The peroxyacid oxidation of acridine

Abstract

Acridine reacted with peroxybenzoic acid to yield the 1 O-oxide, 2-(2-hydroxyanilino) benzaldehyde, and 2-( 2hydroxyanilino) benzoic acid. With 3-chloroperoxybenzoic acid, the 1 O-oxide, the aldehyde, and NN'-oxydi-B. Adcock, Flintshire College of Technology, Connah's Quay, Flintshire 9-acridone were obtained.ALTHOUGH various 9-substituted acridines lS react with peroxybenzoic acid to give the 10-oxides in good yield, acridine itself gives only about 20% of the pure Noxide l s 4 along with another compound mentioned earlier.ly2 This compound, 2-(2-hydroxyanilino)benzaldehyde (2), is the major product, in our experience, for oxidations performed in chloroform, ether, or benzene, and is extracted from the crude oxidation product by sodium hydroxide. Although all attempts to oxidise it directly to the corresponding acid failed, some of this acid was isolated from the acridine oxidation mixture. The aldehyde reduced both ammoniacal silver nitrate and Fehling's solution, gave a deep purple colour with ferric chloride, and a 2,4-dinitrophenylhydrazone. Distillation from zinc dust gave a mixture of acridine and acridone, and cyclisation to 4-hydroxyacridine took place in acetic acid-sodium acetate under reflux. This limited possible structures for the aldehyde to that proposed and that of 2-anilino-3-hydroxybenzaldehyde. All attempts to synthesise the aldehyde (2) from 2-aminophenol and 2-chlorobenzaldehyde or its diethyl acetal, or by the McFadyens and Stevens reduction of the corresponding acid, failed. The aldehyde is thought to possess structure (2) because of the isolation of some of the corresponding acid from the acridine oxidation mixture, and because under oxidative conditions the breaking of the 8a,9-bond of the acridine ring is more likely to introduce a hydroxy-group than a hydrogen atom at C-8a. The mass spectrum of (2) is consistent with this hypothesis. The major fragment lost is the aldehyde group, but there are fragments at m/e 94 and 119 which correspond to the ion radicals derivable from phenol and anthranil respectively. We have not been able to account for these fragments on the basis of the alternative structure. The n.m.r. spectrum of (2) shows the aldehyde hydrogen atoni as a very sharp singlet, a broader singlet at a normal position (T 4.63) ti for a phenolic proton, and a relatively broad singlet assigned to NH; the last two protons t Present address:

Effects of Supramolecular Architecture on Halogen Bonding between Diiodine and Heteroaromatic N-Oxides

“…ClQnO was prepared by the reaction of 4-nitroquinoline N- oxide with HCl . AcrO was prepared by the oxidation of acridine by peroxobenzoic acid in CH 2 Cl 2 and purified using flash chromatography on silica gel (eluent CH 2 Cl 2 /MeOH 10:1), following recrystallization from an ethanol–water (2:1) solution and subsequent drying in a desiccator over P 2 O 5 for a week …”

“…67 AcrO was prepared by the oxidation of acridine by peroxobenzoic acid in CH 2 Cl 2 and purified using flash chromatography on silica gel (eluent CH 2 Cl 2 /MeOH 10:1), following recrystallization from an ethanol−water (2:1) solution and subsequent drying in a desiccator over P 2 O 5 for a week. 68 Cocrystals of diiodine with various N-oxides were prepared by cooling or slow evaporation of dichloromethane solutions containing 1:1 molar ratios of both components. In particular, to prepare adducts with PyO, MePyO, and ClQnO, diiodine (102 mg, 0.40 mmol) was dissolved in 4 mL of anhydrous dichloromethane, and the equivalent amounts (0.40 mmol) of the corresponding N-oxides were added to these solutions.…”