- Effect of GO nanosheets on spectrophotometric determination of tyrosine in urine and serum using nitrosonaphthol
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Here, we aimed to use graphene oxide to improve the selectivity and sensitivity of Tyr determination via the reaction with 1-nitroso-2-naphthol as a selective reagent of Tyr. The reaction between Tyr and 1-nitroso-2-naphthol in absence and presence of GO was studied spectrophotometrically. Different parameters such as concentrations, temperature, incubation time were optimized. The obtained data showed that the maximum absorbance was achieved by using 2 mL of 0.03% 1-nitroso-2-naphthol at temperature 60 °C for 10 min. On the basis of calibration curve of various concentrations of Tyr in the presence of 20 μg mL?1 GO, the limit of detection was 6.4 × 10?6 M (1.15 μg mL?1), where in absence of GO was 1.1 × 10?5 M (19.9 μg mL?1). The selectivity of Tyr in presence of other amino acids and phenols was studied with and without GO. The data obtained revealed that the selectivity of Tyr in presence of GO with respect to some amino acids and phenols was improved. The proposed method has been applied for the determination of Tyr in urine and serum samples. Therefore, GO is a powerful catalytic surface for the sensitive and selective determination of Try in biological fluids.
- Nassef, Hossam M.,Hagar, Mohamed,Othman, Abdelhameed M.
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- Purification method of 1-nitroso-2-naphthol
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The invention relates to a purification method of 1-nitroso-2-naphthol. The method comprises the following steps of 1, mixing 1-nitroso-2-naphthol (coarse products) with a structure formula shown as acompound (II) with an addition reagent and a solvent-1; performing stirring under the room temperature condition until the reaction is completed; obtaining addition products; 2, mixing the addition products with the solvents 2; adding alkali under the room temperature and stirring conditions to obtain 1-nitroso-2-naphthol (fine product) with the structure formula shown as a compound (II). The formulas are shown in the description. The invention discloses a purification method of an organic compound with nitroso groups in a molecular structure. Concretely, the 1-nitroso-2-naphthol (coarse products) and the sodium hydrogen sulfite (or similar substances) are subjected to addition reaction to obtain addition products; the addition products and alkali react to obtain the 1-nitroso-2-naphtholfine product with the purity being not less than 99 percent. By using the method provided by the invention, the product yield is high; the operation is convenient and fast; the industrialization is easy.
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Paragraph 0026; 0028; 0029; 0031; 0032; 0034; 0035; 0037
(2020/03/29)
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- Photochromism in spiroindolinonaphthoxazine dyes: Effects of alkyl and ester substituents on photochromic properties
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The impact of substituents on the photochromism of some spirooxazines has been explored. A series of photochromic spiroindolino[2,1-b][1,4]naphthoxazine dyes was prepared with varying alkyl substitution patterns in the 3- to 6-positions of the indoline system. It was found that placing methyl functions onto the phenyl ring produced bathochromic shifts in λmax of the photomerocyanine as expected, but contrary to literature indications lowered photocoloration half-life. However, replacing the 3,3-dimethyl pattern with 3-ethyl-3-methyl substitution led to more intense photochromism: half-life increased without affecting λmax. In contrast, introduction of a cyclohexyl ring to give a 3,3-pentamethylene fragment and substitution at the 5′-position of the naphthoxazine moiety with either ester or hydroxymethyl groups significantly increased the speed of fade in general contrast to literature reports for analogous dye series. Similar effects were also observed concerning alkyl substitution in a smaller synthesised set of photochromic [1,2-b][1,4]oxazines.
- Partington, Steven M.,Towns, Andrew D.
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p. 123 - 130
(2014/02/14)
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- NO2/H3BO3 as an effective nitrosonium source for electrophilic aromatic nitrosation under MW-promoted solvent-free conditions
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[Bmim]NO2/H3BO3 was used as a nitrosonium source for the efficient synthesis of nitrosoarenes. The reaction was accomplished under MW irradiation at 60 W in a solventless system. Side processes such as oxidation or dealkylation were not observed during the nitrosation of alkyl phenyl ethers in the presence of this new reagent. The satisfactory results were obtained with very short reaction time, simplicity in the experimental procedure and good to excellent yields.
- Valizadeh, Hassan,Gholipour, Hamid
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experimental part
p. 963 - 966
(2012/04/23)
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- New nitrite ionic liquid (IL-ONO) and nanoparticles of organosilane-based nitrite ionic liquid immobilized on silica as nitrosonium sources for electrophilic aromatic nitrosation
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An improved method for the synthesis of nitrosoarenes has been developed using a new nitrite ionic liquid (IL-ONO) and immobilized nitrite ionic liquid. These ionic liquids play as nitrosonium sources for electrophilic aromatic nitrosation of active aromatics at 0-5 °C. Their action was accomplished in water and the satisfactory results were obtained under the mild conditions in short reaction time.
