Hydroxide reaction with elemental sulfur

Flotation Reagents. Only one sulfide mineral flotation collector is manufactured from phosphine, ie, the sodium salt of bis(2-methylpropyl)phosphinodithioic acid [13360-78-6]. It is available commercially from Cytec Industries Inc. as a 50% aqueous solution and is sold as AEROPHINE 3418A promoter. The compound is synthesized by reaction of 2-methyl-1-propene [115-11-7] with phosphine to form an iatermediate dialkylphosphine which is subsequently treated with elemental sulfur [7704-34-9] and sodium hydroxide [1310-73-2] to form the final product (14). The reactions described ia equations 10 and 11... 

The metal and ammonium salts of dithiophosphinic acids tend to exhibit far greater stability with respect to this thermal decomposition reaction, and consequently these acids are often prepared directly in their salt form for convenience and ease of handling. Alkali-metal dithiophosphinates are accessible from the reaction of diphosphine disulfides with alkali-metal sulfides (Equation 22) or from the reaction of alkali-metal diorganophosphides with two equivalents of elemental sulfur (Equation 23). Alternatively, they can be prepared directly from the parent dithiophosphinic acid on treatment with an alkali-metal hydroxide or alkali-metal organo reagent. Reaction of secondary phosphines with elemental sulfur in dilute ammonia solution gives the dithiophosphinic acid ammonium salts (Equation 24). 

Europeum generally is produced from two common rare earth minerals monazite, a rare earth-thorium orthophosphate, and bastnasite, a rare earth fluocarbonate. The ores are crushed and subjected to flotation. They are opened by sulfuric acid. Reaction with concentrated sulfuric acid at a temperature between 130 to 170°C converts thorium and the rare earths to their hydrous sulfates. The reaction is exothermic which raises the temperature to 250°C. The product sulfates are treated with cold water which dissolves the thorium and rare earth sulfates. The solution is then treated with sodium sulfate which precipitates rare earth elements by forming rare earth-sodium double salts. The precipitate is heated with sodium hydroxide to obtain rare earth hydrated oxides. Upon heating and drying, cerium hydrated oxide oxidizes to tetravalent ceric(lV) hydroxide. When the hydrated oxides are treated with hydrochloric acid or nitric acid, aU but Ce4+ salt dissolves in the acid. The insoluble Ce4+ salt is removed. 

Elemental sulfur is present in most soils and sediments (especially anaerobic), and is sufficiently soluble in most common organic solvents that the extract should be treated to remove it prior to analysis by ECD-GC or GC-MS. The most effective methods available are (1) reaction with mercury or a mercury amalgam [466] to form mercury sulfide (2) reaction with copper to form copper sulfide or (3) reaction with sodium sulfite in tetrabutyl ammonium hydroxide (Jensen s reagent) [490]. Removal of sulfur with mercury or copper requires the metal surface to be clean and reactive. For small amounts of sulfur, it is possible to include the metal in a clean-up column. However, if the metal surface becomes covered with sulfide, the reaction will cease and it needs to be cleaned with dilute nitric acid. For larger amounts of sulfur, it is more effective to shake the extract with Jensen s reagent [478]. 

Reaction of a/i/iyt/ro-3-hydroxy-7-methyl-2-phenylimidazo[2,l-8]thi-azolium hydroxide (452) with isocyanates in boiling benzene readily provides the stable I I cycloadducts, hexahydro-l-methyl-6-phenyl-8-R-6,8a-epithioimidazo[l,2-a]pyrimidin-5,7-diones (453a-c). Structures were characterized by IR, H-NMR, C-NMR, and mass spectral data the latter indicated that all components of the reactants were retained in the adduct (79JOC3803) (Scheme 104). With maleimides, maleic anhydride, furanonitrile, DMAD, or dibenzoylacetylene, compound 452 did not yield the desired cycloadducts (454, 456,458), but gave sulfur-free compounds 455 and 457, presumably via the cycloadducts, with the elimination of H2S or elemental sulfur as illustrated in Scheme 104. 

In addition to this comprehensive scheme, other determinations may be carried out by utilizing specific properties of the sulfur compound types (54, 72). Sulfur may be determined by removal with elemental mercury 51, 70), or by reaction with a mercaptan. In the latter case the sulfur determination is made by measurement of the excess mercaptan after the sample has been treated with litharge, sodium hydroxide, and a known excess of butyl mercaptan 78,81). A qualitative method of detecting elemental sulfur in gasoline is by the addition of sodium hydroxide to a pyridine solution of the gasoline which turns blue if sulfur is present 67). Free sulfur can also be determined polarographically 60). 

Starch dialdehyde also reacts with carbanions. For instance, reaction with nitromethane produces a nitro compound that after reduction with iron(II) hydroxide in ammonia afforded an animated product.539 Molded articles from starch dialdehyde and elemental sulfur were also patented.540... 

Sulfur removal Elemental sulfur removal prior to analysis by ECD-GC or GC-MS by the reaction with (a) mercury or a mercury amalgam to form mercury sulfide, (b) copper to form copper sulfide, or (c) sodium sulfite in tetrabutyl ammonium hydroxide (Jensen s reagent) Removal of sulfur with mercury or copper requires the metal surface to be clean and reactive The need to dean with dilute HNO3 if the metal surface becomes covered with sulfide 1... 

Dilution with water reverses the reaction, and heating the solution Hberates sulfur dioxide. Upon being added to a solution of teUurides, teUurium forms colored polyteUurides. Unlike selenium, teUurium is not soluble in aqueous sodium sulfite. This difference offers a method of separating the two elements. Like selenium, teUurium is soluble in hot alkaline solutions except for ammonium hydroxide solutions. Cooling reverses the reaction. Because teUurium forms solutions of anions, Te , and cations, Te" ", teUurium films can be deposited on inert electrodes of either sign. 

In a chemical equation, like the one for the reaction between sulfuric acid and potassium hydroxide, the reactants (the substances being mixed together) are always written on the left-hand side of the equation. The products (the substances made when the reactants react with each other) are placed on the right-hand side of the equation. Atoms cannot be made or destroyed in a chemical reaction, only rearranged. This is called the law of conservation of matter. Therefore, there must always be the same number of atoms of each element on the reactant side of the equation as there are on the product side. 

Elemental composition Na 58.93%, N 35.90%, H 5.17%. The compound may he decomposed cautiously with water (reaction is violent) under cooling to yield sodium hydroxide and ammonia. (Or it may he decomposed with anhyrous alcohol to form ammonia and sodium alcoholate. The alcoholate then may he treated with water to form sodium hydroxide). Ammonia liberated is dissolved in water and the solution is measured using an ammonia-selective electrode. Alternatively, ammonia is collected over horic acid solution containing a small quantity of methyl red indicator. The solution is titrated with a standard solution of sulfuric acid. Sodium hydroxide is measured hy titration with a standard solution of hydrochloric or sulfuric acid. 

Evidence for the existence of PoS is much stronger. Aqueous solutions in HCl containing Po and Po yield a precipitate of PoS. During the course of this reaction, Po is reduced to Po with the concurrent oxidation of sulfide to free sulfur. The same sulfide can be prepared by the reaction between polonium hydroxide and ammonium sulfide. The compound has not been successfully prepared by the direct reaction between the elements. 

---