Tetrolic acid

Tetrolic acid
Names
	Preferred IUPAC name But-2-ynoic acid
	Other names 2-Butynoic acid; Butynoic acid
Identifiers
CAS Number	590-93-2;
3D model (JSmol)	Interactive image;
ChemSpider	61810 ;
ECHA InfoCard	100.008.815
PubChem CID	68535;
UNII	W3AM9ANZ22 ;
CompTox Dashboard (EPA)	DTXSID4060444 ;
	InChI InChI=1S/C4H4O2/c1-2-3-4(5)6/h1H3,(H,5,6) Key: LUEHNHVFDCZTGL-UHFFFAOYSA-N;
	SMILES CC#CC(=O)O;
Properties
Chemical formula	CH3C≡CCO2H
Molar mass	84.074 g·mol−1
Density	0.9641 g/cm3
Melting point	78 °C (172 °F; 351 K)
Boiling point	203 °C (397 °F; 476 K)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

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.

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:

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 can be recrystallized from non-polar solvents (such as heptane, hexane or 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]

Accelerated rate calorimetry (ARC) showed exothermic onset from 135 °C, precluding short-path distillation as a means of purification.^[7]

References

^ ^a ^b ^c Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, Florida: CRC Press. p. 3.88. ISBN 1-4398-5511-0.
^ Geuther, A. (1871). "Ethyldiacetic Acid and some of its Derivatives". J. Chem. Soc. 24: 812–837. doi:10.1039/JS8712400808.
^ Smith, W. (1973) "Preparation of tetrolic acid" U.S. patent 3752848A
^ 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.
^ Kauer, J. C.; Brown, M. (1962). "Tetrolic Acid (2-Butynoic Acid)". Organic Syntheses. 42: 97. doi:10.15227/orgsyn.042.0097; Collected Volumes, vol. 5, p. 1043.
^ 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.
^ ^a ^b 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. S2CID 146028375.

[b92-1] Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, Florida: CRC Press. p. 3.88. ISBN 1-4398-5511-0.

[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 3752848A

[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; Collected Volumes, vol. 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.

[stability-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. S2CID 146028375.

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