Vanadium-Catalysed Oxidative Bromination Using Dilute Mineral Acids and Hydrogen Peroxide:  An Option for Recycling Waste Acid Streams

2000 ◽  
Vol 4 (4) ◽  
pp. 270-274 ◽  
Author(s):  
Gadi Rothenberg ◽  
James H. Clark
Keyword(s):  
Hydrogen Peroxide ◽  
Mineral Acids ◽  
Acid Streams ◽  
Oxidative Bromination ◽  
Waste Acid

Acid-catalyzed rearrangement of hydroperoxides. II. Phenylcycloalkyl hydroperoxides

1968 ◽  
Vol 46 (9) ◽  
pp. 1561-1570 ◽  
Author(s):  
Glenn H. Anderson ◽  
James G. Smith
Keyword(s):  
Hydrogen Peroxide ◽  
Ferrous Sulfate ◽  
Phenyl Group ◽  
Ring Expansion ◽  
Steric Interaction ◽  
Ring Strain ◽  
Mineral Acids ◽  
Acid Catalyzed

The acid-catalyzed rearrangement of 1-phenylcycloalkyl hydroperoxides has been investigated using the cyclohexyl, cyclopentyl, and cyclobutyl compounds. Evidence was sought for rearrangement of the cycloalkyl group in competition with migration of the phenyl group during the reaction. Such a rearrangement would result in ring expansion of the cycloalkyl group to give, ultimately, products formed by cycloalkyl ring opening.No evidence for such a reaction was found in the case of 1-phenylcyclohexyl hydroperoxide; only the expected products, phenol and cyclohexanone, were detected. However, rearrangement of 1-phenylcyclopentyl hydroperoxide gave, besides the expected phenol and cyclopentanone, significant amounts of the ring-opened compound 4-hydroxyvalerophenone as its acetate. A second product, 1-phenylcyclopentene, arose by elimination of hydrogen peroxide from the hydroperoxide.1-Phenylcyclobutyl hydroperoxide proved to undergo ring expansion with great facility. Only the ring expanded products, 2-phenyl-2-tetrahydrofuryl hydroperoxide and its corresponding peroxide, could be isolated in the treatment of 1-phenylcyclobutanol with hydrogen peroxide using catalytic amounts of mineral acids. However, in the absence of catalysts, 1-phenylcyclobutyl hydroperoxide was formed in detectable amounts and its presence was demonstrated by decomposition with ferrous sulfate to butyro-phenone and 1,6-dibenzoylhexane.It seems reasonable that ring strain is the factor promoting the ring expansion of 1-phenylcyclobutyl hydroperoxide. In the case of 1-phenylcyclopentyl hydroperoxide, it is suggested that the steric interaction of the ortho hydrogens of the phenyl group with the cyclopentyl ring protons has the effect of slowing the migration of the phenyl group sufficiently that alkyl migration can occur to give the observed ring-opened products.

scholarly journals Recovery of Cerium Dioxide from Spent Glass-Polishing Slurry and Its Utilization as a Reactive Sorbent for Fast Degradation of Toxic Organophosphates

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Pavel Janoš ◽  
Pavel Kuráň ◽  
Jakub Ederer ◽  
Martin Šťastný ◽  
Luboš Vrtoch ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Cerium Oxide ◽  
Cerium Dioxide ◽  
Degradation Efficiency ◽  
Organophosphate Pesticide ◽  
Optimal Temperature ◽  
Precipitation Procedure ◽  
Mineral Acids ◽  
Carbonate Precursor ◽  
Glass Polishing

The recovery of cerium (and possibly other rare earth elements) from the spent glass-polishing slurries is rather difficult because of a high resistance of polishing-grade cerium oxide toward common digestion agents. It was shown that cerium may be extracted from the spent polishing slurries by leaching with strong mineral acids in the presence of reducing agents; the solution may be used directly for the preparation of a ceria-based reactive sorbent. A mixture of concentrated nitric acid and hydrogen peroxide was effective in the digestion of partially dewatered glass-polishing slurry. After the removal of undissolved particles, cerous carbonate was precipitated by gaseous NH3and CO2. Cerium oxide was prepared by a thermal decomposition of the carbonate precursor in an open crucible and tested as reactive sorbent for the degradation of highly toxic organophosphate compounds. The samples annealed at the optimal temperature of approximately 400°C exhibited a good degradation efficiency toward the organophosphate pesticide fenchlorphos and the nerve agents soman and VX. The extraction/precipitation procedure recovers approximately 70% of cerium oxide from the spent polishing slurry. The presence of minor amounts of lanthanum does not disturb the degradation efficiency.

