Hydroquinone derivative

The coupling reaction of an a ,/3-unsaturated chromium carbene complex, e.g. 1, and an alkyne 2, through coordination to the chromium center, is called the Dotz reaction. The initial product is the chromium tricarbonyl complex of a hydroquinone derivative 3, which can easily be converted to a free hydroquinone or quinone. 

Ni(0)-mediated homocouplings of 2-subslituted l,4-phcnylenebis(triflate)s have been reported by Percec et al. [15] to provide substituted poly(/ -phenylene)s 7 containing alkyl, aryl or ester substituents in the 2- and 3-positions of the 1,4-phenylcnc skeleton. This method of preparation appears to be broad in scope, especially due to the ease of preparation of the bis(lriflatc) monomers starting from the corresponding hydroquinone derivatives. 

Providing an ion exchanger with a sufficient number of redox groups so that conduction can occur by a relay-type redox-change mechanism. Examples are hydroquinone-derived redox polymers and polyvinyl polymers with a tetrathia-fulvalene, ferrocene, or carbazole group, which have been found useful for research and analytical applications. 

V. REDOX REACTIONS BETWEEN OXYGEN IN W AND A HYDROQUINONE DERIVATIVE IN 0 AT THE W/0 INTERFACE [23]... 

The reduction of O2 in W by hydroquinone derivatives (QH2) in O is a subject of interest, since the reaction might offer the fundamental information on the electron transport coupled with the proton transport at a biomembrane realized by the respiration [2,3,56]. 

The results of the methanolic solvolysis study shown in Fig. 7.15 reveals that nucleophilic attack on the cyclopropyl quinone methide by methanol affords the pyrido[1,2-a]indole (73 ppm) and azepino[l,2-a]indole (29ppm) trapping products. Initially, nucleophilic attack on the cyclopropane ring affords the hydroquinone derivatives (see Scheme 7.17) that oxidizes to the quinones upon aerobic workup. 

In the past, various leuco benzoquinone dyes4 were used as mordant dyes but recently they have been displaced by the azo mordant dyes. The reaction of j9-benzoquinone with j9-chloroaniline gives the hydroquinone derivative (5). Compound 5 undergoes oxidation to the corresponding benzoquinone 6. A mixture of hydrosulfite and compound 6 is marketed as a sulfurized vat dye which gives brown and khaki colors. 

Shindo H, Huang PM (1985a) The catalytic power of inorganic components in the abiotic synthesis of hydroquinone-derived humic polymers. Appl Clay Sci 1 71-81... 

Wang MC, Huang PM (1986) Humic macromolecular interlayering in nontronite through interaction with phenol monomers. Nature (London) 323 529-531 Wang MC, Huang PM (1988) Catalytic power of nontronite, kaolinite, and quartz and their reaction sites in the formation of hydroquinone-derived polymers. Appl Clay Sci 4 43-57... 

Allylations of hydroquinone derivatives, 32 459-461 Allyl chloride oxidation, 41 305 thermal decomposition, 41 80 tl-Allyl complexes, 25 129-134 Allyl hydroperoxide, 27 187-189 Allylic alcohols, olefinic substitution of, 26 343-345... 

The structures of six new geranyl-hydroquinone-derived compounds, from Cordia alliodora, provide additional support for proposed biogenesis in Cordia species (see Vol. 4, p. 69). The isolation of ethuliacoumarin (260) and cycloethuliacoumarin (261) from Ethulia conyzoides suggests an ocimenone (54) biogenetic origin, ... 

Tetrahydrobenzo[l,2-3 4,5-3 ]difuran is efficiently synthesized using an intramolecular cyclization approach from the hydroquinone derivative using -butyllithium (Equation 65) <1996JME2953, 1997JME2997>. 

Hydroquinone Derivatives. The nine hydroquinone derivatives listed in Table V all appear to act as monophenols. It appears from the quin-... 

Table V. Molar Absorptivities in the Total Phenol Assay and Precipitability with Acidic Formaldehyde Hydroquinone Derivatives...

In some cases, a single chemical substance can serve both as a dye and as a pigment. For example, indanthrone [81-77-6] (Pigment Blue 60) functions as a blue pigment or as a dye. As a pigment, indanthrone is a particulate, insoluble solid dispersed directly into a vehicle, whereas as a dye it is reduced to a base-soluble hydroquinone derivative and then reoxidized onto a solid substrate. 

Several chlorinated hydroquinone derivatives with cytotoxic activity have been isolated from the toxic mushroom Russula subnigricans, russuphelins A-D (33-36) and the tetramer russuphelol (37), the latter... 

Figure 8.27 Structures and energies of a hydroquinone derivative in the course of intramolecular proton transfer (a), and examples of fluorescence spectra of these species under jet-cooled conditions (b)...

Oxidation of hydroquinone derivatives (p-dihydroxybenzenes) with Cr(VI) reagents is a method for preparing quinones. 

Cycloaddition of a ketene complex with unsaturated bonds other than alkenes and alkynes is also possible. The ketene 312, formed from 311, adds to imine 313 to give the /1-lactam 314 under sunlight photolysis. The optically active /1-lactam 314 was prepared from the optically active carbene complex 311 with 99% ee, and converted to 315 [95]. Irradiation of carbene complex 316 generates ketene 317, which cyclizes to the o-hydroquinone derivative 318 [96],... 

A subsequent route by Joule and his collaborators846 made use of the primary alcohol (118) corresponding to (116). This was manipulated as shown, and cyclized to the quinone (119) before completion of the carbon skeleton, the cyclization stage being accompanied by spontaneous aerial oxidation of the initially formed hydroquinone derivative. Finally, the methyl groups were introduced by reaction with methyl-lithium, and the synthesis was completed by reduction (with NaBH4). 

The hydroquinone-derived polymers formed in the presence of the tephroite system (Shindo and Huang, 1985a) have similar IR absorption bands to those of soil humic substances (Schnitzer, 1978). The surface features of these polymers... 

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