Carbon disulfide production

Trends in carbon disulfide production have closely paralleled those of the viscose rayon industry, one of its largest users (HSDB 1995 Mannsville Chemical Products Corp. 1985 Timmerman 1978 WHO 1981). Production increased by nearly 50% between 1941 and 1969, from 242,000 to 362,000 metric tons. This increase was partly due to a sudden rise in demand for carbon tetrachloride, an intermediate in the production of fluorocarbon propellants and refrigerants carbon disulfide is used in the production of carbon tetrachloride. The 1969 production level remained relatively stable until about 1974 when it declined sharply to the 1975 level of 217,000 metric tons (Timmerman 1978). Carbon disulfide production levels continued to decline, with fluctuations, to 168,000 metric tons in 1984 (Mannsville Chemical Products Corp. 1985 Timmerman 1978). In 1985, production was estimated to be 143,000 metric tons (Mannsville Chemical Products Corp. 1985). No information was found on production levels after 1985. 

Carbon disulfide s most important industrial use, however, has been in the manufacture of regenerated cellulose rayon by the viscose process (viscose rayon) and of cellophane (Davidson and Feinleib 1972 EPA 1978a NIOSH 1977 Timmerman 1978 WHO 1981). In 1974, over 80% of the carbon disulfide manufactured was used to make viscose rayon and cellophane (Austin 1974). This proportion fell to 50% in 1984, but the rayon and cellophane uses still accounted for the greatest fraction of carbon disulfide production (Mannsville Chemical Products Corp. 1985). Since 1989, the consumption of carbon disulfide in the production of carbon tetrachloride has increased to 38%, while the rayon industry s consumption has dropped to 34% (HSDB 1995). 

Another principal industrial use for carbon disulfide has been as a feedstock for carbon tetrachloride production (Mannsville Chemical Products Corp. 1985 NIOSH 1977 Timmerman 1978). While only 10% of U.S. carbon disulfide production was used to produce carbon tetrachloride in 1960, this increased to 32% in 1974, largely because of a rapid increase in the demand for carbon tetrachloride for the production of fluorocarbon propellants and refrigerants (Timmerman 1978). Although most chemical manufacturers have switched to methanol as a raw material for carbon tetrachloride, beginning in 1985, Akzo America, Inc., continued to use carbon disulfide for this purpose (Mannsville Chemical Products Corp. 1985). Beginning in 1989, 38% of the carbon disulfide produced was used to manufacture carbon tetrachloride (HSDB 1995). 

Carbon disulfide production furnace tubes up to 850 °C H2S-sulfidation, carburization... 

About 45% of carbon disulfide production is used to produce agricultural chemicals. Another 25% is used to make rayon while another 25% is used to produce rubber chemicals. 

Although not fully characterized, 2-carbethoxy-4-hydroxythiazole (230a), R, = C02Et, R2 = H, apparently results from the reaction of chloroacetonitrile with ethyl thiooxamate (2), Ri = C02Et (417). a-Chlorothioacids (232) condensed with thiobenzamide in the presence of carbon disulfide (542) yield the corresponding 2-phenyl-4-hydroxy-thiazole (234). The same product was obtained from 233 (Scheme 121). 

When a dilute solution of 6 phenylhexanoyl chloride in carbon disulfide was slowly added (over a period of eight days ) to a suspension of aluminum chloride in the same solvent it yielded a product A (C12H14O) in 67% yield Oxidation of A gave benzene 1 2 dicarboxyhc acid... 

Again, irrespective of the hardware the chemistry is consistent. The partially regenerated fiber from the spinning machine is contaminated with sulfuric acid, 2inc sulfate, sodium sulfate, carbon disulfide, and the numerous incompletely decomposed by-products of the xanthation reactions. The washing and drying systems must yield a pure cellulose fiber, suitably lubricated for the end use, and dried to a moisture level of around 10%. 

Electronic excitation from atom-transfer reactions appears to be relatively uncommon, with most such reactions producing chemiluminescence from vibrationaHy excited ground states (188—191). Examples include reactions of oxygen atoms with carbon disulfide (190), acetylene (191), or methylene (190), all of which produce emission from vibrationaHy excited carbon monoxide. When such reactions are carried out at very low pressure (13 mPa (lO " torr)), energy transfer is diminished, as with molecular beam experiments, so that the distribution of vibrational and rotational energies in the products can be discerned (189). Laser emission at 5 p.m has been obtained from the reaction of methylene and oxygen initiated by flash photolysis of a mixture of SO2, 2 2 6 (1 )-... 

