4971-61-3Relevant articles and documents
CsOH catalyzed aerobic oxidative synthesis of p-quinols from multi-alkyl phenols under mild conditions
Liang, Yu-Feng,Wu, Kai,Liu, Zhiqing,Wang, Xiaoyang,Liang, Yujie,Liu, Chenjiang,Jiao, Ning
, p. 1334 - 1339 (2015/03/18)
p-Quinols are ubiquitous structural motifs of various natural products and pharmaceutical compounds, and versatile building blocks in synthetic chemistry. The reported methods for the synthesis of p-quinol require stoichiometric amounts of oxidants. Molecular oxygen is considered as an ideal oxidant due to its natural, inexpensive, and environmentally friendly characteristics. During the ongoing research of C-H bond hydroxylation, we found that multi-alkyl phenols could react with molecular oxygen under mild conditions. Herein, we describe an efficient oxidative de-aromatization of multi-alkyl phenols to p-quinols. 1 atm of molecular oxygen was used as the oxidant. Many multi-alkyl phenols could react smoothly at room temperature. Isotopic labeling experiment was also performed, and the result proved that the oxygen atom in the produced hydroxyl group is from molecular oxygen.
Solvolysis of 4-halogeno-4-alkyl-2,6-di-tert-butylcyclohexa-2,5-dienones induced by positive halogen donors as electrophiles
Omura, Kanji
, p. 1386 - 1392 (2013/12/04)
Positive halogen donors such as N-iodosuccinimide (NIS) induce solvolysis of dienones 1, as model 4-halogenocyclohexa-2,5-dienones, in different hydroxylic solvents (ROH), yielding the 4-RO-cyclohexa-2,5-dienones (2). The rate of the solvolysis with NIS is highly dependent on the structure of ROH. The problem of such dependency is overcome by running the reaction in ROH diluted with MeCN, a polar aprotic solvent, in place of pure ROH; the rate of the reaction in the ROH-MeCN solvent mixture is almost independent of the structure (or the polarity) of ROH, and the reaction is completed faster or markedly faster than in neat ROH. The results suggest that the solvolysis rate is controlled by the polarity of the solvent system, although the hydrogen-bond acceptability of MeCN for dilution also accelerates the reaction. A mechanism for the solvolysis is proposed, involving electrophilic attack of a positive halogen donor at the halogen atom of 1, generating the 4-oxocyclohexa-2,5-dienyl cation intermediates (8) via the rate-limiting polar transition states. CSIRO 2013.
Organo-peroxyl compounds via catalytic oxidation of a hindered phenol and aniline utilizing new manganese(II) bis benzimidazole diamide based complexes
Bakshi, Ruchi,Mathur, Pavan
experimental part, p. 3477 - 3488 (2011/02/15)
Bis benzimidazole diamide ligand-N,N′-bis(2-methylbenzimidazolyl) propanediamide [GBMA = L] has been synthesized and utilized to prepare new Mn(II) complexes of general composition [Mn(L)X2]·nH 2O where X is an exogenous anionic ligand(X = Cl-, CH 3COO-, SCN-). The geometry of the ligand and its Mn(II) complex have been optimized at the level of UHF, by using ZINDO/1 method. Binding energies, heat of formation and bond lengths of geometry optimized structures for the ligand and complex have been obtained. The oxidation of 2,4,6-tri-tert.-butylphenol (TTBP) and 2,4,6-tri-tert.-butylaniline (TTBA) has been investigated using these Mn(II) complexes as catalyst and TBHP as an alternate source of oxygen. The organo-peroxyl compounds have been isolated and characterized by 1H NMR, 13C NMR, IR and mass data. A different product profile was obtained when H2O2 is used as an oxidant.
P-quinols and p-quinol Ethers from 2,4,6-trialkylphenols
Omura, Kanji
experimental part, p. 208 - 210 (2010/03/03)
The oxidation of 2,4,6-trialkylphenols with lead(IV) oxide and 70% perchloric acid in water-acetone or in alcohols gives p-quinols or p-quinol ethers, respectively. Some nonmetallic oxidants serve the same purpose. Georg Thieme Verlag Stuttgart.
