Sulfur compound

Sulfur compounds present in the fuel will contaminate certain catalysts, making it difficult to run this type of system from ordinary gasoline. Work being done by Kataria, Ayyappan, and Abraham around rhodium-based, sulfur-tolerant catalysts at 800°C with jet fuel may be pertinent to automotive applications [7], 

Sulfur compounds are very important atmospheric constituents, since in clean tropospheric air as well as in the stratosphere the majority of aerosol particles are composed of ammonium sulfate or sulfuric acid (see Chapter 4). This finding is particularly interesting since with the exception of sea salt sulfur, a predominant portion of sulfur emission is in gaseous form. 

The study of the atmospheric sulfur cycle is a rapidly expanding field because human activity provides an important sulfur dioxide source. In the atmosphere S02 is converted to sulfate containing aerosol particles which can modify the radiation balance of the Earth-atmosphere system, the optical properties and the precipitation forming ability24 of the air. 

Sulfur compounds in the atmosphere are provided by the decomposition of organic matter, combustion of fossil fuels, production of sea salt particles and volcanic activity. We can rather well quantify the strength of these sources, except the intensity of biological sulfur production. 

23 If the role oflightning in NOA production is significant the value of the biological source strength is less. 

24 By acting as condensation nuclei. It is well documented (e.g. Twomey. 1971) that atmospheric condensation nuclei consist mainly of ammonium sulfate. 

Ninety percent or more of the sulfur in fossil fuels is emitted in the form of sulfur dioxide (S02) during 

FIGURE 2.7 Contribution of various sources to the total anthropogenic CO emissions in the United States in 1996 (from EPA 1997). 

Natural emissions of sulfur compounds to the atmosphere occur from a variety of sources, including volcanic eruptions, sea spray, and a host of biogenic processes (e.g., Aneja, 1990). Most of the volcanic sulfur is emitted as S02, with smaller and highly variable amounts of hydrogen sulfide and dimethyl sulfide (CH3SCH3). Sea spray contains sulfate, some of which is carried over land masses. 

FIGURE 2.8 S02 emissions in many different regions as a function of rate of fuel consumption. Data for Europe and the United States are for 1980, and those for Asia are for 1987 (from Kato and Akimoto, 1992). 

Biogenic processes, however, emit reduced forms of sulfur, including dimethyl sulfide and hydrogen sulfide, with lesser amounts of carbon disulfide (CS2), dimethyl disulfide (CH3SSCH3), carbonyl sulfide (COS), and methyl mercaptan (Cl I3SH). These reduced sulfur compounds are then oxidized in the atmosphere as described in detail in Chapter 8.E. 

Organic Chemistry of Bivalent Sulfur, Chemical Publishing Co., New York (1958), Vol 1, p 115 (Raney Ni) 

Kharasch and C. Y. Meyers, The Chemistry of Organic Sulfur Compounds, Pergamon Press, New York (1966), Vol 2, p 35 (Raney Ni) 

See also page 47, Section 93 and page 49, Section 9.4, for reduction of sulfur-containing derivatives of alcohols and phenols and page 229, Section 4, for reduction of allylic sulfonates and sulfones with double bond transposition. 

Ni(OAc)2, r-AmOH (R=l° alkyl, aryl) NaBH, NiCl2-6H20(R = r, 2° alkyl) 

nickelocene (R — 1°, 3° alkyl aryl) UAIH4, NiBrrDME, PPh3 (R = l°, 3° alkyl aryl) 

The oxidation of some sulfur-containing compounds, such as thioke-tones and thioamides (derivatives of ketones and acids, respectively), has been mentioned in earlier sections. 

The typical frequencies for some common functional groups containing sulfur bonds, such as mercaptans (R—S— H), disulfides (R—S—— R) and thioethers (R—S—R), are presented in Table 43j. 

The assignment of modes to a variety of oxygen-containing sulfur compounds, such as sulfoxides (R—SO—R), sulfones (R—SO2—R), sulfonic acids (R— 802—OH) and sulfonamides (R—SO2——), are shown in Table 4.3k. 

