2.6- Dimethoxy-p benzoquinone

Salcomine is a useful catalyst for the selective oxygenation of 2,6-disubstituted phenols to the corresponding p-benzoquinones when dimethylformamide is used as the solvent laborious procedures are avoided and high yields of pure p-benzoquinones are obtained. Following the procedure described above, the authors have prepared 2,6-diphenyl-p-benzoquinone (m.p. 134—135°, yield 86%) and 2,6-dimethoxy-p-benzoquinone (m.p. 252°, yield 91%) from the appropriate phenols. 

To date, several naturally occurring compounds which are capable of inducing the development of the haustorium have been characterized. The first haustorial inducers identified were the xenognosins, and their connection with the host s constitutive antibiotics suggested that they were specific recognition cues (8). 2,6-Dimethoxy-p-benzoquinone, the only active principle... 

Continuous irradiation at 400 nm of a solution of [Ru(bipy)3p and PhCHjS in dry oxygen-free MeCN has been observed to give a quantitative yield of [Ru(bipy)3]. In the presence of BU4NQO4, this same system can act as a two-compartment cell if coupled with the reduction of a weak electron-acceptor such as 9,10-anthraquinone, 1,3-dinitrobenzene, or 2,6-dimethoxy-p-benzoquinone. The temperature dependence of the reductive quenching of electronically excited [RuLj] (where L = bipy or 4,7-dimethyl-l,10-phenanthroline) by aromatic amines in MeOH has been studied and fitted by theoretical expressions. Activation parameters for a series of quenching reac-... 

In connection with hgnan chemistry, oxygenation of syringyl alcohol (247) with O2 in the presence of 10% of the 5-coordinate catalyst 231 or 229-pyridine complex afforded 2,6-dimethoxy-p-benzoquinone (248) in 71 and 88% yields, respectively (Scheme 52). A peroxy-p-quinalato-cobalt complex 249 is a plausible intermediate in the oxidation . ... 

Analogous results were reported earlier concerning the Perkin reaction of quinones. Treatment of 2,6-dimethoxy-p-benzoquinone with propionic anhydride in the presence of sodium propionate affords a mixture of condensation-derived products (12) and (13) (Scheme 6). However, when the reaction is carried out under milder conditions, among the products isolated is the 3 lactone (14). Compound (14) can be converted under Perkin conditions to (12) and (13). It is noted that (14) could be in equilibrium with dimethoxybenzoquinone and methylketene its isolation does not prove with certainty its intermediacy in the formation of (12) and (13). Thus, the actual mechanism of this condensation is not necessarily as simple as indicated in Scheme 2 and may involve more than one distinct pathway, depending on the exact nature of the particular substrate or base employed. 

Cosgrove D.J., Daniels D.G.H., Whitehead J.K. and Goulden J.D.S. (1952) Fermentation products of wheat germ. Identification of methoxy- and 2 6-dimethoxy-p-benzoquinone. IR absorption of some quinones and 1 2-dicarbonyl compounds. J. Chem. Soc. 4821-3. 

Finally, a fifth antidote to benzimidazole fungicides was isolated from 13 kg of the aerial parts of P. thunbergii in very poor yield (ca 1 mg). However, comparison of its physicochemical and chromatographic properties with those of authentic 2,6-dimethoxy-p-benzoquinone (21) [13] confirmed that the compounds were identical. This benzoquinone has... 

Constituent of Bvcalyptus eonghymerata oil Jlp. 62-62 5 . CrOj— 2 6-dimethoxy-p-benzoquinone. 

It gains some interest for turned articles and as a veneer for inlays in high-class furniture. Cases of occupational contact dermatitis have been described by Freise (1932), Dantin-Galego et al. (1952), Heyl (1966) and Gon alo (1992) in joiners and flooring manufacturers. The heartwood contains at least five quinonoid constituents, of which two could be identified 2,6-dimethoxy-p-benzoquinone and bowdichi-one (Hausen et al. 1972 Brown et al. 1974). A third, still unknown, quinone seems to be related to the dalbergi-ones, as cross reactivities have been observed in a sucupira-sensitive patient (Hausen 1981). 

Hausen BM (1978) Sensitizing capacity of naturally occurring quinones. V. 2,6-Dimethoxy-p-benzoquinone. Contact Dermatitis 4 204-213... 

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