Showing papers on "Quinone published in 1973"

Tingenone and hydroxytingenone, triterpenoid quinone methides from Euonymus tingens

Abstract: Spectroscopic and crystallographic studies have established that the pigment tingenone is a triterpenoid quinone methide closely related to pristimerin. A second pigment isolated from E. tingens is 20-hydroxytingenone.

Liquid crystal composition

Abstract: A liquid crystal composition having long-life dynamic light scattering properties under application of DC or AC voltage, comprising (1) at least one liquid crystalline substance selected from the group consisting of nematic and cholesteric, and (2) at least one additive selected from the group consisting of (A) mixtures of at least one first organic cyclic compound selected from the group consisting of quinone compounds, quinoneimine compounds, imino compounds, desoxybenzoin compounds, dibenzyl methane compounds and triphenyl methane compounds, with at least one second organic cyclic compound selected from the group consisting of hydroquinone compounds, aromatic amino compounds, heterocyclic amino compounds and alicyclic amino compounds, and (B) aromatic, heterocyclic and alicyclic compounds having at least one radical selected from the group consisting of carbonyl and imino radicals and at least one radical selected from the group consisting of hydroxyl and amino radicals

Synthetic studies in the diterpene series. Part VIII. Synthesis of miltirone, a diterpenoid quinone

Abstract: Miltirone (I), a diterpenoid quinone has been synthesised from p-bromoanisole, the key intermediate being 6-isopropyl-7-methoxy-1-tetralone (VI). A Reformatsky reaction on compound (VI) with methyl γ-bromocrotonate, followed by aromatisation, treatment with methylmagnesium iodide, and cyclisation gave 1,2,3,4-tetrahydro-1,1 -dimethyl-6-methoxy-7-isopropylphenanthrene. The corresponding phenol was oxidised to a quinone, identical with miltirone, either by air or by Fremy's salt.

Quinone adducts of cobalt(II) and iron(II) complexes with a quadridentate Schiff's base

Abstract: The reactions of some p- and o-quinones with N,N′-ethylenebis(salicylideneiminato)cobalt(II), Co(salen), and N,N′-ethylenebis(salicylideneiminato)iron(II), Fe(salen), have been studied. A low-spin 2 : 1 adduct of the cobalt complex with p-benzoquinone was isolated in pyridine: its formula is [Co(salen)(py)]2C6H4O2 and a dimeric structure with a bridging quinone and six-co-ordinate cobalt(III) is proposed for it. The iron complex in tetrahydrofuran suspension yielded 2 : 1 adducts with p-quinones (p-benzoquinone, tetramethyl-p-benzoquinone, and tetrachloro-p-benzoquinone) of formula [Fe(salen)]2quinone: a dimeric structure with a bridging quinone is suggested for them mainly on the basis of magnetic properties. With o-quinones(9,10-phenanthrenequinone and 1,2-naphthoquinone), 1 : 1 adducts of formula Fe(salen)(quinone) were obtained.

Photooxidation of chlorophyll B by quinones studied by chemically-induced dynamic nuclear polarization.

Abstract: The photooxidation of chlorophyll b by 1,4-benzoquinone and 2,6-dimethyl-1,4-benzoquinone was investigated by the technique of chemically-induced dynamic nuclear polarization. Polarization of the proton magnetic resonance lines of the quinone was detected. A mechanism for the photooxidation was postulated that invokes the reaction of the quinone with the excited singlet state of the chlorophyll to form a radical pair. This mechanism, together with a theoretical model and parameters taken from the literature, yields a theoretical proton magnetic resonance spectrum for the polarized quinone that agrees well with that observed experimentally.

Reactions between 2,5-di-t-butyl-1,4-benzoquinone and certain primary aliphatic amines

Abstract: The title quinone reacts with n-propyl- and n-butyl-amine in the absence of air to give benzoxazoles and 3-amino-2,5-di-t-butyl-1,4-benzoquinone. In the presence of air, the formation of aminated quinone epoxides is observed to be a major reaction. No products were detected in the dark reaction of the title quinone with t-butylamine, but in the presence of light, aminated quinones containing a rearranged side-chain are obtained.

Recovery and recycle process for anodic oxidation of benzene to quinone

Abstract: In a combination recovery and recycle process for the anodic oxidation of benzene to quinone in electrolysis cells, recycle benzene of low quinone content is provided by contacting the cell-converted benzene with a water solution of hydroquinone, the quinone extracting into the water solution and forming precipitated quinhydrone, which is recovered therefrom. The spent hydroquinone water solution is separated from the residual benzene, which is recycled to the electrolysis system. This combination process favors efficient conversion of benzene to quinone by keeping the quinone content of the benzene supplied to the electrolysis cells at a low value, and the recycling of soluble impurities in the benzene improves the purity of the quinhydrone. The product is readily convertible into quinone or hydroquinone, or it may be stored until such conversion is desired.

