91301-68-7Relevant articles and documents
pKa VALUES OF 2- AND 2,6-DISUBSTITUTED PYRIDINE DERIVATIVES CONTAINING SULFENYL AND SULFINYL GROUPS AND ?* AND ES VALUES OF SEVERAL SULFENYL AND SULFINYL GROUPS
Furukawa, Naomichi,Iida, Keiko,Kawai, Tsutomu,Ogawa, Satoshi,Oae, Shigeru
, p. 239 - 254 (2007/10/02)
pKa Values of pyridine derivatives having sulfenyl and sulfinyl groups attached to either 2- or 2,6-positions in the pyridine nuclei were measured affording the following values; 2-SCH3 (3.64), 2-S(O)CH3 (0.17), 2-CH2SCH3 (5.40), 2-CH2S(O)CH3 (3.10), 2-CH2OCH3 (4.35), 2,6-(SCH3)2 (2.37), 2,6-(CH2SCH3)2 (4.10), 2,6-(CH2S(O)CH3)2 (1.53), 2,6-(CH2OCH3)2 (3.50).These pKa values together with several other 2-substituted pyridines: 2-X-C5H4N in which X is Cl, Br, I, CN, CO2C2H5, CH3, H, OCH3, were plotted against Taft ?* values to afford a good straight line giving ρ*= -4.5.From fitting the above pKa values on this line, the ?* values of these groups were determined.Furthermore, Es values of CH3S(O)-, CH3SCH2-, CH3S(O)CH2- CH3OCH2-groups were determined and the application of the ?* values was tested by measuring both acid and alkaline hydrolyses rates of the corresponding p-nitrophenyl acetates, the modified Taft method.The additivity of these ?* values in the 2,6-positions in the pyridine nuclei was examined.The cation-transfer experiments were undertaken by using 2,6-bis(methylsulfinylmethyl)pyridine as mediator.
