Tetrachloro QUINONES

Chlorine-substituted quinones, and especially chloranil (i.e., tetrachloro-quinone), are predominantly transfer agents rather than inhibitors. Nuclear substitution as in the first step of reaction (55) may be involved with subsequent transfer of a chlorine atom to a monomer molecule. ... 

The nucleophilic displacement of the halogen from 2,4-dinitrohalobenzenes by azide ion is catalysed by macrotricyclic ammonium salts [69], Kinetic studies indicate that the azide ion is entrapped and transported within the macrocyclic cage. The highly explosive tetra-azido-p-benzoquinone is obtained when the tetrachloro-quinone is reacted with an excess of sodium azide under phase-transfer catalytic conditions [70]. When only a twofold excess of the azide is used, the 2,5-diazido-3,6-dichloro compound is obtained. 

In contrast to the transition metal catalysts above, nickel complexes have been studied intensely for the polymerization of CHD and its derivatives. jr-Allylnickel-based complexes were employed by Dolgoplosk et al. for CHD polymerization. They used n-alkenylnickel halides, for example, K-metallyl nickel dichloride and it-allyl nickel dibromide, combined with electron acceptors such as chloranil (tetrachloro-/ -quinone) or nickel trichloroacetate. Unfortunately, the true propagating species of the above catalytic systems are not clear, but they were moderately active for CHD polymerization and the polymer obtained appeared to have a predominantly 1,4-linked structure. However, the stereoregularity of the polymer was not very high based on its Tm (270 °C). 

DDQ has proved to be the most versatile of the high-potential quinones although certain others, notably chloranil (previous section) and tetrachloro-o-benzoquinone have been used on occasion. 

Quinones, which become reduced to the corresponding hydroquinones. Two important quinones often used for aromatizations are chloranil (2,3,5,6-tetrachloro-1,4-benzoquinone) and DDQ (2,3-dichloro-5,6-dicyano-l,4-ben-zoquinone). The latter is more reactive and can be used in cases where the substrate is difficult to dehydrogenate. It is likely that the mechanism involves a transfer of hydride to the quinone oxygen, followed by the transfer of a proton to the phenolate ion °... 

Trans oxidative addition of CH3I to [Ir(acac)(cod)] affords the structurally determined complex [Ir(acac)(cod)(CH3)1].241 The reaction of [(Npet)2Ir]Cl, Npet = o-(diphenylphosphino)benzylide-nejethylamino, with tetrachloro-o-quinone yields the structurally characterized product (135).242 The synthesis and characterization of the water-soluble complex (136) have been described.243... 

With chlorinated quinones. New heterocycles containing 1,2-dihydro-imidazo [l,2- ]imidazol-3-one 405 or 1/7-imi-dazo[l,2- ]pyrazole moieties were obtained via charge-transfer interaction of creatinine or 3-aminopyrazole with some 7i-deficient compounds such as 2,3-dichloro-5,6-dicyano-l,4-benzoquinone, 2,3,5,6-tetrachloro-l,4-benzoquinone, 2,3-dichloro- or 2,3-dicyano-1,4-naphthoquinone, and 3,4,5,6-tetrachloro-l,2-benzoquinone (Equation 183) C1996BSB159, 2001HC0541, 2000PS1>. 

The reactivity of stable germaphosphenes has been previously investigated and reviewed.3,4,7 The chemical behavior of Mes2Ge = PAr 155 toward orthoquinones (tetrachloro-o-benzoquinone, 3,5-di-terr-butyl-o-benzoqui-none, and 1,2-naphthoquinone) and ce-diketones (benzil and biacetyl) has been examined. The reaction with o-quinones involved probably radical intermediates, and in each case only the less encumbered isomer of the corresponding [2 + 4] cycloadduct 156 was formed. Benzil led in a very similar manner to a l,4,2,3-dioxagermaphosphin-5-ene 157, whereas, as was observed with acetone, an ene-reaction occurred with biacetyl to afford 158138 (Scheme 29). 

Reacts with amines and alkali metals forming the corresponding water-soluble salts (Sanborn et al, 1977). Reacts with nitric acid forming a mixture of tetrachloro-o and p quinones (Monsanto, 1963). 

Dichloro-2-hydroxy-5-2, 4, 5, 6 -tetrachloro-3-hydroxyphenoxy-p-benzo-quinone, see... 

