Polysulfides, preparation

Concerning the composition of alkali polysulfide, the yield of thiolane 7 suffered none in utilizing alkali polysulfide prepared from hydrated sodium sulfide or lithium or potassium sulfide rather than anhydrous sodium sulfide. When the ratio of sulfur to hydrated sodium sulfide was 8 1 or greater, the thiolane 7 resulted whereas at a ratio of 4 1, or using commercial Na, several components containing both sulfur and carbon were detected in me solid proauct. 

Willgerodt reaction. In its original form this reaction involved heating an aryl alkyl ketone in a sealed tube at 210-230° with an aqueous solution of yellow ammonium polysulfide, prepared by dissolving sulfur in ammonium sulfide solution. The product is an aryl substituted aliphatic aciil amide, together with some of the corresponding carboxylic acid and often the hydrocarbon. An example is the... 

Polysulfides prepared heavy residues from vinyl chloride production [150]. 

A suspension of 20.1 g 1,5-dimethoxy-2,4-dinitrobenzene (90.0 mmol) in 117 mL water was stirred under reflux and treated dropwise over 30 min with a solution of sodium polysulfide, prepared by heating 28.6 g Na2S-9H20 (119 mmol) and 6.8 g sulfur (213 mmol) in 120 mL water. The reaction mixture was stirred under reflux for a further 3 h and then cooled and evaporated under reduced pressure at 45°C to give a dark residue. This was extracted several times with warm EtOAc, and the combined extracts were filtered through a short column of silica gel. The eluates were washed with water and evaporated to dryness. The residue was dissolved in 1 N HCl, filtered, and basified with aqueous NaOH to give 11.0 g l-amino-2,4-dimethoxy-5-nitrobenzene, in a yield of 63%, m.p. 126-128°C. 

Another problem to be discussed is the nonequilibrium state of the powdered polysulfides prepared by solid-gas interactions. In these cases the rate-controlling process is most often the sulfur diffusion in solids. A thick product layer formed on the unreacted starting solid inhibits the sulfur diffusion, resulting in a nonequilibrium state. To describe this state, one can use some indicators which are shared by many sulfide materials (Vaughan and Craig 1978). First, there is a greater number of phases on the surface of the solids than would follow from Gibbs rule the duration of the experiment has a dramatic effect on the number of phases and the compositional identity of the final products. 

Second, there is no reproducibility of the resulting compositions in duplicate experiments. Third, die final products of the same gross composition reactions, for instance, R+2S or RS. 50+0-5S, are not always identical, and depend on the origin of the starting products and the sequence of temperature and pressure variation. With these principles, one can suggest that the powdered polysulfides prepared by different authors (see sect. 3.3) can hardly be related to equilibrium materials. A multiphase surface state of powders has a serious effect on many properties and, thus, merits detailed consideration here. It is apparent that special means must be used to provide data on the gross composition and the spatial variation of the sulfur content over the grain. 

Polythiodipropionic acids and their esters are prepared from acryUc acid or an acrylate with sulfur, hydrogen sulfide, and ammonium polysulfide (32). These polythio compounds are converted to the dithio analogs by reaction with an inorganic sulfite or cyanide. 

The dinuclear ion Mo2(S2) g (F - prepared from the reaction of molybdate and polysulfide solution (13) is a usehil starting material for the preparation of dinuclear sulfur complexes. These disulfide ligands are reactive toward replacement or reduction to give complexes containing the Mo2S " 4 core (Fig. 3f). 

Agrochemical Products. Hydrazones of vanillin have been shown to have a herbicidal action similar to that of 2,4-D, and the zinc salts of dithiovanillic acid. Made by the reaction of vanillin and ammonium polysulfide in alcohoHc hydrochloric acid, dithiovanillic acid is a vulcanization inhibitor. 5-Hydroxymerciirivanillin, 5- a cetoxym erci iri va n ill in, and 5-ch1oromercurivani11in have been prepared and found to have disinfectant properties. 

Hydrogen cyanide (HCN) and aliphatic nittiles (RCN) can be used to form imidazolines. For example, EDA and HCN form 2-imidazoline (38). In the presence of sulfur or polysulfides as catalysts, 2-aIkyl-2-imidazolines can be prepared from ahphatic nitriles and EDA (39,40). 