1100-1000 (strong) S=0 stretching Sulfones, sulfonic acids and sulfonamides 

The origin of the majority of sulfur-containing aroma compounds formed by microorganisms is sulfate, which is initially incorporated into the sulfur amino acids (L-methionine and L-cysteine) and the peptide, glutathione [112]. These sulfur-containing precursors are metabolized to a variety of aroma compounds of sensory significance. Spinnler et al. [112] have provided a good discussion of this process. 

Cysteine may react with carbonyls to yield flavor compounds (e.g., trithiolanes) or be decarboxylated to give cysteamine, deaminated to provide a-keto-3-thiopro-pionic acid or degraded to free HjS. While each of these pathways may yield significant aroma compounds, the formation of free H2S is particularly important. H2S is a flavor compound in its own right and also is very reactive with carbonyls and free radicals to form very potent aroma compounds (e.g., ethyl sulfide, diethyl disulfide, amyl mercaptan, and 3-methyl-2-butenethiol). 

Some of the mechanisms leading to the formation of several classes of flavor compounds via microbial activity are outlined in this chapter. At this point, two additional ideas should be mentioned. First, we have only considered the formation of flavor via metaboUc activity of the living microorganism. Miaoorganisms could 

FIGURE 5.15 Conversion of methionine and Acyl-CoA to thioesters. (From Spinnler, H.E., N. Martin, P. Bonnarme, HeteroatomicAroma Compounds, G.A. Reineccius, T.A. Reineccius, Eds., Amer. Chem. Soc., Washington, D.C., 2002, p. 54. With permission.) 

Schieberle, R, K.H. Engel, Eds., Frontiers of Flavour Science, Deutsche Eorschung. Lebensmittel., Garching, 2000, p. 602. 

It has been shown by mineralogical, chemical and X-ray-diffraction analyses that the major part of reduced sulfur occurs in the form of pyrite in ancient sediments (Lein, 1978)81). It has been also established that pyrite may form rapidly in muds of recent sediments. In anoxic bottom waters, pyrite formation can take place before and after burial even during sedimentation (Berner, 1984)89). Also the geological occurrence and chemical stability relations indicate that authigenic pyrites can be synsedimentary or diagenetic (Kalliokosky, 1966)90). 

Pyrite occurs in sediments in the form of single crystals, crystal clusters, spheres, framboids or as replacement for organic structures. Miroprobe analysis of pyritic aggregates often show the presence of appreciable carbon, and some coarser carbonaceous matter is visible microscopically. Microcrystals of pyrites are frequently found in organic particles when examined in the TEM. Sometimes a thin bright rim occurs around each crystal, which indicates that it is enclosed within a carbonaceous shell (Oberlin et al., 1980)19). 

In these cases, pyritization of microstructures must have occured before compaction of the sediments. Once the petrifying iron sulfide was deposited, it probably did not undergo further alteration (Fig. 20a). 

The occurrence of bacteria-like structures inside of large, well-formed crystals also may deserve consideration. Small inclusions, distinctly different from fluid 

The existence of sulfate-reducing bacteria as old as 2.8 Ga and possibly 3.2 Ga has been established by means of 34S/32S ratios from sedimentary pyrites found in Precambrian rocks. The values show dissimilatory fractionation similar to those produced by extant sulfate-reducing bacteria. Thus it appears that this type of mineralization process, may have evolved in the early Precambrian (Schidlowski et al., 1983) 87). 

Ni(OAc)2, f-AmOH (R= 1° alkyl, aryl) NaBH NiCI2-6H20 R = 1°, 2° alkyl) 

The S-S linkage of disulfides and the C-S linkage of certain sulfides can undergo photoinduced homolysis. The low reactivity of the sulfur-centered radicals in addition or abstraction processes means that primary radical termination can be a complication. The disulfides may also be extremely susceptible to transfer to initiator (Ci for 88 is ca 0.5, Sections 6.2.2.2 and 9.3.2). However, these features are used to advantage when the disulfides are used as initiators in the synthesis of tel ec he lies295 or in living radical polymerizations. 96 The most common initiators in this context are the dithiuram disulfides (88) which are both thermal and photochemical initiators. The corresponding monosulfides [e.g. (89)J are thermally stable but can be used as photoinitiators. The chemistry of these initiators is discussed in more detail in Section 9.3.2. 

