetrolic acid sublimes at temperatures above 20°C, and should ideally be stored in a sealed container in a refrigerator.[7]

Safety

Tetrolic acid is thermally unstable at high temperatures. Testing using accelerated rate calorimetry (ARC) showed exothermic onset from 135 °C, precluding short-path distillation as a means of purification.[7]

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References

  1. Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 3.88. ISBN 1439855110.
  2. Geuther, A. (1871). "Ethyldiacetic Acid and some of its Derivatives". J. Chem. Soc. 24: 812–837. doi:10.1039/JS8712400808.
  3. Smith, W. (1973) "Preparation of tetrolic acid" U.S. Patent 3,752,848A
  4. Hartzoulakis, Basil; Gani, David (1994). "Synthesis of (2S, 3R)- and (2S, 3S)-3-methylglutamic acid". J. Chem. Soc., Perkin Trans. 1. 1994 (18): 2525–2531. doi:10.1039/P19940002525.
  5. Kauer, J. C.; Brown, M. (1962). "Tetrolic Acid (2-Butynoic Acid)". Organic Syntheses. 42: 97. doi:10.15227/orgsyn.042.0097.; Collective Volume, 5, p. 1043
  6. Flakus, Henryk T.; Hachuła, Barbara (2008). "Effects of "excessive" exciton interactions in polarized IR spectra of the hydrogen bond in 2-butynoic acid crystals: Proton transfer induced by dynamical co-operative interactions involving hydrogen bonds". Chemical Physics. 345 (1): 49–64. Bibcode:2008CP....345...49F. doi:10.1016/j.chemphys.2008.01.035.
  7. Golden, M. (2019). "Thermal Stability of 2-Butynoic Acid (Tetrolic acid)". Org. Process Res. Dev. 23, (5) (5): 1101–1104. doi:10.1021/acs.oprd.9b00106.
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