Photochemical Reaction of 2,3-Dichloro-1,4-naphthoquinone (Dichlone) in the Presence of Oxygen

Reductive dehalogenated compounds of 2, 3-dichloro-l, 4-naphthoquinone (Dichlone), such as 2-chloro-l, 4-naphthoquinone, 1, 4-naphthoquinone and 1, 4-naphthalenediol, were produced during the initial stage of photochemically reacting Dichlone in various solvents either in the presence or absence of oxygen. On longer photoreaction in the presence of oxygen, phthalic acid and phthalic anhydride (phthalic acid mono ester instead of the anhydride in an alcoholic solvent) were isolated as the main products. Minor products of reacting Dichlone in a mixture of benzene and 2-propanol were salicylic acid, 2-chloro-3-hydroxy-1, 4-naphthoquinone, 2-chloro-3-phenoxy-1, 4-naphthoquinone and 2, 3-dichloro-4-hydroxy-l-keto-2-phenyl-1, 2-dihydronaphthalene, and isopropyl 1-chloro-2, 3-dioxo-l-indanecarboxylate.