Hydrosulfides

Zinin Reduction. The method of reducing aromatic nitro compounds with divalent sulfur is known as the Zinin reduction (57). This reaction can be carried out in a basic media using sulfides, polysulfides, or hydrosulfides as the reducing agent. These reactions can be represented as follows when the counter ion is sodium ... 

The compound can be prepared from 2,4,6-trinitrophenol (picric acid [88-89-1]) by reduction with sodium hydrosulfide (163), with ammonia —hydrogen sulfide followed by acetic acid neutralization of the ammonium salt (164), with ethanolic hydrazine and copper (165), or electrolyticaHy with vanadium sulfate in alcoholic sulfuric acid (159). Heating 4,6-dinitro-2-benzamidophenol in concentrated HQ. at 140°C also yields picramic acid (166). 

Sohd ammonium sulfide decomposes to ammonia and ammonium hydrosulfide at about — 18°C consequently it is normally marketed as a 40—44% aqueous solution. In June 1991 the price was 507 per metric ton. 

Ammonium Hydrosulfide. The reaction of equimolar amounts of ammonia and hydrogen sulfide results in the formation of ammonium hydrosulfide [12124-99-1/, NH HS, which is also produced by the loss of ammonium from ammonium sulfide. The hydrosulfide is very soluble in water,... 

Chloropyridine N-oxide reacts with sodium hydrosulfide to give pyrithione [1121-31-9] (45), the zinc salt of which is used as an... 

Fig. 1. Density of sodium hydrosulfide solutions ia water, where the numbers on the vertical lines represent concentrations of NaSH ia wt % (1).

Economic Aspects and Uses. Production and sales values for high purity sodium hydrosulfide are Hsted ia Table 1. These figures exclude the low purity material produced by oil refiners, beHeved to be sold primarily to pulp mills. Estimates of uses of NaHS ia the United States for 1994 are as shown (3,4) ... 

In many appHcations sodium hydrosulfide and sodium sulfide are interchangeable. Where either chemical may be used, 28% less sodium hydrosulfide is required by weight to achieve a given level of sulfidity and is therefore the more economical choice. If desired, the sodium hydrosulfide can be converted to sodium sulfide by the addition of sodium hydroxide ... 

Another process involves two steps. Sodium hydrosulfide from equation 1 reacts with sodium hydroxide to yield sodium sulfide (eq. 2). Concentration by evaporation to 60 wt % is practiced unless concentrated sodium hydroxide is used. 

A double end point, acid—base titration can be used to determine both sodium hydrosulfide and sodium sulfide content. Standardized hydrochloric acid is the titrant thymolphthalein and bromophenol blue are the indicators. Other bases having ionization constants in the ranges of the indicators used interfere with the analysis. Sodium thiosulfate and sodium thiocarbonate interfere quantitatively with the accuracy of the results. Detailed procedures to analyze sodium sulfide, sodium hydro sulfide, and sodium tetrasulfide are available (1). 

Sodium Sulfide and Sodium Hydrosulfide as Heavy MetalPrecipitants, Technical Service Bulletin, PPG Industries, New Martinsville, W. Va., 1995. 

Strontium carbonate also precipitates from strontium sulfide solution with carbon dioxide. Hydrogen sulfide is generated as a by-product of this reaction and reacts with sodium hydroxide to produce sodium hydrosulfide, which is sold as by-product. The abiUty of the black ash process to produce a product exceeding 95% strontium carbonate, from ores containing <85% strontium sulfate, has led to its predorninance. 

Anhydrous gaseous or Hquid hydrogen sulfide is practically nonacidic, but aqueous solutions are weakly acid. The for the first hydrogen is 9.1 X 10 at 18°C for the second, is 1.2 x 10 . Reaction of hydrogen sulfide with one molar equivalent of sodium hydroxide gives sodium hydrosulfide with two molar equivalents of sodium hydroxide, sodium sulfide forms. Hydrogen sulfide reacts with sodium carbonate to produce sodium hydrosulfide... 

Manufacture. Small cylinders of hydrogen sulfide are readily available for laboratory purposes, but the gas can also be easily synthesized by action of dilute sulfuric or hydrochloric acid on iron sulfide, calcium sulfide [20548-54-3], zinc sulfide [1314-98-3], or sodium hydrosulfide [16721 -80-5]. The reaction usually is mn in a Kipp generator, which regulates the addition of the acid to maintain a steady hydrogen sulfide pressure. Small laboratory quantities of hydrogen sulfide can be easily formed by heating at 280—320°C a mixture of sulfur and a hydrogen-rich, nonvolatile aUphatic substance, eg, paraffin. Gas evolution proceeds more smoothly if asbestos or diatomaceous earth is also present. 

Hydrogen sulfide has been produced in commercial quantities by the direct combination of the elements. The reaction of hydrogen and sulfur vapor proceeds at ca 500°C in the presence of a catalyst, eg, bauxite, an aluminosihcate, or cobalt molybdate. This process yields hydrogen sulfide that is of good purity and is suitable for preparation of sodium sulfide and sodium hydrosulfide (see Sodium compounds). Most hydrogen sulfide used commercially is either a by-product or is obtained from sour natural gas. 

Prereduced Powders. These are usually made from press cake paste to which a reducing agent has been added, such as sodium sulfide, sodium hydrosulfide, or sodium dithionite, which solubili2e the dye in water. Before drying, the dye paste may be mixed with dispersing and stahi1i2ing agents to aid appHcation. 

Grains. Grains are usually prereduced powders. The quantities of sodium sulfide, hydrosulfide, and mineral salts are adjusted to give a grainy product when the paste slurry is dried on a steam-heated dmm dryer. Grains offer the advantage of not being dusty. 

Liquids. Some Hquid dyes are made directly from the thionation melt by additions of caustic soda and sodium hydrosulfide. Hydrotropic substances are sometimes added, either at the initial thionation stage or after the polysulfide melt is finished in order to keep the reduced dye in solution. Pardy reduced Hquids are also available. They are usually more concentrated than fully reduced Hquids, thus saving packaging and transportation costs. However, they require a further addition of reducing agent to the dyebath in order to obtain full color value. On the other hand, fully reduced Hquids are... 

Manufacture. Sodium thiosulfate has been produced commercially by the air oxidation of sulfides, hydrosulfides, and polysulfides. 

Barium hydro sulfide [25417-81-6], Ba(HS)2, is formed by absorption of hydrogen sulfide into barium sulfide solution. On addition of alcohol, barium hydrosulfide tetrahydrate [12230-74-9], Ba(HS)2 4H2O, crystallizes as yellow rhombic crystals that decompose at 50 °C. Sohd barium hydro sulfide is very unstable. Its solubility in water is... 

BaS hydrolyzes to Ba(OH)2 and barium hydrosulfide. Cooling of an aqueous BaS solution can precipitate the double salt barium hydroxide sulfide hydrate [42821-46-3J, Ba(OH)2 Ba(SH)2 -xH O. 

The use of piperidine starting materials for preparation of perhydro derivatives is also seen in the reaction of the ethoxymethyleneaminonitrile (119) with sodium hydrosulfide to give (120) (66AG(E)308). 

Many other examples are known of non-selective reactions of halo groups in pyridopyridazines with amines, alkoxides, sulfur nucleophiles such as hydrosulfide and thiolate ions, or thiourea, hydrazine(s), cyanide ion and dimethyl sulfoxide, or on catalytic reduction. 

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