Preparative polysulfides

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. 

Thiols can be utilized to prepare polysulfides such as 2,2,6,6-tetramethyl-3,4,5-trithiaheptane. These are prepared (eq. 20) using sulfur as the only oxidant (34,35). 

In contrast to polysulfides, cationic polymerization is the only method to prepare high-molecular-weight polyamines. Polyethyleneimine is the only polymer commercialized among the group of cationically prepared polysulfides and polyamines. Branched polyethyleneimines, are used on the technical scale mostly as flocculants. 

The reaction of formaldehyde (paraformaldehyde) and hydrogen chloride (anhydrous) with tetrahydrofuran has been used to produce -chlorobutyl chlor-omethyl ether [15] a halide useful for preparing polysulfides [Eq. (3)]. 

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. 

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]. 

Consequently, sulfur dissolves in polysulfide solutions much faster than in equimolar monosulfide solutions [73]. In this context it is of interest that the analogous decaselenium dianion Scio has been prepared and structurally characterized in solid [PPN]2Seio [74]. This anion is however bi-cyclic. 

More recently, 84 may have been identified by ESR spectroscopy of solutions of Li2S ( >6) in DMF at 303 K. The lithium polysulfide was prepared from the elements in liquid ammonia. These polysulfide solutions also contain the trisulfide radical anion ( 2.0290) but at high sulfur contents a second radical at g=2.031 (Lorentzian lineshape) was formed which was assumed to be 84 generated by dissociation of octasulfide dianions see Eq. (32) [137],... 

Since heptasulfane is difficult to prepare, a mixture of polysulfanes known as crude sulfane oil was used instead (average composition H2S6.2, accessible from sodium polysulfide and hydrochloric acid [71]). From 104 g of... 

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