Sulfur, liquid ammonia solutions

Sulfur—nitrogen anions in sulfur—liquid ammonia solutions... 

Reduction. Benzene can be reduced to cyclohexane [110-82-7], C5H12, or cycloolefins. At room temperature and ordinary pressure, benzene, either alone or in hydrocarbon solvents, is quantitatively reduced to cyclohexane with hydrogen and nickel or cobalt (14) catalysts. Catalytic vapor-phase hydrogenation of benzene is readily accomplished at about 200°C with nickel catalysts. Nickel or platinum catalysts are deactivated by the presence of sulfur-containing impurities in the benzene and these metals should only be used with thiophene-free benzene. Catalysts less active and less sensitive to sulfur, such as molybdenum oxide or sulfide, can be used when benzene is contaminated with sulfur-containing impurities. Benzene is reduced to 1,4-cydohexadiene [628-41-1], C6HS, with alkali metals in liquid ammonia solution in the presence of alcohols (15). 

Acetylene and Potassium in Liquid Ammonia Potassium (40 g) is dissolved in 1 liter of dry liquid ammonia. Dry acetylene is then bubbled into the solution until the blue color is discharged. A solution of 15 g of estrone in 300 ml of dioxane is prepared and diluted with 300 ml of ether, cooled, and added to the potassium acetylide solution over a period of 10 min. The liquid ammonia is allowed to evaporate, an additional 500 ml of ether is added, and the mixture is allowed to stand overnight. About 3 liters of 5 % sulfuric acid is added and the organic layer separated. The water layer is re-extracted with fresh ether, and the combined ether extracts are washed twice with 5 % sodium carbonate solution, th6n several times with water, and finally evaporated under reduced pressure. The residue is dissolved in 150 ml of methanol, then an equal quantity of hot water is added and the mixture cooled. The precipitated solid is collected, washed with cold 60 % methanol and crystallized once from methanol-water to give 14.8 g (85%) of 17a-ethynylestradiol mp 143-144°. 

Sulfur dissolves in liquid ammonia to give intensely coloured solutions. The colour is concentration-dependent and the solutions are photosensitive.Extensive studies of this system by several groups using a variety of spectroscopic techniques, primarily Raman,... 

In about 250 cc of liquid ammonia (cooled with dry ice and acetone) are dissolved about 7.5 g of potassium and into the solution acetylene is passed until the blue color has disappeared (about 3 hours). Then slowly a solution or suspension of 3 g of estrone in 150 cc of benzene and 50 cc of ether is added. The freezing mixture is removed, the whole allowed to stand for about 2 hours and the solution further stirred overnight. Thereupon the reaction solution is treated with ice and water, acidified with sulfuric acid to an acid reaction to Congo red and the solution extracted five times with ether. The combined ether extracts are washed twice with water, once with 5% sodium carbonate solution and again with water until the washing water is neutral. Then the ether is evaporated, the residue dissolved in a little methanol and diluted with water. The separated product is recrystallized from aqueous methanol. The yield amounts to 2.77 g. The 17-ethiny I-estradiol-3,17 thus obtained melts at 142°C to 144°C . 

Ammonia is one of the most important inorganic chemicals, exceeded only by sulfuric acid and lime. This colorless gas has an irritating odor, and is very soluble in water, forming a weakly basic solution. Ammonia could be easily liquefied under pressure (liquid ammonia), and it is an important refrigerant. Anhydrous ammonia is a fertilizer by direct application to the soil. Ammonia is obtained by the reaction of hydrogen and atmospheric nitrogen, the synthesis gas for ammonia. The 1994 U.S. ammonia production was approximately 40 billion pounds (sixth highest volume chemical). 

The chemistry of elemental sulfur and sulfur-rich molecules including polysulfides in liquid ammonia [82] and in primary as well as secondary amines [83] is complex because of the possible formation of sulfur-nitrogen compounds. Therefore, polysulfide solutions in these solvents will not be discussed here. Inert solvents which have often been used are dimethylfor-mamide (DMF) [84-86], tetrahydrofuran (THF) [87], dimethylsulfoxide (DMSO) [87], and hexamethylphosphoric triamide (HMPA) [86, 88]. 

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],... 

Some illustrative examples of the application of 14N NMR spectroscopy in sulfur-nitrogen chemistry include (a) studies of the (NSC1)3<->3NSC1 equilibrium in solution28 and (b) identification of the S-N species present in solutions of sulfur in liquid ammonia.29... 

