Study of the reaction of nitrosobenzene with haemoglobine

1979 ◽  
Vol 44 (3) ◽  
pp. 981-985
Author(s):  
Václav Holeček ◽  
Jan Kopecký ◽  
Stanislav Škramovský
Keyword(s):  
Polarographic Determination ◽  
Molar Ratio ◽  
Stoichiometric Ratio ◽  
Sh Groups ◽  
Oxidative Splitting

During the reaction of haemoglobine with nitrosobenzene, the latter was determined polarographically. Nitrosobenzene bound by coordination to the divalent Fe atom of haemoglobine was polarographically inactive; it was set free from this complex by oxidation of the iron with ferricyanide and then determined. At a molar ratio of nitrosobenzene to haemoglobine of 4 : 1, at which the molar ratio of iron to nitrosobenzene is 1 : 1, 0.9 mol of nitrosobenzene is bound by coordination to the iron while 0.1 mol is reduced by SH groups to azo- and azoxybenzene. After the SH groups of haemoglobine had been blocked by cyanoethylation or oxidation, nitrosobenzene was bound to iron in a stoichiometric ratio. Accordingly, the conditions for the polarographic determination of nitrosobenzene after oxidative splitting of the complex with haemoglobine are defined.

scholarly journals Sensitive and Selective Extractive Spectrophotometric Method for the Determination of Hydroxyzine Dihydrochloride in Pharmaceuticals

2019 ◽  
Vol 54 (4) ◽  
Author(s):  
Nagaraju Rajendraprasad ◽  
Kanakapura Basavaiah ◽  
Kanakapura Basavaiah Vinay ◽  
Hosakere Doddarevanna Revanasiddappa
Keyword(s):  
Spectrophotometric Method ◽  
Limit Of Detection ◽  
Ion Pair ◽  
Molar Ratio ◽  
Complexing Agent ◽  
Official Method ◽  
Stoichiometric Ratio ◽  
Experimental Conditions ◽  
Relative Standard

Hydroxyzine dihydrochloride (HDH), a piperazine H1-receptor antagonist and antihistamine, is a rapid acting anxiolytic used principally as an anti-emetic. A sensitive, selective, and precise and accurate spectrophotometric method based on the formation of an ion-pair with orange II (ORG II) as ion-pair complexing agent was developed and validated for the determination of HDH in pharmaceuticals. The chloroform-extractable ion-pair complex exhibited an absorption maximum at 480 nm. Optimization of different experimental conditions is described. Beer’s law is obeyed in the range of 1.5-15 μg mL-1 with an apparent molar absorptivity value of 2.07 x 104 L mol-1 cm-1 and Sandell’s sensitivity value of 0.0216 μg cm-2. The limit of detection (LOD) and limit of quantification (LOQ) are 0.14 and 0.41 μg mL-1, respectively. A Job’s plot of absorbance versus molar ratio of HDH to ORG II indicated (1:2) stoichiometric ratio. Within- and between-day relative standard deviations at three different concentration levels were < 3%. The developed method was successfully applied to commercial tablets. The results obtained were in good agreement with those obtained using the official method. No interference was encountered from co-formulated substances. Recoveries were 96-109 %.

DC polarographic determination of surfactants

1987 ◽  
Vol 52 (3) ◽  
pp. 609-615
Author(s):  
A. Díaz ◽  
S. González ◽  
A. Arévalo
Keyword(s):  
Quantitative Determination ◽  
Polarographic Determination ◽  
Method Of Determination

The minimum on the polarographic curves for Bi(III) reduction in HCl solutions occurring when small amounts of surfactants are present can be used for their quantitative determination. The form of the polarograms was examined with respect to the concentration of the surfactant, and the range of concentrations in which the method of determination can be used is discussed.

