0000000001082729
AUTHOR
R. Wamßer
Die Dissoziationskonstanten von 2,3?-und 2,4?-Dihydroxydiphenylmethanderivaten
The pK-values of the first and second degree of dissociation of 2.3′-dihydroxy-6′-methyl-3.5-dinitro-diphenylmethane, 2.3′-dihydroxy-6′-methyl-5-nitro-diphenylmethane, 2.3′-dihydroxy-5.6′-dimethyl-3-nitro-diphenylmethane, 2.4′-dihydroxy-3′. 5′-dimethyl-3.5-dinitro-diphenylmethane, 2.4′-dihydroxy-3′. 5′-dimethyl-5-nitro-diphenylmethane and 2.4′-dihydroxy-3′.5.5′-trimethyl-3-nitrodiphenylmethane were determined in aqueous solution at 25°C by the spectrophotometric method. The observed pK-values are compared with those of 2-methyl-4.6-dinitro-phenol, 2-methyl-4-nitrophenol, 2.4-dimethyl-6-nitrophenol, 3.4-dimethylphenol and 2.4.6-trimethylphenol which serve as model compounds for the single ph…
Die Dissoziationskonstanten von 2,2?-Dihydroxydiphenylmethanderivaten
The pK-values of the first and second degree of dissociation of 2.2′-dihydroxy-5-methyl-3′.5′-dinitro-diphenylmethane, 2.2′-dihydroxy-5-methyl-5′-nitro-diphenylmethane and 2.2′-dihydroxy-5.5′-dimethyl-3′-nitro-diphenylmethane were determined in aqueous solution at 25°C spectrophotometrically. Comparing the observed pK-values with those of 2-methyl-4.6-dinitrophenol, 2-methyl-4-nitrophenol, 2.4-dimethyl-6-nitro-phenol and 2.4-dimethylphenol, we found a decrease of the values of pK1 and an increase of pK2. We explain this by the formation of an intramolecular hydrogen bridge which stabilizes the anion of the half dissociated form. This assumption is supported by the UV spectra.