- A green catalytic method for selective synthesis of iodophenols via aerobic oxyiodination under organic solvent-free conditions
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A highly efficient catalytic method for aerobic oxyiodination of various phenols catalysed by copper(II) nitrate was achieved under mild conditions using I2as an iodinating reagent, molecular oxygen as an oxidant, and water as a solvent. The catalyst shows not only high activity for phenols with either electron-donating or electron-withdrawing groups, but also a remarkable selectivity for the formation of para-iodo substituted phenols. This study offers a green method for iodination of aromatic phenols with high atom economy.
- Xin, Hongchuan,Hu, Liangning,Yu, Jianqiang,Sun, Wenshou,An, Zengjian
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- Green and efficient method for the iodination of phenols in water
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In this article, green conversion of phenols to the corresponding iodide derivatives is reported. The reactions were conducted in water, using potassium iodide as the source of iodine and potassium ferrate as the oxidizing agent. The selected phenols were successfully iodinated in good to excellent yields in mild and non-toxic reaction conditions. Copyright Taylor & Francis Group, LLC.
- Tajik, Hassan,Dadras, Akbar,Hosseini, Abolfazl
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experimental part
p. 258 - 261
(2011/06/26)
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- HIO4/Al2O3 as a new system for iodination of activated aromatics and 1,3-dicarbonyl compounds
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The use of a periodic acid/alumina system for the iodination of activated aromatics and 1,3-dicarbonyl compounds is described.
- Khalilzadeh, Mohammad A.,Hosseini, Abolfazl,Shokrollahzadeh, Mojtaba,Halvagar, Mohammad R.,Ahmadi, Daryoush,Mohannazadeh, Farajollah,Tajbakhsh, Mahmoud
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p. 3525 - 3528
(2007/10/03)
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- Synthesis of 2,5- and 2,6-di-t-butyl-4-halo- or -4-methoxy-phenols using silica, lithium perchlorate and lithium bromide as neutral catalysts
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When a mixture of 4-halo- or 4-methoxy-phenol and excess of t-butyl chloride in the presence of neutral catalyst such as silica or lithium perchlorate or lithium bromide was refluxed, 2,5-and 2,6-di-t-butyl-4-halo or 4-methoxy phenols were obtained in good yields.
- Bandgar,Uppalla,Sadavarte
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p. 582 - 583
(2007/10/03)
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- Efficient synthesis of 2,5-di-t-butyl-4-fluorophenol
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When 4-fluorophenol was refluxed with excess of t-butyl chloride in the presence of various catalysts, e.g. Envirocat EPZG, EPZ10, EPIC, sulfated zirconia, natural kaolinitic clay, zirconium nitrate, zinc chloride and bismuth nitrate, the product obtained was 2,5,di-t-butyl 4-fluorophenol in excellent yield.
- Bandgar,Kasture,Dudhmal, Chaya
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- 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
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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.
- Omura, Kanji
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p. 2006 - 2012
(2007/10/03)
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- Iodination of phenols and anilines with bis(sym-collidine)iodine(I) hexafluorophosphate
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Iodination of a wide range of phenols and anilines was achieved by the action of the title reagent in methylene chloride.
- Brunel, Yves,Rousseau, Gerard
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p. 8217 - 8220
(2007/10/02)
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- Oxidation of Phenols with Iodine in Alkaline Methanol
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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.
- Omura, Kanji
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p. 3046 - 3050
(2007/10/02)
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