3.5- di-tert-butyl-l,2-benzoquinone

An immediate reaction takes place between 178 or 179 and 3,5-di-tert-butyl-l,2-benzoquinone to lead to the dioxagermole 189, the formal adduct of the germylene (ArO)2Ge with the quinone. A single electron mechanism, supported by an ESR study and depicted in Scheme 37, was postulated to account for the formation of 189.132... 

The electrochemical properties of the quinone-containing complex [Ru(tpy)(Q)(H20)] " (Q = 3,5-di-tert-butyl-l,2-benzoquinone) in the presence of base have been studied in detail and differences in the behavior of aqua and hydroxo complexes analyzed and applied to the conversion of the proton gradient to electricity. ... 

To our knowledge, the first examples of asymmetrically substituted monocyclic phosphoranes are 60 and 61, described by Moriarty et al.135 and involving the reaction of a substituted o-benzoquinone136,137 (Scheme 6) on an aminophosphine (59), itself obtained by alcoholysis of 58 with l-( — )-menthol. In contrast to the amino phosphine 53 (Scheme 5), 59 is a mixture of the diastereoisomers 59a and b, and its reaction with 3,5-di-tert-butyl-l,2-benzoquinone yields two diastereoisomeric phosphoranes, 60a and b. Finally, alcoholysis of the P(V)—NR2 bond138 in 60a and b leads to 61a and b or 62. 

These are of great variety and importance. Catecholates,35 such as MnIvpy2(3,5-DBcat)2 (3,5-DBcat = 3,5-di-tert-butyl-l,2-benzoquinone), show dramatic ther-mochromic effects on heating in toluene due to a 2e transfer to give the Mn11 semiquinone tautomer ... 

Primary aliphatic amines can be oxidized to aldehydes or ketones. Other reagents used have been V-bromoacetamide (for benzylic amines), 3,5-di-tert-butyl-l,2-benzoquinone, and aqueous NaOCl with phase-transfer catalysts. Benzylic amine salts PhCHRNRj H" " Cl (R,R = H or alkyl) give benzal-dehydes or aryl ketones when heated in DMSO. Several indirect methods for achieving the conversion RR CHNH2 RR C=0 (R = alkyl, aryl, or H) have been reported. ... 

When indium metal is treated with 3,5-di-tert-butyl-l,2-benzoquinone (TBQ) in a 1 3 mole ratio, a paramagnetic, green solid In(TBSQ)(TBQ)2 (where TBSQ = 3,5-di-tert-butyl-l,2-benzo-semiquinonate) forms. The same product may be obtained from Inl3 and three equivalents of NaTBSQ." The ESR results confirm that the indium atom in this product is in the -fl state (and also confirm the presence of the semiquinone moiety). The paramagnetic indium(I) compound In(TBSQ) has also been reported. It can be stabilized by coordination to 1,10-phenanthroline. ... 

ROO-CHD XVI is formed in the yield of 5-10 % in the reaction of 2,4-di-tert-butylphenol with tert-Bu0233 via the phenoxyl VI (Scheme 3). Its isolation from the reaction mixture is difficult, because it is cleaved on silica gel to 2-tert-butyl-l,4-benzoquinone. Also the isomeric ROO-CHD XIV is the intermediary formed from the same phenol, but it is immediately cleaved to 3,5-di-tert-butyl-l,2-benzoquinone XV. 2,2 -Biphenyldiol X, originating as a consequence of C-C coupling of phenoxyl VI, is not the final product in the presence of excess of RO 2 and ROO-CHD s XI to XIII are formed (the compound XII in the yield as high as 60 %). Also the phenolic derivative VIII undergoes further oxidation, giving ROO-CHD IX as the final product. 

One class of complexes, that of substituted catecholate ligands, has yielded a variety of mono- and di-nuclear Mo complexes. Mo(CO)e reacts with the oxidized form of the 3,5-di-rert-butylcatechol i.e. 3,5-di-tert-butyl-l,2-benzoquinone) to yield Mo(dbcat)s which reacts with O2 to give the dinuclear complex [MoO(dbcat)2]2- In contrast, reaction of Mo(CO)s with 3,4,5,6-tetrachloro-l,2-benzoquinone yields the dinuclear non-oxo complex Mo2(02C6Cl)e. The complex Mo20s(phenSQ) has already been discussed. This complex... 

After the reactor had been cleaned, evacuated and purged with N2, 1.29 g of 2,5-di-tert-butyl-l,4-benzoquinone (5.85 mmol) were added, taking care that the benzoquinone did not touch the ATR sensor. After the desired jacket temperature had been reached, a reference background infrared spectrum was recorded. Then, 19.2 mL dioxan, 8 mL EtOH and 8 mL tert-butyl hydroperoxide (70% solution in water, 58.5 mmol) were added, the stirrer was turned on to 400 rpm and the desired reaction temperature was set. After degassing the solution for 3 minutes with N2, Triton B (0.8 mL of a 40% solution in methanol, 1.78 mmol) was added within 24 seconds into the closed reactor to start the reaction. 

