Butyltriphenylborate

Irradiation of an oxygen-free benzene solution of a cyanine -butyltriphenylborate at 532 nm gives n-octane among other products. Since octane can only form from the coupling of n-butyl radicals, one can conclude that irradiation of cyanine n-butyltriphenylborate generates free butyl radicals. 

The data summarized in Table 2 indicate that the series of cyanine borates with the n-butyltriphenylborate counterion possess a negative AGei value, i.e., they fulfill the basic Rehm Weller requirements for effective photoinduced electron transfer processes. Extending this to a practical application of the Marcus equation (see... 

Table 5. Reduction potentials ( red), excited triplet (singlet for NTAB and CTAB) energies, free energy changes (AGet) and quenching rate constants (A q, measured for n-butyltriphenylborate anion) of the light absorbing molecules used as initiators of free-radical polymerization.

A representative mechanism proposed for processes occurring via either singlet or triplet states for the n-butyltriphenylborate compounds and involving inter- and intra-ion-paris is given in Scheme 7. 

Neckers and coworkers have prepared diaryliodonium butyltriphenylborate salts 15-18 (Figure 7.2) by anion exchange of the respective diaryliodonium halides with tetramethylammonium butyltriphenylborate... 

Figure 7.2 Photoinitiators based on diaryliodonium butyltriphenylborate salts.

Lund, T, Photoinduced alkylation of anthracene by butyltriphenylborate ion. A comparison between products from the photochemical and electrochemical butylation of anthracene, Acta Chem. Scand., 50, 64, 1996. 

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