The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Rao M Uppu - One of the best experts on this subject based on the ideXlab platform.
-
synthesis of peroxyNitrite using Isoamyl Nitrite and hydrogen peroxide in a homogeneous solvent system
Analytical Biochemistry, 2006Co-Authors: Rao M UppuAbstract:Abstract A method for the synthesis of peroxyNitrite is described. It involves nitrosation of H2O2 at pH ⩾ 12.5 by Isoamyl or butyl Nitrite in mixed solvents of isopropyl alcohol (IPA) and water at 25 ± 1 °C. Maximum yields of peroxyNitrite are obtained after 15 min of incubation at IPA concentrations of 30–70% (v/v). The solutions of peroxyNitrite are processed for removal of IPA and Isoamyl alcohol by solvent extraction. Unreacted H2O2 is removed by catalytic decomposition on granular MnO2. The post processed solutions of peroxyNitrite are useful in several chemical and biochemical investigations where bolus additions are required. The method as reported is amenable for large scale synthesis as it involves sequential mixing of solvents (water and IPA) to alkali followed by the addition of H2O2 and alkyl Nitrite.
-
BIPHASIC SYNTHESIS OF HIGH CONCENTRATIONS OF PEROXYNitrite USING WATER-INSOLUBLE ALKYL Nitrite AND HYDROGEN PEROXIDE
Methods in Enzymology, 2004Co-Authors: Rao M Uppu, William A PryorAbstract:Publisher Summary This chapter discusses the biphasic synthesis of high concentrations of peroxyNitrite using water-insoluble alkyl Nitrite and hydrogen peroxide. A method that allows the preparation of peroxyNitrite solutions up to 1 M is reviewed. These solutions have hydrogen peroxide as an impurity; however this can be reduced to less than about 1 mM after passage through a manganese dioxide column. This synthesis is carried out in a two-phase system based on a displacement reaction by the hydroperoxide anion on Isoamyl Nitrite. When expressed as a fraction of the concentration of peroxyNitrite present, these peroxyNitrite solutions contain less Nitrite than those prepared by the ozonation of azide, the reaction of Nitrite with acidified H 2 O 2 , or the autooxidation of hydroxylamine. This method is a practical alternative to the azide–ozone method in situations in which high concentrations of peroxyNitrite are needed and trace levels of azide. Isoamyl alcohol and the unreacted Isoamyl Nitrite form a separate organic phase, which can be easily removed from the aqueous phase containing peroxyNitrite, using a separatory funnel after a brief centrifugation.
-
DIRECT AND SIMULTANEOUS ULTRAVIOLET SECOND-DERIVATIVE SPECTROPHOTOMETRIC DETERMINATION OF Nitrite AND NITRATE IN PREPARATIONS OF PEROXYNitrite
Methods in Enzymology, 2004Co-Authors: Rachel M. Bolzan, Rao M Uppu, Rafael Cueto, Giuseppe L. Squadrito, William A PryorAbstract:Publisher Summary This chapter discusses the direct and simultaneous ultraviolet second-derivative spectrophotometric determination of Nitrite and nitrate in preparations of peroxyNitrite. This chapter discusses three methods for synthesizing peroxyNitrite that are most commonly used for investigation of the NO 2 - and NO 3 - either present as impurities or produced during peroxyNitrite decomposition: (1) ozonation of azide (2) reaction of Isoamyl Nitrite with hydrogen peroxide, and (3) reaction of hydrogen peroxide with nitrous acid. Commonly used methods for the detection of NO 2 - and NO 3 - involve the reduction of nitrate to Nitrite. The initial concentrations of Nitrite and nitrate for three different methods of synthesizing peroxyNitrite have been determined using an ultraviolet second-derivative spectroscopy method.
