27574-87-4Relevant academic research and scientific papers
A mechanistic approach to the reaction of 2,6-di-tert-butylphenol with an iodinating agent in methanol: Electrophilically assisted solvolysis of intermediary 4-iodocyclohexa-2,5-dienones
Omura, Kanji
, p. 2006 - 2012 (1996)
Reactions of the title phenol (1) and of 4-iodophenol 2 with an iodinating agent, I2 and H2O2, are conducted in MeOH for varying times with varying amounts of I2, and the results are compared. The reaction of 1 gives 2, 4,4′-biphenol 3, 4,4′- diphenoquinone 4, 4-methoxyphenol 5, and p-benzoquinone 6, exclusively. The yields of the phenolic products (2, 3, and 5) vary with reaction time, but they disappear or almost disappear eventually, to make 4 and 6 the almost exclusive products. The reaction of 2 always gives 4 and 6 alone. In both of the reactions of 1 and of 2, employment of a higher initial I2 concentration not only completes the formation of 4 and 6 faster but also makes the final proportion of 6 higher. However, the ultimate yield of 6 from the reaction of 1 is significantly higher than that from the reaction of 2, irrespective of the initial I2 concentration. These results are interpreted as follows. 4-Iodocyclohexa-2,5-dienone 12, the primary product of electrophilic iodination of 1, undergoes solvolysis (methanolysis), which is electrophilically assisted by I2. The solvolysis of 12 can be so fast as to overwhelm its prototropic rearrangement to give 2. 4-Methoxycyclohexa-2,5-dienone 13, which is the primary product of the methanolysis of 12 and is suggested to be detectable by 1H NMR spectroscopy, is converted into 6 via 5. Benzoquinone 6 can also arise from 4,4-diiodocyclohexa-2,5-dienone 7, the product of iodination of 2, by an analogous mechanism. The selectivity of the formation of 6 from 7 is low because the competing reaction, homolytic scission of the C-I bond in 7, predominates. The mechanism of the formation of 3 and 4 is also discussed.
