Redox reactions in non-aqueous media: determination of organic isothiocyanates alone, in formulations and in important mixtures.
A simple potentiometric method for the determination of organoisothiocyanates is described. The isothiocyanate is treated in acetonitrile medium with an excess of primary amine to convert it into a substituted thiourea and the surplus amine is converted into a dithiocarbamate by addition of carbon disulphide. The solution is then titrated with a copper(II) solution in acetonitrile. The three-step titration curve enables the results to be calculated on the bash of the dithiocarbamate and/or thiourea formed. The method has been successfully applied to the analysis of a commercial insecticide formulation based on isothiocyanate and important mixtures containing isothiocyanates.
Analytical applications of copper(II) and copper(I) in acetonitrile: potentiometric and spectrophotometric determination of dithiocarbamates.
The use of copper(II) perchlorate and tetra-acetonitrilocopper(I) perchlorate (in acetonitrile) for the potentiometric and spectrophotometric determination of dithiocarbamates in acetonitrile medium is described. The proposed methods are simple, accurate and reliable and show promise of wide applicability. They are recommended for routine determination of dithiocarbamates. Their advantages over the carbon disulphide evolution method, commonly employed for the determination of these compounds, are discussed.
Evaluation and Control of Collapsible Soils
Some compacted soils wetted under certain conditions of compaction and loading may exhibit additional settlement (collapse). To investigate the effect of the soil type, compaction water content, initial dry unit weight and applied pressure at wetting on collapse potential, 138 single‐oedometer tests were conducted on eight different soils. The results indicate that well‐graded soils tend to collapse more than poorly graded ones under similar conditions. Furthermore, collapse potential decreases with an increase in (1) The difference between the sand and clay percentages; (2) compaction water content; and (3) initial dry unit weight, while it increases with pressure at wetting. A multiple regression analysis was performed on the laboratory results to provide a collapse‐predictive model that was substantiated by data reported by several researchers. A chart is presented to estimate (1) The collapse potential of soils under various conditions; and (2) the critical water content beyond which no collapse is ex...