In the case of lead and copper ores, the use of xanthates,  [c.476]

The examples in the preceding section, of the flotation of lead and copper ores by xanthates, was one in which chemical forces predominated in the adsorption of the collector. Flotation processes have been applied to a number of other minerals that are either ionic in type, such as potassium chloride, or are insoluble oxides such as quartz and iron oxide, or ink pigments [needed to be removed in waste paper processing [92]]. In the case of quartz, surfactants such as alkyl amines are used, and the situation is complicated by micelle formation (see next section), which can also occur in the adsorbed layer [93, 94].  [c.478]

Carbon disulphide is an excellent solvent for fats, oils, rubber, sulphur, bromine and iodine, and is used industrially as a solvent for extraction. It is also used in the production of viscose silk, when added to wood cellulose impregnated with sodium hydroxide solution, a viscous solution of cellulose xanthate is formed, and this can be extruded through a fine nozzle into acid, which decomposes the xanthate to give a glossy thread of cellulose.  [c.202]

Xanthates (or xanthogenates), t.g., CS(OR)SK, are formed by the reaction between carbon disulphide and an alcoholic solution of potassium hydroxide, for example  [c.496]

The xanthates react with alkyl halides to give the di-esters of dithiocarbonic acid 0=C(SH)2 S=C(SH)0H, for example  [c.496]

Potassium ethyl xanthate Ethyl S-ethyl xanthate  [c.496]



Place 32 g. of potassium ethyl xanthate (Section 111,166) and 50 ml. of absolute ethyl alcohol in a 500 ml. round-bottomed flask provided with a double surface condenser. Add 32 g. (16-5 ml.) of ethyl iodide. No reaction appears to take place in the cold. Heat on a water bath for 3 hours a reaction sets in within 15 minutes and the yellow reaction mixture becomes white owing to the separation of potassium iodide. Add about 150 ml. of water, separate the lower layer, and wash it with water. Dry it with anhydrous calcium chloride or anhydrous calcium sulphate and distil from a 50 ml. Claisen flask. Collect the ethyl S-ethyl xanthate at 196-198°. The yield is 23 g.  [c.499]

Ethyl S-n-butyl xanthate. Use 32 g. of potassium ethyl xanthate, 37 g. (23 ml.) of n-butyl iodide (Section 111,40) and 50 ml. of absolute ethyl alcohol. Reflux on a water bath for 3 hours. Pour into 150 ml. of water, saturate with salt (in order to facilitate the separation of the upper layer), remove the upper xanthate layer, wash it once with 25 ml. of saturated salt solution, and dry with anhydrous calcium chloride or anhydrous calcium sulphate. Distil from a 50 ml. Claisen flask under reduced pressure. Collect the pale yellow ethyl S-n-butyl xanthate at 90-91°/4 mm. The yield is 34 g.  [c.499]

Rayon. Viscose rayon is obtained by reacting the hydroxy groups of cellulose with carbon disulfide in the presence of alkali to give xanthates. When this solution is poured (spun) into an acid medium, the reaction is reversed and the cellulose is regenerated (coagulated).  [c.1015]

The cellulose molecule contains three hydroxyl groups which can react and leave the chain backbone intact. These alcohol groups can be esterified with acetic anhydride to form cellulose acetate. This polymer is spun into the fiber acetate rayon. Similarly, the alcohol groups in cellulose react with CS2 in the presence of strong base to produce cellulose xanthates. When extruded into fibers, this material is called viscose rayon, and when extruded into sheets, cellophane. In both the acetate and xanthate formation, some chain degradation also occurs, so the resulting polymer chains are shorter than those in the starting cellulose.  [c.18]

Cellulose xanthate, sodium salt [9051-13-2]  [c.180]

Cyanoethyl cyclohexyl xanthate [85909-d3-3]  [c.268]

Methyl ethyl xanthate [623-54-1]  [c.623]

Methyl isoamyl xanthate [70061-61-9]  [c.624]

Methyl (3-methyl-2-penten-l-yl) xanthate [3817-83-2]  [c.625]

Nickel ethyl xanthate [52139-56-7]  [c.671]

Potassium n-butyl xanthate [871-58-9]  [c.802]

Potassium ethyl xanthate [140-89-6]  [c.803]

Various chemical tricks are possible. Zinc ores are not well floated with xanthates, but a pretreatment with dilute copper sulfate rectifies the situation by electrodepositing a thin layer of copper on the mineral particles (note Ref. 83 for complexities). Chelating agents such as oximes may be used instead of xanthates [84]. Treatment of an ore containing a mixture of iron, zinc, and lead minerals with dilute cyanide solution will inhibit adsorption of the collector on the first two, but not on the last. In this case, cyanide is called a depressant. Depressants are also used to inhibit the undesired coflotation of talc, sulfate, graphite, and so on organic polymers have been useful [85]. STM and AFM studies of galena (PbS) surfaces show the formation of 0.3-0.6-nm pits during the surface chemical reactions controlling flotation [86].  [c.477]

Into a 500 ml. round-bottomed flask, fitted with a reflux condenser, place 42 g. of potassium hydroxide pellets and 120 g. (152 ml.) of absolute ethyl alcohol. Heat under reflux for 1 hour. Allow to cool and decant the liquid from the residual solid into another dry 500 ml. flask add 57 g. (45 ml.) of A.R. carbon dtsulphide slowly and with constant shaking. Filter the resulting almost solid mass, after cooling in ice, on a sintered glass funnel at the pump, and wash it with two 25 ml. portions of ether (sp. gr. 0-720), followed by 25 ml. of anhydrous ether. Dry the potassium ethyl xanthate in a vacuum desiccator over silica gel. The yield is 74 g. If desired, it ma be recrystallised from absolute ethyl alcohol, but this is usually unneceasary.  [c.499]

Potassium n-butyl xanthate. Use 100 g. (123 -5 ml.) of dry n-butyl alcohol, 18 g. of potassium hydroxide pellets, and 36 g. (28 -5 ml.) of A.R. carbon disulphide. The yield of pure, dry potassium n-butyl xanthate CS(0C4H, )SK, is 42 g.  [c.499]

See pages that mention the term Xanthates : [c.428]    [c.477]    [c.496]    [c.597]    [c.54]    [c.145]    [c.138]    [c.180]    [c.180]    [c.310]    [c.377]    [c.383]    [c.383]    [c.383]    [c.407]    [c.619]    [c.619]    [c.619]    [c.623]    [c.630]   
See chapters in:

Encyclopedia of chemical technology volume 25  -> Xanthates

Textbook on organic chemistry (1974) -- [ c.496 , c.499 , c.597 ]

Organic syntheses based on name reactions and unnamed reactions (1994) -- [ c.231 ]

Chemistry of the elements (1998) -- [ c.317 , c.646 ]