Naphthoquinones vitamin

In the case of ubiquinones we have already considered the ability of quinones to react with superoxide and other free radicals. Naphthoquinones, vitamin K and its derivatives, especially menadione, are the well known producers of superoxide through redox cycling with dioxygen. However, in 1985, Canfield et al. [254] have shown that vitamin K quinone reduced the oxidation of linoleic acid while vitamin K hydroquinone stimulated lipid peroxidation. Surprisingly, later on, conflicting results were reported by Vervoort et al. [255] who found that only hydroquinones of vitamin K and its analogs inhibited microsomal lipid peroxidation. 

The MCPTresearchteam investigated the synthesis of2-methyl-l,4-naphthoquinone (vitamin K3) by the oxidation of 2-methylnaphthalene [57]. 

Using surfactant chromophores, trans-bilayer electron transfer can also be observed, although in the absence of a mediator, the chromophore must be embedded in both surfaces of the bilayer structure. Thus, MV " in the bulk aqueous phase can be reduced by EDTA or sodium ascorbate in the inner water pools if they are separated by a bilayer consisting of 5,10,15-tris(l-methyl-pyridine)-4-yl-20-(4-stearoxyphenyl)porphinatozinc colyophilized with dipalmitoyl-L-phos-phatidylcholine (DPPC). l imilar results are obtained using surfactant derivatives of [Ru(bipy)3] and increased rates of formation are observed if mediators such as hexadecyl-viologen, 2-methyl-1,4-naphthoquinone (vitamin didodecyl- or dibutyl-alloxazine... 

Quinones and, in particular, naphthoquinone derivatives are industrially valuable products for further processing and for direct use due to their pronounced bioactivity [la,b], 2-Methyl-1,4-naphthoquinone, vitamin K3 ( menadione ), is the basis of the vitamin K group (coagulation vitamins). The skeleton of 2-methyl-1,4-naphthoquinone is common to all fat-soluble K vitamins. Derivatives of vitamin K promote the formation of prothrombin and other blood coagulation factors. They are used on an industrial scale as supplement in animal feed, but are also employed in the treatment of Melaena neonatorum in newborn babies. Trimethyl-p-benzoquinone is a key compound for the synthesis of vitamin E, active as antioxidant agent. As an example, the current method of the production of trimethyl-p-benzoquinone on an industrial scale is p-sulfo-nation of 2,3,6-trimethylphenol followed by stoichiometric oxidation using Mn02 [Ic]. 

The dienol ether 3-cyclopropylidene-l-ethoxyprop-l-ene was reacted with methylmaleic anhydride, various alkyl-substituted 1,4-benzoquinones, 2-methyl-1,4-naphthoquinone (vitamin K3), and dimethyl acetylenedicarboxylate to give the corresponding Diels-Alder adducts, e.g. 4-6, in moderate to high yield.In complete analogy, 2-(trialkylsiloxy)allylidenecyclopropanes react with a variety of dienophiles to give 5-(trialkylsiloxy)spiro[2.5]oct-4-ene derivatives which can be hydrolyzed to spiro[2.5]octan-5-ones in high yield. For example, formation of 7 and 8. ... 

Cycloadditions. Epoxidation of 2-methyl-1,4-naphthoquinone (vitamin-Ks) by NaOCl is best catalyzed by de-O-methylquinine anthracyl-9-methochloride, according to a computer analysis. Epoxidation of 2-cycloaIkenones by H2O2 with 9-epiamino-9-deoxyquinine as catalyst shows opposite enantioselectivity as that with (f ,f )-l,2-dipheny lethanediamine. ... 

The first part of this account deals with the more recent chemistry of the alkenyl members typified by the Cg, isopentenylphenols, the Ck, dimethyloctadienyl-phenols, the C g, farnesylphenols, and Cjq, phytylphenols. The ubiquinones in the monocyclic and the naphthoquinone vitamins K, and Kj in the bicyclic series are related chemically but are not discussed in this account. 

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). 

PS I reaction center contains two molecules of phylloquinone (2-methyl-3-phytyl-l, 4-naphthoquinone=vitamin K2)[3-5], one of which functions as the electron acceptor A [5-10] and mediates the electron transfer between the reduced electron acceptor chlorophyll a (Aq ) and... 

A unique class of polymer, polyquinone-bearing sulfonic acid functional groups, when combined with Pd(II), displayed activities for the oxidation of aUcenes to aldehyde, without the need for a cocatalyst such as CuCl2. ° Here the polymer matrix serves both as a catalyst carrier and a redox mediator. A remarkable solvent effect on the selectivities of a polymer-bound palladium catalyst was observed with the oxidation of 2-octene, affording 97% 2-octayne in Et0H-H20 and 89% 2-octanone when EtOH was replaced with dixoane. Oxidation of 2-methylnaphthalene to 2-methyl-1,4-naphthoquinone (vitamin K3) can be effected by palladium absorbed on ion exchanged resin with aqueous H2O2. 

Another application of extraction techniques occurs in the determination of 2-methyl-1,4-naphthoquinone vitamin K, menadione) in poultry feed.< > The sample of poultry feed is extracted in the absence of light in an extraction apparatus devised by Berntrop. The sample solution should be exposed to as little light as is possible, to avoid the photochemical decomposition of naphthoquinones. 10 ml. of the extract is then mixed with 25 ml. of 0-08 N ammonia, 0-08 N ammonium chloride (pH 9) in isopropanol containing 10 per cent of water. An aliquot is finally subjected to polarographic electrol)rsis. 

Werbin, H., and E.T. Strom Photochemistry of Electron-Transport Quinones. I. Model Studies with 2-Methyl-1,4-naphthoquinone (Vitamin K3). J. Am. Chem. Soc. 90, 7296 (1968). 

---