Source of sulfur

Sulfonation (Section 12 4) Sulfonic acids are formed when aromatic compounds are treated with sources of sulfur trioxide These sources can be concentrated sulfuric acid (for very reactive arenes) or solutions of sulfur trioxide in sulfuric acid (for ben zene and arenes less reactive than ben zene)... 

Sulfur deficiency usually is not a problem for mminants because the mminal microflora can utilize sulfur-containing amino acids. A deficiency can occur, however, when an NPN source is fed. L-Methionine [63-68-3] is the most biologically available source of sulfur (21). Various sulfates are intermediate in sulfur avadabiHty, and elemental sulfur is the least available source of sulfur. 

Immobile hydrocarbon sources requite refining processes involving hydrogenation. Additional hydrogen is also requited to eliminate sources of sulfur and nitrogen oxides that would be emitted to the environment. Resources can be classified as mostiy consumed, proven but stiU in the ground, and yet to be discovered. A reasonable estimate for the proven reserves for cmde oil is estimated at 140 x 10 t (1.0 x 10 bbl) (4). In 1950 the United States proven reserves were 32% of the world s reserve. In 1975 this percentage had decreased to 5%, and by 1993 it was down to 2.5%. Since 1950 the dominance of... 

Sources of sulfur are called voluntary if sulfur is considered to be the principal, and often the only, product. Sulfur has also been recovered as a by-product from various process operations. Such sulfur is termed involuntary sulfur and accounts for the largest portion of world sulfur production (see Sulfur REMOVAL AND RECOVERY). 

Occurrence. The metal sulfides, which are scattered throughout most of the world, have been an important source of elemental sulfur. The potential for recovery from metal sulfides exists, although these sources are less attractive economically and technologicaky than other sources of sulfur. Nevertheless sulfide ores are an important source of sulfur in other forms, such as sulfur dioxide and sulfuric acid. 

Pyrite is the most abundant of the metal sulfides. Eor many years, until the Erasch process was developed, pyrite was the main source of sulfur and, for much of the first half of the twentieth century, comprised over 50% of world sulfur production. Pyrite reserves are distributed throughout the world and known deposits have been mined in about 30 countries. Possibly the largest pyrite reserves in the world are located in southern Spain, Portugal, and the CIS. Large deposits are also in Canada, Cypms, Einland, Italy, Japan, Norway, South Africa, Sweden, Turkey, the United States, and Yugoslavia. However, the three main regional producers of pyrites continue to be Western Europe Eastern Europe, including the CIS and China. 

Pyrites production is the main source of sulfuric acid for both fertilizer and nonfertilizer uses in China and has been increasing steadky. However,... 

Sulfur is produced from a variety of sources using many different techniques in many countries around the world. Worldwide changes have affected not only the sources of sulfur, but also the amounts consumed. Sulfur sources in the United States underwent significant changes during the 1980s. Voluntary sulfur from the Frasch process (mines) suppHed only 25% of the sulfur in the United States in 1995, compared to about 53% in 1980, whereas recovered or involuntary sulfur suppHed 63% of the sulfur in the United States in 1995, compared to 34% in 1980. About 12% is suppHed from other forms, primarily by metallurgy (21,33). 

Manufacture of thiophene on the commercial scale involves reactions of the two component method type wherein a 4-carbon chain molecule reacts with a source of sulfur over a catalyst which also effects cyclization and aromatization. A range of suitable feedstocks has included butane, / -butanol, -butyraldehyde, crotonaldehyde, and furan the source of sulfur has included sulfur itself, hydrogen sulfide, and carbon disulfide (29—32). 

Permanent coloration can also be achieved by exposing hair to certain metals copper, silver, and especially lead salts. Preparations containing aqueous solutions of lead acetate may include a source of sulfur, usually thiosulfate, which may react with cystine in the hair to produce some cysteine or may react directiy with the metal ion to form dark metallic sulfides. Preparations of this type, which darken hair gradually, are not universally considered safe. 

