Abstract
The effect of N-substituent on the stability in an aqueous solution of AET was studied. By the substitution, both the transguanylation and the cyclization were hindered. The reactive species of N-Et-AET, and probably of N'-Et-AET, for the transguanylation is the monoionic conjugate base. N'-Et-AET, being relatively stable in the presence of less than one equivalent alkali, may be dissociated through the two-steps ionization to the neutral conjugate base, which would be considered as one of the reactive species. The degree of the transformation of N-ethylated AET derivatives was as follows ; the transguanylation in the presence of 0.5 equivalent NaOH for 4 min at 15° : AET ; 0.95, N'-Et-AET ; 0.84, N'-Et-AET ; 0.27. the cyclization in 3 days at 30° : AET ; 0.95, N'-Et-AET ; 0.36, N'-Et-AET ; 0.29. The relationship between the transguanylation and the pH drop in the solution was discussed.
