112752-54-2Relevant articles and documents
Amidines. Part 24. Influence of Alkyl Substituents at the Amidino Carbon Atom on the Sensitivity to Substitution at the Imino Nitrogen Atom. pKa Values of N1N1-Dimethylamidines
Oszczapowicz, Janusz,Ciszkowski, Konrad
, p. 663 - 668 (2007/10/02)
Three series of N1N1-dimethylamidines, propionamidines, isobutyramidines, and pivalamidines, each containing the same set of 25 substituents Rx at the imino nitrogen atom have been synthesized and their pKa values in 95.6percent ethanol (azeotrope) measured.The pKa values were correlated with ? and?0 constants as well as with the pKa values of the corresponding primary amines RxNH2.Regression parameters for the series studied were compared with those for N1N1-dimethyl-formamidines and -acetamidines.It is shown that the sensitivity of the amidine group to substitution at the imino nitrogen atom depends on the polar effects of substituents at the amidino carbon atom.A good linear correlation between the slope of the correlation line and the ?* value of the substituent at the amidino carbon atom is found.