Anthracene, 9,10-diacyl

Formally related reactions are observed when anthracene [210] or arylole-fines [211-213] are reduced in the presence of carboxylic acid derivatives such as anhydrides, esters, amides, or nitriles. Under these conditions, mono- or diacylated compounds are obtained. It is interesting to note that the yield of acylated products largely depends on the counterion of the reduced hydrocarbon species. It is especially high when lithium is used, which is supposed to prevent hydrodimerization of the carboxylic acid by ion-pair formation. In contrast to alkylation, acylation is assumed to prefer an Sn2 mechanism. However, it is not clear if the radical anion or the dianion are the reactive species. The addition of nitriles is usually followed by hydrolysis of the resulting ketimines [211-213]. 

Friedel-Oafts diacylation of dibenzothiophene with 7-oxo-lH-benzo[d,e]anthracene-3-carbonyl chloride, followed by ring closure in molten sodium chloride-aluminum chloride, is reported to yield 131 which is claimed to be useful as an orange dyestuff. No evidence for the structure of 131 was presented although analogous succinoylation studies (Section VI,G,2) would indicate that the structure is correct. 

Yellow light was emitted, corresponding to the fluorescence of the acid product. No emission was observed from the monoacyl anthracene, although the carboxylic acid product is fluorescent. Acylcarbazoles behave similarly [35]. A fairly extensive study has been made of 1,8- and 1,5-diacyl anthracenes [36]. It was shown that primary and secondary (11, RiOr R2 = H) ketones gave less light than tertiary ketones (Ri = R2 = alkyl). This can be explained by base catalysed elimination of water from the intermediate peroxide when an a-H atom ist present. The chemiluminescence spectra did not match the spectra of fluorescent products, being considerably red-shifted. Complex formation (e. g. an exciplex) was suspected. 

Anthracene-2,3-dicarboxylic acid can be transformed into the corresponding acid chloride with phosphorus pentachloride although chlorination in the 9 -position occurs simultaneously [31]. The question arises as to whether the peroxide (31) would be stable. Since PPO (p. 43) undergoes a catalysed chemiluminescent decomposition in the presence of fluorescers, the anthracene residue in (31) may catalyse an m ramolecular decomposition of the diacyl peroxide group [31]. 

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