Sodium sulfate–hydrogen peroxide–sodium chloride adduct: selective protocol for the oxidative bromination, iodination and temperature dependent oxidation of sulfides to sulfoxides and sulfones

2019 ◽  
Vol 43 (15) ◽  
pp. 6001-6009 ◽  
Author(s):  
Eknath M. Gayakwad ◽  
Khushbu P. Patel ◽  
Ganapati S. Shankarling
Keyword(s):  
Hydrogen Peroxide ◽  
Sodium Chloride ◽  
Sodium Sulfate ◽  
Temperature Dependent ◽  
Oxidation Of Sulfides ◽  
Sulfides Oxidation ◽  
Oxidative Bromination ◽  
Chloride Adduct

Sodium sulfate–hydrogen peroxide–sodium chloride adduct: selective protocols for anilines and sulfides oxidation.

Article

1999 ◽  
Vol 77 (5-6) ◽  
pp. 895-902
Author(s):  
Clifford A Bunton ◽  
Houshang J Foroudian ◽  
Nicholas D Gillitt ◽  
Anurag Kumar
Keyword(s):  
Hydrogen Peroxide ◽  
Ion Exchange ◽  
Rate Constants ◽  
Acid Catalysis ◽  
Sulfide Oxidation ◽  
Methanesulfonic Acid ◽  
Effective Catalyst ◽  
First Order ◽  
Mineral Acids ◽  
Electron Donation

Oxidations of sulfides and phosphorus(V) esters of thiols by H2O2 are catalyzed by H2SO4 and HClO4. Sulfides are 4-ZC6H4SMe, 1a-1e, respectively, Z = MeO, Me, H, Cl, NO2; PhSCH2CH2Cl, 2, Ph2S, 3, and the esters are Ph(R)PO·SEt, 4a, 4b, R = Ph, EtO. Electron donation by Z moderately accelerates reaction, but the sulfides are much more reactive than the esters. Reactions are first order in H2O2 and substrate, and second-order rate constants, k2, in H2SO4 are related to excess acidity, X. Plots of log k2 against X have slopes in the range 0.61-0.85. Rate constants are similar for given concentrations of H2SO4 and HClO4, except that with greater than 50 wt.% H2SO4 peroxymonosulfuric acid is formed and the observed rate constants then increase. Methanesulfonic acid is a less effective catalyst than the mineral acids. Oxidations of the sulfides are also catalyzed by strongly acidic ion-exchange resins.Key words: sulfide oxidation, hydrogen peroxide, acid catalysis, excess acidity.

Peroxidase Localization in Hartmanella Trophozoites

1971 ◽  
Vol 29 ◽  
pp. 346-347 ◽  
Author(s):  
George E. Childs ◽  
Joseph H. Miller
Keyword(s):  
Hydrogen Peroxide ◽  
Ultrastructural Localization ◽  
Pathogenic Strain ◽  
Oxidative Enzymes ◽  
Differential Centrifugation ◽  
Electron Microscopic ◽  
Microscopic Studies ◽  
The Subject ◽  
Axenic Cultures

Biochemical and differential centrifugation studies have demonstrated that the oxidative enzymes of Acanthamoeba sp. are localized in mitochondria and peroxisomes (microbodies). Although hartmanellid amoebae have been the subject of several electron microscopic studies, peroxisomes have not been described from these organisms or other protozoa. Cytochemical tests employing diaminobenzidine-tetra HCl (DAB) and hydrogen peroxide were used for the ultrastructural localization of peroxidases of trophozoites of Hartmanella sp. (A-l, Culbertson), a pathogenic strain grown in axenic cultures of trypticase soy broth.

