Kinetics and mechanism of diazo coupling. XVIII. Influence of polysubstitution on reactivity and selectivity of benzenediazonium ions in coupling reactions with 2-naphthol-6-sulfonic acid

1970 ◽  
Vol 35 (11) ◽  
pp. 3470-3474 ◽  
Author(s):  
J. Kaválek ◽  
J. Panchartek ◽  
V. Štěrba
Keyword(s):  
Sulfonic Acid ◽  
Kinetics And Mechanism ◽  
Coupling Reactions ◽  
Diazo Coupling

scholarly journals New Diazo Coupling Reactions for Visible Spectrophotometric Determination of Alfuzosin in Pharmaceutical Preparations

2007 ◽  
Vol 4 (4) ◽  
pp. 496-501 ◽  
Author(s):  
M. Vamsi Krishna ◽  
D. Gowri Sankar
Keyword(s):  
Pharmaceutical Preparations ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Basic Medium ◽  
Coupling Reactions ◽  
Acetyl Acetone ◽  
Diazo Coupling ◽  
Optimum Reaction ◽  
Diazonium Ion

Simple, rapid and sensitive spectrophotometric procedures were developed for the analysis of Alfuzosin hydrochloride (AFZ) in pure form as well as in pharmaceutical formulations. The methods are based on the reaction of AFZ with nitrite in acid medium to form diazonium ion, which is coupled with ethoxyethylenemaleic ester (Method A) or ethylcyanoacetate (Method B) or acetyl acetone (method C) in basic medium to form azo dyes, showing absorption maxima at 440, 465 and 490 nm respectively. Beer’s law is obeyed in the concentration of 4-20 μg/mL of AFZ for methods A, B and 3-15 μg/mL of AFZ for method C. The molar absorptivity and sandell’s sensitivity of AFZ- ethoxyethylenemaleic ester, AFZ- ethylcyanoacetate and AFZ-acetyl acetone are1.90 × 104, 0.022; 1.93 × 104, 0.021 and 2.67 × 104L mole-1cm-1, 0.015 μg cm-2respectively. The optimum reaction conditions and other analytical parameters were evaluated. The methods were successfully applied to the determination of AFZ in pharmaceutical formulations.

Reactions of the radical cation derived from 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS·+) with amino acids. Kinetics and mechanism

2000 ◽  
Vol 78 (8) ◽  
pp. 1052-1059 ◽  
Author(s):  
C Aliaga ◽  
E A Lissi
Keyword(s):  
Amino Acids ◽  
Radical Cation ◽  
Sulfonic Acid ◽  
Biological Fluids ◽  
Reaction Rates ◽  
Kinetics And Mechanism ◽  
Specific Rate ◽  
Wide Range ◽  
Initial Ph ◽  
Secondary Reactions

Stable free radicals derived from 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS·+) have been extensively employed to monitor the antioxidant capacity of biological fluids and beverages. Besides reacting with typical antioxidants (such as phenols or thiols) these radicals react with a variety of hydrogen or electron donors. The present work reports on the kinetics and mechanism of these radical reactions with several amino acids. Reaction rates notably increase when the pH of the media increases and, when measured under similar conditions, follows the ordercysteine > > tryptophan > tyrosine > histidine > cystineThe kinetics of the process is interpreted in terms of a mechanism comprising an initial pH dependent reversible step, followed by secondary reactions of the substrate derived radical with itself or with another ABTS·+; this simple three-step mechanism leads to very complex kinetic expressions. The specific rate constants of several of the elementary steps were determined by working under a wide range of substrate, radical, and ABTS concentrations. The values obtained for the initial interaction between the ABTS derived radical and the substrate range from 0.5 M–1 s–1 to 1.9 × 106 M–1 s–1 for histidine and cysteine, respectively.Key words: ABTS radical cation, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid), amino acids, kinetics.

ChemInform Abstract: THE ACTIVATING EFFECTS OF AMINO GROUPS IN DIAZO-COUPLING REACTIONS

1974 ◽  
Vol 5 (20) ◽  
pp. no-no
Author(s):  
YOJI HASHIDA ◽  
JUNICHI TAKENAKA ◽  
KOHJI MATSUI
Keyword(s):  
Coupling Reactions ◽  
Amino Groups ◽  
Diazo Coupling

Rapid and efficient diazotization and diazo coupling reactions on silica sulfuric acid under solvent-free conditions

2009 ◽  
Vol 81 (3) ◽  
pp. 240-244 ◽  
Author(s):  
A ZAREI ◽  
A HAJIPOUR ◽  
L KHAZDOOZ ◽  
B MIRJALILI ◽  
A NAJAFICHERMAHINI
Keyword(s):  
Sulfuric Acid ◽  
Solvent Free ◽  
Coupling Reactions ◽  
Silica Sulfuric Acid ◽  
Solvent Free Conditions ◽  
Diazo Coupling
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