ONE-SCALE BASICITIES FROM ANILINES TO PROTON SPONGES
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)
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CONCLUSIONS
In summary, using two solvent systems, we have quantitatively
compared the basicities of 39 aromatic amines mostly with two
amino or dimethylamino groups, but not excluding mono-amines,
tetra-amines and hexa-amines. Basicity strength of 13 compounds
(4, 12, 17, 18, 21, 22, 26, 27, 30, 32, 33, 36, and 37) was measured
for the first time. Both in 20% EtOH and in 80% dioxane, proton
sponges [1,8-bis(dialkylamino)naphthalenes and their derivatives]
are the most basic compounds among all anilines and naphthyl-
amines. Because of specific solvation and lower polarity, aqueous
dioxane frequently reverses the well-known basicity trend when
the N-alkylated derivatives become less basic than the parent
arylamines. For diaminonaphthalenes, in which the amino groups
are situated on the different benzene rings, there observed some
basicity increase if compared with anilines. The data received will
be of help for studying influence of substitution on acid-base equi-
libria of ammonium salts and to predict further steps enhancing ba-
sic properties of simple arylamines.
Acknowledgements
This work was partially supported by the Russian Foundation for
Basic Research (project no. 16-33-60037). The authors acknowl-
edge the Scientific and Educational Laboratory of Resonance
Spectroscopy (Department of Natural and High Molecular Com-
pounds Chemistry of Southern Federal University) for NMR
measurements.
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