Dechlorination of Meso-Substituted Chloroanthracenes (9,10-Dichloro and 9-Chloro Compounds) via Their Radical Anions Produced by a Diffusion-Controlled Reaction of the Lowest Excited Singlet States of Chloroanthracenes with Ground-State Amine (Triethylamine or N,N-Dimethylaniline) in ...

Article abstract of DOI:10.1021/j100204a037

Steady-state photolysis of XA (9,10-dichloroanthracene and 9-chloroanthracene) in acetonitrile-amine (triethylamine or N,N-dimethylaniline) causes the consecutive reactions ( DCA -> CA -> anthracene), but the rate of dechlorination is affected upon addition of azulene and ferrocene in spite of quenching the lowest excited triplet state <³XA(T₁)> of XA by these additives with quenching rate constants of the order for that of a diffusion-controlled reaction.Although not only the intensities of fluorescence spectra due to the lowest excited singlet states <¹XA(S₁)> of XA but also those of triplet-triplet absorption spectra due to ³XA(T₁) decrease with increasing amine concentration, the appearance of absorption spectra due to the chloroanthracene radical anions (XA^.-) within the duration of nanosecond pulse excitation has been attributed to the formation of singlet exciplexes <¹(XA-amine)^*> by a diffusion-controlled reaction of ¹XA(S₁) with ground-state amine followed by decomposition into XA_.- and the amine radical cations.Since ³XA(T₁) are quenched by amine in the microsecond time regime and no evidence supporting the participation of the triplet exciplexes of chloroanthracenes with amine in the dechlorination as proposed by Soloveichik et al. is obtained (cf. ref 2), we have concluded that XA^.- produced via ¹(XA-amine)^* are the reaction intermediates for dechlorination of XA.