Triacetic acid lactone

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Triacetic acid lactone
Triacetic acid lactone.svg
Names
Preferred IUPAC name
4-Hydroxy-6-methyl-2H-pyran-2-one
Other names
  • Triacetate lactone;
  • 3,5-Dihydroxysorbic acid δ-lactone;
  • 4-Hydroxy-6-Methyl-2-Pyrone;
  • 4-Hydroxy-6-Methyl-a-pyrone;
  • 4-Hydroxy-6-Methylpyran-2-one;
  • 6-Methyl-4-Hydroxy-2-Pyrone;
  • 2H-Pyran-2-one;
  • 4-Hydroxy-6-Methyl;
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.010.564 Edit this at Wikidata
EC Number
  • 211-619-2
UNII
  • InChI=1S/C6H6O3/c1-4-2-5(7)3-6(8)9-4/h2-3,7H,1H3
    Key: NSYSSMYQPLSPOD-UHFFFAOYSA-N
  • InChI=1/C6H6O3/c1-4-2-5(7)3-6(8)9-4/h2-3,7H,1H3
    Key: NSYSSMYQPLSPOD-UHFFFAOYAI
  • C/C1=CC(\O)=C/C(=O)O1
Properties
C6H6O3
Molar mass 126.12 g mol−1
Appearance light yellow crystal powder
Density 1.348 g cm−3
Melting point 188 to 190 °C (370 to 374 °F; 461 to 463 K)
Boiling point 285.9 °C (546.6 °F; 559.0 K)
8.60 g L-1 at 20°C in H2O
Hazards
Main hazards Moderately Toxic
GHS labelling:
GHS07: Exclamation mark
Signal word
 Warning
H315, H319, H335
P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
Flash point 127.9 °C (262.2 °F; 401.0 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Triacetic acid lactone (TAL;[1] 4-hydroxy-6-methyl-2-pyrone) is an organic compound derived enzymatically from glucose. It is a light yellow solid that is soluble in organic solvents.

Structure[]

Triacetic acid lactone consists of two main tautomers.

Tautomerization of triacetic acid lactone

The tautomer on the left, featuring a 4-hydroxy group, the C4 carbon, is dominant. Triacetic acid lactone is classified as a 2-pyrone compound owing to the ketone group on the C2 carbon in its dominant form.

Synthesis[]

Triacetic acid lactone is synthesized either from dehydroacetic acid, another 2-pyrone derivative, or from glucose by enzymatic catalysis. In its original synthesis, triacetic acid lactone was obtained by treatment of dehydroacetic acid with sulfuric acid at 135 °C. Dehydroacetic acid undergoes ring-opening and hydration to form "tetracetic acid".[2] Upon cooling, triacetic acid reverts to a lactone ring similar to the dehydroacetic acid structure, and the triacetic acid lactone is recovered by crystallization in cold water.

Synthesis of triacetic acid lactone completed by Collie

Biosynthesis[]

The microbial synthesis of triacetic acid lactone requires the enzyme (2-PS).[3] This enzyme has been examined in two hosts Escherichia coli and Saccharomyces cerevisiae. The Saccharomyces cerevisiae host being used during the synthesis produces a higher yield (70%) compared with the Escherichia coli host, which produces a yield of 40% of triacetic acid lactone. This enzyme catalyzes the synthesis of triacetic acid lactone from acetyl-CoA via two subsequent condensations with malonyl-CoA. This produces an intermediate of 3,5-diketohexanoate thioester, which undergoes ring closure to produce triacetic acid lactone.

Reactivity[]

The lactone is a versatile intermediate in organic synthesis.[4] It has also been described as a platform chemical, meaning that it could be the precursor to other fine chemicals. The lactone undergoes decarboxylation to acetylacetone. It is also a precursor to sorbic acid, , and . Dienoic acid is used to inhibit the growth of various molds and hexenoic acid is used as a flavoring agent.[5] Acetylacetone is used for metal extraction and plating and as a food additive.[6]

References[]

  1. ^ "New Sustainable Production Method Could Advance Plastics and Pharmaceuticals" (Press release). University of Texas. 13 February 2018 – via Drug Discovery & Development Magazine.
  2. ^ Collie, J. Norman (1891). "LVI.?The lactone of triacetic acid". Journal of the Chemical Society, Transactions. 59: 607–617. doi:10.1039/CT8915900607.
  3. ^ Xie, Dongming; Shao, Zengyi; Achkar, Jihane; Zha, Wenjuan; Frost, John W.; Zhao, Huimin (2006). "Microbial synthesis of triacetic acid lactone". Biotechnology and Bioengineering. 93 (4): 727–36. doi:10.1002/bit.20759. PMID 16245348. S2CID 2626483.
  4. ^ Moreno-Mañas, Marcial; Pleixats, Roser (1992). "Dehydroacetic Acid, Triacetic Acid Lactone, and Related Pyrones". Advances in Heterocyclic Chemistry. 53: 1–84. doi:10.1016/S0065-2725(08)60861-2. ISBN 9780120207534.
  5. ^ Jacoby, Mitch (2012). "Teaming Up for Biobased Chemicals". Chem. Eng. News. 90 (32): 37–38. doi:10.1021/cen-09032-scitech1.
  6. ^ Chia, Mei; Schwartz, Thomas J.; Shanks, Brent H.; Dumesic, James A. (2012). "Triacetic acid lactone as a potential biorenewable platform chemical". Green Chemistry. 14 (7): 1850. doi:10.1039/C2GC35343A.
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