- Valizadeh, Hassan,Amiri, Mohammad,Shomali, Ashkan
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experimental part
p. 1103 - 1108
(2012/03/10)
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- 1-[(N-(un)substituted)amidoalkyl]spiroindolinonaphthoxazines, their preparation, compositions and (co)polymer matrices containing them
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The object of the present invention is novel spiroindolinonaphthoxazine compounds as well as the compositions and (co)polymer matrices containing them. Said compounds have interesting photochromic properties. Another object of the present invention is a method of preparing said novel compounds.
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- (Nitrosonaphtholato)metal complex-catalyzed oxidation of phenols and alkenes
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Bis(1-nitroso-2-naphtholato)manganese(II), tris(1-nitroso-2-naphtholato)manganese(III), tris(2-nitroso-1-naphtholato)manganese(III), bis(1-nitroso-2-naphtholato)cobalt(II), bis(1-nitroso-2-naphtholato)nickel(II), bis(1-nitroso-2-naphtholato)copper(II) and bis(1-nitroso-2-naphtholato)zinc(II) were prepared and their catalytic abilities in the oxidation of phenols were examined. The best yields of diphenoquinones were obtained when the catalytic oxidation using bis(1-nitroso-2-naphtholato)manganese(II) was carried out at 23°C under an oxygen atmosphere (1 atm) in the presence of a phosphine ligand. Likewise, phenols were completely converted to the corresponding diphenoquinones together with small amounts of benzoquinones under an oxygen pressure (20 atm) at 50°C in a short period of time. It was proven that the manganese(II) catalyst, molecular oxygen, and phosphine ligand were essential for the catalytic phenol oxidation. On the other hand. bis(1-nitroso-2-naphtholato)manganese(II)-catalyzed epoxidation of alkenes was only effective when iodosylbenzene was used. The catalytic oxidation mechanism was discussed on the basis of the measurement of cyclic voltammograms of the (nitrosonaphtholato)metal complexes, isolated intermediates, and effect of additives.
- Nishino, Hiroshi,Satoh, Hideaki,Yamashita, Mayumi,Kurosawa, Kazu
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p. 1919 - 1924
(2007/10/03)
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- Isoindolinone enantiomers having affinity for the dopamine D4 receptor
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PD 108635 (1) was identified as a potent dopamine D4 ligand and we wanted to replace the benzylic alcohol with a metabolically more stable moiety. Investigations led to the discovery of a series of isoindolinones having D4 affinity.
- Belliotti, Thomas R.,Brink, Wouter A.,Kesten, Suzanne R.,Rubin, John R.,Wustrow, David J.,Zoski, Kim T.,Whetzel, Steven Z.,Corbin, Ann E.,Pugsley, Thomas A.,Heffner, Thomas G.,Wise, Lawrence D.
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p. 1499 - 1502
(2007/10/03)
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- Kinetics of the C-nitrosation of 2-naphthol and its catalysis by nucleophiles and buffers
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In the absence of nucleophiles, the rate of C-nitrosation of 2-naphthol has been found to be independent of the acidity of the medium at pH2.This behaviour is explicable by a reaction mechanism in which the reaction rate is partially controlled by the loss of a proton by the dienone intermediate.The nucleophiles Cl-, Br- and SCN- were all found to catalyse the reaction via the formation of the corresponding nitrosyl compounds, which attack Cl to form a steady state intermediate eventuality yielding 1-nitroso-2-naphthol.Nitrosation by NO+ also took place over the whole range of acidities at which experiments with nucleophiles were carried out.The values calculated for the attack constants of the various nitrosating agents and for the ratio between the rate constants of denitrosation by nucleophile attack and the loss of a dienone proton are discussed in terms of the nature of the nitrosating agents and the substrate.Catalysis by acetic-acetate and monochloroacetic-monochloroacetate buffers is attributed to their basic character.
- Castro, Albino,Iglesias, Emilia,Leis, J. Ramon,Mosquera, Manuel,Pena, Elena
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- Reactive complex chromium-bearing azo dyestuffs
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Complex chromium-bearing dyestuffs of formula: STR1 where A represents a diazotizable amine residue, B represents the residue of a coupling agent, Y1 represents a --O-- or STR2 residue, Y2 represents a --O-- or STR3 residue, E represents the residue of a monoanionic bifunctional chelating agent, Y1 and Y2 are respectively in the ortho position with respect to the --N=N-- group, G represents a neutral monofunctional ligand, and Z represents a reactive group attached to A or B directly or via a bridging group such as STR4 --SO2 NH-- or --CO--NH--, R denoting hydrogen or an alkyl radical having 1 to 2 carbon atoms; their process of preparation, and their application for dyeing of a variety of natural or synthetic fibers and fabrics including regenerated cellulose, wool, silk, synthetic polyamides. They may also be used for the dyeing of leather.
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