Quantum tunneling-driven isomerization of vinyl alcohol in the ISM

Determine whether ground-state quantum tunneling can efficiently interconvert the syn and anti conformers of vinyl alcohol (H2CCHOH) under interstellar conditions, analogous to the tunneling-driven isomerization established for other systems, and quantify the feasibility and rates given the larger conformer energy separation (approximately 550 K).

Background

The paper shows that for several stereoisomeric pairs with small energy separations observed in hot environments, thermodynamic ratios can be reached via multidimensional ground-state quantum tunneling, even when isomerization barriers are high. This has been demonstrated for some imines and for thioformic acid.

The authors hypothesize that similar tunneling-driven interconversion could apply to small-ΔE conformational pairs such as ethanol, isopropanol, and ethylene glycol. However, they note uncertainty for vinyl alcohol (H2CCHOH), which has a larger energy difference (about 550 K) between syn and anti conformers.

They explicitly state that these tunneling processes for vinyl alcohol have not yet been theoretically studied under interstellar conditions, motivating a focused investigation of whether tunneling can drive syn↔anti interconversion in this molecule in space.

References

Meanwhile, for \ce{H2CCHOH}, it remains unclear whether a similar process could occur, since the $\Delta E$ is somewhat larger (550 K). To our knowledge these tunneling processes proposed here have not yet been theoretically studied under ISM conditions, although they certainly merit attention.

— Interstellar stereoisomerism  (2603.24848 - Rivilla et al., 25 Mar 2026) in Section "DISCUSSION: THE ORIGIN(S) OF THE OSR)", paragraph on tunneling-driven mechanisms