Diazido-3,6-di-tert-butyl-l,4-benzoquinone refluxed 45 min. in anhydrous benzene tert-butylcyanoketene. Y almost 100%. - The product is a surprisingly stable yet very reactive ketene. F. e. and reactions of the product s. H. W. Moore and W. Weyler, Jr., Am. Soc. 92, 4132 (1970). 

Hydroperoxide 172 is reduced to 173 by triphenylphosphine. 2,5-Di-tert-butyl-l,3-benzoquinone is isomerized to 174 by boiling with 43 in methylbenzene isomerizations of this type normally must be induced pho-... 

According to121), 2,6-diphenyl-4-tert-butylperoxy-4-methoxy-2,5-cyclo-hexadien-l-one is decomposed under formation of methyl alcohol and 2,6-di-phenyl-l,4-benzoquinone. 4-tert-Butylperoxy-2,4,6-tri-tert-butyl-2,5-cyclohexadiene-1-one XXXVI (R = R1 = tert-Bu) is thermolyzed already at 65 °C to the mixture of compounds, where 2,6-di-tert-butyl-l,4-benzoquinone XXII was identified as the main component31,13°) the mixture contained, according to GPC, also 3,5-di-tert-butyI-4-hydroxybenzaldehyde XXXII and stilbenequinone XXIX. 

Catalytically active metallic ions may play an important role in ageing of polymers. Their effect may become evident also in transformations of an antioxidation system. From this standpoint, data149 dealing with oxidative transformation of 2,6-di-tert-butyl-4-alkylphenols in the presence of Co(II) complexes of Schiff bases are interesting. The mixture of compounds which results in this case contains 2,6,2, 6 -tetra-tert-butyl-4,4 -dioxycyclohexadiene-l-one XCVIII and compounds formed by its cleavage, among them 2,6-di-tert-butyl-4-hydroxy-4-alkyl-2,5-cyclohexadiene-l-one of the type CX, 2,6-di-tert-butyl-l,4-benzoquinone XXII, and 3,5,3, 5 -tetra-tert-butyl-4,4 -diphenoquinone XX. 

An induction period was observed in the decomposition of cumyl hydroperoxide in chlorobenzene at 70 and 110 °C in the presence of phenolic sulphides CXCVIIa,b262). This was a substantial difference with respect to the behaviour of 4,4 -thio-bis(2,6-di-tert-butylphenol) CLXVIIIb which decomposed ROOH under the same conditions without induction period. The result indicates a mechanistic distinction in the action of both types of phenolic sulphides. In the mechanism of transformations of benzyl sulphide CXCVIIb, there are assumed (Scheme 24) the formation of sulphoxide CXCVIII and the intermediary formation of CIC followed by oxidation and formation of sulphinic acid CC. Further transformation of the acid CC depends on the character of R. If R = 3,5-di-tert-butyl-4-hydroxybenzyl, as it is in the formation of CC from CXCVIIa, the total elimination of the sulphurous part of molecule may occur and the transformation products of phenolic or quinoid character may be formed 3,5-di-tert-butyl-4-hydroxybenzyl alcohol XXXI, the corresponding aldehyde XXXII, and 2,6-di-tert-butyl-l,4-benzoquinone XXII were identified. Another possible sulphurless product is 4,4 -ethylenebis(2,6-di-tert-butyl-phenol) XXVIII, which was isolated in small amounts in its oxidized form as 3,5,3 ,5 -tetra-tert-butyl-4,4 -stilbenequinone (XXIX). Quinone methide XXX formed by thermolysis of sulphoxide CXCVIII, may be also the precursor in formation of XXIX. According to66), XXX is further oxidized by hydroperoxides to XXIX... 

F. tert-Butyhyanoketene. Tj-pically the ketene is prepared by dissolving 1 g. of 2,5-diazido-3,6-di-starting material as well as the intermediate cyclopentenedione is followed by thin layer chromatography v(Note 17). When the cyclopentenedione is no longer detectable, after approximately 90 minutes, the heating is stopped. The solution contains ferf-butylcyanoketene in amounts equivalent to at least a 95% yield (Note 18). 

B. 2-CMoro-, Q-di-tert-butyl-l,i-benzoquinone. A 2-1. Erlenmeyer flask is charged with a solution of 112 g. (0.385 mole) of 2,3-dichloro-2,5-di-ieri-butylcyclohex-5-ene-l,4-dione in 800 ml. of ether. A solution of 28.4 g. (0.383 mole) of diethylamine (2V-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-fer/-butyl-l,4-benzo-quinone as a yellow oil which is used without further purification (Note 6). 

