Dibenzo-p-dioxin (Diphenylene Dioxide) 誘導体の研究 (第28報)

2,7-Dimethyldibenzo-p-dioxinのクロル化およびニトロ化反応について

抄録

Chlorination of 2, 7-dimethyldibenzo-p-dioxin (II) with dry chlorine gas in dehyd. benzene, with irradiation of ultraviolet rays, afforded a dichloro compound (III) as colorless needles of m. p. 231°. The dichloro compound (III) was entirely identical with the dichloro compound obtained from the dinitro compound (IV) formed by nitration of (II) with fuming nitric acid in glacial acetic acid, via the diamino compound. It was thereby evidenced that the dichloro compound obtained by the chlorination reaction is not a chloromethyl compound but a ring-substituted dichloro compound.
In order to prove the positions of chlorine and nitro substituted in the ring, the dinitro compound of (II) was derived to the dimethoxyl compound by the route shown in Chart 1. On the other hand, 1-methyl-2-methoxy-4-hydroxy-5-bromobenzene (XVII) was prepared from o-toluidine and the Ullmann reaction of the potassium salt of (XVII) afforded 2, 7-dimethyl-3, 8-dimethoxydibenzo-p-dioxin (VII). These two dimethoxyl compounds were in complete agreement and, consequently, the position on the ring which suffers substitution during chlorination or nitration of 2, 7-dimethyldibenzo-p-dioxin (II) is at 3 and 8.