How to Predict the p Ka of Any Compound in Any Solvent

Busch, MichaelAalto Univ, Sch Chem Engn, Dept Chem & Mat Sci, Espoo 02150, Finland.,Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University, Kemistintie 1, 02150 Espoo, Finland (författare)

Acid-base properties of molecules in nonaqueous solvents are of critical importance for almost all areas of chemistry. Despite this very high relevance, our knowledge is still mostly limited to the pKa of rather few compounds in the most common solvents, and a simple yet truly general computational procedure to predict pKa's of any compound in any solvent is still missing. In this contribution, we describe such a procedure. Our method requires only the experimental pKa of a reference compound in water and a few standard quantum-chemical calculations. This method is tested through computing the proton solvation energy in 39 solvents and by comparing the pKa of 142 simple compounds in 12 solvents. Our computations indicate that the method to compute the proton solvation energy is robust with respect to the detailed computational setup and the construction of the solvation model. The unscaled pKa's computed using an implicit solvation model on the other hand differ significantly from the experimental data. These differences are partly associated with the poor quality of the experimental data and the well-known shortcomings of implicit solvation models. General linear scaling relationships to correct this error are suggested for protic and aprotic media. Using these relationships, the deviations between experiment and computations drop to a level comparable to that observed in water, which highlights the efficiency of our method.

Ahlberg, ErnstUppsala universitet,Institutionen för farmaceutisk biovetenskap,Universal Predict AB, S-42677 Gothenburg, Sweden.,Universal Prediction AB, 42677 Gothenburg, Sweden; Department of Pharmaceutical Biosciences, Uppsala University, Husargatan 3, 75124 Uppsala, Sweden(Swepub:uu)ernah620 (författare)
Ahlberg, Elisabet,1952Gothenburg University,Göteborgs universitet,Institutionen för kemi och molekylärbiologi,Department of Chemistry and Molecular Biology,Univ Gothenburg, Dept Chem & Mol Biol, S-41296 Gothenburg, Sweden.,Department of Chemistry and Molecular Biology, University of Gothenburg, Kemigården 4, 41296 Gothenburg, Sweden(Swepub:gu)xahlbe (författare)
Laasonen, KariAalto Univ, Sch Chem Engn, Dept Chem & Mat Sci, Espoo 02150, Finland.,Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University, Kemistintie 1, 02150 Espoo, Finland (författare)
Aalto Univ, Sch Chem Engn, Dept Chem & Mat Sci, Espoo 02150, Finland.Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University, Kemistintie 1, 02150 Espoo, Finland (creator_code:org_t)

Av författaren/redakt...: Busch, Michael; Ahlberg, Ernst; Ahlberg, Elisabe ...; Laasonen, Kari

Om ämnet

Av lärosätet: Göteborgs universitet; Uppsala universitet; Luleå tekniska universitet

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