The vaulted complex CoA (Rj= Me, Rj = durene) catalyzes the oxidation of 2,6-di-tert-butylphenol in acetonitrile solution. Typically, at 25°C and 1 atm O2 a conversion of 37% is obtained in 24 hours, the products being 5% 2,6-di-tert-butyl-l,4-benzoquinone (DTBQ) and 22% 3,5,3 ,5 -tetra-terf-butyl-4,4 -diphenoquinone (TTBDQ). Irreversible loss of the catalyst occurs due to autoxidation. The product distribution is determined by the competing reactions shown in Figure 62. 

The effect of benzoquinones on thermal oxidation of hydrocarbons was investigated in detail on a liquid substrate. It was found182 that 4-tert-alkyl-l,2-benzoquinones are at 60 °C more powerful retarders in the initiated oxidation of tetra-hydronaphthalene than 2-tert-alkyl-l,4-benzoquinones. The effect of both isomeric hydroxy-tert-alkylbenzoquinones of types CXLin and CLI on this oxidation is entirely negligible. Unsubstituted 1,4-benzoquinone retards the oxidation of ethylbenzene213. However, the retardation effect of 2-tert-butyl- and 2,6-di-tert-butyl-1,4-benzoquinones CXXXVIII and XXII and, in particular, of 3,5,3 -tetra-tert-butyl-4,4 -diphenoquinone XX is much weaker than that of derivatives of quinone methide, e. g., XXIX Moreover, benzoquinones resume their retardation... 

Anhydrous HCl rapidly bubbled through a soln. of 3-bromo-2,5-di-/ r/-butyl-1,4-benzoquinone in glacial acetic acid during 1 hr., and the intermediate quinol oxidized with N2O4 in chloroform -> 2-diloro-3-bromo-5-tert-butyl-l,4-benzo-quinone. Y 75%. F. e. s. H. W. Moore et al., J. Org. Chem. 57, 1984 (1972). 

Abbreviations Ac acetyl Bn benzyl BSP 1-benzenesulfinyl piperidine BTIB bis(trifluoroacetoxy)iodobenzene DAST (diethylamino)sulfur trifluoride DDQ 2,3-dichloro-5,6-dicyano-/)-benzoquinone DMDO dimethyldioxirane DMTSF dimethyl(methylthio)sulfonium tetrafluoroborate DMTST dimethyl(methylthio)sulfonium triflate DTBMP 2,6-Ai-tert-butyl-4-methylpyridine DTBP 2,6-di-tert-butylpyridine DTBPl 2,6-di-tert-butylpyridinium iodide FDCPT l-fluoro-2,6-dichloropyridinium triflate FTMPT l-fluoro-2,4,6-trimethylpyridinium triflate IDCP iodonium dicollidine perchlorate IDCT idonium dicollidine triflate LPTS 2,6-lutidinium p-toluenesulfonate LTMP lithium tetramethylpiperidide Me methyl MPBT S-(4-methoxyphenyl) benzenethiosulflnate NBS A-bromosuccinimide NIS A-iodosuccinimide NlSac A-iodosaccharin PPTS pyridinium p-toluenesulfonate TBPA tris(4-bromophenyl)ammoniumyl hexachloroantimonate Tf trifluoromethanesulfonyl TMTSB methyl-bis(methylthio)sulfonium hexachloroantimonate TMU tetramethylurea Tr trityl TTBP 2,4,6-tri-tert-butylpyrimidine. 

In contrast to o-phenylenediamines, l,8,naphthylenediamine and most of its derivatives react with 2,6-di-tert-buty 1-1,4-benzoquinone to give perimidinespirocy-clohexadienone 11 (Scheme 5).4,6-8 The reaction occurs readily under noncatalytic conditions when refluxing propanol or toluene solutions of the components. By contrast, catalysis of the reaction with strong proton acids (e.g., /Hoi ucncsul Ionic acid) is necessary for the preparation of 2,3-dihydro-2-spiro[4(4//)-2-fert-butyl-l-naphthalenone pcrimidine 4 when 2,6-di- fcrt-buty 1-1,4-benzoquinonc is replaced in this reaction by 2-fert-butyl- 1,4-naphthoquinone. 9... 

Various alkylcyclopropanes have been converted to (l-alkenyl)cyclopropanes by dehydrogenation with trimethylsilyl triflate, selenium dioxide,tetrachloro-1,4-benzoquinone, 2,3-dichloro-5,6-dicyano-l,4-benzoquinone, di-/er/-butyl dicarbonate and potassium tert-butoxide/dimethyl sulfoxide. A related transformation is the Ramberg-Back-lund reaction of bis(l-trimethylsilylcyclopropylmethyl) sulfone which gave ( )-l,2-bis(l-trimethylsilylcyclopropyl)ethene in fair yield. ... 

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