Kinetic reaction analysis of the pyridine derivatives in the T-for-H exchange reaction and the application to the estimation of the reactivity of unknown nicotinic acid derivatives

In order to quantitatively evaluate the influence of tritium (3H or T) in ecosystem and the reactivity of materials having H atoms, the hydrogen isotope exchange reaction (T-for-H exchange reaction) between 6-Chloronicotinic Acid (or 5,6-Dichloronicotinic Acid) and HTO vapor was observed at 50-70°C in the gas-solid system. Applying the A''-McKay plot method to the data obtained in the reaction, the rate constants of the functional groups in each material were obtained. Comparing these constants, following four matters have been found in the T-for-H exchange reaction. (1) With regard to pyridine derivative, the reactivity of carboxyl groups depends on the number and position of chloro groups; (meta-position and para-position of chloro groups): (para-position of chloro groups and meta-position of hydrogen): (meta-position and para-position of hydrogen)=1.9:1.5:1.0. (2) The reactivity of the unknown nicotinate derivatives can be obtained by applying the Hammett plot obtained in this work. (3) Using the A''-McKay plot method, the reactivity of each functional group can be obtained nondestructively, quantitatively, and be analyzed without using any masking reagent. (4) The method used in this work may be useful to determine the reactivity of the functional groups in similar materials. (author)