Fluorescent proteins for in vivo imaging, where's the biliverdin?

2020 ◽  
Vol 48 (6) ◽  
pp. 2657-2667
Author(s):  
Felipe Montecinos-Franjola ◽  
John Y. Lin ◽  
Erik A. Rodriguez
Keyword(s):  
Hydrogen Peroxide ◽  
In Vivo Imaging ◽  
Near Infrared ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Fluorescent Imaging ◽  
Infrared Light ◽  
Red Fluorescent Protein ◽  
Color Palette

Noninvasive fluorescent imaging requires far-red and near-infrared fluorescent proteins for deeper imaging. Near-infrared light penetrates biological tissue with blood vessels due to low absorbance, scattering, and reflection of light and has a greater signal-to-noise due to less autofluorescence. Far-red and near-infrared fluorescent proteins absorb light >600 nm to expand the color palette for imaging multiple biosensors and noninvasive in vivo imaging. The ideal fluorescent proteins are bright, photobleach minimally, express well in the desired cells, do not oligomerize, and generate or incorporate exogenous fluorophores efficiently. Coral-derived red fluorescent proteins require oxygen for fluorophore formation and release two hydrogen peroxide molecules. New fluorescent proteins based on phytochrome and phycobiliproteins use biliverdin IXα as fluorophores, do not require oxygen for maturation to image anaerobic organisms and tumor core, and do not generate hydrogen peroxide. The small Ultra-Red Fluorescent Protein (smURFP) was evolved from a cyanobacterial phycobiliprotein to covalently attach biliverdin as an exogenous fluorophore. The small Ultra-Red Fluorescent Protein is biophysically as bright as the enhanced green fluorescent protein, is exceptionally photostable, used for biosensor development, and visible in living mice. Novel applications of smURFP include in vitro protein diagnostics with attomolar (10−18 M) sensitivity, encapsulation in viral particles, and fluorescent protein nanoparticles. However, the availability of biliverdin limits the fluorescence of biliverdin-attaching fluorescent proteins; hence, extra biliverdin is needed to enhance brightness. New methods for improved biliverdin bioavailability are necessary to develop improved bright far-red and near-infrared fluorescent proteins for noninvasive imaging in vivo.

Protective effect of chitooligosaccharides on hydrogen peroxide-induced PC-12 cells death by inhibition of oxidative damage

2010 ◽  
Vol 34 (8) ◽  
pp. S27-S27
Author(s):  
Xueling Dai ◽  
Ping Chang ◽  
Ke Xu ◽  
Changjun Lin ◽  
Hanchang Huang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Oxidative Damage ◽  
Protective Effect ◽  
Pc 12 Cells ◽  
Cells Death

Signal-regulated oxidation of proteins via MICAL

2020 ◽  
Vol 48 (2) ◽  
pp. 613-620
Author(s):  
Clara Ortegón Salas ◽  
Katharina Schneider ◽  
Christopher Horst Lillig ◽  
Manuela Gellert
Keyword(s):  
Signal Transduction ◽  
Hydrogen Peroxide ◽  
Cell Death ◽  
Redox Regulation ◽  
Signal Transduction Pathways ◽  
Cellular Functions ◽  
Intracellular Signals ◽  
Amino Acid Side Chains ◽  
Specific Receptors ◽  
Sulfur Containing

Processing of and responding to various signals is an essential cellular function that influences survival, homeostasis, development, and cell death. Extra- or intracellular signals are perceived via specific receptors and transduced in a particular signalling pathway that results in a precise response. Reversible post-translational redox modifications of cysteinyl and methionyl residues have been characterised in countless signal transduction pathways. Due to the low reactivity of most sulfur-containing amino acid side chains with hydrogen peroxide, for instance, and also to ensure specificity, redox signalling requires catalysis, just like phosphorylation signalling requires kinases and phosphatases. While reducing enzymes of both cysteinyl- and methionyl-derivates have been characterised in great detail before, the discovery and characterisation of MICAL proteins evinced the first examples of specific oxidases in signal transduction. This article provides an overview of the functions of MICAL proteins in the redox regulation of cellular functions.

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