Formations and Reactions of o-Benzoquinone Mono- and Di-imines. I.

We have succeeded in obtaining o-benzoquinone monoimine (o-BQMI) and o-benzoquinone diimine (o-BQDI) by oxidizing o-aminophenol (o-AP) and o-phenylenediamine (o-PD), respectively, with freshly prepared lead dioxide at −10 °C in several organic solvents, and also with potassium hexacyanoferrate (III) in an aqueous buffer solution. The formations and reactions of o-BQMI and o-BQDI in aqueous buffer solution were investigated by a stopped flow technique together with a conventional electronic absorption measurements. Both o-BQMI and o-BQDI were formed in the pH range 8–12, and the hydrolysis of o-BQMI to produce o-benzoquinone was found in the pH range 6–8. Both o-BQMI and o-BQDI were found to be unstable at a room temperature to produce 2-aminophenoxazin-3-one (APZ) and 2,3-diaminophenazine (DAP), respectively, as the main products. The formation reactions of APZ and DAP were investigated by observing the spectroscopic course of the reactions in o-BQMI- o-AP and o-BQDI- o-PD system in diethyl ether.