The key to reliable global emission estimations are the EF as function from time (changing technology and introduction of flue gas desulfurization) as well as 

More than 90% of SO2 emission is related to the combustion of fossils fuels (coal and oil with an approximate share of two-thirds and one-third, respeetively), primarily metal smelting (Cu, Zn, Mn, and Ni) and sulfuric acid production (only in the past). Since 1980, flue gas desulfurization has been introduced stepwise with different degrees in industrialized countries. FDG works with an efficiency of about 95% hence the country-based SO2 emission can be reduced by about one order of magnitude as has occurred in Germany after instalment of FGD at all large SO2 sources (Fig. 2.53). Germany probably remains an extreme example of changing 

SO2 emissions in a very short period in 1992 the ratio between Eastern and Western Germany in SO2 emission was still 5.1 and dropped 10 years later to 0.25. Such country-based emission changes (expressible in specific emission densities too) also result without any doubt in changes of atmospheric chemistry. 

The only commercial carbon sulfide is carbon disulfide (qv) [75-15-0] There are several unstable carbon sulfides. Carbon subsulfide [12976-57-2]  

is a red Hquid (mp —0.5° C, bp 60—70°C at 1.6 kPa (12 mm Hg)) produced by the action of an electric arc on carbon disulfide (1 4). The stmcture has been shown to be S=C=C=C=S on the basis of its reactions to form malonic acid derivatives and on the basis of physical measurements. It is unstable and decomposes ia a few weeks at room temperature it decomposes explosively when heated rapidly at 100—120°C with formation of a black polymeric substance (C2S2) (5,6). Dilute solutions ia CS2 are fairly stable, but photochemical polymerisation to (C2S2) occurs. 

The reaction of C2S2 with 2-aminopyridine and /V-pbenylbensamidine yields the higher condensed derivatives C2S2 also reacts with p-aminocrotonate to yield H2NC(CH2)=C(COOC2H2)]2S (7). 

Carbon monosulfide [2944-05-0] CS, is an unstable gas produced by the decomposition of carbon disulfide at low pressure ia a silent electrical discharge or photolyticaHy (1 3) ia the presence or absence of sulfur (3). It decomposes with a half-life of seconds or minutes to a black soHd of uncertain composition (1—3). The monosulfide can be stabilized ia a CS2 matrix at — 196°C, and many stable coordination complexes of CS with metals have been prepared by iadirect means (8). 

Carbon monosulfide, CS, which can be produced by passiag CS2 through a high voltage discharge, can react with C H SCl at low temperatures ia toluene to give CgH SC(S)Cl. In a similar manner CS reacts with S2CI2 by double iasertion to yield C1C(S)SSC(S)C1 (9). Carbon monosulfide can also react with amines or thiols ia toluene or DMF (10). A review of the synthetic utiUty of CS has been pubUshed (11). 

T0458 Kenox Technology Corporation, Wet Air Oxidation T0491 MACTEC, Inc., Chemical Oxidation (ChemOx) Process T0595 Peal/Compost Biofiltration—General T0795 Thermatrix, Inc., Flameless Thermal Oxidizer (FTO) 

T0130 Bohn Biofllter Corporation, Bohn Off-Gas Treatment T0144 Caras Chemical Company, CAIROX Potassium Permanganate T0161 Chemical Oxidation—General 

T0251 Energy Biosystems Corporation, Biocatalytic Desulfurization 

T0340 Geo-Microbial Technologies, Inc., Heteroatom Extraction Technology 

T0463 Klean Earth Environmental Company (KEECO, Inc.), KB-SEA 

Incompletely Characterized Carbon Sulfides. A poorly characterized black solid, known as carsul, occurs as a residue in sulfur distillation or as a precipitate in molten Frasch sulfur (12,13). Although this material may approach the composition of a carbon sulfide, it is more likely also to contain some chemically bound hydrogen and possibly other elements. Carbon—sulfur surface compounds of the formula C S, where x is greater than 4, 

Apparently, other photochemical reactions, which occur in the singlet manifold, are faster than intersystem crossing and compete effectively with the [2 + 2[-photocycloaddition [120]. 

