The reaction of the 2,6-di-tert-butyl-4-methylphenoxy radical with phenols
摘要:
Dimer 3 dissociates in solution to give the phenoxy radical 4. When solid 3 is dissolved in a solution of phenol 11a, radical 4 dehydrogenates the phenol to afford phenol 5 and phenoxy radical 12. Radical 12 couples with more 4 to afford principally bis(cyclohexadienone) 16a and a minor amount of the dimeric bis(cyclohexadienone) 13. The preferential formation of 16a over 13 is explained as the result of a solvent-cage reaction. Compounds 13 and 16a are isomerized in the presence of silica gel or triethylamine to 4,4'-dihydroxybiphenyl 14 and phenolic dienone 17a, respectively. Compound 13 is relatively stable in hexane at 30-degrees-C, while 16a slowly dissociates under these conditions to afford parent radicals 4 and 12. If 11a is present, radical 4 either recombines with 12 or dehydrogenates the phenol. Two radicals of 12 generated by the dissociation of 16a and the subsequent dehydrogenation of 11a couple to give 13. Therefore, dissolving 3 in hexane containing excess 11a and keeping the resulting solution at 30-degrees-C results in the preferential formation of 13. Dissolving 3 in triethylamine containing phenols 11 or 21 similarly affords dienones 17 or 23. The yields of these dienones increase with increasing electron-donating capability of the substituent on the phenol ring.
Oxydation selective en para des phenols par un complexe cuivrique oxydant
作者:Patrice Capdevielle、Michel Maumy
DOI:10.1016/s0040-4039(00)94154-6
日期:1983.1
Oxidation of phenols by molecular oxygen in the presence of the μ-oxo cupric catalyst Cu4Cl4O2 (CH3-CN)3 (A), can be selectively directed to give either oxidative coupling or para-hydroxylation (p-quinols or p-quinones) products by the choice of the (A)/(phenol) ratio. The mechanism is discussed and a -OH ligand transfer from CuII to the phenolic para position is proposed.
在μ-氧代铜催化剂Cu 4 Cl 4 O 2(CH 3 -CN)3(A)存在下,分子氧可以氧化酚,从而选择性地进行氧化偶联或对羟基化反应(对-喹啉(对苯二酚或对苯二酚)产品,可以选择(A)/(苯酚)比率。讨论了该机理,并提出了-OH配体从Cu II转移到酚对位的方法。
Characterization and Reactivity of a Terminal Nickel(III)-Oxygen Adduct
作者:Paolo Pirovano、Erik R. Farquhar、Marcel Swart、Anthony J. Fitzpatrick、Grace G. Morgan、Aidan R. McDonald
DOI:10.1002/chem.201406485
日期:2015.2.23
nickel–oxygen adducts are scarce, meaning there is a dearth in the understanding of such oxidants. A monoanionic NiII‐bicarbonate complex has been found to react in a 1:1 ratio with the one‐electron oxidant tris(4‐bromophenyl)ammoniumyl hexachloroantimonate, yielding a thermally unstable intermediate in high yield (ca. 95 %). Electronic absorption, electronic paramagnetic resonance, and X‐ray absorption spectroscopies
Kinetic electron spin resonance spectroscopy of complex reaction systems
作者:Daniel Rüegge、Hanns Fischer
DOI:10.1039/f19888403187
日期:——
Kineticelectronspinresonancespectroscopy with intermittent radical generation has been used to obtain the rate constants of various simultaneous reactions in systems containing 2,6-di-t-butylphenoxyl or 2,6-di-t-butyl-4-methylphenoxyl radicals, the latter terminating reversibly. The radicals were generated in various solvents by photolysis of di-t-butyl peroxide in presence of the parent phenols
A comparative study of the speciation in methanol solution and activity in the oxidative coupling of 2,6-di-tert-butylphenol presented by the complexes: Copper(II)-N,N′-di-tert-butylethylenediamine-halogen and some copper(II)-diamine-halogen complexes
catalyzed by the copper(II)-di-tert-butylethylenediamine-dibromo complex. In order to get more insight about the behavior of the N,N′-dialkyl-diamine cupric complexes and the halide effect on the catalyic activity, a spectrophotometricstudy of the speciation in methanol of copper(II) coordinated with N,N′-di-tert-butylethylenediamine or 1,5-pentanediamine and their respective halides chloride and bromide