I was just searching whether Uracil is aromatic or not and in this link$^1$ it is said that (from the abstract):
High-level computational methods were tested for the enthalpy of hydrogenation of uracil, but only with G3 was possible to obtain results in agreement with the experimental ones. It was found that uracil possesses 30.0% of aromatic character in the gaseous phase.
What is the meaning of this sentence? I have only basic knowledge on Aromaticity limited to Huckel's rule and the names of a few aromatic compounds. I didn't expect Aromaticity to be expressed in percentages. Can someone explain why?
- Tiago L. P. Galvão, Inês M. Rocha, Maria D. M. C. Ribeiro da Silva*, and Manuel A. V. Ribeiro da Silva. J. Phys. Chem. A 2013, 117, 28, 5826–5836. https://doi.org/10.1021/jp404938u