2.5- Dimethoxy-l,4-benzoquinone

Dimethoxy-l,4-benzoquinone [530-55-2] M 168.1, m 256 . Crystd from acetic acid. Sublimes in a vacuum. 

Oxidation of the syringic acid is considered to result in the formation of an unstable semiquinone, which undergoes decarboxylation with concurrent uptake of O2 to form the 2,6-dimethoxy-l,4-benzoquinone (41). The third peak from 475 to 521 ppm, with maxima at 483, 504, and 515 ppm, corresponds to azobenzene nitrogens. These most likely arise from nitrogen to nitrogen coupling reactions between the anilino radicals and free aromatic amino groups in the fulvic acid molecules ... 

M. Lounasmaa,9 of the Technical University of Helsinki. Otaniemi. Finland, refluxed for several hours a solution of 2,6-dimethoxy-l, 4-benzoquinone in acetic anhydride in the presence of sodium acetate, added water, and isolated by extraction with chloroform and crystallization from acetic acid a colorless product melting at 149-150° which, on the basis of analysis (C14H160 ). mass spectrography. and IR and N MR spectroscopy, was assigned the structure (6). 

Dimethoxy-l,4-benzoquinone (38) Cytotoxic activity to parental LS178Y cells 111... 

According to Ref. [40] (2002). Reaction conditions 1 mmol substrate, 1 mLtoluene, 100 °C, 1 atm air employing 0.5 mol% [(C4Pli4COHOCC4Pli4)(p-H)(CO)4Ru2], 20mol% 2,6-dimethoxy-l,4-benzoquinone, and 2 mol% bis(salicylideniminato-3-propyl)methylamino-cobalt(II) as catalysts. 

Schmalle H, Jarchow O, Hausen B M 1977 2,6-dimethoxy-l,4-benzoquinone, a new contact allergen in commercial woods. Naturwissenschaften 64 534... 

Several quinonic compounds have been synthesized and their antioxidant activities are being evaluated. For example, a series of arylthiolated-2,3-dimethoxy-l,4-benzoquinones were chemically prepared and tested for their effect on the respiratory system and the lipid peroxidation in bovine heart mitochondria. These quinones were as efficient as exogenous ubiquinone for the inhibition of lipid peroxidation. 5- and 5,6-diarylthio groups on the quinone ring were found to be favorable for the inhibition of the respiratory system and lipid peroxidation [137], Giorgini et al [138] studied the... 

Qo 2,3-dimethoxy-5-methyl-l,4-benzoquinone DCIP dichlorophenol-indophenol BQ 1,4-benzoquinone PMS phenazine methosulphate DMBQ 2,6-dimethyl-l,4-benzoquinone NQ 1,4-naphthoquinone VK3 2-methyl-1,4-naphthoquinone (vitamin K3). 

Scheme 2.6 Different enzyme-mediator systems used for the regeneration of NAD(P)+ cofactors (a) xylose reductase (Ct-XR) H-9,10-phenanthrenequinone (b) laccase-I-diaphorase (M/-LPD) H-2,5-dimethoxy-l,4-benzoquinone and (c) laccaseH-Meldola s blue.

An alternative regioselective synthesis of 2-anilino-5-methyl-l,4-benzoquinone (842) was developed using 2-bromo-6-methyl-l,4-benzoquinone (846) (route A) and 4,4-dimethoxy-2-methylcyclohexa-2,5-dienone (849) (route B) as synthetic equivalents for methyl-1,4-benzoquinone (841) (623) (Scheme 5.102). 

Dihydroxy-l-tetralone Diisoprene 2,3-Dimethoxy-5,6-dimethyl-l,4-benzoquinone Isosclerone ( )-Limonene Aurantiogliocladin... 

The coenzyme QIO is a natural substance belonging to the family of 2,3-dimethoxy-5-methyl-6-polyprenyl-l,4-benzoquinone, widely known as ubiquinone for its ubiquitous occurrence in animal and plant tissues. This coenzyme plays a pivotal biological role in the electron transport chain in both photosynthetic and respiratory processes. " CoQlO has a chnical effect in human congestive heart failure and hypertension. It also augments the compromised irmrnme system and prevents cardiotoxicity of some of the cancer drags. ... 

A soln. of NaNg in methanol added dropwise to the equivalent amount of methyl 3-chloro-6-methoxy-l,4-benzoquinone-2-carboxylate dissolved in warm methanol 3,5-dimethoxy-4,7-dihydro-2,l-benzisoxazole-4,7-dione. Y 80%. W. Schafer and H. Schlude, Tetrah. Let. 1967, 4313. 

Coenzyme Qo (2,3-Dimethoxy-5-methyl-l,4-benzoquinone, 3,4-dimethoxy-2,5-tolu-quinone, fumigatin methyl ether), colchicine and colchicoside see entries in Chapter 6. 

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