Kinetics of the reaction of p-dinitrobenzene with basic hydrogen peroxide

1987 ◽  
Vol 65 (2) ◽  
pp. 251-255 ◽  
Author(s):  
Raymond A. Heller ◽  
Richard Weiler
Keyword(s):  
Hydrogen Peroxide ◽  
Strong Evidence ◽  
Nmr Spectra ◽  
Visible Region ◽  
Kinetic Studies ◽  
Aqueous Dioxane ◽  
First Time ◽  
Kinetics Of ◽  
Basic Hydrogen Peroxide ◽  
C Nmr

Kinetic studies of the reaction of p-dinitrobenzene with H2O2 and NaOH in 10%, 30%, and 50% aqueous dioxane have been carried out at 30.0 °C. The reaction involves the formation of a reasonably stable intermediate which absorbs strongly in the visible region, with the rate of formation being about 18 times faster than the rate of conversion to final product which is p-nitrophenol. Proton and 13C nmr spectra of the kinetic solution provide strong evidence that the intermediate is p-nitrophenyl hydroperoxide, apparently the first time that a true aryl peroxide species has been identified.

scholarly journals Thymofolinoates A and B, New Cinnamic Acid Derivatives from Euphorbia thymifolia

2012 ◽  
Vol 7 (10) ◽  
pp. 1934578X1200701
Author(s):  
Riaz Hussain ◽  
Bakhat Ali ◽  
Muhammad Imran ◽  
Abdul Malik
Keyword(s):  
Cinnamic Acid ◽  
Nmr Spectra ◽  
Soluble Fraction ◽  
Cinnamic Acid Derivatives ◽  
First Time ◽  
C Nmr

Two new cinnamic acid derivatives, thymofolinoates A (1) and B (2) have been isolated from the chloroform soluble fraction of Euphorbia thymifolia and their structures assigned from 1H and 13C NMR spectra, DEPT and by 2D COSY, HMQC and HMBC experiments. In addition, p-hydroxy cinnamic acid (3), 5-hydroxy-6,7,8,4′-tetramethoxy flavone (4), and 5-hydroxy-3′,4′,6,7,8-pentamethoxy flavone (5) have also been isolated for the first time from this species.

THE THERMAL DECOMPOSITION OF HYDROGEN PEROXIDE VAPOUR

1945 ◽  
Vol 23b (5) ◽  
pp. 167-182 ◽  
Author(s):  
Bruce E. Baker ◽  
C. Ouellet
Keyword(s):  
Hydrogen Peroxide ◽  
Temperature Coefficient ◽  
Pure Hydrogen ◽  
First Order ◽  
Soda Glass ◽  
Manometric Method ◽  
Apparent Activation Energies ◽  
Reaction Vessels ◽  
First Time ◽  
Kinetics Of

The kinetics of the decomposition of hydrogen peroxide in the vapour state have been studied by a manometric method, with pure hydrogen peroxide at a concentration of about 99.5%. The temperature coefficient of the reaction has been measured for the first time. The pressures ranged from 1 to 2 cm. of mercury and the temperatures from 70° to 200 °C. Pyrex reaction vessels of various sizes and shapes, and also a fused Pyrex and a soda-glass vessel, were used. The reaction was purely heterogeneous, of the first order up to 140 °C. but more complicated at higher temperatures. Identical vessels yielded consistent results. The rates were not affected by air, carbon dioxide, or water vapour, but they varied greatly with the size and shape of the vessel. The reaction was very slow on fused Pyrex and very rapid on soda-glass. In one vessel, the temperature coefficient became negligible above 120 °C. No explosion was detected up to 335 °C. at a pressure of 18 cm. of mercury. The apparent activation energies in various vessels ranged from 13.5 to 18.5 kcal. per mole. A tentative reaction mechanism is suggested.