Sulfur and nitrogen form a variety of binary anions with acyclic, cyclic and cage structures.69,70 The Se-N anions are only known in metal complexes. S-N anions play an important role in the formation of cyclic sulfur imides and as constituents of solutions of sulfur in liquid ammonia. 

Sulfur dissolves in liquid ammonia to give intensely coloured solutions. The colour is concentration-dependent and the solutions are photosensitive. Several S-N anions are present in such solutions.76,77 The primary reduction products are polysulfides Sx2, which dissociate to polysulfur radical anions, notably the deep blue S3 ion. In a 1M solution, the major S-N anion is cyc/0-[S7N] with smaller amounts of 21 and a trace of 20.76... 

Note that the word proton refers to the nucleus of a hydrogen atom — an H ion that has been removed from the acid molecule. It does not refer to a proton removed from the nucleus of another atom, such as oxygen or sulfur, that may be present in the acid molecule. As mentioned previously, ions share electrons with any species (ion or molecule) that has a lone pair of electrons. In aqueous solution, the proton bonds with a water molecule to form the hydronium ion. Unlike the Arrhenius theory, however, the Brqnsted-Lowry theory is not restricted to aqueous solutions. For example, the lone pair of electrons on an ammonia molecule can bond with H+, and liquid ammonia can act as a base. 

Reduction of dibenzothiophene with sodium in liquid ammonia has been shown to be sensitive to the experimental methods employed however, the major product is usually 1,4-dihydrodibenzothiophene. 27 -28i The electrochemical reduction of dibenzothiophene in ethylene-diamine-lithium chloride solution has been shown to proceed via stepwise reduction of the aromatic nucleus followed by sulfur elimination. In contrast to the reduction of dibenzothiophene with sodium in liquid ammonia, lithium in ethylenediamine, or calcium hexamine in ether, electrolytic reduction produced no detectable thiophenol intermediates. Reduction of dibenzothiophene with calcium hexamine furnished o-cyclohexylthiophenol as the major product (77%). Polaro-graphic reduction of dibenzothiophene 5,5-dioxide has shown a four-electron transfer to occur corresponding to reduction of the sulfone group and a further site. ... 

It has been known for many years that elemental sulfur dissolves in liquid ammonia to give colored solutions which are green or blue at room temperature and red at lower temperatures. The blue chromophores have recently been identified by Raman spectroscopy as S N and 610 nm) . The former ion is... 

Arsine is produced by the reaction of arsenic trichloride, arsenic trioxide or any inorganic arsenic compound with zinc and sulfuric acid. It is also made by treating a solution of sodium arsenide or potassium arsenide in liquid ammonia with ammonium bromide ... 

Colorless crystals triclinic structure density 2.435g/cm3 at 13°C melts above 315°C decomposes on further heating soluble in water, 28.6 g/lOOmL at 25°C highly soluble in boiling water, lOOg/100 mL at 100°C aqueous solution strongly acidic, pH of 0.1 M solution 1.4 insoluble in liquid ammonia decomposed by alcohol into sodium sulfate and sulfuric acid... 

The dissolution of sulfur in ammonia has been known for more than 100 years [17]. The identification of the chemical species in these solutions was a matter of confusion until the identification of S4N and 83 , by Chivers and Lau [18] and Bernard et al. [19], using Raman spectroscopy. When considering the species formed in the dissolution process, it is quite remarkable that this dissolution is reversible sulfur is recovered after evaporation of ammonia. These solutions are strongly colored (blue), mainly due to the electronic absorption band of S4N at 580 nm. It must be mentioned that this dissolution is moderately fast at room temperature (but much slower than the dissolution of alkali metals) and that the rate is much slower when temperature decreases. It should also be mentioned that concentrated solutions of sulfur in liquid ammonia can be used as the solution at the positive electrode of a secondary battery. The solution at the negative electrode can be a solution of alkali metal in liquid ammonia [20], the electrodes being... 

The reduction of sulfur by hydrogen sulfide in liquid ammonia leads to (NH4)28 , ammonium polysulfide solutions, following ... 

As early as 1804, it was reported that sulfur dissolves in oleum to give brown, green or blue solutions [76]. As for solutions of sulfur in liquid ammonia, the nature of the colored species has been controversial. It was shown 30 years ago that sulfur can be oxidized with S2O6F2, AsFg, or SbFg in various solvents (H2SO4, HFSO3, HF, oleum) to polyatomic cations Sg +,... 

