I'm modelling the thermochemistry of adduct formation between a large, boron substituted aromat and acetonitrile. While I obtained electronic energies at the SCS-MP2/CBS+COSMO level of theory, I used B3LYP-D3/SVP to estimate thermochemical corrections (ORCA 3.0.1). For the latter, it makes a huge difference (tens of kJ/mol) if thermochemical and entropy contributions from rotational and vibrational degrees of freedom are included or excluded. I guess it makes a big difference for rotational and translations degrees of freedom and the respective contributions if the molecule is in solution vs. in gas-phase and hence I think there should be some difference in their treatment. Is there a standard approach? Can I just ignore these contribution in solution?
I think, that better expert in this area is prof Szczepan Roszak:
http://ichfit.ch.pwr.wroc.pl/?q=user/19
You can ask him directly.
I suggest, to compare your results with the data of the paper as follows " Aromatic substitution. 48. Boron trifluoride catalyzed nitration of aromatics......in acetonitrile solution"
J. Org. Chem., 1981, 46 (17), pp 3533–3537
DOI: 10.1021/jo00330a032
Entropy: A concept that is not a physical quantity
https://www.researchgate.net/publication/230554936_Entropy_A_concept_that_is_not_a_physical_quantity
I have in the meantime found an article that answers this very question with the so-called Harmonic Solvation Model. It includes a very convincing demonstration of the approach. You can find it here: Article Quantum chemical approach for condensed-phase thermochemistr...
There is no generally accepted definition of thermodynamic partition functions in the liquid phase. Therefore, a straightforward way to compute reactions in solution could be to do a thermodynamic cycle and calculate the total electronic energies and finite temperature contributions in the gas phase and add a free energy of solvation for each component.
See e.g.:
Article Brick by Brick Computation of the Gibbs Free Energy of React...
x Article Brick by Brick Computation of the Gibbs Free Energy of React...
Somehow the arXiv link are getting destroyed..
Here it is:
arxiv.org/abs/1610.07370
- Badges
- Science topic
- Similar topics
- Correction