The most useful class of inhibitors are molecules that react with chain radicals to yield radicals of low reactivity. Quinones such as benzoquinone and chloranil (2,3,5,6-tetrachloro-benzoquinone) are an important class of inhibitor. The behavior of quinones is quite complex [Eastmond, 1976a,b,c George, 1967 Small, 1975 Yamamoto and Sugimoto, 1979 Yassin and Risk, 1978a, 1978b]. Two major types of products are obtained—quinone and ether—formed by reaction at the C and O atoms of a quinone, respectively. Attack of a propagating radical at oxygen yields the aryloxy radical XXVIII, which can terminate by... 

The phosphorus ring member has phosphenium character. It adds tetrachloro or/Ao-quinone and 2,3-butanedione and it also reacts with dimethylaniline and anisole in a pura-substitution... 

Stade observed an interesting oxidation with tetrachloro-p-benzoquinone. In methylene chloride an intense red coloration appears, but no signal in the ESR spectrum. Apparently only a charge-transfer complex 61 is formed, without electron transfer. A similar observation has been made in the reaction of N, N, N, N -tetramethyl-p-phenylenediamine with tetrachloro-p-benzoquinone in non-polar solvents Here, as in our case, electron transfer does not take place until a polar solvent such as acetonitrile is added. The ESR spectrum initially shows the doublet of 55 (23,2 Gauss) overlapping with the sharp sin et of tetrachloro-semi-quinone 62 (which has a somewhat smaller g factor). The semiquinone signal slowly disappears until finally only the doublet of 58 remains. The following scheme summarizes the reaction course ... 

Evidence has been presented for the metal-independent production of OH by halogenated quinones, including tetrachloro-l,4-benzoquinone (a carcinogenic... 

A system has been proposed which involves quinone/hydroquinone interconversions. A number of such couples are insoluble in acid solution and can therefore be used as active solid masses when made conductive by the addition of graphite. A system which has been studied experimentally is based on anthraquinone, Q, and tetrachloro-p-benzoquinone (chloranil), Qr, and their reduced or hydroforms. The overall cell reactions are then... 

Furans also undergo cycloadditions with o-benzoquinones. Thus furan, 2-methylfuran, 2,5-diphenylfuran and benzo[ >]furan yield dihydrofurobenzodioxins of type (238) with tetrachloro-l,2-benzoquinone (Scheme 83). The reaction of furan with 1,2-benzoquinone affords only a 1% yield of adduct because most of the quinone undergoes polymerization. The reaction with 2-methylfuran produces a 25% yield of adduct, however. The reactions are thought to involve the electrophilic attack of the quinone on the furan to produce a carbonium ion. In the case of 2-methylfuran the more stable carbonium ion (239) is produced. Evidence for a two-step mechanism is the diversion of the intermediate (239) to the addition product (240) which may be isolated when the reaction is conducted in the presence of ethanol (69JCS(C)1694). 

T etra (2 nitrophenylmercapto) l,4 benzo quinone, (02N.C6H4.S)4C602 mw 720.74, Ni 7.78% bm-yel prisms(from nitroben2), mp-e tpl violently when heated diffc sol in common org solvs was prepd by treating tetrachloro-l,4-ben-2oquinone(chloranil) with an excess of 2-nitro-thiophenol in ale... 

Treatment of the salt, [PhsBiCFhCOR1] BF4 with base generates triphenylbis-muthonium 2-oxoalkylide (84 R1 = Buf, Ph). This reacts with 1,2-dicarbonyls to give 2,3-diacyloxiranes (85 from acyclic reactants, MeCOCOR2, R2 = Me, OEt) or 2-acyl-3-hydroxytropones [e.g. (86), from the tetrachloro-o-quinone].123 Both reaction types are of considerable synthetic utility, and both are in marked contrast to the routes followed by the corresponding phosphonium ylids. 

Tetrabutylammonium tetrachloro-iodate(III), 5 176 Tetrach]oroauric(III) acid, and its reduction to gold with hydro-. quinone, 4 14, 15 Tetrachloro (diethylene)diplatinum-(II), 6 210... 

HjCat represents catechol or hydroquinone, Q quinone, SQ semiquinone anion, HCat- catechol monoanion, and Cat2 catechol dianion DTBQ represents 3,5-di-rerr-butyl-o-quinone, o-Q o-benzoquinone, p-Q p-benzoquinone, TCQ tetrachloro-o-benzoquinone, and TFQ tetrafluoro-o-benzoquinone. 

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