Phthaloyl peroxide, luminol

Phthalein dyes, hydrogen peroxide determination, 628-9 Phthaloyl peroxide, luminol chemilumine scence, 1245 Physiological matrices... 

DPA) in dimethylphthalate at about 70°, yields a relatively strong blue Umax =435 nm) chemiluminescence the quantum yield is about 7% that of luminol 64>. The emission spectrum matches that of DPA fluorescence so that the available excitation energy is more than 70 kcal/mole. Energy transfer was observed on other fluorescers, e.g. rubrene and fluorescein. The mechansim of the phthaloyl peroxide/fluorescer chemiluminescence reaction very probably involves radicals. Luminol also chemiluminesces when heated with phthaloyl peroxide but only in the presence of base, which suggests another mechanism. The products of phthaloyl peroxide thermolysis are carbon dioxide, benzoic acid, phthalic anhydride, o-phenyl benzoic acid and some other compounds 65>66>. It is not yet known which of them is the key intermediate which transfers its excitation energy to the fluorescer. 

It has not yet been possible to obtain (24) but during those investigations it turned out that phthaloyl peroxide (24 a) reacting with certain fluorescers, e. g. DPA, exhibited a fairly bright chemiluminescence (ca. 7% of luminol) [24 a]. 

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