Quinone epoxides. Part VII. Stereospecific elaboration of 2-acetyl-1,4-naphthoquinone epoxides

Abstract: The reductive elaboration of 2-acetyl-3-methyl-1,4-naphthoquinone epoxide has been examined in an investigation into the potential of quinone epoxides as intermediates in the stereospecific syntheses of alicyclic compounds from aromatic starting materials. A series of products is obtained by stereospecific and selective reduction with borohydride; these are further transformed stereospecifically. Direct reductive opening of the epoxide ring has not been achieved. Catalytic reduction of the bromohydrin (XIV) obtained in these transformations is stereospecific but not selective. Catalytic reduction of the 3-acetyl-3,4-dihydroxy-2-methyltetralone (XVI) also leads to a mixture of products, one of which undergoes ring expansion under mild conditions to form the benzocycloheptenone derivative (XXVII).

Lignans and related phenols. Part XIV. Selective oxidation of aryltetrahydronaphthalenes

Abstract: The selective oxidation of aryltetrahydronaphthalene lignans by periodate and Fremy's salt has been demonstrated. Steric factors were evident in the reactions of the 5,8-quinone (II), which only underwent Thiele acetylation following its isomerisation to the flexible ‘picro’ derivative (III). U.v. irradiation of the quinone afforded a novel synthesis of a wholly aromatic analogue (V). Configurations were assigned on the basis of c.d. measurements.

The interaction between polymerization initiators and inhibitors in solution. III. The reaction of benzoyl peroxide with 2,5‐dichloro‐1,4‐benzoquinone and 2,3,5,6‐tetrachloro‐1,4‐benzoquinone (chloranil) in chlorobenzene

Abstract: The reaction of benzoyl peroxide with 2,5-dichloro-1,4-benzoquinone and 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil) in chlorobenzene was studied by isolation and identification of the reaction products. In dilute solution (0,02 mol peroxide/dm3), both phenyl and benzoyloxy radicals interact with 2,5-dichloro-1,4-benzoquinone to form the corresponding quinonoid derivatives by substitution of hydrogen atoms in the quinone nucleus. Chloranil does not react under these conditions. In concentrated solution (0,5 mol peroxide/dm3), both 2,5-dichloro-1,4-benzoquinone and chloranil are attacked by radicals of the spontaneous as well as the induced decomposition of the peroxide. Aryl radicals (but not benzoyloxy radicals) can substitute only one chlorine atom of the chloranil molecule. The difficulty is due to the steric hindrance of the chlorine atoms and the instability of the radical intermediate. This probably accounts for the tendency of chloranil to react with polymeric radicals through O- rather than C-atoms. Die bei der Reaktion von Benzoylperoxid mit 2,5-Dichlorbenzochinon und 2,3,5,6-Tetrachlorbenzochinon (Chloranil) in Chlorbenzol auftretenden Produkte wurden isoliert und identifiziert. In verdunnter Losung (0,02 mol Peroxid/dm3) reagieren sowohl Phenyl- als auch Benzoyloxyradikale mit 2,5-Dichlorbenzochinon; unter Ersatz eines Wasserstoffatoms am Chinonkern bilden sich die entsprechenden chinoiden Substitutionsprodukte. Chloranil wird unter diesen Bedingungen nicht angegriffen. In konzentrierter Losung (0,5 mol Peroxid/dm3) greifen sowohl die aus dem spontanen als auch die aus dem induzierten Zerfall des Peroxids resultierenden Radikale′ 2,5-Dichlorchinon und Chloranil an. Dabei vermogen nur die Aryl- und nicht die Benzoyloxyradikale Chlor im Chloranil zu ersetzen; dies ist jedoch auf ein Chloratom pro Chloranilmolekul beschrankt. Verantwortlich fur diese Beschrankung ist eine sterische Hinderung der Chloratome und die Unbestandigkeit der dabei gebildeten radikalischen Zwischenprodukte. Darin liegt auch eine mogliche Erklarung dafur, das Chloranil mit Polymerradikalen eher uber die O- als uber die C-Atome reagiert.

