Hydrocarbons, hydrocarbon xanthates

Sulfur Elemental, organic monosulfide, organic disulfide and higher polysulfides, sulfurized fats, sulfur-ized hydrocarbons, xanthates, dithio-carbonates... 

BARTON MC COMBIE Deoxygenation Deoxygenation ot secondary alcohols to hydrocarbons (via xanthates)... 

Trim-butyl tin hydride Hydrocarbons from xanthates... 

The heavy metal salts, ia contrast to the alkah metal salts, have lower melting points and are more soluble ia organic solvents, eg, methylene chloride, chloroform, tetrahydrofiiran, and benzene. They are slightly soluble ia water, alcohol, ahphatic hydrocarbons, and ethyl ether (18). Their thermal decompositions have been extensively studied by dta and tga (thermal gravimetric analysis) methods. They decompose to the metal sulfides and gaseous products, which are primarily carbonyl sulfide and carbon disulfide ia varying ratios. In some cases, the dialkyl xanthate forms. Solvent extraction studies of a large number of elements as their xanthate salts have been reported (19). 

The wastewater generated in the membrane cell and other process wastewaters in the cell are generally treated by neutralization.28 Other pollutants similar to those in mercury and diaphragm cells are treated in the same process stated above. Ion exchange and xanthate precipitation methods can be applied in this process to remove the metal pollutants, while incineration can be applied to eliminate some of the hydrocarbons. The use of modified diaphragms that resist corrosion and degradation will help in reducing the amount of lead, asbestos, and chlorinated hydrocarbon in the wastewater stream from the chlor-alkali industry.28... 

Xanthates, which are easily prepared from the reaction of alcohols, carbon disulfide, and methyl iodide in the presence of a base, or from the reaction of alcohols with N,Nf-thiocarbonyldiimidazole, can generally be used for the deoxygenation of alcohols to the corresponding hydrocarbons. So, eq. 3.19 shows the deoxygenative cyclization of... 

In a similar way, the reaction of xanthates under radical conditions leads to products and selectivities that are totally different from those in thermal rearrangements. The radical transformation usually furnishes unsubstituted hydrocarbons as reaction products. The major accomplishment of the reaction is the deoxygenation of secondary alcohols to furnish the corresponding hydrocarbons when tributylstannane is used with 0-cycloalkyl thiobenzoates or S-methyl dithiocarbamates [13]. However, the rearranged product may be observed as a byproduct [14,15]. 

The alkali metal dithiocarbonates (xanthates) are prepared by reacting carbon disulfide with alcohols or phenols in the presence of an alkali metal hydroxide (usually KOH) using as solvent an excess of alcohol reagent,176 a hydrocarbon, or acetone.177... 

A third crystalline modification, y-monoclinic sulfur, was first obtained by W. Muthmann in 1890. It is also called nacreous or mother-of-pearl sulfur and can be made by slowly cooling a sulfur melt that has been heated above 150°, or by chilling hot concentrated solutions of sulfur in EtOH, CS2 or hydrocarbons. However, it is best prepared as pale-yellow needles by the mechanistically obscure reaction of pyridine with copper(I) ethyl xanthate, CuSSCOEi. Like a- and j0-sulfur, y-monoclinic sulfur comprises cydo-Sg molecules but the packing is more efficient and leads to a higher density (2.19 g cm It reverts slowly to a-Sg at room temperature but rapid heating leads to a mp of 106.8°. 

Collectors for nonsulfide minerals containing O atom, such as fatty acids and sulfonates, react with various metallic ions by ionic bond, and they have high solubility in water. The solubility becomes low only when the hydrocarbon chains in the molecules are long. In contrast, collectors for sulfide minerals, such as xanthates possessing only a short chain, the S bonding atom reacts with metallic ions to form covalent bonds with lower polarity. 

The variations of decomposition rate constant (Kq) with the magnitude of hydrocarbon chains of xanthates are as follows ... 

The perfomance of xanthate with aliphatic unsaturated hydrocarbon is close to that of normal alkyl xanthate. It was reported that those aliphatic xanthates include propylene-propyl and propylene-butyl xanthates [2],... 

Cellophanes. Cellophane looks and acts like a hydrocarbon-based plastic material, but is not one. The viscose process is used to extract cellulose as cellulose xanthate, which is then treated and processed to regenerate the cellulose as Rayon, a material used extensively as fibers. The same material, however, can be made in sheet form, in which it is essentially a modified cellulose paper. 

Flotation is a method of separating solids Irom streams by creating a froth to which they are attracted. Thus in a slurry circuit, flocculants are added to create a froth rich with the metal concentrate. The trick is to make mineral particles hydrophobic, or water repellant. Flotation involves the selected adsorption of hydrocarbons (e.g., ethyl xanthate) on liberated minerals (e.g., chalcopyrite), which can then be attached to and transported by air bubbles in the slurry to a so-called froth layer and then separated from the hydrophilic (wetted) particles. 

It has also been demonstrated that trialkylsilanes, which are poor radical-based reducing agents due to their low hydrogen donation abilities [79], can reduce alkyl halides and xanthates (equation (36)) to the corresponding hydrocarbons in the presence of a catalytic amount of an alkanethiol [80]. The reaction consists of a chain process in which the key propagation step is the hydrogen transfer from the silane to the alkanethiyl radical. This approach has also been used for the hydrosilylation of chiral alkenes by Ph2SiH2 [81]. 

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