Electron transfer between protonated and unprotonated phenoxyl radicals
Omura, Kanji
, p. 858 - 867 (2008/09/19)
(Chemical Equation Presented) The reaction of phenoxyl radicals with acids is investigated. 2,4,6-Tri-tert-butylphenoxyl radical (13), a persistent radical, deteriorates in MeOH/PhH in the presence of an acid yielding 4-methoxycyclohexa-2,5-dienone 18a and the parent phenol (14). The reaction is facilitated by a strong acid. Treatment of 2,6-di-tert-butyl-4-methylphenoxyl radical (2), a short-lived radical, generated by dissociation of its dimer, with an acid in MeOH provides 4-methoxycyclohexa-2,5-dienone 4 and the products from disproportionation of 2 including the parent phenol (3). A strong acid in a high concentration favors the formation of 4 while the yield of 3 is always kept high. Oxidation of the parent phenol (33) with PbO2 to generate transient 2,6-di-tert-butylphenoxyl radical (35) in AcOH/H2O containing an added acid provides eventually p-benzoquinone 39 and 4,4′-diphenoquinone 42, the product from dimerization of 35. A strong acid in a high concentration favors the formation of 39. These results suggest that a phenoxyl radical is protonated by an acid and electron transfer takes place from another phenoxyl radical to the protonated phenoxyl radical, thus generating the phenoxyl cation, which can add an oxygen nucleophile, and the phenol (eq 5). The electron transfer is a fast reaction.
New insights into the reactivity of nitrogen dioxide with substituted phenols: A solvent effect
Astolfi, Paola,Panagiotaki, Maria,Greci, Lucedio
, p. 3052 - 3059 (2007/10/03)
Various alkyl-substituted phenols react readily with nitrogen dioxide (.NO2) in different solvents at room temperature. In all cases nitration is the major reaction and leads to the formation of mono- and dinitrophenols and 4-nitrocyclohexa-2,5-dienones from 2,4,6-tri-substituted phenols. Oxidation, dimerisation and, in one case, nitrosation are also observed. The reaction pathway followed changes according to the solvent and to the nature and the number of substituents on the phenolic ring. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
Reactivity and selectivity of aryloxylium ions
Hegarty, Anthony F.,Keogh, Joseph P.
, p. 758 - 762 (2007/10/03)
The reactivity and selectivity of aryloxylium ions in acetonitrile-water mixtures are described. The 4-bromo-2,4,6-trialkylcyclohexa-2,5-dienones used as substrates were synthesised by electrophilic bromination in yields of 60% (3 R = Me) and 52% (7 R = B
Synthesis and structure of 2,4,6-Tri-tert-butyl-4-hydroxy-2,5-cyclohexadienone
Sharutin,Sharutina,Osipov,Dorofeeva,Bel'skii
, p. 1254 - 1255 (2007/10/03)
2,4,6-Tri-tert-butyl-4-hydroxy-2,5-cyclohexadienone was synthesized by reaction of pentaphenyl-or penta-p-tolylantimony and 2,4,6-tri-tert-butylphenol in toluene in the presence of water. According to the X-ray diffraction data, the cyclohexadiene ring ad
Free Radical Reactions of N-Heterocyclic Compounds. XIII. Oxidation of Cyclic Hydrazo Compounds with 2,4,6-Tri-tert-butyl-phenoxy Radical and Reactions of Radical Combination Products
Schulz, Manfred,Meske, Michael,Kluge, Ralph
, p. 350 - 354 (2007/10/02)
H-Heterocyclic compounds 1a,b containing the hydrazo structure were oxidized with 2,4,6-tri-tert-butyl-phenoxy radical (2).It was shown that the oxidation did not lead to the azo compounds 5a,b, but rather to radical combination products 6a,b of 2 via the intermediate hydrazyls 4a,b.The decomposition of adducts 6a,b was found to be similar to the reaction of radical combination products of aryl hydrazyls and CH-acidic compounds.The main reactions consisted of cleavage to starting radicals or elimination of isobutene forming the respective phenolic compounds 13a-c.
A Simple and Efficient Procedure for the Preparation of p-Quinols by Hypervalent Iodine Oxidation of Phenols and Phenol Tripropylsilyl Ethers
McKillop, Alexander,McLaren, Lee,Taylor, Richard J. K.
, p. 2047 - 2048 (2007/10/02)
Oxidation of para-substituted phenols with benzene (BTIB) in aqueous acetonitrile at 0 deg C gives p-quinols in moderate to good yields; higher yields are obtained when tripropylsilyl ethers of phenols are used.
