Carbon acidity of the alpha-pyridinium carbon of a pyridoxamine analog.
We report second-order rate constants of kDO = 120 dm(3) mol(-1) s(-1) and kB = 6.4 x 10(-4) dm(3) mol(-1) s(-1) for exchange for deuterium of the first alpha-methylene proton of the 4-(aminomethyl)pyridine dication in D2O at 25 degree C and I= 1.0 (KCl). These data are consistent with a carbon acid pKa between 17 and 19 for ionization of this simple carbon acid and they show that the effect of an alpha-pyridinium substituent on carbon acidity is similar to that of an alpha-ester substituent.
Crugeiras
Juan
J
Departmento de Química Física, Universidad de Santiago, 15706 Santiago de Compostela, Spain.
Rios
Ana
A
Amyes
Tina L
TL
Richard
John P
JP
D002244:Carbon / Q000737:chemistry*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D011726:Pyridinium Compounds / Q000737:chemistry*; D011733:Pyridoxamine / Q000737:chemistry*
D011726:Pyridinium Compounds; D011733:Pyridoxamine; D002244:Carbon