The chlorination of propiophenone; determination of pKa value and of the course of the reaction

1990 ◽  
Vol 68 (11) ◽  
pp. 2060-2069 ◽  
Author(s):  
J. Peter Guthrie ◽  
John Cossar
Keyword(s):  
Aqueous Solution ◽  
Aromatic Acids ◽  
Alkaline Aqueous Solution ◽  
Pka Value

Chlorination of propiophenone in alkaline aqueous solution leads to formation of α-hydroxypropiophenone as the first detectable intermediate; this undergoes slower oxidation to aromatic acids without any accumulation of further intermediates. From the rates of the initial chlorination we have been able to determine the pKa value as 17.56 ± 0.51. Keywords: propiophenone, chlorination, hydrolysis, rearrangement, pKa.

The chlorination of isobutyrophenone: determination of its pKa value and of the course of the reaction

1990 ◽  
Vol 68 (3) ◽  
pp. 397-403 ◽  
Author(s):  
J. Peter Guthrie ◽  
John Cossar
Keyword(s):  
Aqueous Solution ◽  
Alkaline Hydrolysis ◽  
Subsequent Oxidation ◽  
Alkaline Aqueous Solution ◽  
Pka Value

Chlorination of isobutyrophenone in alkaline aqueous solution leads to formation of α-hydroxyisobutyrophenone as the first detectable intermediate; a slow subsequent oxidation gives benzoate. From the rates of the initial chlorinations we have been able to determine the pKa value for the ketone as 18.18 ± 0.50. α-Chloroisobutyrophenone undergoes surprisingly rapid alkaline hydrolysis, kOH = 71.9 ± 1.5 M−1 s−1. Keywords: isobutyrophenone, chlorination, enolization, pKa, hydrolysis.

Application of Silica Nanoparticles in the Determination of Herbicides in Environmental Water Samples Using Liquid Chromatography-Mass Spectroscopy

2020 ◽  
Vol 16 (5) ◽  
pp. 748-756
Author(s):  
Mir Waqas Alam ◽  
Tentu Nageswara Rao ◽  
Yarasani Prashanthi ◽  
Vourse Sridhar ◽  
Adil Alshoaibi ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Liquid Chromatography ◽  
Silica Nanoparticles ◽  
Solid Phase ◽  
Silica Nanoparticle ◽  
Environmental Water ◽  
Phase Extraction ◽  
Functionalized Nanoparticles ◽  
Supporting Material

Background: Herbicides are very beneficial in the crop yield with the aid of controlling weeds within the agriculture, but several herbicides are chronic in soil. Objective: In this study, nanoparticles and the packages of synthesized novel silica nanoparticles were studied for the preconcentration of herbicides. Methods: These nanoparticles prepared by the Stöber mechanism were purified and functionalized. Nanoparticles thus prepared successfully were used as supporting material for the preconcentration of residues of herbicides in the water. Results: Preconcentration was achieved by preparing the silica-based solid-phase-extraction cartridges. Nanoparticles used for this purpose were within the range of 50-250 nm. An SPE cartridge was prepared by packing 200 mg of silica nanoparticle in the empty cartridge of diameter 5.5 cm and length 0.6 cm in between PTFE frits. Aqueous solutions of 0.1 μg/ml of herbicides were prepared separately, and 10 ml of the solution was passed through the cartridge at the rate of 0.2 ml/min. After passing 10 ml volume of the aqueous solution, residues adsorbed on the cartridge were eluted using 2 ml of acetonitrile. The eluate was injected to determine the herbicide residue adsorbed on the SPE cartridge. Conclusion: In the study, it was found that greater than 90% of the herbicide residues were trapped on silica nanoparticle-based SPE cartridge. An analytical method was developed for the simultaneous determination of these herbicides. The residues were quantified by LC-MS/MS with ESI mode.

Enzymatic colorimetry of lecithin and sphingomyelin in aqueous solution.

1983 ◽  
Vol 29 (8) ◽  
pp. 1513-1517 ◽  
Author(s):  
M W McGowan ◽  
J D Artiss ◽  
B Zak
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Amniotic Fluid ◽  
Enzymatic Reaction ◽  
Detergent Solution ◽  
Enzymatic Determination ◽  
Red Color ◽  
Hydrolysis Of ◽  
Zwitterionic Detergent

Abstract A procedure for the enzymatic determination of lecithin and sphingomyelin in aqueous solution is described. The phospholipids are first dissolved in chloroform:methanol (2:1 by vol), the solvent is evaporated, and the residue is redissolved in an aqueous zwitterionic detergent solution. The enzymatic reaction sequences of both assays involve hydrolysis of the phospholipids to produce choline, which is then oxidized to betaine, thus generating hydrogen peroxide. The hydrogen peroxide is subsequently utilized in the enzymatic coupling of 4-aminoantipyrine and sodium 2-hydroxy-3,5-dichlorobenzenesulfonate, an intensely red color being formed. The presence of a non-reacting phospholipid enhances the hydrolysis of the reacting phospholipid. Thus we added lecithin to the sphingomyelin standards and sphingomyelin to the lecithin standards. This precise procedure may be applicable to determination of lecithin and sphingomyelin in amniotic fluid.

Determination of the effective charge on muonium during its reaction in aqueous solution

1979 ◽  
Vol 6 (1-4) ◽  
pp. 409-412 ◽  
Author(s):  
Y. C. Jean ◽  
J. H. Brewer ◽  
D. G. Fleming ◽  
D. M. Garner ◽  
D. C. Walker
Keyword(s):  
Aqueous Solution ◽  
Effective Charge
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