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Basicity Limits of Neutral Organic Superbases
Author(s) -
Leito Ivo,
Koppel Ilmar A.,
Koppel Ivar,
Kaupmees Karl,
Tshepelevitsh Sofja,
Saame Jaan
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201503345
Subject(s) - chemistry , substituent , acetonitrile , ionic bonding , organic base , computational chemistry , saturation (graph theory) , molecule , inorganic chemistry , organic chemistry , ion , mathematics , combinatorics
The potential limits of superbasicity achievable with different families of neutral bases by expanding the molecular framework are explored using DFT computations. A number of different core structures of non‐ionic organosuperbases are considered (such as phosphazenes, guanidinophosphazenes, guanidino phosphorus ylides). A simple model for describing the dependence of basicity on the extent of the molecular framework is proposed, validated, and used for quantitatively predicting the ultimate basicities of different compound families and the rates of substituent effect saturation. Some of the considered bases (guanidino phosphorus carbenes) are expected to reach gas‐phase basicity around 370 kcal mol −1 , thus being the most basic neutral bases ever reported. Also, the classical substituted alkylphosphazenes were predicted to reach p K a values of around 50 in acetonitrile, which is significantly higher than previously expected.