Sulfur, another inorganic petrochemical, is obtained by the oxidation of hydrogen sulfide 2H2S + O2 — 2H2 0 + 2S. Hydrogen sulfide is a constituent of natural gas and also of the majority of refinery gas streams, especially those off-gases from hydrodesulfurization processes. A majority of the sulfur is converted to sulfuric acid for the manufacture of fertilizers and other chemicals. Other uses for sulfur include the production of carbon disulfide, refined sulfur, and pulp and paper industry chemicals. 

AEROPHINE 3418A promoter is widely used ia North and South America, AustraHa, Europe, and Asia for the recovery of copper, lead, and ziac sulfide minerals (see Elotatton). Advantages ia comparison to other collectors (15) are said to be improved selectivity and recoveries ia the treatment of complex ores, higher recoveries of associated precious metals, and a stable grade—recovery relationship which is particularly important to the efficient operation of automated circuits. Additionally, AEROPHINE 3418A is stable and, unlike xanthates (qv), does not form hazardous decomposition products such as carbon disulfide. It is also available blended with other collectors to enhance performance characteristics. 

Chemical Properties The formation of salts with acids is the most characteristic reaction of amines. Since the amines are soluble in organic solvents and the salts are usually not soluble, acidic products can be conveniendy separated by the reaction with an amine, the unshared electron pair on the amine nitrogen acting as proton acceptor. Amines are good nucleophiles reactions of amines at the nitrogen atom have as a first step the formation of a bond with the unshared electron pair of nitrogen, eg, reactions with acid anhydrides, haUdes, and esters, with carbon dioxide or carbon disulfide, and with isocyanic or isothiocyanic acid derivatives. 

Plastics and Other Synthetic Products. Sulfur is used in the production of a wide range of synthetics, including cellulose acetate, cellophane, rayon, viscose products, fibers, and textiles. These uses may account for 2% of sulfur demand in developed countries. Sulfur intermediates for these manufacturing processes are equally divided between carbon disulfide and sulfuric acid. 

Carbonyl sulfide occurs as a by-product ia the manufacture of carbon disulfide and is an impurity ia some natural gases, ia many manufactured fuel gases and refinery gases, and ia combustion products of sulfur-containing fuels (25). It tends to be concentrated ia the propane fraction ia gas fractionation an amine sweetening process is needed to remove it. 

Manufacture. Trichloromethanesulfenyl chloride is made commercially by chlorination of carbon disulfide with the careful exclusion of iron or other metals, which cataly2e the chlorinolysis of the C—S bond to produce carbon tetrachloride. Various catalysts, notably iodine and activated carbon, are effective. The product is purified by fractional distillation to a minimum purity of 95%. Continuous processes have been described wherein carbon disulfide chlorination takes place on a granular charcoal column (59,60). A series of patents describes means for yield improvement by chlorination in the presence of dihinctional carbonyl compounds, phosphonates, phosphonites, phosphites, phosphates, or lead acetate (61). 

Commercial-scale processes have been developed for the production of hydrogen sulfide from heavy fuel oils and sulfur as well as from methane, water vapor, and sulfur. The latter process can be carried out in two steps reaction of methane with sulfur to form carbon disulfide and hydrogen sulfide followed by hydrolysis of carbon disulfide (116). 

This reaction can also be mn in a continuous fashion. In the initial reactor, agitation is needed until the carbon disulfide Hquid phase reacts fully. The solution can then be vented to a tower where ammonia and hydrogen sulfide are stripped countercurrendy by a flow of steam from boiling ammonium thiocyanate solution. Ammonium sulfide solution is made as a by-product. The stripped ammonium thiocyanate solution is normally boiled to a strength of 55—60 wt %, and much of it is sold at this concentration. The balance is concentrated and cooled to produce crystals, which are removed by centrifiigation. 

Sulfur reacts with alkanes to either dehydrate (eq. 1), oxidize, forming carbon disulfide and hydrogen sulfide (eq. 2), or cyclize, forming thiophenes (eq. 3). The products of alkane sulfurization depend on the temperature, the time at the temperature, and the stmcture of the hydrocarbon (1). 

