Benzo quinone reactions

Benzo[b]thiophene-2 -indole indigo, 4, 910 Benzo[b]thiophene-2,3-quinone reactions, 4, 824... 

In its catalyzed form [catalyzed with hydroquinone (HQ), benzo-quinone, or copper], DEHA has a very fast reaction rate, almost as fast as catalyzed sulfite. Hydroquinone is the most popular catalyst for DEHA, and it is likely that the rapid reaction rate is, in part at least, due to the catalyst simply acting as an oxygen scavenger in its own right. 

B. 2-Chloro-3,6-di-tert-butyl-l,4-benzoquirwne. A 2-1. Erlenmeyer flask is charged with a solution of 112 g. (0.385 mole) of 2,3-dichloro-2,5-di-fer<-butylcyclohex-5-ene-l,4-dione in 800 ml. of ether. A solution of 28.4 g. (0.383 mole) of diethylamine (N-ethylethanamine) in 50 ml. of ether is added in one portion to the vigorously swirled flask (Note 5). The reaction is instantaneous, resulting in a voluminous precipitate. The mixture is washed with two 1-1. portions of water and then with 500 ml. of aqueous saturated sodium chloride. The yellow ether solution is dried over anhydrous magnesium sulfate, the drying agent removed by filtration, and the solvent removed on a rotary evaporator to yield 96-97 g. (98-99%) of 2-chloro-3,6-di-ferf-butyl-l,4-benzo-quinone as a yellow oil which is used without further purification (Note 6). 

Popp BV, Stahl SS (2007) Palladium-Catalyzed Oxidation Reactions Comparison of Benzo-quinone and Molecular Oxygen as Stoichiometric Oxidants. 22 149-189 Prashad M (2004) Palladium-Catalyzed Heck Arylations in the Synthesis of Active Pharmaceutical Ingredients. 6 181-204 Prestipino C, see Zecchina A (2005) 16 1-35 Pretraszuk C, see Marciniec B (2004) 11 197-248... 

These carbonylation reactions can also take place by using catalytic amounts of Pd(II) salts in the presence of an oxidant such as CUCI2, CUCI/O2, FeClj, Ce(lV) salts or benzo-quinone, the most effective of them being CuCl2. °... 

It has been found that AAs do not react with 3,4-disubstituted o-benzo-quinones in the expected Strecker degradation reaction instead, a decar-boxylative condensation reaction afforded the corresponding benzoxazoles. A mechanistic explanation has been advanced for this transformation. It should be mentioned, however, that other quinones or diones did not react in the described manner (78JOC509). 

Researchers have found that the substitution of two methyl groups on the benzene ring in the acetaminophen molecule results in the formation of an analog that is essentially resistant to the metabolic reactions that result in the formation of N-acetyl-p-henzo-quinone imine and, hence, prevent toxic reactions involved with the use of acetaminophen. Researchers believe that the presence of the methyl groups interferes with enzyme actions that, in the first step of the reaction by which N-acetyl-p-benzo-quinone imine is produced, convert hydrogen atoms on the benzene rings in acetaminophen to hydroxyl groups. 

Murphy and Bertrand reported a second total synthesis (+ )-bismurrayaquinone-A (215) via the bromoquinone-enaminone annulation (633). Reaction of the 4-methoxybenzyl-protected enamino ketone 1058 and 5-bromo-2-methyl-l,4-benzo-quinone (878) with copper(II) chloride in the presence of sodium bicarbonate and 3 A molecular sieves (MS) afforded, in low yield, the dimer 1059. Mechanistically, the... 

Naphthalene oxidation is very similar to benzene oxidation except for the much greater importance of naphthoquinone, compared with benzo-quinone, as a reaction intermediate. Roughly equal amounts of phthalic anhydride and naphthoquinone are initially formed from naphthalene. A suitable simplified reaction scheme is... 

Carbonyl groups in polyfluorinated quinones assist the hydrolysis of fluorine. In tetrafluoro-1,4-benzoquinone (18). one or two of the fluorine atoms can thus be replaced by hydroxy groups, depending on the reaction conditions, to give 2,3,5-trifluoro-6-hydroxy-l,4-benzo-quinone (17) or 2.5-difluoro-3,6-dihydroxy-l,4-benzoquinone (19).24... 

The ultrasonic irradiation of aqueous solution of PNP was carried out with a Branson 200 sonifier that was operated at 20 KHz and with an output of electrical power of 84 W. Reactions were performed in a stainless-steel, continuous-flow reaction cell operated in the batch mode. All reactions were carried out with air-saturated solutions, and the concentration of p-benzo-quinone (p-BQ) was determined spectrophotometrically. Hydrogen peroxide... 

Schuchmann MN, Bothe E, von Sonntag J, von Sonntag C(1998) Reaction of OH radicals with benzo-quinone in aqueous solutions. A pulse radiolysis study. J Chem Soc Perkin Trans 2 791-796 Schuchmann MN, Schuchmann H-P, Knolle W, von Sonntag J, Naumov S, Wang W-F, von Sonntag C (2000) Free-radical chemistry of thiourea in aqueous solution, induced by OH radical, H atom, cx-hydroxyalkyl radicals, photoexcited maleimide.and the solvated electron. Nukleonika 45 55-62... 

The reaction of rhodium(II) pivalate dimer, Rh2(02CCMe3)4, with 1,4-benzo-quinone (BQ) in hexane gave a chain complex, [Rh2(02CCMe3)4 BQ] , where the rhodium(II) pivalate dimers are connected by the bifunctional ligation of the p-quinone through its carbonyl oxygen or C = C double bond, i.e., the chain structure consists of two kinds of dimer units 963 and 964 [235-237] ... 

The electrical conductance of Ni(dpg)2 (dpg = diphenylglyoxime anion) becomes much greater on reaction with halogens, forming Ni(dpg)2X (X = Cl or Br).614 Similar effects were observed in the Ni(bdq)2I c (x = 0.6—0.7) (bdq = 1,2-benzo-quinone dioxime) system.615 The structure of Ni3(BQ3)2 has been determined.616... 

Crozet, Vanelle and coworkers94 have also described the first example of an S l reaction involving an oxazole system activated by a non-fused tetrasubstituted p-benzo-quinone 17, with 2-nitropropane anion (equation 26). 

The oxidation of 2-iodo-l,3,2-diheteroarsolanes by tetrachloro-o-benzo-quinone has been studied by Wieber and Gotz (193). In this reaction the cleavage of the As—I bond occurred with the formation of spirocyclic arsoranes ... 

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