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Electrochemistry of pteridine

1975; Elsevier BV; Volume: 59; Issue: 1 Linguagem: Inglês

10.1016/s0022-0728(75)80048-9

2590-2954

David L. McAllister, Glenn Dryhurst,

Conducting polymers and applications

Over the pH range 1–12, pteridine is reduced at the dropping mercury electrode (DME) and pyrolytic graphite electrode (PGE) by way of three polarographic or voltammetric processes. The first, least negative process, is a reversible 2e-2H+ reduction of pteridine to 5,8-dihydropteridine. The latter species reacts with pteridine in a base-catalyzed Michael reaction producing a dihydro dimer, probably 7,7′,8,8′-tetrahydro-7,7′-dipteridyl. The second process involves reduction of the monohydrated form of pteridine (3,4-dihydro-4-hydroxypteridine) which exists in major amounts at low pH which is also reduced in a 2e-2H+ reaction to 5,8-dihydropteridine but in an irreversible process. Again the latter compound reacts with pteridine to give a dimer. The third process is reduction of the anion of 3,4-dihydro-4-hydroxypteridine in the same overall process as is observed for the two previous reactions forming, ultimately, the same dihydropteridine dimer. The latter dimer is also reducible electrochemically in a 2e-2H+ irreversible process to give 7,8-dihydropteridine. Rate constants have been obtained for the reversible electron transfer and for the dimerization reaction of 5,8-dihydropteridine with pteridine.