Quinone naphtho

Naphtho-quinone-4-sulfonic acid sodium salt... 

CioHsNaOjS M, = 260.20 1,2-Naphtho-quinone-4-sulfonic acid sodium salt... 

Condensed benzo[i>]furan molecules can be prepared by inter- or intra-molecular Diels-Alder reactions from furo[3,4-b]benzofurans, and some interesting intermolecular examples are listed below. As can be seen, the furo[3,4-i>]benzofuran 60 underegoes Diels-Alder reactions with naphtho-l,4-quinone in the presence of Znl2 as a Lewis acid to form the aromatized cycloadduct. When the diene precursor reacts with benzo-l,4-quinone in the absence of Znl2, the product is obtained as an endo-exo mixture <00JCS(P1)1387>. 

C Red No. 2) has been utilised by Hill2 and by Bufton and Saddlerl42 to assay neomycin in aqueous solution. Amaranth may also be used to determine neomycin in production samples from fermentation-recoveryl68. The dye, Orange II, has been similarly described(A max. = 484 nm). Complex formation between neomycin and the dye is very dependant on the ionic strength of the solution, thus necessitating careful control of reaction conditions to ensure complete precipitation of the complex during the assay procedure. Reaction of sodium 1,2-naphtho-quinone-4-sulphonate with... 

Air (NB) Collection in ethanol reaction with concentrated HCl and zinc dust react with sodium salt of 1,2-naphtho-quinone-4 sulfonic acid at pH 8.0 extraction with CCl concentration separation by paper chromatography extraction of fractions with CCl ... 

Benzofuroxans can be prepared by oxidation of o-quinone dioximes with, for example, fer-ricyanide or hypohalite in a process which closely parallels the formation of monocychc furoxans from glyoximes. Its utility is restricted by the availability of the starting materials which are themselves often best made by reduction of the furoxan. However, it is a valuable approach when the parent quinone or its monooxime is accessible by other means. It was, for example, the route originally used for naphtho[l,2-c]furoxan, the first aromatic-fused derivative <1886CB176>, and it is the method of choice for acenaphthofuroxans (11). In other cases oxidation of o-nitroanilines or thermolysis of o-nitroaryl azides are more suitable. 

Ludewig, G, Dogra, S. Glatt, H. (1989) Genotoxicity of 1,4-benzoquinone and 1,4-naphtho-quinone in relation to effects on glutathione and NAD(P)H levels in V79 cells. Environ. Health Perspect., 82, 223-228... 

Naphtho 2,3-c]pyroxidation with CAN undergo oxidative cyclization. 

Addition of water to quinones. The yields of the known Michael addition of water or an alcohol to a 1,4-naphthoquinone such as 5,8-dimethoxy-l,4-naphtho-qninonc arc improved by addition of an oxidant such as Fe2(S04)3 to convert the initial 2-hydroxynuphlhohydroquinone to the corresponding quinone. The presence til ll 1 rcc pert-hydroxy group interferes with the reaction. 

In an effort to elucidate the mechanism of oxidative phosphorylation, 6-hydroxy-2,2,5-trimethyl-2H-naphtho[l,2-6]pyran (183) was treated with silver(II) oxide. The product (184) was a stable quinone hemiketal (71JOC4045). 

The oxidative cyclization of the alcohol (214) with ceric ammonium nitrate gave a mixture of the two naphthopyrans (215) and (216) in a ratio of 3 1 (81CC534). The reaction is of interest because of the natural occurrence of quinones containing the naphtho[2,3-c]pyran ring system. 

Several dibenzo[6,tf ]pyran-6-ones (360) have been prepared by the reaction of substituted phenols with 2-methoxycarbonyl-l,4-benzoquinone in the presence of trifluoroacetic acid (79HCA2833). Treatment with silver oxide converts the products into the related quinones which may be elaborated to benzo[6]naphtho[[Pg.800]

A [4 + 2] cycloaddition is used for constructing bicyclic quinone 64, which is then reduced to -y-hydroxyme-thylcarboxylate 65. The latter is cyclized to lactone 66, which has a skeleton of naphtho[6c]furan... 

Amino naphtho Is, such as l-amino-2-naphthol and several 1-aminonaphthol-sulfonic acids, such as l-amino-2-naphthol-4-sulfonic acid, are oxidized to the respective quinone by nitrous acid. Diazotization can, however, take place under normal conditions in the presence of catalytic quantities of metal salts, such as copper or zinc salts. 

Among other reported p-quinone adducts with N,N,-ethylene-/h.v(salicylidenimi-nate), there is a cobalt one. o-Quinone complexes with the same ligands have the composition 1 1 [Fe(salen)Q] (Q = 9,10-phenanthrenequinone and 1,2-naphtho-quinone) and [Co(salen)(py)]2Q [239]. 

Methylallyloxy)-l, 4-naphtho-quinone 0.5 140 — 3-(a-Methylallyl)-2-hydroxy-l,4- naphthoquinone >85% 126... 

Fur an, 2-methylfuran, and other compounds react slowly in the naphtho series. The quinones form as a result of oxido-reduction. The yields are moderate with acetylnaphthaquinone (12), but with the methoxylated quinones (13) and (14) there is no reaction in a... 

Positive Photoresists. Positive resists are entirely different from negative resists. For the purposes of this discussion we restrict ourselves to visible-light-sensitive materials. Typically, these materials are mixtures of low-molecular-weight phenol-formaldehyde polymers and derivatives of naphtho-1,2-quinone diazide, the photosensitive component. The former is soluble in aqueous alkali, but the presence of the latter, a hydrophobic species, inhibits attack of this developer on the film. On irradiation the "sensitizer" is converted to a ketene, which, after reaction with water, forms a base-soluble carboxylic acid. Thus the irradiated part of the film is rendered soluble in the developer and it can be removed selectively. The important feature of this system is that the unirradiated areas are not swollen by the developer and the resolution of this material is quite high. It is possible to prepare gratings having several... 

A similar domino sequence in an intramolecular Diels-Alder version of the previous example provided access to pyrano benzo-[60] and naphtho-[61] quinones as shown in Scheme 25. Depending on substitution patterns of the aldehyde 111, para-(112 and 116) or ortho- H3 and 117) adducts or both were obtained. Typically high diastereoselectivity was observed. Libraries 114 and 115 were tested for their ability to reverse the multidrug resistance phenotype resulting from overexpression of drug efflux pumps. The compounds were evaluated in mammalian... 

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