Sulfane, crude

The HgSgn+m, which is formed as an intermediate, reacts in turn with the Sj Clg. Again, HCl is split off. The formation of a homologous mi rture of sulfanes (= crude sulfane, HgSx) is based on this fact. (See also p. 353). 

The lower members of the polysulfane series with n=2-6 have been prepared as pure compounds, while all members with n values up to 35 have been detected by H-NMR spectroscopy in so-called crude sulfane [31]. The gas-phase structures of the first three members of the polysulfane series are well established from either microwave spectra (H2S2 [32], H2S3 [33]) or high-level ab initio MO calculations (H2S4 [34]). Systematic ab initio studies of the structures, vibrational frequencies and heats of formation of H2S with i up to 6 have also been reported [4, 16]. 

Disulfane is usually made from a sulfane mixture known as crude sulfane oil while various methods are available for the preparation of the higher sulfanes. Deuterated sulfanes may be prepared by isotopic exchange with DCl [17]. 

The molecular composition of crude sulfane oil has been determined by... 

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. 

There are a number of other methods to prepare crude sulfane oils, e.g., from hquid H2S and elemental chlorine or bromine [10] or by reaction of H2S with sulfur fluorides [10] or sulfur chlorides [20] but these processes are of httle practical importance. 

Table 1 Concentration of the sulfanes H2Sn and of Sg in two crude sulfane oils A and B (S chemical shift in ppm vs TMS after [19])...

Older Raman data obtained using a mercury lamp are available for the sul-fanes H2S (n=5-8) and for crude sulfane oil. However, there is some suspicion that the lines observed near 150 and 217 cm result from Ss as a byproduct of the preparation reactions or as a photochemical decomposition... 

The homocyclic sulfur oxide SsO was prepared by condensation of thionylchloride with crude sulfane oil at -40 °C applying the dilution principle. It is believed that the product results from the heptasulfane content of the sulfane oil [88] ... 

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... 

A mixture of sulfanes (H S, n = 3, 4,... n = 6) known as crude sulfane reacts with both SeCl4 and Se Cl in carbon disulfide at low temperatures to form cyclic selenium sulfides of types Se Sg and Se Sj2 - On extraction and recrystallization from carbon disulfide a mixture of twelve-membered ring molecules was obtained as yellow crystals with a selenium content of up to 29 weight-% corresponding to the formula SOj 3. As this sample was much less soluble in CSj than both S,2 and compounds of type Se S8 , it could easily be separated from the latter. The twelve-membered ring molecules have so far been characterized by X-ray crystallography only (see 3.2). 

Crude polysulfanes with x = 7 -12 can be obtained in up to 50% yield at the cathode by reduction of SO2/H2SO4 solutions. The initial reaction product at the cathode is dithionous acid H2S2O4, which decomposes in strong acid to give sulfurous acid and sulfane. Persulfate is obtained at the anode. 

Garbrecht prepared the reagent by stirring 10-11 1. of dimethylformamide under a condenser with protection against moisture, cooling to 0-5°, and dropping in 2 lbs. of crude sulfur trioxide in the form of Sulfan B over a period of 4-5 hrs. Some crystalline complex separated, but stirring was continued until it had all dissolved. 

Preparation of S12 from S2CI2 and a polysulfane mixture H2S sulfanes H2S and dichlorosulfanes S Cl2 react with each other with elimination of HCl forming new S-S bonds. Since piue sulfanes with more than two sulfur atoms are difficult to prepare, this synthesis uses a mixture of sulfanes, called crude sulfane oil , which can easily be prepared from aqueous sodium polysulfide and concentrated hydrochloric acid at 0 °C [39, 40] ... 

If crude sulfane is to be prepared continuously in fairly large quantities, the apparatus described by F. Feher and W. Laue should be used. 

Use of sulfane for the preparation of H Sg and H2S3 A crude sulfane which is especially rich in H2S4 and is therefore suited for the production of tetrasulfane is prepared in the followii manner ... 

A solution of NagSg is prepared by heatii 480 g. of NagS OHgO, 64 g. of powdered S and 500 ml. of H3O for three hours in a two-liter round-bottom flask on a steam bath. The cooled solution, suction-filtered to remove S residues, is then decomposed in the manner described above, using four liters of dilute HCl. The yield is 32 ml. of crude sulfane having the approximate composition H3S4.5. 

The number of moles of reagents, a and 6, in the equation below gives the average composition x and the quantity o of crude sulfane formed when the quantity d of unreacted sulfane distilled off after the reaction is determined. The equation was derived on the basis of assumption about the molecular distribution obtained in the condensation of sulfanes and halosulfanes (F. Feher and W. Laue) however, it holds only for the above described reactions under the further restriction that no other reactions take place. 

Interfering side reactions which lead to a h her S content of the crude sulfane are favored, among other things, by too violent a reaction and by too small a sulfane excess. Because of its ease of preparation, only HgS (n = 1) is of importance as a raw material for crude oil. The reagents for the preparation of chlorosulfane are SClg (m = l)and SgClg (m = 2). Elementary chlorine, which reacts very violently, may also be used. Since the product is either distilled or cracked, the formation of side products is of no particvilar Importance. 

The choice of the second component in the reaction with liquid H3S usually depends either on the sulfane which is to be distilled directly from the crude mixture or, if cracking is to follow the primary reaction, on the composition of the sulfane mixture which is best suited for that process. 

Both of these hydrc en sulfide compounds are formed by crackii of crude sulfane, usii the apparatus shown in Fig. 154. 

An oven-dried amber vial was charged with PhaPAuCl (25 mg, 0.050 mmol) and AgBp4 (9.7 mg, 0.050 mmol) under an atmosphere of N2. The mixture was stirred in anhydrous CH2CI2 (1.0 mL) for several minutes. To this was added benzenethiol (0.10 mL, 1.0 mmol), then 3-methylpenta-1,3-diene (cis/trans mixture, 0.14 mL, 1.2 mmol), and the mixture was stirred overnight. The mix was then filtered through a Celite 545 pad and the solvent removed via rotavap. The crude material was then purified by column chromatography on silica gel (hexane), and the solvent was removed to yield (3-methylpent-3-en-2-yl)(phenyl)sulfane as an off-white oil (0.17 g, 90%). ... 

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