A Study of the Mechanism and Intermediates in the Precipitation of Cations with Thioacetamide¹

Abstract

Possible mechanisms for the precipitation of cations with thioacetamide are considered. I n some cases the cation is precipitated by the hydrogen sulfide liberated in the hydrolysis of thioacetamide. In other cases a metal-thioacetamide intermediate is formed.In a study a t room temperatures carbon containing intermediates were obtained in the reaction in acid solution between thioacetamide and cuprous or cupric chloride, cuprous or cupric bromide or mercuric chloride. No carbon containing intermediates were isolated for the other cations studied. The empirical formulas for the copper-thioacetamide compounds were C2HsNSCuCl and CIHsNSCuBr.The stoichiometry of the precipitation reactions was determined, and copper was found to be present in the cuprous form.The X-ray powder diffraction patterns for these two compounds were satisfactorily indexed assuming hexagonal unit cells. The conditions of formation, solubility, stability and chemical properties of these compounds were investigated. The infrared spectra of these compounds, thioacetamide, n-substituted thioamides, tetrakisthioacetamide cuprous and argentous chloride and s-ethyl thioimidoacetate hydrochloride were determined. Structures in which the thioacetamide is in the thion form and in which the copper of the cuprous halide is apparently either coordinately bound to nitrogen or t o nitrogen and sulfur are consistent with the observed properties of these two compounds.The evidence for the existence of such compounds is reviewed. IntroductionThioacetamide is used as a reagent in precipitating cations as metallic sulfides in qualitative3 and quantitative4 analysis. The stoichiometric equation for these precipitations is

An Effective Two‐Emulsion Approach to the Synthesis of Doped ZnS Crystalline Nanostructures

“…As a matter of fact, thioacetamide is labile towards acidic hydrolysis, which promotes the decomposition to acetic acid with a concomitant release of H 2 S, the true active species. This decomposition is usually favored at pH < 4 and temperatures that range from 60 to 80 °C 12. Nevertheless, in our case, the use of Na 2 S easily led to the formation of a crystalline precipitate, whereas sodium thioacetamide was not successful in promoting the formation of the desired product and consequently it was not further considered.…”

S-Nitrosation of Aminothiones

“…Degassing all solutions of TA and TU with nitrogen for at least 15 min prior to experiments ensures anaerobic conditions. The signals at 420 nm form the basis for studying these reactions to avoid interference from absorption of nitrous acid and buffers at lower wavelengths as in related literature. , Furthermore, traces of copper ions in solution potentially inhibit proton addition at either the nitrogen or sulfur atom . With a need to apply EDTA to remove these ions, separate experiments ascertained negligible effect of EDTA addition on S -nitrosation.…”

“…19,22 Furthermore, traces of copper ions in solution potentially inhibit proton addition at either the nitrogen or sulfur atom. 43 With a need to apply EDTA to remove these ions, separate experiments ascertained negligible effect of EDTA addition on S-nitrosation.…”

Crystal Structures of Two New Complexes Produced by Reaction of Copper(I) Cyanide with Thioacetamide. In Situ Formation of the Thiosulfate Anion

“…The spontaneous production of the thiosulfate anion in a neutral, aqueous, room-temperature solution of CuCN and thioacetamide was totally unexpected. We were well aware of the long established use of thioacetamide in qualitative analysis as a source of hydrogen sulfide, which is used for the pH-dependent, selective precipitation of metal sulfides. The hydrolysis of ta in acidic or neutral conditions is described by the following equation: Aqueous solutions of pure thioacetamide (typically 8−10%) have been found to be stable for months at room temperature, and the hydrolysis procedure to generate hydrogen sulfide is ordinarily conducted at temperatures above 80 °C.…”