Physical properties of the solvent are used to describe polarity scales. These include both bulk properties, such as dielectric constant (relative permittivity), refractive index, latent heat of fusion, and vaporization, and molecular properties, such as dipole moment. A second set of polarity assessments has used measures of the chemical interactions between solvents and convenient reference solutes (see table 3.2). Polarity is a subjective phenomenon. (To a synthetic organic chemist, dichloromethane may be a polar solvent, whereas to an inorganic chemist, who is used to water, liquid ammonia, and concentrated sulfuric acid, dichloromethane has low polarity.)... 

The concentrations of O17 used in the work of Jackson, Lemons, and Taube proved too low for very accurate determination of hydration numbers. Water samples more highly enriched in O17 should provide the basis for important studies of solvation phenomena in solution. This approach could be extended to other solvent systems such as liquid ammonia, amines, and acetonitrile (N14 or N16 resonances), ethers, sulfur dioxide, and di-methylsulfoxide (O17), and BrF3 (F19). 

The flask is charged with about 3 1. of liquid ammonia (Note 1), the stirrer is started, and a rapid stream of acetylene gas (about 5 bubbles per second) is passed in for about 5 minutes to saturate the ammonia. The acetylene from a tank is sufficiently purified by passage through a sulfuric acid wash bottle a safety trap also should be inserted in the line. Sodium (92 g., 4 gram atoms) is cut in strips (about by 3 by 3 in.) so that they can be inserted through the side neck of the flask. One of these pieces of sodium is attached to the fish-hook and is gradually lowered into the liquid ammonia while a rapid stream of acetylene is passed in. fl he sodium should be added at such a rate that the entire solution does not turn blue. If it does, the sodium should l)i raised above the level of the ammonia until the color is discharged (Note 2). I lie rest of the sodium is added in a similar... 

Indirect effects in nonaqueous media have received very little attention. It is likely that semiselective chemical reactions will occur in organic solvents containing active solutes. Liquid ammonia and sulfur dioxide also might offer some possibilities as solvents. The direct action of densely ionizing radiation on ammonia to produce hydrazine might yield reasonable quantities of this important reagent. 

Almost all of the reactions that the practicing inotganic chemist observes in the laboratory take place in solution. Although water is the best-known solvent, it is not the only one of importance to the chemist. The organic chemist often uses nonpolar solvents sud) as carbon tetrachloride and benzene to dissolve nonpolar compounds. These are also of interest to Ihe inoiganic chemist and, in addition, polar solvents such as liquid ammonia, sulfuric acid, glacial acetic acid, sulfur dioxide, and various nonmctal halides have been studied extensively. The study of solution chemistry is intimately connected with acid-base theory, and the separation of this material into a separate chapter is merely a matter of convenience. For example, nonaqueous solvents are often interpreted in terms of the solvent system concept, the formation of solvates involve acid-base interactions, and even redox reactions may be included within the (Jsanovich definition of acid-base reactions. 

The oxidation-reduction potentials of metal ions differ in different solvents due chiefly to differences in the strength of coordination of the solvents to the metal ions. Thus, Schaap and coworkers,33 who measured reduction potentials polarographically in anhydrous ethylenediamine, found the order of half-wave potentials to be Cd2+ > Pb2+ > Cu2+ - Cu+ > Ti+, whereas, in aqueous solution, the order is Cd2+ > Ti+ > Pb2+ > Cu2+ -> Cu+. Oxidation—reduction potentials have been measured in a great variety of non-aqueous solvents, both protonic and non-protonic. Among the former are liquid ammonia and concentrated sulfuric acid.34 Among the latter are acetonitrile, cyanopropane, cyanobenzene, dimethyl sulfoxide, methylene chloride, acetone, tet-rahydrofuran, dimethylformamide and pyridine.34... 

Other low-temperature studies have been motivated by the desire to characterize and understand processes occurring in unusual media. For example, the use of liquid ammonia [8-10] and liquid sulfur dioxide [11-13] naturally requires reduced temperatures unless high pressures are used, as is done for electrochemistry in supercritical fluids [14]. Frozen media are interesting systems in terms of mass transport phenomena and microstructural effects. Examples include glasses of acetonitrile and acetone [15], frozen dimethyl sulfoxide solutions [16,17], and the solid electrolyte HC104 5.5 H20 [18-20]. 

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