91731-55-4Relevant academic research and scientific papers
Amidines. Part 31. pKa Values of N1,N1-Dialkyl-N2-phenylformamidines in Water-Ethanol Solutions
Oszczapowicz, Janusz,Jaroszewska-Manaj, Jolanta
, p. 1677 - 1680 (1991)
The pKa values of three series (30 compounds in all) of N1,N1-dialkyl-N2-phenylformamidines (XC6H4N=CHNRR) have been measured in water-ethanol mixtures.The obtained pKa values of the amidines have been correlated with Hammett-type substituent constants and the pKa values of the corresponding primary amines determined in the same solvent.The applicability of various ? values is discussed and it is shown that, in each case, for substituents on the phenyl ring at the amino nitrogen atom ?0 values should be used.It is found that the slopes of regression lines for correlations with Hammett-type constants depend on the substituents at the amino nitrogen atom, as well as on the solvent.
AMIDINES.PART XI. BASICITY OF N1,N1-DIMETHYLFORMAMIDINES
Oszczapowicz, Janusz,Raczynska, Ewa
, p. 419 - 428 (2007/10/02)
The pKa values of twenty four N1,N1-dimethyl-N2-phenyl- and N1,N1-dimethyl-N2-alkyl-formamidines in 95.6percent ethanol (azeotrope) at 25+/-0.2 degC have been measured by the potentiometric method.The pKa values of N2-phenyl derivatives obey Hammett equation and obtained ρ value is ca. 2/3 of that for symmetrically disubstituted N,N'-diphenylformamidines.It is shown that there is a good correlation, common for both N2-alkyl as well as for N2-aryl formamidines between pKa values of dimethylformamidines and pKa of corresponding primary amines.The slope of this correlation line is also ca. 2/3 of that for symmetricall y disubstituted N,N'-dialkyl- and N,N'-diarylformamidines.Experimental conditions securing reliable results of pKa determinations by potentiometric method in ethanol are discussed.
