Abstract
The hydrogen-isotope exchange reaction (T-for-H exchange reaction) between tritium-labeled poly (vinyl alcohol ) and each normal chain diamine has been observed in the range of 50 to 90°C. Consequently, the activity of the diamine increased with increasing reaction time. Applying the A″-McKay plot method to the observed data thus obtained, the rate constants (k) for the diamines were also obtained. Using each k thus obtained, the relation between the number of methylene groups in the diamine and the reactivity of the diamine was quantitatively compared.
Then, in order to clarify the effect of relative atomic charge of N atom in the amino group on the reactivity of the diamine, the MOPAC method was used. From both the above-mentioned and the obtained previously, the following five items were found as to normal chain amines in the T-for-H exchange reaction. (1) Increasing the number of methylene groups in each diamine leads to decreasing k for the diamine. (2) The decreasing ratio of the reactivity of the diamine, where the number of methylene groups in each diamine increases from one to three (and to five), is larger than the decreasing ratio of the reactivity of the diamine, where the number of the methylene groups in the diamine increases from two to four (and to six) . (3) The effect of temperature on the reactivity of several compounds is in the following order: (dicarboxylic acids) < (diamines) < (diols) < (aromatic compounds) . (4) When the number of methylene groups is odd, the relative atomic charge of the N atom in the amino group decreases with increasing number of methylene groups in the diamine. When the number of methylene groups is even, the relative atomic charge of the N atom has a tendency to increase with increasing number. (5) We have a high possibility that the structure of normal chain diamine in a certain solvent may be stereo-chemically estimated by applying both the MOPAC method and the method used in this work.