Polarographic Determination of Acetone

1959 ◽  
Vol 31 (7) ◽  
pp. 1217-1219 ◽  
Author(s):  
R. E. Van Atta ◽  
D. R. Jamieson
Keyword(s):  
Polarographic Determination

scholarly journals Charge Transfer Complexes of Ketotifen with 2,3-Dichloro-5,6-dicyano-p-benzoquinone and 7,7,8,8-Tetracyanoquodimethane: Spectroscopic Characterization Studies

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2039
Author(s):  
Gamal A. E. Mostafa ◽  
Ahmed Bakheit ◽  
Najla AlMasoud ◽  
Haitham AlRabiah
Keyword(s):  
Charge Transfer ◽  
Spectroscopic Characterization ◽  
Molar Ratio ◽  
Charge Transfer Complexes ◽  
Physical Parameters ◽  
Spectrophotometric Methods ◽  
Theoretical Approaches ◽  
The Stability ◽  
Ct Complexes

The reactions of ketotifen fumarate (KT) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as π acceptors to form charge transfer (CT) complexes were evaluated in this study. Experimental and theoretical approaches, including density function theory (DFT), were used to obtain the comprehensive, reliable, and accurate structure elucidation of the developed CT complexes. The CT complexes (KT-DDQ and KT-TCNQ) were monitored at 485 and 843 nm, respectively, and the calibration curve ranged from 10 to 100 ppm for KT-DDQ and 2.5 to 40 ppm for KT-TCNQ. The spectrophotometric methods were validated for the determination of KT, and the stability of the CT complexes was assessed by studying the corresponding spectroscopic physical parameters. The molar ratio of KT:DDQ and KT:TCNQ was estimated at 1:1 using Job’s method, which was compatible with the results obtained using the Benesi–Hildebrand equation. Using these complexes, the quantitative determination of KT in its dosage form was successful.

scholarly journals Reaktive E=C(p–p)π Systeme, XXXIV Addition von Alkoholen oder primären Aminen an Phosphaalkene F3CP=C(F)OR. Neue Trifluormethylphosphane und -phosphaalkene/Reactive E = C( p – p ) π-Systems, XXXIV Addition of Alcohols or Primary Amines to Phosphaalkenes F3CP= C(F)OR . Novel Trifluoromethylphosphanes and Phosphaalkenes

1993 ◽  
Vol 48 (1) ◽  
pp. 58-67 ◽  
Author(s):  
Joseph Grobe ◽  
Duc Le Van ◽  
Gudrun Lange
Keyword(s):  
High Resolution Mass Spectrometry ◽  
Molar Ratio ◽  
Primary Amines ◽  
The Novel ◽  
Experimental Conditions ◽  
Pull System ◽  
Fragment Ions ◽  
New Compounds ◽  
C Nmr

The course of the reactions o f fluorophosphaalkenes F3CP = C (F)OR [R = Me (1), Et (2)] with methanol or ethanol strongly depends on the experimental conditions. Thus at 70 °C a mixture of the 2-phosphapropionic acid ester F3CP (H )CO2R [R = Me (3), Et (4)] and trifluoromethylphosphane H2PCF3 is formed [molar ratio: 3 or 4 /H2 CF3 ≈1/1]. If the precursors F3CP (H )CO2R [R = Me (3), Et) are used as starting materials, the reaction with ROH under the same conditions affords 3 and 4, respectively, (90 to 95% yield) with only traces of H2PCF 3. In the presence o f iPr2NH these precursors react with R′OH to give the novel trifluoromethylphosphaalkenes F3CP = C (OR )OR [R /R′: Me/Me (6); E t/E t (7); Me/Et (8)]. With Et2NH , 3 undergoes an addition/elimination process yielding the interesting push/pull system Et2N(F)C = P-CO2Me (5). 1 and 2 react with primary amines R′NH2 (R′= tBu, Me) with stereoselective formation of the fairly labile phosphaalkenes F3CP = C(OR)NHR′ [R /R′: Me/tBu (9), Et/tBu(10), Me/Me (11)] with trans-positions for CF3 and NHR′.The new compounds 3 -11 were characterized by spectroscopic investigations (1H , 19F, 31P, 13C NMR ; IR, MS) and determination of M+ or typical fragment ions [M+ -OR ] by high resolution mass spectrometry.

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