4370-49-4Relevant articles and documents
A Catalyst-Controlled Aerobic Coupling of ortho-Quinones and Phenols Applied to the Synthesis of Aryl Ethers
Huang, Zheng,Lumb, Jean-Philip
, p. 11543 - 11547 (2016/11/17)
ortho-Quinones are underutilized six-carbon-atom building blocks. We herein describe an approach for controlling their reactivity with copper that gives rise to a catalytic aerobic cross-coupling with phenols. The resulting aryl ethers are generated in high yield across a broad substrate scope under mild conditions. This method represents a unique example where the covalent modification of an ortho-quinone is catalyzed by a transition metal, creating new opportunities for their utilization in synthesis.
Manganese(II) catalyzed oxidation of 2,4-xylidine by periodate - A kinetic-mechanistic study
Kaushik,Kumar, Dharmendra,Kumar, Anuj,Kumar, Ajay
experimental part, p. 811 - 816 (2011/04/22)
The kinetics of the periodate oxidation of 2,4-xylidine (XYL) in acetone-water medium has been followed by monitoring the increase in the absorbance of reaction intermediate, C4, and the main reaction product 3,5-dimethyl-1,2-benzoquinone. Results under pseudo-first order conditions, [IO4-] >> [XYL], are in agreement with the rate law : d[C]/dt = kK3K4Kw[Mn II] [S] [IO4-]0 [H +]/{K2Kw + (Kw + KbK 2)[H+] + Kb[H+]2} where kK3K4 is the empirical composite rate constant, K w is ionic product of water, K2 is acid dissociation constant of H4IO6- and Kb is base dissociation constant of XYL. In agreement with the rate law the 1/k cat versus [H+] profile passes through the minimum. Free radical scavengers do not affect the reaction rate. The values of thermodynamic parameters are : Ea = 4.9 kcal mol-1, A = 8.7 × 103 dm3 mol-1 s-1; ΔS # = -47.2 cal mol-1 K-1, ΔG# = 18.9 kcal mol-1 and ΔH# = 4.3 kcal mol -1.
Multiple Electron Oxidation of Phenols by an Oxo Complex of Ruthenium(IV)
Seok, Won K.,Meyer, Thomas J.
, p. 7358 - 7367 (2007/10/02)
The kinetics of oxidation of phenol and alkylated phenol derivatives by (2+) and (2+) (bpy is 2,2'-bipyridine and py is pyridine) to give the corresponding quinones have been studied in aqueous solution and in acetonitrile.The reactions are first order in both phenol and Ru(IV)=O(2+) or Ru(III)-OH(2+).They proceed via a detectable intermediate, which is a Ru(II) complex. 18O isotopic labeling experiments show that transfer of the oxo group from Ru(IV)=O(2+) to phenol is quantitative.The reactions are facile.With Ru(IV)=O(2+) as oxidant k(25 deg C, CH3CN) = 1.9 (+/-0.4) E2M-1s-1; with Ru(III)-OH(2+) as oxidant k(25 deg C, CH3CN) = 4.0 (+/-0.4) E1M-1s-1.On the basis of the rate laws, the magnitude of OH/OD and CH/CD kinetic isotope effects, and the 18O labeling results, the most reasonable mechanisms for oxidation of phenol by Ru(IV)=O(2+) appears to be electrophilic attack on the aromatic ring.For Ru(III)-OH(2+), oxidation appears to occur by CH/H atom transfer in CH3CN and OH/H atom transfer in water.