Hydroxyphenylazo-1,2,4-triazoles

Abstract: Azo dyes have been prepared by coupling phenols with diazotized C- amino-1,2,4-triazole and p-aminophenyl-1,2,4-triazoles. Spectroscopic proofs of structure establish preferential para-coupling. The dyes exist in the azo form without evidence for quinone hydrazone tautomers. Spectroscopic evidence and chelation not involving the phenolic hydroxyl group suggest trans-configuration.

The chemistry of trisulphenamides [N(SR)3]. Part II. Reactions of tribenzenesulphenamide with electron-rich molecules

Abstract: Tribenzenesulphenamide (I) reacts with tetraphenylfuran to give 2,4,5,6-tetraphenylpyrimidine (IV), 2-hydroxy-2,3,4,5-tetraphenyl-2H-pyrrole and traces of tetraphenylpyrrole. Similarly the trisulphenamide reacts with tetra-phenylpyrrole to give the pyrimidine (IV). Reactions of the trisulphenamide (I) with hydrazones give the phenylthioimine (X) and quinone di-imine (XI).

Ultraviolet holdback of nonsilver photosensitive systems by incorporating therein certain organic additives

Abstract: A non-silver, photosensitive composition comprising: at least one aminoaryl ethylene color forming compound and at least one activator for said color forming compound, wherein the composition includes in addition at least one organic compound the addition of which produces imagery having improved ultraviolet holdback, such compounds being selected from the group consisting of heterocyclic compounds, quinone compounds, multifunctional aromatic hydroxy compounds and aromatic carbonyl containing compounds.

The identification by electron spin resonance spectroscopy of dimeric species formed in the autoxidation of hydroquinone and quinone

Abstract: Some of the e.s.r. spectra observed during the autoxidation of hydroquinone and quinone appear to arise from the formation of dimeric products in the reaction since these spectra can be obtained from diquinone under similar conditions. The hyperfine splittings in these types of radicals can be explained in terms of the oxidation states of the two quinonoid rings.

Use of chloranil to trap free radicals in nylon 6

Abstract: Nylon 6 in the form of bundles of fibers or rods was treated to contain traces of chloranil of other quinones. When stressed within an EPR cavity, the radicals produced were trapped in a relatively stable form containing the quinone. This method offers a quantitative measurement of the integrated number of free radicals produced during a stress history.

Quinone epoxides. Part VIII. C-acetyl fission and C→O-acetyl migration in reactions of acetylquinone epoxides and related compounds

Abstract: Loss of the acetyl group occurs when 2-acetyl-1,4-naphthoquinone epoxide (I; R = H) is treated with hydrogen bromide in acetic acid, whereas the acetyl group in the 3-methyl homologue (I; R = Me) is retained under these conditions. However it is the acetyl group in the latter epoxide only which is lost when the compounds are reduced by catalytic hydrogenation. C→O-Acetyl migration occurs when 2-acetyl-r-2,3-epoxy-3;4-dihydro-c-4-hydroxynaphthalen-1 (2H)-one (II; R = H) is treated with anhydrous magnesium bromide, and loss or C→O migration of the acetyl group is observed when 2-acetyl-t-3-bromo-2,3-dihydro-r-2-hydroxy-3-methyl-1,4-naphthoquinone (III; R = Me) is catalytically reduced. 3-Acetyl-3,4-dihydro-t-3,c-4-dihydroxy-r-2-methylnaphthalen-1 (2H)-one (IX; R = Me), which is also formed in the latter reaction, undergoes a major conformational change on transferring from dimethyl sulphoxide to chloroform solution. The stereospecific formation of this compound and its lower homologue and the behaviour of compounds (I; R = H),(I; R = Me), and (III; R = Me) under conditions of catalytic reduction are interpreted in terms of competing processes at substrate–catalyst complexes.

Vat dyestuffs, their manufacture and use

Abstract: The present invention relates to new vat dyestuffs of the general formula WHEREIN A represents vattable polycyclic quinone, X represents oxygen or sulphur, B represents a 6-membered heterocycle with 2 to 3 nitrogen atoms which optionally contains further fused carbocyclic rings, R represents an aromatic radical at which the substituent -X-B is in ortho- or meta-position to the amide group, Z is hydrogen or -X-B, and a represents hydrogen or

Catalysts for cycloolefin polymerisation - contg tungsten halide, quinone deriv and organo-aluminium cpd

Abstract: Cycloolefins are polymerised at -60 to +60 degrees C in presence of catalysts contg. (A) a W halide, (B) a quinone deriv. with >=1 halogen or nitro substit. attached to a C atom adjacent to the quinoid CO group, or an adjacent C atom in a fused ring, and (C) an organo-Al cpd. Molar ratio of (A) : (B) : (C) is 1 : 0.01 - 50 : 0.1 - 100. Examples of (A) are WCl6, WOCl4, WBr6, WCl5, etc. (B) is an o- or p-benzoquinone, naphthoquinone, naphthodiquinone, anthraquinone or similar quinone deriv. (C) is Al trimethyl, diethyl Al chloride, ethyl Al dichloride, etc. Activity, stability and monomer conversion are much higher than known catalysts, and recovery of unreacted monomer is not always necessary. The catalysts are also efficient mol. wt. regulators.

