Determination of the substituent constant σp- for the thioamide group -CSNH2 from the ionization of anilines and phenols

1991 ◽  
Vol 56 (12) ◽  
pp. 2964-2968 ◽  
Author(s):  
Miroslav Polášek ◽  
Karel Waisser ◽  
Tomáš Bouček
Keyword(s):  
Ultra Violet ◽  
Ionization Constants ◽  
Amino Group ◽  
Substituted Phenols ◽  
Substituent Constant ◽  
Substituted Anilines ◽  
Phenolic Hydroxy Group ◽  
Thioamide Group ◽  
Phenolic Hydroxy

Thermodynamic ionization constants pKa 2.62 ± 0.01 for the primary aromatic amino group of 4-aminothiobenzamide and pKa 8.28 ± 0.01 for the phenolic hydroxy group of 4-hydroxythiobenzamide have been determined by ultra-violet spectrophotometry at 25°C. By using these pKa values and the Hammett equations (log Ka vs σ) for the ionization of fourteen 3- or 4-substituted phenols and thirteen 3- or 4-substituted anilines the substituent constant σp- = 0.68 (from the ionization of anilines) or σp- = 0.73 (from the ionization of phenols) of the thioamide group -CSNH2 was calculated.

Microwave-Accelerated Solvent- and Catalyst-Free Synthesis of 4-Aminoaryl/alkyl-7-chloroquinolines and 2-Aminoaryl/alkylbenzothiazoles

2007 ◽  
Vol 60 (5) ◽  
pp. 369 ◽  
Author(s):  
Hashim F. Motiwala ◽  
Raj Kumar ◽  
Asit K. Chakraborti
Keyword(s):  
Lewis Acid ◽  
Acid Catalyst ◽  
Amino Group ◽  
Efficient Synthesis ◽  
Phenolic Hydroxy Group ◽  
Aromatic Nucleophilic Substitution ◽  
Solvent Free Conditions ◽  
Lewis Acid Catalyst ◽  
Phenolic Hydroxy ◽  
Aromatic And Aliphatic Amines

An efficient synthesis of 4-aminoaryl/alkyl-7-chloroquinolines and 2-aminoaryl/alkylbenzothiazoles has been developed by microwave-accelerated regioselective aromatic nucleophilic substitution of 4,7-dichloroquinoline and 2-chlorobenzothiazole with aromatic and aliphatic amines under solvent-free conditions in the absence of any added protic or Lewis acid catalyst. Chemoselective reaction with the amino group in preference to the phenolic hydroxy group was observed. Thus, the treatment of 4,7-dichloroquinoline (1 equiv.) with a mixture of aniline (2 equiv.) and phenol (2 equiv.) afforded exclusive formation of 4-aminophenyl-7-chloroquinoline. When 4,7-dichloroquinoline (1 equiv.) was separately treated with 2-aminophenol (2 equiv.) and 4-aminophenol (2 equiv.), 4-(2′-hydroxyphenyl)-7-chloroquinoline and 4-(4′-hydroxyphenyl)-7-chloroquinoline, respectively, were formed.

scholarly journals DETERMINATION OF THE STABILITY OF COMPLEX COMPOUNDS OF COPPER (II), ZINC (II), CADMIUM (II) AND SILVER (I) WITH COVALENTLY IMMOBILIZED SULFUR CONTAIN LIGANDS

2021 ◽  
pp. 22-29
Keyword(s):  
Coordination Compounds ◽  
Complex Compounds ◽  
Ionization Constants ◽  
Amino Group ◽  
Acid Base ◽  
Polyester Matrix ◽  
The Stability ◽  
Sulfur Containing ◽  
Polymer Ligands

"The purpose of this study is to determine the stability of the obtained coordination compounds of some d-metals with covalent immobilized sulfur-containing ligands. To achieve this goal, coordination compounds of copper (II), zinc (II), cadmium (II) and silver (I) ions with covalent immobilized sulfur-containing ligands - О,О-di- (2-aminoethyl) -dithiophosphate potassium - polyester matrix (KD2AEDTP-PEM), O,O-di- (2-aminoethyl) -dithiophosphate potassium - carbamide-formaldehyde matrix (KD2AEDTP-KFM). Studies were carried out to determine the acid-base properties of covalent-immobilized sulfur-containing ligands - KD2AEDTP-PEM, KD2AEDTP-KFM and the concentration stability of the obtained coordination compounds with ions of copper (II), zinc (II), cadmium (II), and silver (I). Based on the results of integral and differential potentiometric titrations, it was established that the ionization constants (pK) of the dithiophosphoric group in KD2AEDTP-PEM and KD2AEDTP-KFM are 3.23 and 3.35, and the ionization constants of the amino group are 9.76 and 9.63, respectively. As a result of studies of polymer ligands by potentiometric titration via the method of individual weighed portions, it was shown that polyfunctional polymer ligands have the ability to form stable coordination compounds with metal ions of copper (II), zinc (II), cadmium (II) and silver (I). "