Assignment of Nitrogen Stereochemistry of Agroclavine and Elymoclavine 6-N-Oxides

1995 ◽  
Vol 60 (12) ◽  
pp. 2165-2169 ◽  
Author(s):  
Vladimír Křen ◽  
Jan Němeček ◽  
Věra Přikrylová
Keyword(s):  
Hydrogen Peroxide ◽  
Absolute Configuration ◽  
Molecular Modelling ◽  
Nmr Spectra ◽  
Peroxide Oxidation ◽  
Hydrogen Peroxide Oxidation ◽  
C Nmr

Both possible 6-N-oxides of agroclavine (I) and elymoclavine (II) were prepared by hydrogen peroxide oxidation. Their 1H and 13C NMR spectra were assigned and the conformation of the D ring (half-chair) was determined. Absolute configuration at 6-N was established by NMR and molecular modelling.

Theoretical and experimental studies of IR and NMR spectra of gem-2,2-diamino-4,4,6,6-tetraphenoxy-1,3,5-cyclo-triaza-λ5-phosphorine

2010 ◽  
Vol 75 (11) ◽  
pp. 1125-1138
Author(s):  
Lenka Dastychová ◽  
Dalibor Dastych ◽  
Pavel Kubáček ◽  
Milan Alberti
Keyword(s):  
Density Functional ◽  
Nmr Spectra ◽  
Experimental Studies ◽  
Normal Modes ◽  
Chemical Calculation ◽  
Functional Theory ◽  
Calculation Results ◽  
Vibrational Bands ◽  
First Time ◽  
C Nmr

The vibrational spectra of gem-2,2-diamino-4,4,6,6-tetraphenoxy-1,3,5-cyclo-triaza-λ5-phosphorine were studied using density functional theory. Selected vibrational bands were assigned to normal modes on the basis of DFT calculation with the ADF program package. The 1H and 13C NMR spectra, the higher order 31P, 31P{1Ham.(sel.)} and 31P{1Harom.(sel.)} NMR spectra were measured and the values of 1J(C,H), 2J(C,H) and 2J(PI,PII) were found. Nearly the complete spin system (ABB′M4X4X4′) for the symmetry C2 was simulated with the gNMR simulation program and the values of 2J(PI,Ham.), 4J(PII,Ham.), 4J(PII,Harom.), 6J(PI,Harom.) and 6J(PII,H′arom.) were determined for the first time. The experimental NMR data were also compared with quantum chemical calculation results.

A THEORETICAL INVESTIGATION OF STRUCTURAL, SPECTROSCOPIC AND THERMODYNAMIC PROPERTIES OF CYCLODECANE

2007 ◽  
Vol 06 (02) ◽  
pp. 281-299 ◽  
Author(s):  
DALVA E. C. FERREIRA ◽  
WAGNER B. DE ALMEIDA ◽  
HÉLIO F. DOS SANTOS
Keyword(s):  
Quantum Chemical ◽  
Nmr Spectra ◽  
Energy Surface ◽  
Chemical Methods ◽  
Quantum Chemical Methods ◽  
Torsion Potential ◽  
Good Accordance ◽  
First Time ◽  
Good Agreement ◽  
C Nmr

The torsion potential energy surface for cyclodecane has been examined using molecular mechanics and quantum chemical methods. The boat-chair-boat (BCB) conformer is predicted as the most stable structure at all levels of theory employed, in agreement with low temperature experiments. We found 13 low-energy conformers that cover a range of ~10 kcal mol-1. The relative abundance of the main isomers (named BCB, TBC, TBCC and TCCC) as a function of the temperature is discussed. In addition, energy calculations at high correlated levels of theory (MP4(SDTQ) and CCSD(T)) were for the first time performed for these conformations. In general, the predicted Gibbs population is in fairly good agreement with the experimental data. The simulated IR, VCD and 13 C NMR spectra were obtained showing good accordance with the observed data, providing important features for conformational analysis of cyclodecane.

scholarly journals Pregnane Derivatives from Potentilla evestita

2011 ◽  
Vol 6 (8) ◽  
pp. 1934578X1100600
Author(s):  
Rehan Khan ◽  
Farah Siddiq ◽  
Itrat Fatima ◽  
Shazia Yasmeen ◽  
Aman Karim ◽  
...  
Keyword(s):  
Ethyl Acetate ◽  
Natural Product ◽  
Nmr Spectra ◽  
Soluble Fraction ◽  
First Time ◽  
C Nmr