Menaquinone function in the electron transport system of an antibiotic-producing strain of Bacillus brevis.

Abstract: Bacillus brevis ATCC I 0068 grown under appropriate growth conditions produces a mixture of tyrocidine and gramicidin, which are potent inhibitors of electron transport and oxidative phosphorylation processes. We have recently characterized the electron-transport system of this strain and have identified a menaquinone (MK-7) by thin-layer chromatography and by U.V. and mass spectroscopy to be the sole quinone component (Fynn, Thomas & Seddon, 1972). Pentane extraction (Szarkowska, I 966) and acetone extraction (Fynn & Redfearn, 1964) were used to remove the endogenous quinone in an attempt to confirm a functional role for MK-7 in the electron transport system. Although these methods were successful in removing 90 to 95 % of the quinone and largely abolishing the NADH oxidase activity of the preparation, the addition of MK-7 in various carrier systems failed to restore the latter activity. However, from the literature it is clear that while restoration of succinoxidase activity of acetone-extracted preparations has been successfully demonstrated, the reactivation of the NADH oxidase pathway has been more difficult to achieve. Also the pentane extraction technique suffers from the disadvantage that it can only be successfully employed to extract lyophilized material. The lyophilization process itself involves some structural damage to the electron transport particle since the NADH oxidase activity falls to 40 to 60 % of its original value. We now report on the U.V. irradiation of fresh material as a means of inactivating the endogenous menaquinone and providing the basis for a further investigation of quinone function in the organism. METHODS U.V. irradiation. Irradiation with 364 nm light was most effective in abolishing the NADH oxidase activity of the freshly prepared 105 P material (Seddon & Fynn, 1971): shorter wavelength (254 nm) was less effective and produced a general inactivation of the enzyme activities of the preparation. Irradiation was carried out with a 125 W Phillips 57236 F/70 mercury arc source placed at a distance of 10 cm above a Petri dish containing a 3m~ depth of 105 P preparation in tris-HC1 buffer (0.1 M, pH 7.4). The preparation was stirred on ice by means of a magnetic stirrer and kept covered with a borosilicate glass plate to avoid evaporation losses. Quinone/phospholipid rnicelles. The appropriate phospholipid (see Results) to give a final concentration of 15 mg/ml was dissolved in a minimum volume of chloroform and the calculated volume of a IO-~ M-ethanolic solution of quinone added. The mixture was evaporated to dryness on a rotary evaporator at 20 "C and resuspended in 0.01 M, pH 7.8, tris-EDTA buffer. The suspension was sonicated for 15 min at o "C using a MSE-Mullard type 4200 60 W ultrasonic disintegrator fitted with a stainless-steel vibrator probe of 6 mm end diameter and 9: I end ratio. The sonicated material was centrifuged at Iooooog for 45 min and any insoluble residue discarded.

Synthesis and some reactions of 4-hydroxy-2-methoxycarbonylquinoline-5,8-quinone

Abstract: The title quinone was prepared by oxidation of 5,8-dihydroxy-2-methoxycarbonyl-4(1H)-quinolone with cerium(IV) ammonium nitrate. Addition of hydrogen chloride, toluene-p-sulphinic acid, and hydrazoic acid to the quinone yielded the corresponding 6-substituted hydroquinones. Attempted Diels–Alder addition of cyclohexa-1,3-diene to the quinone gave a low yield of the expected adduct but 1,3-dimethoxycyclohexa-1,3-diene gave a product tentatively formulated as a derivative of benzofuro[3,2-h]quinoline.

Studies of photodegradable polystyrene

Abstract: The photodegradation of Polystyrenes containing sensitizers, such as aromatic nitro or quinone compounds, has been investigated. It was found that 1,4-naphthoquinone is the most effective sensitizer for the photodegradation of polystyrene among those tested in this study. The products of the light-irradiated polystyrene were examined by the IR spectroscopy and the thin layer chromatography. It is concluded that the photodegradation of the polystyrene proceeds mainly through the photo-oxidation of polymer.