scholarly journals II. The wave-lengths of A, a , and of prominent lines in the infra-red of the solar spectrum

1883 ◽  
Vol 36 (228-231) ◽  
pp. 137-138
Keyword(s):  
Solar Spectrum ◽  
Ultra Violet ◽  
Infra Red

M. Fievez has recently sent me a map of the solar spectrum from C to A* inclusive, and as part of this region is one which I have been measuring, I have examined the new publication with great interest. Photography and eye measurements do not exactly coincide in the detail of the grouping of the little a group as far as A, and A itself is shown by M. Fievez’s map as wanting some details which appear in the photographs. Thus in the photographs there are some seventeen lines, whilst in M. Fievez’s map there are but thirteen. Between A and a there are several lines of marked intensity in the photograph which are not shown in the new map. The wave-lengths of the different lines from above “ a ” to A are not the same as those given by Fievez, when they are taken from comparison photo-graphs of the 1st order of the red and 2nd of the ultra-violet on the same plate, or when checked by photographs of the 2nd order of the red with the 3rd order of the green taken in a similar manner. In my paper, “Phil. Trans.,” Part II, 1880, I gave a method of using mirrors by which this could be effected, but since Professor Rowland introduced his concave gratings this is much more readily carried out. He has kindly furnished me with gratings for the purpose, having about 14,400 lines to the inch, with focal distances of 7 feet 6 inches and 12 feet 6 inches respectively. These have been employed in determining the wave-lengths of this part of the spectrum. Cornu’s map was used as a reference for the ultra-violet wave-lengths, and Ångström’s map for those in the blue and green. The two maps may be taken as equally exact. The determination of A has been made by Maseart, Smyth, and others, besides Ångström and Langley, with discordant results. I think the above may be taken as accurate as are Cornu’s and Ångström maps.

scholarly journals Bioanalytical Method Development and Validation for Determination of Sulfasalazine in Rabbit Plasma by HPLC-UV

2021 ◽  
Vol 33 (7) ◽  
pp. 1692-1698
Author(s):  
S.S. Jadiya ◽  
N. Upmanyu ◽  
S. Arulmozhi ◽  
V. Jain ◽  
S. Sankaran ◽  
...  
Keyword(s):  
High Performance ◽  
Method Development ◽  
High Efficiency ◽  
Internal Standard ◽  
Ultra Violet ◽  
Precipitation Method ◽  
Pharmacokinetic Studies ◽  
Rabbit Plasma ◽  
Bioanalytical Method

In present study, an advanced, simple and a rapid reverse phase high performance liquid chromatography (RP-HPLC) method was developed for the quantitative determination of sulfasalazine in rabbit plasma. Sulfasalazine was separated using Chromatopak C-18 basic peerless (250 mm × 4.6 mm, 5μ) column in an isocratic mode using mobile phase consisting of the mixture of 10mM Ammonium acetate pH adjusted to 4.5 and acetonitrile (70:30 v/v) with a flow rate of about 1.0 mL/min at ambient temperature. An ultra-violet detection of sulfasalazine and the internal standard was carried out at 362 nm. Both sulfasalazine and internal standard (IS, 4-hydroxy benzoate) were extracted from plasma matrices with high efficiency using a simple protein precipitation method. The method was found to be highly selective with no carryover effects. Linearity of sulfasalazine was found with the range of 2.5-100 μg/mL with the value of r2 > 0.995 a correlation coefficient. At all three quality control levels, developed bioanalytical method was found as repeatable and reproducible as well. The average recoveries of sulfasalazine from plasma were in the range of 95.59-97.16%. The bioanalytical samples showed good and acceptable stability of sulfasalazine solution at different storage, packaging and handling conditions. Hence, in conclusion, the validated and developed HPLC-UV method could be effectively utilized for determination of sulfasalazine in pharmacokinetic studies involving novel formulations.

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