Studies on the Reaction between Polynitrobenzene Compounds and Active Methylene Groups. VIII. On the Janovsky Reaction of Trinitroanisole in Acetone

Abstract

Janovsky reaction of 2, 4, 6-trinitroanisole (TNA) and acetone in the presence of sodium methoxide was studied. By comparing the ratios of intensity of the peak at shorter wave length to that at longer one in the different solvents, the initial peaks at 418 and 488 mμ that observed three seconds after start of the reaction were assigned to be due to the Meisenheimer complex IVa and not to IIIa. That the final spectrum having maxima at 443 and 531 mμ in the reaction mixture coincides with the formation of Janovsky complex IVb, were clarified by NMR spectroscopy (Fig. 8) of IVb and by chemical way such as transferring it to 3-acetonyl-2, 4, 6-trinitroanisole. Contrary to the observation by Foster, et al. in the state of higher concentration, in the diluted acetone solution of IIIb extra sodium methoxide was necessary for transferring IIIb to IIIc. When TNA was added to the mixture prepared beforehand with acetone and sodium methoxide, the initial rate of increase in the absorbances at 443 and 531 mμ became higher than that in the simultaneous mixture of these three reactants. These would indicate that there was no solvolysis of IVa by acetone but the initial step was the deprotonation of solvent by the methoxide ion dissociated from IVa and the acetonate ion thus generated then attacked the dissociated TNA forming IVa. The rate of color development varied with the different interval between the addition of sodium methoxide and of TNA (Fig. 9) ; the reaction mixture of TNA, diacetone alcohol and sodium methoxide gave gradually the similar pattern having maxima at 445 and 526 mμ. The process of this reaction may thus be represented in Eq. (1), (3), (4), (5), and (6) ; Eq. (2) being excluded. The logarithmic equilibrium constant of the overall reaction was obtained as 5.4.