1-Thiocoumarin (127) underwent [2 + 2]-photocycloaddition reactions in better yields than 126. In contrast to coumarin, cis- and trans-fused products are being found, however, for example, in the reaction with 2,3-dimethyl-2-butene, possibly because the thiopyran ring is more flexible than the pyran ring due to the longer C—S bonds. HTproduct is favored with electron donor-substituted olefins [121]. Electron acceptor substitution in 3-position, as in 3-cyano-l-thiocoumarin (128), leads to an improved performance in [2 + 2]-photocycloaddition reactions [122]. 

Entry Starting material3 Product(s) Mechanism Section 

Similarly to carbonyl compounds (Section 6.3.1), thiocarbonyl compounds abstract hydrogen upon irradiation however, both n,7t and n,n excited states are reactive and the hydrogen atom can be added to either the sulfur (Table 6.17, entry 1) or carbon (entry 2) atoms of the C=S bond. Aliphatic and aromatic thiocarbonyl compounds can also undergo photocycloaddition to unsaturated compounds from both singlet or triplet excited states to form thietanes (analogously to the Paterno Biichi reaction see Section 6.3.2) (entry 3) or 1,4-dithianes. On the other hand, fragmentation of the S C bond is a typical primary process observed in excited sulfones and sulfonates (entry 4), followed by efficient SO2 extrusion from the radical intermediate. 

SO2 0-0.5 ppmv (urban) 20-200 pptv (remote) Oxidation of fossil fuel S Oxidation of S gases Direct reaction with Earth surface, oxidation to sulfate 

H2S 0—40 pptv Biological decay of protein in anaerobic water Oxidation to SO2 

CH3SCH3 20-200 pptv Oceanic phytoplankton and algae Oxidation to SO2 

In addition to solute from CCN, clouds contain dissolved gases (e.g. SO2, NH3, HCHO, H2O2, HNO3, and many more). In turn, some of these may react in the cloud droplets to form other substances which subsequently can appear in rainwater. Finally, falling raindrops can collect other materials (e.g. large dust particles) on their way to the Earth s surface. Thus, rainwater composition does not uniquely reflect the chemistry of the CCN. 

There is a large variety of atmospheric sulfur compounds, in the gas, solid, and liquid phases. Table 

FIGURE 2.67 The infrared speetrum of leucine (Nujol mull, KBr plates). Dots indicate the Nujol (mineral oil) absorption bands (see Fig. 2.8). 

Infrared spectral data for sulfur-containing compounds are covered in this section. Included here are single-bonded compounds (mercaptans or thiols and sulfides). Double-bonded S=0 compounds are also included in this section. 

S—H Stretch, one weak band, occurs near 2550 cm and virtually confirms the presence of 

Little useful information is obtained from the infrared spectrum. 

FIGURE 2.68 The infrared spectmm of benzenethiol (neat liquid, KBr plates). 

024156 Hydrogen sulfide is produced from reduced glutathi- 

Copyright 2013 Cengage Learning. AH Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. 

Asymmetric stretch (strong) occurs at 1300 cm symmetric stretch (strong) at 1150 cm-.  

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A knowledge of these compounds is important because they often have undesirable attributes, e.g., unpleasant odor, the SO2 formed by combustion, catalyst poisoning. There are a number of refining processes to eliminate sulfur compounds. 

The aromatic extracts are black materials, composed essentially of condensed polynuclear aromatics and of heterocyclic nitrogen and/or sulfur compounds. Because of this highly aromatic structure, the extracts have good solvent power. 

Sulfur compounds No reaction at sodium plumbite test (NF M 41-006) Pass hydrogen sulfide test (ISO 8819, future NF EN 28819)... 

The H2S formed can react with the sulfates or rock to form sulfur i (Equation 8.2) that remains in suspension as in the case of crude from Goldsmith, Texas, USA, or that, under the conditions of pressure, temperature I and period of formation of the reservoir, can react with the hydrocarbons to give sulfur compounds ... 

