Figure 5. The facile isomerization of NHPI to IA can also be induced by other halogenated quinoid compounds.

(A) IA could be generated from the reaction of NHPI and other halogenated quinones. (B–E) The optimization of experimental conditions for maximum IA production from the reaction of NHPI and 2,3-DCBQ: pH, 7.4; CH₃CN, 40% (V%); T, 10 °C; NHPI: 2,3-DCBQ. (B) NHPI, 0.2 mM; 2,3-DCBQ, 0.2 mM; 5 min; 30 °C; (C) NHPI, 0.2 mM; 2,3-DCBQ, 0.2 mM; pH, 7.4; (D) NHPI, 0.2 mM; 2,3-DCBQ, 0.8, 0.4, 0.2, 0.1, and 0.05 mM; pH, 7.4; 45 min; and (E) NHPI, 0.2 mM; 2,3-DCBQ, 0.4 mM; pH, 7.4; 10 °C; 45 min.