-
synthesis of peroxyNitrite in a two phase system using Isoamyl Nitrite and hydrogen peroxide
Analytical Biochemistry, 1996Co-Authors: Rao M Uppu, William A PryorAbstract:Abstract A new method for the preparation of high concentrations of peroxyNitrite (up to 1 M ) is described. The synthesis uses a two-phase system and involves a displacement reaction by the hydroperoxide anion (in the aqueous phase) on Isoamyl Nitrite (in the organic phase). The product peroxyNitrite remains in the aqueous phase, whereas Isoamyl alcohol forms a new organic phase along with the unreacted Isoamyl Nitrite. The aqueous phase contains some 0.15 M Isoamyl alcohol and the unreacted hydrogen peroxide, but no Isoamyl Nitrite. Removal of Isoamyl alcohol or traces of Isoamyl Nitrite is accomplished by washing the aqueous phase with dichloromethane, chloroform, or hexane. A near total removal of hydrogen peroxide is then achieved by passing the solutions through a short column of manganese dioxide. The peroxyNitrite in these postprocessed solutions has a broad absorption spectrum with a maximum around 302 nm, follows a characteristic first-order decomposition at pH 7.2 and 25°C ( k = 0.34 ± 0.1 s −1 ), and reacts with organic compounds to give either nitrated or one-electron transfer products. When stored frozen at −20°C, these peroxyNitrite solutions decompose at a rate of about 1.7% per day and should be used within 2–4 weeks. For short-term storage of about 1 week or less, these solutions can be stored at refrigerator temperatures (∼5°C) where peroxyNitrite has a half-life of about 7 days.
William A Pryor - One of the best experts on this subject based on the ideXlab platform.
-
DIRECT AND SIMULTANEOUS ULTRAVIOLET SECOND-DERIVATIVE SPECTROPHOTOMETRIC DETERMINATION OF Nitrite AND NITRATE IN PREPARATIONS OF PEROXYNitrite
Methods in Enzymology, 2004Co-Authors: Rachel M. Bolzan, Rao M Uppu, Rafael Cueto, Giuseppe L. Squadrito, William A PryorAbstract:Publisher Summary This chapter discusses the direct and simultaneous ultraviolet second-derivative spectrophotometric determination of Nitrite and nitrate in preparations of peroxyNitrite. This chapter discusses three methods for synthesizing peroxyNitrite that are most commonly used for investigation of the NO 2 - and NO 3 - either present as impurities or produced during peroxyNitrite decomposition: (1) ozonation of azide (2) reaction of Isoamyl Nitrite with hydrogen peroxide, and (3) reaction of hydrogen peroxide with nitrous acid. Commonly used methods for the detection of NO 2 - and NO 3 - involve the reduction of nitrate to Nitrite. The initial concentrations of Nitrite and nitrate for three different methods of synthesizing peroxyNitrite have been determined using an ultraviolet second-derivative spectroscopy method.
-
BIPHASIC SYNTHESIS OF HIGH CONCENTRATIONS OF PEROXYNitrite USING WATER-INSOLUBLE ALKYL Nitrite AND HYDROGEN PEROXIDE
Methods in Enzymology, 2004Co-Authors: Rao M Uppu, William A PryorAbstract:Publisher Summary This chapter discusses the biphasic synthesis of high concentrations of peroxyNitrite using water-insoluble alkyl Nitrite and hydrogen peroxide. A method that allows the preparation of peroxyNitrite solutions up to 1 M is reviewed. These solutions have hydrogen peroxide as an impurity; however this can be reduced to less than about 1 mM after passage through a manganese dioxide column. This synthesis is carried out in a two-phase system based on a displacement reaction by the hydroperoxide anion on Isoamyl Nitrite. When expressed as a fraction of the concentration of peroxyNitrite present, these peroxyNitrite solutions contain less Nitrite than those prepared by the ozonation of azide, the reaction of Nitrite with acidified H 2 O 2 , or the autooxidation of hydroxylamine. This method is a practical alternative to the azide–ozone method in situations in which high concentrations of peroxyNitrite are needed and trace levels of azide. Isoamyl alcohol and the unreacted Isoamyl Nitrite form a separate organic phase, which can be easily removed from the aqueous phase containing peroxyNitrite, using a separatory funnel after a brief centrifugation.
