The Eyring equation can be summarised as

Ln (k/T) = 23.76 – ΔG/RT

Putting in T = 175K, and the requirement that the half life be **at least** 24 hours to allow X-ray data collection, one can approximate Ln (k/T) ~ -16.9, which from the above equation renders ΔG ~ 14.1 kcal/mol.

Since the various ΔG^{‡} noted in the post for model reactions are notably less than this, and the entropic effect imposed by the cavity is unlikely to substantially increase the free energy barrier (*via* what would have to be unusual entropic contributions), it seems a reasonable inference from the calculations that data could **not** be collected on 1,3-dimethylcyclobutadiene and carbon dioxide as separate species inside a host with acid catalyst components.