1,1,2‐Ethenetriol: The Enol of Glycolic Acid, a High‐Energy Prebiotic Molecule

• Published in: Angewandte Chemie International Edition 2021-07, Vol.60 (28), p.15313-15316
• Main Authors: Mardyukov, Artur, Keul, Felix, Schreiner, Peter R.
• Format: Article
• Language: English
• Subjects: Acids; Argon; Communication; Communications; Energy; enols; Glycolic acid; Isomers; Organic chemistry; photochemistry; Photolysis; prebiotic chemistry; Pyrolysis; Tartronic acid; Tautomers; Temperature requirements; Vapor phases
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202104436

As low‐temperature conditions (e.g. in space) prohibit reactions requiring large activation energies, an alternative mechanism for follow‐up transformations of highly stable molecules involves the reactions of higher energy isomers that were generated in a different environment. Hence, one working model for the formation of larger organic molecules is their generation from high‐lying isomers of otherwise rather stable molecules. As an example, we present here the synthesis as well as IR and UV/Vis spectroscopic identification of the previously elusive 1,1,2‐ethenetriol, the higher energy enol tautomer of glycolic acid, a rather stable and hence unreactive biological building block. The title compound was generated in the gas phase by flash vacuum pyrolysis of tartronic acid at 400 °C and was subsequently trapped in argon matrices at 10 K. The spectral assignments are supported by B3LYP/6–311++G(2d,2p) computations. Upon photolysis at λ=180–254 nm, 1,1,2‐ethenetriol rearranges to glycolic acid and ketene. The simple yet uncharacterized high energy tautomer of glycolic acid, namely 1,1,2‐ethenetriol, an important molecule in the abiotic synthesis of sugar acids, has now been identified by IR and UV/Vis spectroscopy. With these data now in hand, it now awaits its identification in space as another building block for prebiotic chemistry.