Xanthates


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Xanthates

 

derivatives (salts and esters) of xanthic acids

where R is a hydrocarbon radical and R’ is a metal (salts) or a hydrocarbon radical (esters).

Xanthates (salts), unlike xanthic acids [acidic esters of dithio-carbonic acid ROC(=S)SH], are stable compounds. The xanthates of alkali metals disolve readily in water. They are generally prepared by the interaction of carbon disulfide and alcohol in the presence of an anhydrous alkali:

CS2 + ROH + NaOH → ROCSSNa

Xanthates (esters)—full esters of dithiocarbonic acid—can be obtained by alkylation:

ROCSSK + R’l → ROCSSR’ + KI

Xanthates (esters) decompose upon heating into mercaptan, car-bonyl sulfide, and an unsaturated hydrocarbon (Chugaev reaction), for example:

C2H5O—CSSCH3→ CH3SH + COS + CH2=CH2

The most valuable xanthate, cellulose xanthate, is used in the manufacture of viscose fiber. Certain xanthates (salts) are used in the flotation of sulfide ores and in the preparation of insecticides. They also serve as accelerators in the vulcanization of rubber and as preparations for the analytical determination of molybdenum.

V. N. FROSIN

References in periodicals archive ?
It has been found practically that sphalerite mineral rarely floats well with xanthate because of relatively high solubility of zinc-xanthate complex.
Table 4 represent the optimum reagent consumption for lead flotation as 70 g/t potassium ethyl xanthate, 300 g/t sodium silicate, 150 g/t sodium cyanide, 30 g/t of polyglycol and Table 6 for zinc flotation as 80 g/t potassium amyl xanthate, 400 g/t copper sulphate, 300 g/t sodium silicate, 40g/t of polyglycol at rougher flotation stage.
This article will discuss xanthate accelerators in vulcanization systems for isobutylene-based elastomers.
One means to overcome this issue is through use of xanthate accelerators.
The products provided include the full range of xanthates.
SF-113, sodium isopropyl xanthate, is the better known of the xanthates, used as a collector in the flotation of copper, iron, molybdenum, zinc and lead ores.
When coupled with the already existing xanthate collectors, an estimated 95% of all flotation chemicals in use today were being produced and industrially available by 1960.
Figure 4 shows, for an Arizona chalcopyrite ore, a fairly typical set of comparable Cu recovery, rougher grade, and pyrite content data produced by MRI S-701, MRI C-211, MRI F-100, and potassium amyl xanthate.
Xanthates are the oldest and least selective but are widely available, cheap, and effective.
It is common to use a selective promotor as a primary collector, usually added to the grind, and follow up with a xanthate in the scavenger cells as a "kicker".
Laboratory and plant data demonstrated significant flexibility with respect to grade and recovery at dosages lower than those typically used for xanthates.
Oxidation and wetting behaviour of chalcopyrite in the absence and presence of xanthates, Minerals and Metallurgical Processing, 7, August 1990, pp.