Chemical Constitution and Activity of Bipyridinium Herbicides. XIII. Synthesis, Reduction Potential and Biological Activity of 1-Methyl-4-[[(methylpyridinium-4-yl)Imino]methyl]pyridinium Diiodide

1980 ◽  
Vol 33 (6) ◽  
pp. 1397 ◽  
Author(s):  
J Rockley ◽  
L Summers

A diquaternary salt from the azomethine N-(pyridin-4- ylmethylene)pyridin-4-amine has been prepared. The salt is slowly reduced by zinc dust in aqueous solution to a red radical cation at a potential (E0) of -0.64 V in the pH range 5.2-8.0. In keeping with its low reduction potential the salt is very much less active than paraquat as a post-emergent herbicide.

1974 ◽  
Vol 29 (1-2) ◽  
pp. 89-90 ◽  
Author(s):  
L. A. Summers

2,2′-Bipyridyl dimethiodide in aqueous solution in the pH range 5.0-8.9 gives a symmetrical one-electron reduction wave independent of pH and concentration at a potential of —0.96 V against a standard calomel electrode due to the formation of the corresponding radical cation. At a much lower potential it also shows a second reduction wave which is pH dependent.


1981 ◽  
Vol 34 (12) ◽  
pp. 2683 ◽  
Author(s):  
JE Rockley ◽  
LA Summers

4,4'-Azobis(1-methylpyridinium) bis(methyl sulfate) is reduced in aqueous solution by zinc powder to the corresponding hydrazo diquaternary salt.


1965 ◽  
Vol 18 (5) ◽  
pp. 651 ◽  
Author(s):  
RW Green ◽  
PW Alexander

The Schiff base, N-n-butylsalicylideneimine, extracts more than 99.8% beryllium into toluene from dilute aqueous solution. The distribution of beryllium has been studied in the pH range 5-13 and is discussed in terms of the several complex equilibria in aqueous solution. The stability constants of the complexes formed between beryllium and the Schiff base are log β1 11.1 and log β2 20.4, and the distribution coefficient of the bis complex is 550. Over most of the pH range, hydrolysis of the Be2+ ion competes with complex formation and provides a means of measuring the hydrolysis constants. They are for the reactions: Be(H2O)42+ ↔ 2H+ + Be(H2O)2(OH)2, log*β2 - 13.65; Be(H2O)42+ ↔ 3H+ + Be(H2O)(OH)3-, log*β3 -24.11.


1995 ◽  
Vol 412 ◽  
Author(s):  
C. Oda ◽  
H. Yoshikawa ◽  
M. Yui

AbstractPalladium solubility was measured in a dilute aqueous solution at room temperature in the pH range from 3 to 13 under anaerobic conditions. Crystalline Pd metal was clearly visible and the concentration of palladium in solution decreased gradually with aging time. The palladium concentrations in solution were less than 9.4×10-10M in the pH range from 4 to 10 and increased to 10-7M in the pH range greater than 10. This study suggests that palladium concentrations in certain high-level waste repository environments may be limited by Pd metal and may be less than 10-9M.


1982 ◽  
Vol 35 (7) ◽  
pp. 1357 ◽  
Author(s):  
TJ Broxton

The hydrolysis of 2-acetyloxybenzoic acid in the pH range 6-12 has been studied in the presence of micelles of cetyltrimethylammonium bromide (ctab) and cetylpyridinium chloride (cpc). In the plateau region (pH 6-8) the hydrolysis is inhibited by the presence of micelles, while in the region where the normal BAC2 hydrolysis (pH > 9) occurs the reaction is catalysed by micelles of ctab and cpc. The mechanism of hydrolysis in the plateau region is shown to involve general base catalysis by the adjacent ionized carboxy group both in the presence and absence of micelles. This reaction is inhibited in the presence of micelles because the substrate molecules are solubilized into the micelle and water is less available in this environment than in normal aqueous solution.


2005 ◽  
Vol 23 (3) ◽  
pp. 255-266 ◽  
Author(s):  
J. O'Brien ◽  
T. Curtin ◽  
T.F. O'Dwyer

Zeolite beta, a large-pore zeolite, was investigated in this study with a view to examining it as a potential adsorbent for the removal of aniline from aqueous solutions. Two different metal-loaded zeolites were prepared by exchanging H-beta zeolite (SiO2/Al2O3 = 75:1) with copper. The influence of exchanged copper on the uptake level was assessed. The effect of varying the silica-to-alumina ratio of the H-beta zeolite on the aniline uptake level was also examined, using three different H-beta zeolites with ratios of 25:1, 75:1 and 150:1 as adsorbents. The sorption experiments indicated an uptake level of ca. 110–120 mg/g for each zeolite and this level was also adsorbed by the copper-modified H-beta zeolites (SiO2/Al2O3 = 75:1). In all cases, the adsorption process followed the Langmuir model for adsorption and the level of aniline adsorbed was largely unaffected by a change in temperature or the presence of extra framework copper. The stability of the exchanged copper on these zeolites was then examined by measuring the quantity of copper leached from each zeolite into solution as a function of pH. Minimum copper leaching was observed in the pH range 5–11. This provided a stable pH working range for the adsorbent materials.


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