A new pregnane derivative, 2,6β,7β-trihydroxy-4-methyl-19-norpregna-1,3,5(10)-trien-17-one, has been isolated from the ethyl acetate soluble fraction of Potentilla evestita along with a pregnane derivative, 11α,17α,21-trihydroxypregna-4,16(22)-diene-3,20-dione, that is reported for the first time as a natural product. Their structures were elucidated with the aid of 1H and 13C NMR spectra and by COSY, HMQC, HMBC and NOESY experiments.

scholarly journals Bromotyrosine Alkaloids with Acetylcholinesterase Inhibitory Activity from the Thai Sponge Acanthodendrilla sp

2015 ◽  
Vol 10 (11) ◽  
pp. 1934578X1501001 ◽  
Author(s):  
Natchanun Sirimangkalakitti ◽  
Opeyemi J. Olatunji ◽  
Kanokwan Changwichit ◽  
Tongchai Saesong ◽  
Supakarn Chamni ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
Nmr Assignments ◽  
Therapeutic Potential ◽  
2D Nmr ◽  
Inhibition Kinetics ◽  
Ache Inhibitory Activity ◽  
First Time ◽  
Kinetics Of ◽  
Resolution Mass ◽  
C Nmr

Twenty bromotyrosine alkaloids, including a new compound, 13-oxosubereamolline D (5), were isolated from the Thai sponge Acanthodendrilla sp. Their structures were determined by analyses of 1D- and 2D-NMR, high-resolution mass, and circular dichroism data. The complete 1H and 13C NMR assignments of 5,7β-dichlorocavernicolin (19) and 5,7α-dichlorocavernicolin (20) are described herein for the first time. The acetylcholinesterase (AChE) inhibitory activity of all isolated compounds was evaluated. Only homoaerothionin (7) and fistularin 1 (10) exhibited inhibitory activity against human recombinant AChE ( hrAChE) with IC50s of 4.5 and 47.5 μM, respectively. The hrAChE inhibition kinetics of 7, the most potent alkaloid, showed increased K m and unchanged V max values, suggesting its competitive mode of inhibition. The spirocyclohexadienylisoxazole and the length of the alkyl diamine linkage were proposed as the crucial parts for its strong inhibitory activity. This finding indicates a therapeutic potential for 7 in acetylcholine-related diseases, most importantly Alzheimer's disease.

Autoxidation of model membranes. The kinetics and mechanism of autoxidation of mixed phospholipid bilayers

1987 ◽  
Vol 65 (11) ◽  
pp. 2541-2550 ◽  
Author(s):  
Lawrence Ross Coates Barclay ◽  
Kimberly Ann Baskin ◽  
David Kong ◽  
Steven Jeffrey Locke
Keyword(s):  
Nmr Spectra ◽  
Linear Trend ◽  
Kinetic Studies ◽  
Phospholipid Bilayers ◽  
Water Soluble ◽  
Oxidative Conversion ◽  
Dipalmitoyl Phosphatidylcholine ◽  
Kinetic Order ◽  
Lamellar Structures ◽  
Kinetics Of

Kinetics of autoxidation of bilayer mixtures of oxidizable dilinoleoylphosphatidylcholine (DLPC) with saturated phospholipids as solvents (dimyristoyl-, DMPC, and dipalmitoyl-phosphatidylcholine, DPPC) follow the classical rate law of autoxidation: −d[O2]/dt = kp/2kt1/2[RH]Ri1/2. The kinetic order in substrate [RH] was found to be unity for peroxidation initiated by a lipid-soluble initiator, azobis-2,4-dimethylvaleronitrile (ADVN), and by the water-soluble azobis(2-amidinopropane•HCl) (ABAP). The kinetic order in rate of chain initiation, Ri, was found to be one-half for both initiation by ADVN, photochemically decomposed, and by ABAP. The oxidizability of unilamellar DLPC liposomes (kp/2kt1/2 = 0.232 M−1/2 s−2) is twice that of multilamellar DLPC (kp/2kt1/2 = 0.116 M−2 s−2). Analysis of the hydroperoxides formed during ABAP-initiated autoxidations of mixed DLPC + DPPC liposomes showed a linear trend between the ratio of cis,trans to trans,trans geometrical isomeric hydroperoxides and [DLPC], consistent with the peroxidation mechanism proposed for homogeneous systems.31P nmr spectra of mixed bilayers were used to distinguish between heterogeneous and homogeneous mixtures of DLPC + DPPC. Such spectra taken at various stages of oxidation indicate that the bilayer structure of DLPC is preserved at least to the 10% extent of oxidation used in kinetic studies. At much higher oxidative conversion, the spectra indicate changes in lamellar structures.

