2179-38-6Relevant 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 (2007/10/03)
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.
The Reactions of an o-Quinone Monoimide with Some Phenols
Heine, Harold W.,Ciaccio, James A.,Carson, Kenneth G.,Taylor, Carol M.
, p. 4039 - 4043 (2007/10/02)
The o-quinone monoimide N-(2,4-dichloro-6-oxo-2,4-cyclohexadien-1-ylidene)-4-nitrobenzamide (1) reacts with 2,6-dimethoxy-, 2,6-dimethyl-, and 2,6-dichlorophenols (2a-c) to form N-(2,4-dichloro-6-hydroxyphenyl)-N-(3,5-dimethoxy-, 3,5-dimethyl-, 3,5-dichloro-4-hydroxy)-4-nitrobenzamides (3a-c), respectively.Oxidation of 3a by 1 and 3b by DDQ lead to N-aryl-p-iminoquinones 4a,b.Oxidative dimerizations by either C-C or C-O coupling occur when 1 is admixed with the sterically hindered 2,6-di-tert-butyl-, 2,4-di-tert-butyl-, 4-bromo-2,6-di-tert-butyl-, and 2,4,6-tri-tert-butylphenols.
Oxidation of Phenols with Iodine in Alkaline Methanol
Omura, Kanji
, p. 3046 - 3050 (2007/10/02)
The use of iodine as an oxidizing agent for phenolic compounds has been explored.The reaction has been conducted in methanol containing such alkali as potassium hydroxide and, depending on the nature of the substituents and on the amount of iodine employed, leads to iodination, oxidation to give a stable phenoxy radical, oxidative dimerization, or benzylic oxidation.In general the reaction proceeds smoothly at room temperature, and under appropriate conditions yields of products are good to excellent.Oxidative dimerization of 2,4- and 2,6-di-tert-butylphenols invol-ves iodination followed by iodine-catalyzed dimerization.The oxidation of 4-methylphenols with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in methanol has been carried out for comparison.