Sulfur dyes are used for dyeing ceUulosic fibers. They are insoluble in water and are reduced to the water-soluble leuco form for appHcation to the substrate by using sodium sulfide solution. The sulfur dye proper is then formed within the fiber pores by atmospheric oxidation (5). Sulfur dyes constitute an important class of dye for producing cost-effective tertiary shades, especially black, on ceUulosic fibers. One of the most important dyes is Cl Sulfur Black 1 [1326-82-5] (Cl 53185), prepared by heating 2,4-dinitrophenol with sodium polysulfide. 

Hydrocarbon Gngnard reagents give the alkyl cyanides, whereas perfluo-rinated Grignard reagents produce the sulfides This reaction is useful for the preparation of alkyl perfluoroalkyl sulfides to the exclusion of di and polysulfides, which are produced by other methods... 

The polysulfanes were at one time made by fusing cmde Na2S.9H20 with various amounts of sulfur and pouring the resulting polysulfide solution into an excess of dilute hydrochloric acid at — 10°C. The resulting cmde yellow oil is a mixture mainly of H2S (n = 4-7). Polysulfanes can now also be readily prepared by a variety of other reactions, e.g. ... 

Since the chain-lengths of the molecules present in crude sulfane oil is different from the chain-length of the anions in the original sodium polysulfide solution one has to conclude that in addition to the reaction at Eq. (4) the reactions at Eqs. (5) and (6) also take place during the preparation by protonation of the polysulfide anions. 

MeO)2S [36]. These evidently originated from the reaction of the dichloro-sulfanes with the methanol solvent used in the preparation of the sulfanes by mixing sodium polysulfide with dichlorosulfanes. 

Abstract Inorganic polysulfide anions and the related radical anions S play an important role in the redox reactions of elemental sulfur and therefore also in the geobio chemical sulfur cycle. This chapter describes the preparation of the solid polysulfides with up to eight sulfur atoms and univalent cations, as well as their solid state structures, vibrational spectra and their behavior in aqueous and non-aqueous solutions. In addition, the highly colored and reactive radical anions S with n = 2, 3, and 6 are discussed, some of which exist in equilibrium with the corresponding diamagnetic dianions. 

On the other hand, the large activation energy for the formation of sulfate from 8g and water makes it possible to prepare polysulfides as well as other reduced sulfur compounds as metastable products in aqueous solution at ambient conditions. 

Polysulfides have been prepared with many different types of cations, both monoatomic Hke alkah metal ions and polyatomic Hke ammonium or substituted ammonium or phosphonium ions. In this chapter only those salts will be discussed in detail which contain univalent main-group cations although a large number of transition metal polysulfido complexes have been prepared [7-9]. 

The reaction at Eq. (12) allows the preparation of Na2S4 and K2S5 from the alkali metals, hydrogen sulfide and sulfur in anhydrous ethanol (ROH). First the metal is dissolved in the alcohol with formation of ethanolate (MOR) and hydrogen. Bubbling of H2S into this solution produces the hydrogen sulfide (MHS). To obtain the polysulfide the solution is refluxed with the calculated amount of elemental sulfur. After partial evaporation of the solvent and subsequent cooling the product precipitates. 

Polysulfides with two-valent complex cations, e.g., [M(N-methyhmida-zole)6]Ss have been prepared with M = Mn, Fe, Ni, Mg [51]. 

The generated polysulfide dianions of different chain-lengths then establish a complex equilibrium mixture with all members up to the octasulfide at least see Eqs. (5) and (6). For this reason, it is not possible to separate the polysulfide dianions by ion chromatography [6]. The maximum possible chain-length can be estimated from the preparation of salts with these anions in various solvents (see above). However, since the reactions at Eqs. (22) and (23) are reversible and Sg precipitates from such solutions if the pH is lowered below a value of 6, the nonasulfide ion must be present also to generate the Sg molecules by the reverse of the reaction at Eq. (22). The latter reaction (precipitation of Sg on acidification) may be used for the gravimetric determination of polysulfides [11]. There is no evidence for the presence of monoprotonated polysulfide ions HS - in aqueous solutions [67, 72]. 

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