Silicon sulphides

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. ... 

Treatment of steroid dienones with tetraphosphorus decasulphide gave the previously unreported purple-blue dienethiones (6). An analogous reaction is claimed to yield 2-arylindane-l,3-dithione. Sulphurization with boron sulphide or silicon sulphide was applied to the synthesis of pyran-4-thione rings. A new... 

Further studies have been reported of the use of boron and silicon sulphides in sulphurization reactions. One of the products obtained in the pyrano-pyrone series has been converted into the l,6-dioxa-6a-thiapentalene (28). 

The presence of active sulphate-reducing bacteria usually results in graphitic corrosion and this has led to a useful method of diagnosing this cause of corrosion. The leaching out of iron from the graphitic residue which is responsible for the characteristic appearance of this type of corrosion leads to an enriched carbon, silicon and phosphorus content in the residue as compared with the original content of these elements in the cast iron. Sulphur is usually lost to some extent but when active sulphate-reducing bacteria are present, this loss is offset by the accumulation of ferrous sulphide in the residue with a consequent increase in the sulphur content of the residue out... 

In general, greatly reduced rates of attack are observed for impure or dilute nickel alloys compared with pure nickel when exposed to SO2 + O2 atmospheres. Haflan et al. have attributed this to the segregation of impurities at the sulphide/oxide interface causing breakup of the sulphide network. For example in the case of silicon additions, it has been shown that silicates form and it has been proposed that these alter the wetting characteristics of the sulphide and prevent the establishment of an interconnected sulphide network. 

Heating with the following solids, their fusions, or vapours (a) oxides, peroxides, hydroxides, nitrates, nitrites, sulphides, cyanides, hexacyano-ferrate(III), and hexacyanoferrate(II) of the alkali and alkaline-earth metals (except oxides and hydroxides of calcium and strontium) (b) molten lead, silver, copper, zinc, bismuth, tin, or gold, or mixtures which form these metals upon reduction (c) phosphorus, arsenic, antimony, or silicon, or mixtures which form these elements upon reduction, particularly phosphates, arsenates,... 

The arrangement of oxygen atoms in ice I is isomorphous with the wurtzite form of zinc sulphide, and also with the silicon atoms in the tridymite form of silicon dioxide. Hence, ice I is sometimes referred to as the wurtzite or tridymite form of ice (Eisenberg Kauzmann, 1969). 

The chemistry of a-haloketones, a-haloaldehydes and a-haloimines Nitrones, nitronates and nitroxides Crown ethers and analogs Cyclopropane derived reactive intermediates Synthesis of carboxylic acids, esters and their derivatives The silicon-heteroatom bond Syntheses of lactones and lactams The syntheses of sulphones, sulphoxides and cyclic sulphides... 

These incorporate membranes fabricated from insoluble crystalline materials. They can be in the form of a single crystal, a compressed disc of micro-crystalline material or an agglomerate of micro-crystals embedded in a silicone rubber or paraffin matrix which is moulded in the form of a thin disc. The materials used are highly insoluble salts such as lanthanum fluoride, barium sulphate, silver halides and metal sulphides. These types of membrane show a selective and Nemstian response to solutions containing either the cation or the anion of the salt used. Factors to be considered in the fabrication of a suitable membrane include solubility, mechanical strength, conductivity and resistance to abrasion or corrosion. 

The Ag2 S ISEs used in practice are of three kinds with a heterogeneous membrane containing Ag2 S precipitate (preferably precipitated from excess sulphide or by the action of H2 S [228]) in a matrix of silicon rubber [346] or a thermoplastic material [248], with a pressed pellet as a membrane [235,... 

Boron and silicon likewise decompose hydrogen sulphide at high temperatures, liberating hydrogen and forming sulphides.11... 

The sulphides of aluminium and silicon are decomposed immediately by water at the ordinary temperature, whilst even the sulphides of the heavier metals such as copper, lead and iron are decomposed by steam at a red heat3 (see also p. 50) ... 

The combustion of fluorine in moist hydrogen sulphide or the interaction of fluorine and dry hydrogen sulphide in a glass vessel (the last-named supplying the necessary oxygen) also gives rise to a mixture of sulphuryl fluoride with thionyl fluoride, sulphur hexafluoride and silicon fluoride.3... 

It attacks glass at a red heat, giving silicon tetrafluoride and sulphur trioxide. Carbon and boron are without action on the gas at a red heat, but sodium at a temperature considerably above the melting-point causes gradual decomposition with absorption. Hydrogen sulphide, aided by heat, attacks both thionyl and sulphuryl fluorides, inducing decomposition.1... 

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