Heating or irradiating alkenes in the presence of sulfur gives relatively low yields of thiiranes. For example, a mixture of sulfur and norbornadiene in pyridine-DMF-NHa at 110 °C gave a 19% yield of the monoepisulfide of norbornadiene as compared with a 78% yield by the method of Scheme 120 (79JCS(Pi)228). Often 1,2,3-trithiolanes are formed instead of thiiranes. The sesquiterpene episulfides in the essential oil of hops were prepared conveniently by irradiation of the terpene and sulfur in cyclohexane (Scheme 135) (80JCS(Pl)3li). Phenyl, methyl or allyl isothiocyanate may be used as a source of sulfur atoms instead of elemental sulfur. 

Although it is not a catalytic process, the roasting of iron sulfide in fluidized beds at 650 to 1,100°C (1,202 to 2,012°F) is analogous. The pellets are 10-mm (0.39-in) diameter. There are numerous ants, but they are threatened with obsolescence because cheaper sources of sulfur are available for making sulfuric acid. 

Ammonium sulfate fertilizer is made by reacting ammonia with sulfuric acid. In many parts of the world, calcium sulfate is in mineral form convertible to ammonium sulfate by combining it with ammonia and water - a virtually limitless source of sulfur. 

At about the same time Pedersen s work was underway, Bradshaw and his coworkers had undertaken the systematic preparation of numerous mono- and polysulfur macrocycles The syntheses were carried out in a fashion similar to that shown in Eq. (6.3). The two principal sources of sulfur in the first paper from this groupwere sodium sulfide and 1,2-ethanedithiol. The latter was utilized in the presence of sodium hydroxide base. Ethanol was generally used as solvent and the reactions were conducted at high dilution. Products were purified either by vacuum distillation or recrystallization as appropriate. The yields were generally in the 5—30% range. 

Oil shales represent a further source of sulfur though here (unlike the tar sands which yield crude oil and H2S) the sulfur is predominandy in the form of pyrites. US oil shales contain about 0.7% S of which abtiut 80% is pyritic other... 

Finally, sulfur occurs in many localities as the sulfates of electropositive elements (see Chapters 4 and 5) and to a lesser extent as sulfates of Al, Fe, Cu and Pb, etc. Gypsum (CaS04.2H20) and anhydrite (CaSO ) are particularly notable but are little used as a source of sulfur because of high capital and operating costs. Similarly, by far the largest untapped source of sulfur is in the oceans as the dissolved sulfates of Mg, Ca and K. It has been estimated that there are some 1.5 x 10 cubic km of water in the oceans of the world and that 1 cubic km of sea-water contains approximately 1 million tonnes of sulfur combined as sulfate. 

The third major source of sulfur is pyrite and related sulfide minerals. The ore is roasted to secure SO2 gas which is then usually used directly for the manufacture of H2SO4 (p. 708). Again air pollution by vS02 gas emissions has been the subject of increasing legislation and control during the past three decades (p. 698). 

The principal source of sulfur dioxide, the precursor of sulfuric acid, is high-sulfur coal. Coal used in power plants can contain up to 4% sulfur, mostly in the form of minerals such as pyrite, FeS2. Combustion forms sulfur dioxide ... 

Chalcopyrite, CuFeS2, is an important source of copper. A typical chal-copyrite ore contains about 0.75% Cu. What volume of sulfur dioxide at 25°C and 1.00 atm pressure is produced when one boxcar load (4.00 X 103 ft3) of chalcopyrite ore (d = 2.6 g/cm3) is roasted Assume all the sulfur in the ore is converted to S02 and no other source of sulfur is present. 

Gasoline normally contains 0.04% by weight of sulfur, which is oxidized into sulfur dioxide in the engine. Automobiles contribute about 2% of manmade sources of sulfur in the air. It has been reported recently that oxidation catalysts may accelerate the oxidation of sulfur dioxide to sulfates, which is a more serious respiratory hazard than sulfur dioxide. It may be necessary to reduce the sulfur in gasoline. 

The sulfuric acid concentration should be at that required for the particular product application. Sources of sulfuric acid in LAS are as follows ... 

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