ISSN:
0170-2041
Keywords:
Acidity constants
;
Basicity
;
Imines
;
Solvation
;
Steric shielding
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
NMR spectra in combination with pH measurements are shown to provide a simple and convenient procedure for determining the basicities of imines which are either slowly hydrolyzed (4, 5) or completely stable but inconveniently weak bases (11-13). The method has the advantage that it does not require any precise knowledge of the concentrations of the substrates or reagents. N-Alkyl (4, 15) and N-unsubstituted imines (5, 8, 9, 14) show quite similar basicities with a weak solvent dependence (from pure water to 99.5% methanol) which is akin to that of pyridine. The N-aryl imines 10-13 are less basic by ca. 4 pK units. It is concluded that spatial solvent exclusion by bulky substituents has remarkably little effect on the pKa′ values.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199419940916
