Sulfides, preparation

Permanent coloration can also be achieved by exposing hair to certain metals copper, silver, and especially lead salts. Preparations containing aqueous solutions of lead acetate may include a source of sulfur, usually thiosulfate, which may react with cystine in the hair to produce some cysteine or may react directiy with the metal ion to form dark metallic sulfides. Preparations of this type, which darken hair gradually, are not universally considered safe. 

Alkyl phosphates, preparation, 16, 9 Alkyl sulfides, preparation, 15, 72 JV-Alkyl- -toluidines, 18, 42 Allantoin, 13,1... 

Octachlorodibenzothiophene (88) has been formed by irradiation of a solution of pentachlorobenzenesulfenyl chloride in CCI4 in a low-pressure, cold cathode mercury arc (62%). A similar photolysis of bis-(pentachlorophenyl) sulfide, prepared by the action of sulfur monochloride and sulfuryl chloride on benzene in the presence of aluminum chloride, also yielded 88 (42%). Both routes are shown in Scheme 4. 

Though Raman spectroscopy and HPLC provide important tools for the chemistry of cyclic selenium sulfides it will be essential to design new chemical reactions for the preparation of as pure phases as possible. With identification and characterization of each new molecule a new standard for HPLC has been obtained and more information gained of the nature of sulfur-selenium pha s. Synthetic chemistry, Raman spectroscopy, and HPLC may well provide the key for a better understanding of the molecular composition of the cyclic selenium sulfides prepared according to the above-mentioned methods. 

XPS has been of use in revealing the oxidation of MC species in LB films. For example with films containing CdS, constructed from a mixed BeH/octadecyl amine monolayer on a subphase of stabilized CdS particles, only one oxygen state was found (79). By contrast, three oxygen states were found for the colloid in solution, indicating that the CdS in the film is protected from oxidation. This result correlated well with an observation that copper sulfide made in an LB film is resistant to oxidation when compared to copper sulfide prepared analogously in solution (9). The decomposition, via oxidation, of PbS made in films of StH has been followed by XPS (68,70). One study found that the decomposition rate of PbS was much slower for films deposited at faster rate (70). It was suggested that films deposited at the faster deposition rate were more ordered and this presented a barrier to PbS decomposition via oxidation. 

Bis(2-pyrrolyl) sulfides, prepared from the reaction of the pyrrole with sulfur dichloride, are useful precursors in the synthesis of corroles and related compounds, as it is possible to cause the extrusion of the sulfur atom with the consequent formation of a bipyrrolic unit within the macrocycle <72JCS(P1)1124). 

Cement, dry process Cement, wet process, 44% water Limestone calcination Dolomite calcination Alumina preparation Barium sulfide preparation Ignition of inorganic pigments Iron pyrite roasting... 

Polyferrocenylphosphines, via polycondensation, 12, 321 Polyferrocenylphosphine-sulfides, preparation, 12, 338—339 Polyferrocenylsilane block co-polymers... 

Several chiral sulfides have been found to be suitable organocatalysts for enantiose-lective epoxidation as illustrated in Scheme 6.87A. An early example was reported by the Furukawa group using sulfides prepared from (+)-camphorsulfonic acid... 

Small Quantities. Wear nitrile rubber gloves, eye protection, laboratory coat, and respirator (or work in hood). The selenium salt is dissolved in water and the solution is neutralized by the addition of 1 M NaOH (prepared by dissolving 4 g of NaOH in 100 mL of water) or 1 M sulfuric acid (prepared by cautiously adding 5 mL of concentrated acid to 85 mL of cold water). A 1 M solution of sodium sulfide (prepared by dissolving 7.8 g of Na2S in 100 mL of water) is added to the selenium salt solution and the pH is again adjusted to neutral with 1 M sulfuric acid solution. The precipitate is separated by filtration or decantation. Wash, dry, and recycle or send for disposal in a secure landfill.1 ... 

Cycloalkenyllithiums.3 Alkenyllithiums are usually prepared by reductive lithiation of trisylhydrazones of ketones with butyllithium, but this method fails with the hydrazones of cyclic ketones. However, the cycloalkenyl sulfides, prepared by reaction of cyclic ketones with thiophenol, can be reductively lithiated with LDBB at -78°. This lithiation fails in the case of cyclopentenyl sulfides, but is useful in the case of the vinyl sulfides obtained from 6-, 7-, and 8-membered cycloalkanones. 

The approach described later on in this chapter builds upon a report in 2002, in which we proposed microfluidic reactors as favourable systems for nanoparticle synthesis, and showed that nanocrystalline cadmium sulfide prepared in such reactors exhibited improved monodispersity compared with particles prepared in conventional bulk-scale vessels (Edel et al., 2002). 

Tin(IV) sulfide can be prepared by hydrogen sulfide precipitation of Sn(IV) from solution, to produce a microcrystalline material that is contaminated with oxide. Mosaic gold is a crystalline form of tin(IV) sulfide prepared by high-tempera-ture sublimation procedures. Mosaic gold is the reported product of heating mixtures of (1) tin and sulfur (2) tin, sulfur, and ammonium chloride (3) tin, sulfur, mercury, and ammonium chloride 9 (4) tin(II) oxide, sulfur, and ammonium chloride 9 (5) tin(II) chloride and sulfur 9 (6) tin(II) sulfide, tin(II) chloride, and sulfur.9... 

This is well illustrated by the case of tetrahydrothiophene. This monomer cannot be polymerized at ambient temperatures because AG , calculated from a ringstrain of 2.0 kcal (50) and assuming AS equal to —20 cal K-1 mol-1 has a value of +4.0 kcal at 300 °K which would correspond to an equilibrium monomer concentration of more than 1G2 mol l-1, a value that can never be obtained. Inversely, poly-(tetramethylene sulfide), prepared by polycondensation, should degrade to form tetrahydrothiophene when the reactive species, necessary to allow this degradation, are introduced in the polymer. It was indeed shown that addition of a catalytic amount of triethyloxonium tetrafluoroborate to a solution of poly(tetramethy-lenesulfide) resulted in degradation of the polymer with formation of tetrahydrothiophene (51). 

The nonstoichiometric phases TiS2 and Ti2S3 have been studied in sulfides prepared by direct synthesis at 1000° and 800° C. Lattice constants and densities have been measured as functions of composition. Characteristics of the transition from the TiS2 crystal structure to the Ti2S3 structure have been investigated. 

S/Ti 1.7 then a discontinuity in the c parameter appears at this composition. This value agrees precisely with the phase limit reported by Ehrlich (2) yet careful examination of the patterns obtained with the monochromator reveals that, beyond a value of about 1.8 in the S/Ti ratio, additional sharp lines appear alongside those of the TiS2 phase, whose lattice constants, however, do not stop changing (6). For sulfides prepared at 1000° C. these additional lines first appear at S/Ti = 1.810, and for 800° C. at S/Ti = 1.818. The limits determined in this way are known with a precision estimated at 0.005. 

Figure 4. Variation of parameters as a function of composition Sulfides prepared at 8000 C.

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