Solid state oxidation of phenols to quinones with sodium perborate on wet montmorillonite K10

Hashemi, Mohammed M.; Eftekhari‐Sis, Bagher; Khalili, Behzad; Karimi‐Jaberi, Zahed

doi:10.1590/s0103-50532005000600029

Cited by 9 publications

(2 citation statements)

References 19 publications

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“…There have been a number of recent reports of the oxidation of phenols to quinones in good to excellent yields under exceptionally mild conditions when promoted by Montmorillonite K10 [1][2][3] or silica gel. 4 The oxidants are perborate, 1 iodic acid, 2 so-called percarbonate, 3 and peroxydisulfate.…”

Section: Department Of Biochemistry the Ohio State University Colummentioning

confidence: 99%

Failure of Montmorillonite K10 or silica gel to promote the conversion of phenols to quinones by several oxidants

Behrman

2007

J. Braz. Chem. Soc.

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There have been a number of recent reports of the oxidation of phenols to quinones in good to excellent yields under exceptionally mild conditions when promoted by Montmorillonite K10 1-3 or silica gel. 4 The oxidants are perborate, 1 iodic acid, 2 so-called percarbonate, 3 and peroxydisulfate. 4 I have been unable to reproduce these results. Table 1 summarizes the published yields for the oxidations of phenol and hydroquinone together with my findings. Reactions were carried out according the references except that analyses were done by extraction into chloroform and measurement of the absorbance at 440 nm where p-benzoquinone has ε = 22.3 mol -1 L cm -1 . 5 The temperature was not specified for the oxidations by percarbonate and perborate; I used 25 o C.There is a recurring statement in the experimental sections of references 1 to 4. This is that the quinones were said to be freed of contaminating phenols by washing a chloroform solution of the crude reaction mixture with 5% NaOH. This cannot be correct as quinones undergo a very rapid reaction with hydroxide ions; the half-time with 1mol L -1 OH -at 22 o C is about 0.3 s. 6 Accordingly, I have found that that when 1,4-benzoquinone is dissolved in chloroform and then shaken with 5% NaOH, the yellow color of the quinone vanishes immediately from the chloroform layer and appears in the aqueous phase with a darkening reddish color. Rapid addition of HCl does not reverse this process.I have also found that the apparent yield of quinone can be slightly increased (to ca. 5%) by conducting the initial extraction with methanol instead of chloroform. This is probably because any quinhydrone that is formed is rather insoluble in chloroform.The iodic acid oxidations reported in reference 2 produce highly colored complex mixtures of a number of oxidation products. The NMR spectrum shows that the p-benzoquinone singlet at δ 6.79 is approximately 6% of the protons in the aromatic region.

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Section: Department Of Biochemistry the Ohio State University Colummentioning

confidence: 99%

Failure of Montmorillonite K10 or silica gel to promote the conversion of phenols to quinones by several oxidants

Behrman

2007

J. Braz. Chem. Soc.

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“…28 SPB has been widely used as a green oxidizing agent for organic oxidation reactions. [29][30][31][32] It was employed as the oxidant in the oxidation of organoboranes and gave satisfying yields. [33][34][35] Inspired by these, we expected SPB to act as an oxidant in the catalyst-free ipso-hydroxylation of aryl boronic acids to phenols through the release of nucleophilic species.…”

Section: Introductionmentioning

confidence: 99%

Catalyst- and solvent-freeipso-hydroxylation of arylboronic acids to phenols

et al. 2019

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Stereoselective Synthesis of β‐Amino Ketones via Direct Mannich‐Type Reactions, Catalyzed with ZrOCl₂·8H₂O under Solvent‐Free Conditions

et al. 2006

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Solid state oxidation of phenols to quinones with sodium perborate on wet montmorillonite K10

Cited by 9 publications

References 19 publications

Failure of Montmorillonite K10 or silica gel to promote the conversion of phenols to quinones by several oxidants

Failure of Montmorillonite K10 or silica gel to promote the conversion of phenols to quinones by several oxidants

Catalyst- and solvent-freeipso-hydroxylation of arylboronic acids to phenols

Stereoselective Synthesis of β‐Amino Ketones via Direct Mannich‐Type Reactions, Catalyzed with ZrOCl₂·8H₂O under Solvent‐Free Conditions

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Solid state oxidation of phenols to quinones with sodium perborate on wet montmorillonite K10

Cited by 9 publications

References 19 publications

Failure of Montmorillonite K10 or silica gel to promote the conversion of phenols to quinones by several oxidants

Failure of Montmorillonite K10 or silica gel to promote the conversion of phenols to quinones by several oxidants

Catalyst- and solvent-freeipso-hydroxylation of arylboronic acids to phenols

Stereoselective Synthesis of β‐Amino Ketones via Direct Mannich‐Type Reactions, Catalyzed with ZrOCl2·8H2O under Solvent‐Free Conditions

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Stereoselective Synthesis of β‐Amino Ketones via Direct Mannich‐Type Reactions, Catalyzed with ZrOCl₂·8H₂O under Solvent‐Free Conditions