Investigations of the reactivity of pyridine carboxylic acids with diazodiphenylmethane in protic and aprotic solvents. Part II. Pyridine mono-carboxylic acid N-oxides

• Published in: Journal of the Serbian Chemical Society Vol. 71; no. 2; pp. 89 - 101
• Main Authors: MILICA MISIC-VUKOVIC, ALEKSANDAR D. MARINKOVIC, BRATISLAV Z. JOVANOVIC, SASA Z. DRMANIC
• Format: Journal Article
• Language: English
• Published: Serbian Chemical Society 01.02.2006
• Subjects: diazodiphenylmethane; protic and aprotic solvents; pyridine carboxylic acid N-oxides; pyridine carboxylic acids; rate constants; solvent parameters
• ISSN: 0352-5139

The rate constants for the reaction of three isomeric pyridine mono-carbocylic acid N-oxides with diazodiphenylmethane were determined at 30 ºC in thirty two protic and aprotic solvents by the well known UV spectrophotometric method. The rate constants are generally higher than for pyridine mono-carboxylic acids in a similar range of solvents, except for picolinic acid N-oxide, and also higher in protic than in aprotic solvents. The determined rate constants were correlated with solvent parameters using the Kamlet–Taft solvatochromic equation bymeans ofmultiple regression analysis. The sing of the equation coefficients were in agreement with the postulated reaction mechanism. The mode of the in fluences of the solvent is discussed on the basis of the correlation coefficients, taking into account the specific structures of the pyridine mono-carboxylic acid N-oxides.