Ring-butylamination of Toluquinone: Isolation of Products by TLC and an Observation of Their Reaction Course on the Basis of Molecular Reactivity Index

The ring-butylamination of toluquinone with n-butyl-amine was carried out in a chloroform or ethanolic solution at room temperature or at 25.0°C with various molar ratios of the quinone to the amine (designated as Q/A). For the successful separation of each product, TLC was applied, while polarography was used for following the change in the composition of the reacting mixture as well as for measuring the amount of the amino-quinone separated from the reacting mixture by TLC. In the butylamination of toluquinone with excess butylamine (Q/A: 1/5) for 10 hr, the major products were 3,6-bis-(n-butylamino)-toluquinone (32%) and 2,5-bis(n-butylamino)-p-benzoquinone (8%), accompanied by a relatively large amount of unknown by-products: with a Q/A of 2/1 for 2 hr, the major products were 3- and 4-n-butylamino-toluquinone (17% and 21%) and 3,6-bis(n-butylamino)-toluquinone (3.3%) together with toluhydroquinone (47%). The quantitative formation of 3,6-bis(n-butylamino)-toluquinone from 3-n-butylamino-toluquinone or the formation of 2,5-bis(n-butylamino)-p-benzoquinone (34%) and 3,6-bis-(n-butylamino)-toluquinone (1%) from 4-n-butylamino-toluquinone was also found (Q/A: 1/4, 3 hr or 13 hr), where a faster reaction was found for the 3-isomer than for the 4-isomer under the present conditions. The pathway of the formation of each product was discussed on the basis of the calculated reactivity index of toluquinone or its butylaminated toluquinone isomers toward the amine-attacking.