Other components in the feed gas may react with and degrade the amine solution. Many of these latter reactions can be reversed by appHcation of heat, as in a reclaimer. Some reaction products cannot be reclaimed, however. Thus to keep the concentration of these materials at an acceptable level, the solution must be purged and fresh amine added periodically. The principal sources of degradation products are the reactions with carbon dioxide, carbonyl sulfide, and carbon disulfide. In refineries, sour gas streams from vacuum distillation or from fluidized catalytic cracking (FCC) units can contain oxygen or sulfur dioxide which form heat-stable salts with the amine solution (see Fluidization Petroleum). 

Tar sand has been defined as sand saturated with a highly viscous cmde hydrocarbon material not recoverable in its natural state through a well by ordinary production methods (2—8). Technically the material should perhaps be called bituminous sand rather than tar sand because the hydrocarbon is bitumen, ie, a carbon disulfide-soluble oil. 

Agricultural grades of ammonium thiosulfate are prepared by similar processes and contain some excess sulfur. The sulfur can be removed by washiug with carbon disulfide. A typical sulfur-free product contaius 87% (NH 2S203 3.4% (NH 2SC)3, and 9.6% (NH 2SC)4 (67). 

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). 

For the manufacturiag of potassium ethyl xanthate, 400% excess of alcohol and equimolar quantities of 50 wt % aqueous potassium hydroxide and carbon disulfide were used (77). After 30 min at 40°C, the mixture was vacuum dmm dried. The product was obtained ia near quantitative yield and assayed at 95%. It is claimed that potassium amyl xanthate can be made with almost the same ratio of reactants and 80 wt % caustic potash (78). 

Trinidad asphalt has a relatively uniform composition of 29% water and gas, 39% bitumen soluble in carbon disulfide, 27% mineral matter on ignition, and 5% bitumen that remains adsorbed on the mineral matter. Refining is essentially a process of dehydration by heating the cmde asphalt to ca 165°C. The refined product averages 36% mineral ash with a penetration at 25°C of about 2 (0.2 mm), a softening point (ring and ball method) of 99°C, a flash point (Cleveland open cup) of 254°C, a sulfur content of 3.3%, and a saponification value of 45 mg KOH/g. The mineral matter typically contains... 

Carbon disulfide [75-15-0] (carbon bisulfide, dithiocarbonic anhydride), CS2, is a toxic, dense liquid of high volatiUty and fiammabiUty. It is an important industrial chemical and its properties are well estabUshed. Low concentrations of carbon disulfide naturally discharge into the atmosphere from certain soils, and carbon disulfide has been detected in mustard oil, volcanic gases, and cmde petroleum. Carbon disulfide is an unintentional by-product of many combustion and high temperature industrial processes where sulfur compounds are present. 

Hot surfaces and electric sparks are potential ignition sources for carbon disulfide. The ignition temperature depends on specific conditions, and values from 90 to 120°C in air have been reported (2,22). Data on carbon disulfide oxidation and combustion have been summarized (18). Oxidation products ate generally sulfur dioxide [7446-09-5] and carbon dioxide [124-58-9J ... 

CeUulose is subsequendy regenerated from the viscose solution in sulfuric acid and carbon disulfide is Hberated. These are the basic steps in manufacturing viscose rayon. The production of regenerated ceUulose is estimated to account for mote than 75% of the total carbon disulfide consumption woddwide... 

The earliest method for manufacturiag carbon disulfide involved synthesis from the elements by reaction of sulfur and carbon as hardwood charcoal in externally heated retorts. Safety concerns, short Hves of the retorts, and low production capacities led to the development of an electric furnace process, also based on reaction of sulfur and charcoal. The commercial use of hydrocarbons as the source of carbon was developed in the 1950s, and it was still the predominate process worldwide in 1991. That route, using methane and sulfur as the feedstock, provides high capacity in an economical, continuous unit. Retort and electric furnace processes are stiU used in locations where methane is unavailable or where small plants are economically viable, for example in certain parts of Africa, China, India, Russia, Eastern Europe, South America, and the Middle East. Other technologies for synthesis of carbon disulfide have been advocated, but none has reached commercial significance. 

Sulfur vapor is an equiUbrium mixture of several molecular species, including Sg, S, and S2. The equiUbrium shifts toward S2 at higher temperatures and lower pressures. The overall reaction is endothermic and theoretically consumes 1950 kj/kg (466 kcal/kg) of carbon disulfide when the reactants are at 25°C and the products are at 750°C. Most of the heat input goes into dissociation of sulfur vapor to the reactive species, S2. Equation 25 is slightly exothermic when the reactants are at a constant temperature of 750°C. 

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