-
synthesis of peroxyNitrite in a two phase system using Isoamyl Nitrite and hydrogen peroxide
Analytical Biochemistry, 1996Co-Authors: Rao M Uppu, William A PryorAbstract:Abstract A new method for the preparation of high concentrations of peroxyNitrite (up to 1 M ) is described. The synthesis uses a two-phase system and involves a displacement reaction by the hydroperoxide anion (in the aqueous phase) on Isoamyl Nitrite (in the organic phase). The product peroxyNitrite remains in the aqueous phase, whereas Isoamyl alcohol forms a new organic phase along with the unreacted Isoamyl Nitrite. The aqueous phase contains some 0.15 M Isoamyl alcohol and the unreacted hydrogen peroxide, but no Isoamyl Nitrite. Removal of Isoamyl alcohol or traces of Isoamyl Nitrite is accomplished by washing the aqueous phase with dichloromethane, chloroform, or hexane. A near total removal of hydrogen peroxide is then achieved by passing the solutions through a short column of manganese dioxide. The peroxyNitrite in these postprocessed solutions has a broad absorption spectrum with a maximum around 302 nm, follows a characteristic first-order decomposition at pH 7.2 and 25°C ( k = 0.34 ± 0.1 s −1 ), and reacts with organic compounds to give either nitrated or one-electron transfer products. When stored frozen at −20°C, these peroxyNitrite solutions decompose at a rate of about 1.7% per day and should be used within 2–4 weeks. For short-term storage of about 1 week or less, these solutions can be stored at refrigerator temperatures (∼5°C) where peroxyNitrite has a half-life of about 7 days.
Jim Peterson - One of the best experts on this subject based on the ideXlab platform.
-
comparison of the relative propensities of Isoamyl Nitrite and sodium Nitrite to ameliorate acute cyanide poisoning in mice and a novel antidotal effect arising from anesthetics
Chemical Research in Toxicology, 2013Co-Authors: Leah Cambal, Andrew C Weitz, Huihua Li, Yang Zhang, Xi Zheng, Linda L Pearce, Jim PetersonAbstract:Isoamyl Nitrite has previously been considered acceptable as an inhaled cyanide antidote; therefore, the antidotal utility of this organic Nitrite compared with sodium Nitrite was investigated. To facilitate a quantitative comparison, doses of both sodium Nitrite and Isoamyl Nitrite were given intraperitoneally in equimolar amounts to sublethally cyanide-challenged mice. Righting recovery from the knockdown state was clearly compromised in the Isoamyl Nitrite-treated animals, the effect being attributable to the toxicity of the Isoamyl alchol produced during hydrolysis of the Isoamyl Nitrite to release Nitrite anion. Subsequently, inhaled aqueous sodium Nitrite aerosol was demonstrated to ameliorate sublethal cyanide toxicity, when provided to mice after the toxic dose, by the more rapid recovery of righting ability compared to that of the control animals given only the toxicant. Aerosolized sodium Nitrite has thus been shown by these experiments to have promise as a better alternative to organic Nitrites...
-
P63: The antidotal action of Nitrites toward cyanide intoxication: An example of medicine disguised as quackery
Nitric Oxide, 2013Co-Authors: Jim Peterson, Linda L PearceAbstract:Sodium Nitrite ameliorates sub-lethal cyanide toxicity in mice when given from ∼1 h before until 20 min after the toxic dose as demonstrated by the recovery of righting ability. In most experiments Nitrite was given intraperitoneally, but may also be administered as an inhaled aqueous vapor-contrary to recommended EMR protocols, it is not necessary to infuse the antidote intravenously and the co-administration of adjuvants (specifically thiosulfate) is unnecessary. Intraperitoneally administered Nitrite rapidly produces NO in the bloodstream as judged by the dose-dependent appearance of EPR signals attributable to nitrosylhemoglobin and methemoglobin. However, the commonly held belief that the antidotal mechanism of Nitrites involves the scavenging of cyanide anion by methemoglobin is firmly contraindicated by recent evidence. Intriguingly, the FDA-approved and clinically tested cyanide scavenger cobalamin has, in fact, rather indifferent binding affinity for cyanide anion. It follows that the clinical usefulness of cobalamin may be dependent on endogenous nitric oxide displacing the cyanide from the active site of cytochrome c oxidase to facilitate the cyanide-scavenging action of cobalamin. Antagonism of cyanide inhibition of cytochrome c oxidase by NO appears to be the crucial antidotal activity rather than any methemoglobin-forming action of Nitrite. Concomitant addition of sodium thiosulfate to Nitrite-treated blood results in the production of sulfidomethemoblobin as detected by EPR spectroscopy. Sulfide is a product of thiosulfate hydrolysis and, like cyanide, is known to be a potent inhibitor of cytochrome c oxidase; the effects of the two inhibitors being essentially additive under standard assay conditions, rather than dominated by either one. The findings afford a plausible explanation for an observed detrimental effect in mice associated with the use of the standard Nitrite-thiosulfate combination therapy at sub-lethal levels of cyanide intoxication. Isoamyl Nitrite, given intraperitoneally in equimolar amounts to sodium Nitrite, is comparatively less effective at restoring the righting recovery of cyanide-challenged mice. The results of investigations with the hydrolysis products of Isoamyl Nitrite, Isoamyl alcohol and Nitrite anion, suggest that the toxicity of Isoamyl alcohol renders the organic Nitrite a less desirable antidotal agent than sodium Nitrite. Disclosure Supported by the CounterACT Program, National Institutes of Health Office of the Director (NIH OD), and the National Institute of Neurological Disorders and Stroke (NINDS), Grant No. NS063732 to J.P and L.L.P and Bruce R. Pitt.
