Aqueous pKa values of strong organic bases -DBU, TBD, MTBD, different phosphazene bases, etc -were computed with CPCM, SMD and COSMO-RS approaches. Explicit solvent molecules were not used. Direct computations and computations with reference pKa values were used. The latter were of two types: (1) reliable experimental aqueous pKa value of a reference base with structure similar to the investigated base or (2) reliable experimental pKa value in acetonitrile of the investigated base itself. The

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... rrelations of experimental and computational values demonstrate that direct computations do not yield pKa predictions with useful accuracy: mean unsigned errors (MUE) of several pKa units were observed. Computations with reference bases lead to MUE below 1 pKa unit and are useful for predictions. Recommended aqueous pKa values are proposed for all investigated bases taking into account all available information: experimental pKa values in acetonitrile and water (if available), computational pKa values, common chemical knowledge.