I H2S reacts in another way with the olefinic hydrocarbons producing thiols and sulfur compounds (Equation 8.3 and 8.4) ... 

Of the general formula, R - S — H, where R represents an aliphatic or cyclic radical, the thiols —also known as mercaptans— are acidic in behavior owing to their S—H functional group they are corrosive and malodorous. Their concentration in crude oils is very low if not zero, but they are created from other sulfur compounds during refining operations and show up in the light cuts, as illustrated in Table 8.6. 

The major part of the sulfur contained in crude petroleum is distributed between the heavy cuts and residues (Table 8.10) in the form of sulfur compounds of the naphthenophenanthrene or naphthenoanthracene type, or in the form of benzothiophenes, that is, molecules having one or several naphthenic and aromatic rings that usually contain a single sulfur atom. 

Organic sulfur compounds such as sulfurized spermaceti oil, terpene sulfides, and aromatic disulfides have been used. Encumbered phenols such as di-tertiary-butylphenols and amines of the phenyl-alphanaphthylamine type are effective stopping the kinetic oxidation chain by creating stable radicals. 

Mercaptans are naturally present in crude oil (Chapters 1 and 8), or they result from the decomposition of other sulfur compounds during thermai or catalytic cracking operations. 

Rail, H.T., C.J. Thompson, H.J. Coleman and R.L. Hopkins (1972), "Sulfur compounds in crude oil". Bureau of Mines Bull. No. 659. Distributed by National Technical Information Service (NTIS), US Dpt of Commerce, Springfield, VA. 

Table 7. Open-chain difunctional sulfur compounds.

Table 9. Open-chain tiifunctional nitrogen, halogen and sulfur compounds.

The a-thiocyanatoketones are easily obtainable from a-halocarbonyl compounds and metal thiocyanates (sodium, potassium, barium, or lead thiocyanate) (416, 484, 519, 659) in an alcoholic solution. Yields ranged from 80 to 95%. They are very sensitive substances that isomerize when reacted upon by acids, bases, or labile hydrogen and sulfur compounds. 

Other sulfur compounds such as thiourea, ammonium dithiocarbamate, or hydrogen sulfide also lead to 2-mercaptothiazoles. Thus thiourea has been used in the syntheses of 4,5-dimethyl (369) and 4-aryl-2-mercapto-thiazoles (Table 11-30) (519). The reactions were carried out by condensing the ia -thiocyanatoketones with thiourea in alcohol and water acidified with hydrochloric acid. By this procedure, 4-aryl-2-mercaptothiazoles were obtained in yields of 40 to 80% with bis-(4-aryl-2-thiazolyl) sulfides as by-products (519). These latter products (194) have also been observed as a result of the action of thiourea on 2-chloro-4-arylthiazole under the same experimental conditions. They can be separated from 2-mercaptothiazoles because of their different degrees of solubility in sodium hydroxide solution at 5%. In this medium bis-(4-phenyl-2-thiazolyl)sulfide is... 

The very high rate of thiophenoxy substitution, compared with low stability of Meisenheimer-like sulfurated compounds, can explain the simple behavior of the ihiophenoxy-substitution reaction. 

Tricoordmate sulfur compounds are chiral when sulfur bears three different sub stituents The rate of pyramidal inversion at sulfur is rather slow The most common compounds m which sulfur is a chirality center are sulfoxides such as... 

Interpreting the mass spectra of sulfur compounds is aided by the observation of an M+2 peak because of the presence of the mass 34 isotope of sulfur The major cleav age pathway of thiols is analogous to that of alcohols... 

Radicofunctional nomenclature finds some use in naming ethers, sulfides, sulfoxides, sulfones, selenium analogs of the preceding three sulfur compounds, and azides. 

TABLE 7.36 Raman Frequencies of Sulfur Compounds Continued)... 

Nickel Aluminum, aluminum(III) chloride, ethylene, 1,4-dioxan, hydrogen, methanol, nonmetals, oxidants, sulfur compounds... 

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