Hydrogen sulphide chemistry

Desulphurisation of hydrocarbon fuels prior to combustion has been seen to be primarily achieved by reducing the inherent sulphur values to hydrogen sulphide. In post combustion desulphurisation the sulphur values are almost exclusively in the oxidised SO2 form. While this is hardly surprising in view of the oxidative nature of the fuel combustion process, it does mean that essentially different chemistry is involved and the nature of the oxidant - air - introduces large volumes of inert diluent -nitrogen. 

On account of its tendency to oxidation, hydrogen sulphide is frequently employed as a reducing agent in organic chemistry. In the case of solutions in N-hydrochloric acid the oxidation is catalytically accelerated by a mixture of manganese and iron.4... 

In addition to his work on titrimetry, Gay-Lussac made important contributions in other areas of analytical chemistry. He studied the reactions of hydrogen sulphide in different media, thus laying the foundations for the classification of metals into different analytical groups, and in conjunction with Thenard, he developed the first truly practicable method for the determination of carbon and hydrogen in organic compounds.54... 

In Inorganic Chemistry, typical spray reagents for cations include potassium iodine (0.2%, aqueous), hydrogen sulphide (saturated aqueous solution), ammonium sulphide (0.2 N, aqueous), quercetin (0.1%, alcoholic), l-(2-pyridylazo)-2-naphthol (PAN) (0.2%, methanolic), oxine (8-hydroxyquinoline) (1% methanolic, view under visible and UV light), and sodium rhodizonate (0.5%, aqueous). Reaction with dithizone to produce coloured dithizonate chelates of many metals is particularly suitable if quantitative spectrometric analysis (in situ or after elution) is to be carried out. Anions are detected with bromocresol purple (0.1%, alcoholic), 1% ammoniacal silver nitrate + 0.1% alcoholic fluorescein/UV light, zirconium alizarin lake (0.1% in HC1 solution), and ammonium molybdate (1%, aqueous) followed by SnCl2 (1%) and HC1 (10%). Typical detection limits range from 10 ng (10 9g) to several pg (10 6g). 

The atmospheric chemistry of hydrogen sulphide involves both photochemical and chemical oxidation with the terminal oxidation products being sulphuric acid (H SOJ and inorganic sulphate (SO ). There have been very few studies on the persistence and interconversions of hydrogen sulphide in the atmosphere or imder atmospheric conditions in the laboratory. However, two reports have calculated that the residence of hydrogen sulphide is approximately... 

The chemistry of pitting is quite complex and is explained in most chemistry text books. However, the principle is fairly simple, especially where chlorides are present. At some suitable site on the steel surface (often thought to be a void in the cement paste or a sulphide inclusion in the steel) the passive layer is more vulnerable to attack and an electrochemical potential difference exists that attracts chloride ions. Corrosion is initiated and acids are formed, hydrogen sulphide from the MnS inclusion and HCl from... 

Nils Gabriel Sefstrom (Ilsbo, North Helsingland, 2 June 1787-Stockholm, 30 November 1845), M.D. Uppsala 1813, at first a hospital physician (1813-1817), was from 1812 lecturer in chemistry in the Royal Military Academy at Carlberg and to 1820 assistant in chemistry at the Caroline Institute of Medicine and Surgery, teacher of chemistry at the new School of Mines in Fahlun (1820-39) and (from 1818) professor in the Artillery School in Marie-berg. He published a description of a powerful laboratory blast-furnace, in which he prepared silicon sulphide as a sublimate by heating silica in a carbon crucible in a current of hydrogen sulphide, and other papers. ... 

Certain dissolved gases such as oxygen and carbon dioxide alter groundwater chemistry others affect the use of water. For example, hydrogen sulphide in concentrations of more than 1 mg renders groundwater unfit for human consumption because of the objectionable odour. 

Bandosz TJ. Effect of pore structure and surface chemistry on virgin activated carbons on removal of hydrogen sulphide. Carbon 1999 36(3) 483-491. 

Ugo R, La Monica G, Cenini S, Sergre A, Conti F (1971) Zerovalent platinum chemistry. Part VI. The reactions of bis- and tris-triphenylphosphineplatinum(O) with hydrogen sulphide, hydrogen selenide, sulphur, and related molecules. J Chem Soc A 1971 522-528... 

The corrosion of tin by nitric acid and its inhibition by n-alkylamines has been reportedThe action of perchloric acid on tin has been studied " and sulphuric acid corrosion inhibition by aniline, pyridine and their derivatives as well as sulphones, sulphoxides and sulphides described. Attack of tin by oxalic, citric and tartaric acids was found to be under the anodic control of the Sn salts in solution in oxygen free conditions . In a study of tin contaminated by up to 1200 ppm Sb, it was demonstrated that the modified surface chemistry catalysed the hydrogen evolution reaction in deaerated citric acid solution. 

Another marked physical difference between sulphides and sulphoxides (or sulphones) is that sulphoxides (and lower alkyl sulphones) are hygroscopic and dissolve quite readily in water or protic solvents such as alcohols, and even more so lower alkyl or alkyl aryl sulphoxides are almost freely miscible with water. This can be accounted for by the formation of the strong hydrogen bond between the S—O bond in the sulphoxides and water molecules. Moreover, lower alkyl sulphoxides and sulphones such as dimethyl sulphoxide (DMSO) or sulpholene can dissolve a number of metallic salts, especially those of alkali and alkaline earth metals, and hence these compounds have been widely utilized as versatile and convenient solvents in modern organic chemistry (Table 3). 

Correlations between catalytic activity and a variety of bulk properties of semiconductors have been reported (i) the average band gap of III-V and II-VI semiconductors and activity towards hydrogenation of isopropanol (ii) enthalpy of oxides and their activity towards oxidation of propylene and (iii) number of d-electrons (and crystal field stabilization energy) or 3rf-metal oxides and their activity towards N2O decomposition. The last correlation, due to Dowden (1972), is important since it provides a connection between heterogeneous catalysis and coordination chemistry of transition-metal compounds. A correlation between the catalytic activity of transition-metal sulphides towards hydrodesulphurization of aromatic compounds and the position of the transition metal in the periodic table has been made by Whittingham ... 

Moreover, this study points out the ability of sulphides to catalyze either reactions involving the conversion of sulphur containing molecules without desulphurization (DHN of THT) or desulphurization of these molecules (HDS of thiophene) as well as classical hydrogenation reactions (HN of BP). These properties make the sulphide catalysts interesting to be applied to organic chemistry, particularly in thiochemistry. 

This chapter is concerned with the thermal decompositions of oxides and peroxides. There are obviously very important connections with the reactions of hydroxides (Chapter 8) and so-called peroxysalts, which contain hydrogen peroxide of crystallization (included in Chapter 7 on hydrates). Hydrated oxides vary from compounds accurately represented by the stoichiometric formula M(OH) , to phases which contain discrete HjO molecules. The chemistry of oxides should also be considered in the context of the other binary compounds (e.g. hydrides, nitrides, carbides, sulphides etc.) dealt with in Chapter 10. 

The most employed reducing agents in the old tellurium chemistry were alkali sulphites or hydrogen sulphites, methyhnagnesium iodide and sodium sulphide hydrate. The last reagent is still used, together with the more recently introduced sodium borohydride, TUDO, hydrazine, samarium diiodide and sodium ascorbate. ... 

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