4. Supported Mechanistic Pathway. Based on the results from problems 1-3, which of the five possible mechanistic pathways for the Bergman cyclization can be ruled out? Which of the five possible mechanistic pathways should still be considered? Let's evaluate the results of some non-kinetic experimental studies on the Bergman cyclization to differentiate the five possible mechanistic pathways proposed in the lecture notes for this reaction (some of these are hypothetical, some are actual literature studies). The five proposed mechanisms (three intramolecular cyclizations I1I3 and two dissociative (fragmentation-recombination) mechanisms F1 and F2 ) are summarized below. Intramolecular Mechanistic Pathways I1 SOHH Radical 12 HHHH lonic Fragmentation-Recombination Mechanistic Pathways F1 solH Radical F2 lonic: 4. Supported Mechanistic Pathway. Based on the results from problems 1-3, which of the five possible mechanistic pathways for the Bergman cyclization can be ruled out? Which of the five possible mechanistic pathways should still be considered? Let's evaluate the results of some non-kinetic experimental studies on the Bergman cyclization to differentiate the five possible mechanistic pathways proposed in the lecture notes for this reaction (some of these are hypothetical, some are actual literature studies). The five proposed mechanisms (three intramolecular cyclizations I1I3 and two dissociative (fragmentation-recombination) mechanisms F1 and F2 ) are summarized below. Intramolecular Mechanistic Pathways I1 SOHH Radical 12 HHHH lonic Fragmentation-Recombination Mechanistic Pathways F1 solH Radical F2 lonic