He Jing - One of the best experts on this subject based on the ideXlab platform.
-
solid sulfonic acid promoted oxidation of benzyl alcohol catalyzed by Isoamyl Nitrite
Chinese Journal of Catalysis, 2010Co-Authors: Sheng Xuebin, Ma Hong, Li Decai, He JingAbstract:Isoamyl Nitrite was employed to catalyze the selective oxidation of benzyl alcohol to benzyl aldehyde using molecular oxygen, in which solid sulfonic acid was used to promote the in situ generation of nitrosonium cation. Solid acid prepared by treating Amberlyst 15 at 300 degrees C demonstrated the best promotion effect, with which 90% conversion and 97% selectivity for benzyl aldehyde could be achieved at 80 degrees C under 0.5 MPa for 2 h. The differences of solid acids and their influence on oxidation were investigated by Fourier transform infrared spectroscopy, derivative thermogravimetry, and acid-base titration. Nitrosonium cation was detected by the derivative method using ultraviolet-visible absorption spectrometry.
O. N. Chupakhin - One of the best experts on this subject based on the ideXlab platform.
-
One-pot non-cyanide synthesis of 1-(pyridin-2-yl)isoquinoline-3-carbonitrile by reaction of 1-phenyl-2-[6-phenyl-3-(pyridin-2-yl)-1,2,4-triazin-5-yl]ethanone with 1,2-dehydrobenzene in the presence of Isoamyl Nitrite
Russian Journal of Organic Chemistry, 2017Co-Authors: D. S. Kopchuk, I. L. Nikonov, A. P. Krinochkin, I. S. Kovalev, G. V. Zyryanov, V. L. Rusinov, O. N. ChupakhinAbstract:The reaction of 1-phenyl-2-[6-phenyl-3-(pyridin-2-yl)-1,2,4-triazin-5-yl]ethanone with 1,2-dehydrobenzene generated in situ from anthranilic acid and excess Isoamyl Nitrite afforded in one step 1-(pyridin-2-yl)-4-phenylisoquinoline-3-carbonitrile. This reaction may be regarded as a non-cyanide method for the synthesis of 3-cyanoisoquinolines.
-
Preparation of 3-Cyano-1-(2-pyridyl)isoquinolines by Using Aryne Intermediates.
ChemInform, 2015Co-Authors: D. S. Kopchuk, I. L. Nikonov, I. S. Kovalev, G. V. Zyryanov, V. L. Rusinov, O. N. ChupakhinAbstract:A new and convenient method for the synthesis of the title compounds (III) via reaction of 5-cyanotriazines (I) with 1,2-dehydrobenzene, generated in situ from Isoamyl Nitrite and anthranylic acid, is given.
-
Benzyne-Mediated Rearrangement of 3-(2-Pyridyl)-1,2,4-triazines into 10-(1H-1,2,3-Triazol-1-yl)pyrido[1,2-a]indoles.
ChemInform, 2014Co-Authors: I. L. Nikonov, D. S. Kopchuk, I. S. Kovalev, G. V. Zyryanov, V. L. Rusinov, Albert F. Khasanov, Pavel A. Slepukhin, O. N. ChupakhinAbstract:Surprisingly, the treatment of triazines with benzyne generated in situ from 2-aminobenzoic acid and Isoamyl Nitrite results in the formation of the title indole derivatives.