Kinetic Study on Delignification of Kraft-AQ Pine Pulp with Hydrogen Peroxide Catalyzed by Mn(IV)-Me4DTNE

Holzforschung ◽  
2000 ◽  
Vol 54 (4) ◽  
pp. 413-419 ◽  
Author(s):  
Yu Cui ◽  
Pratuang Puthson ◽  
Chen-Loung Chen ◽  
Josef S. Gratzl ◽  
Adrianna G. Kirkman
Keyword(s):  
Hydrogen Peroxide ◽  
Initial Phase ◽  
Model Compound ◽  
Kinetic Studies ◽  
Kappa Number ◽  
Lignin Model Compound ◽  
First Order Kinetics ◽  
Residual Phase ◽  
Lignin Model ◽  
Kinetics Of

Summary The kinetics of delignification of a kraft-AQ southern pine pulp with hydrogen peroxide catalyzed by [LMn(IV)(μ-O)3Mn(IV)](ClO4)2 (1), where L = 1,2-bis(4,7-dimethyl-1,4,7-triazacyclonon-1-yl)ethane was studied. The degree of delignification was significantly improved by using the catalyst. The pulp was bleached for 2 hours at 80°C, in 10% consistency with 2% NaOH, 4% H2O2 and 60 ppm catalyst charges on pulp (O.D.). Kappa number of the pulp was reduced from 31.6 to 16.8 corresponding to a degree of delignification of approximately 4%, while GE brightness was increased from 24.2 to 44.7. At the same time, viscosity of the resulting pulp was reduced from 31.1 mPa•s to 20.1 mPa•s compared to the reduction from 31.1 mPa•s to 20.1 mPa•s in the uncatalyzed bleaching under the same reaction condition. This indicates that the degradation of the carbohydrates was moderate in the catalyzed bleaching compared to the uncatalyzed bleaching. The delignification was found to follow pseudo first order kinetics with respect to kappa number, i.e., residual lignin, in the initial phase and quickly slowed down after 30 minutes (residual phase) under all the reaction temperatures investigated. The delignification rate constants in the initial phase were 0.17, 0.18, and 0.21 min−1 at 50, 60, and 80°C, respectively. Degree of delignification at the delignification time of 30 minutes is approximately 40% at 80°C. The possible delignification mechanism was discussed on the basis of the kinetic studies and lignin model compound experiments.

scholarly journals Configurational Study of an Aporphine Alkaloid from Annona purpurea

2018 ◽  
Vol 13 (7) ◽  
pp. 1934578X1801300 ◽  
Author(s):  
Julio C. Ontiveros-Rodríguez ◽  
Eleuterio Burgueño-Tapia ◽  
Javier Porras-Ramírez ◽  
Pedro Joseph-Nathan ◽  
L. Gerardo Zepeda
Keyword(s):  
Nitrogen Atom ◽  
Absolute Configuration ◽  
Nmr Spectra ◽  
Optical Rotation ◽  
Vibrational Circular Dichroism ◽  
Aporphine Alkaloid ◽  
Stereogenic Center ◽  
First Time ◽  
C Nmr

Purpureine (1), norpurpureine (2), and 3-hydroxyglaucine (4) were isolated from the leaves of Annona purpurea. A vibrational circular dichroism study for the absolute configuration determination of 1 provides evidence for the mutually dependent atropisomerism, local chirality of the sole stereogenic center, and the geometry of the tetrahedral nitrogen atom in aporphine alkaloids. The observed change in the optical rotation sign between 2 and its hydrochloride 3 might explain why this compound has been reported as dextrorotatory and levorotatory from the same botanical source. Furthermore, 1H and 13C NMR spectra of 1, 2 and 4 were fully assigned for the first time.

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