Sulfur trioxide, formation

Only a small amount of sulfur trioxide can have an adverse effect as it brings about the condensation of sulfuric acid and causes severe corrosion. Although diminution of the excess air reduces sulfur trioxide formation considerably, other considerations, such as soot formation, dictate that the excess air level cannot be lowered sufficiently to eliminate sulfur trioxide entirely. 

Catalysts based on zeolites have also been used successfully to remove NOX from the emissions of large and small-scale stationary sources. The zeolite can be extmded directly as a monohth or applied as a washcoat on preformed cordi-erite supports. The use of several zeolites—including wide-pore mor-denite— for this reaction has been patented. Up to 95% NOX conversion can be achieved with mordenite, with no promoters, and some zeolites are stable at temperatures up to 600°C. Long catalyst lives have been achieved in retrofitted coal based SCR units with low sulfur trioxide formation and good poisons resistance. Spent zeolite catalysts can be disposed of in approved landfill sites because they have negligible heavy-metal content. ... 

Looking more closely at the Haber process in practical terms, we note that, like sulfur trioxide formation in the contact process, it is an equilibrium reaction and also exothermic. 

The older methods have been replaced by methods which require less, if any, excess sulfuric acid. For example, sulfonation of naphthalene can be carried out in tetrachloroethane solution with the stoichiometric amount of sulfur trioxide at no greater than 30°C, followed by separation of the precipitated l-naphthalenesulfonic acid the filtrate can be reused as the solvent for the next batch (14). The purification of 1-naphthalenesulfonic acid by extraction or washing the cake with 2,6-dimethyl-4-heptanone (diisobutyl ketone) or a C-1—4 alcohol has been described (15,16). The selective insoluble salt formation of 1-naphthalenesulfonic acid in the sulfonation mixture with 2,3-dimethyl aniline has been patented (17). 

Reaction with cold nitric acid results primarily ia the formation of 5-nitrosahcyhc acid [96-97-9]. However, reaction with fuming nitric acid results ia decarboxylation as well as the formation of 2,4,6-trinitrophenol [88-89-1] (picric acid). Sulfonation with chlorosulfonic acid at 160°C yields 5-sulfosahcyhc acid [56507-30-3]. At higher temperatures (180°C) and with an excess of chlorosulfonic acid, 3,5-disulfosahcyhc acid forms. Sulfonation with hquid sulfur trioxide ia tetrachloroethylene leads to a nearly quantitative yield of 5-sulfosahcylc acid (1). 

The mechanism for sulfonation of hydrogenated fatty esters is accepted as a two-stage process. A rapid sequence of reactions leads to the formation of intermediates having approximately 2 1 stoichiometry of sulfur trioxide to ester. In the subsequent slower and higher temperature aging step, the SO is released for further reactions and the starting material conversion proceeds to completion (133). 

Sulfamation is the formation (245) of a nitrogen sulfur(VI) bond by the reaction of an amine and sulfur trioxide, or one of the many adduct forms of SO. Heating an amine with sulfamic acid is an alternative method. A practical example of sulfamation is the artificial sweetener sodium cyclohexylsulfamate [139-05-9] produced from the reaction of cyclohexylamine and sulfur trioxide (246,247) (see Sweeteners). Sulfamic acid is prepared from urea and oleum (248). Whereas sulfamation is not gready used commercially, sulfamic acid has various appHcations (see SuLFAMiC ACID AND SULFAMATES) (249—253). 

Other problems that can be associated with the high dust plant can include alkaH deterioration from sodium or potassium in the stack gas deposition on the bed, calcium deposition, when calcium in the flue gas reacts with sulfur trioxide, or formation and deposition of ammonium bisulfate. In addition, plugging of the air preheater as weU as contamination of flyash and EGD wastewater discharges by ammonia are avoided if the SCR system is located after the FGD (23). 

The use of dimethyl sulfoxide-acetic anhydride as a reagent for the oxidation of unhindered steroidal alcohols does not appear to be as promising due to extensive formation of by-products. However, the reagent is sufficiently reactive to oxidize the hindered 11 j -hydroxyl group to the 11-ketone in moderate yield. The use of sulfur trioxide-pyridine complex in dimethyl sulfoxide has also been reported. The results parallel those using DCC-DMSO but reaction times are much shorter and the work-up is more facile since the separation of dicyclohexylurea is not necessary. Allylic alcohols can be oxidized by this procedure without significant side reactions. 

Two-component methods represent the most widely applied principles in sulfone syntheses, including C—S bond formation between carbon and RSOz species of nucleophilic, radical or electrophilic character as well as oxidations of thioethers or sulfoxides, and cheletropic reactions of sulfur dioxide. Three-component methods use sulfur dioxide as a binding link in order to connect two carbons by a radical or polar route, or use sulfur trioxide as an electrophilic condensation agent to combine two hydrocarbon moieties by a sulfonyl bridge with elimination of water. 

One stage in the manufacture of sulfuric acid is the formation of sulfur trioxide by the reaction of S02 with 02 in the presence of a vanadium(V) oxide catalyst. Predict how the equilibrium composition for the sulfur trioxide synthesis will tend to change when the temperature is raised. 

Sulfur trioxide reacts with MesSiCl 14 to give the trimethylsilyl ester of chloro-sulfonic acid 1334 [96], which on treatment vvdth iodosobenzene forms iodosoben-zenedichloride 1335, HMDSO 7, and regenerated SO3 [97]. Addition of olefins such as cyclohexene leads to the formation of sulfones such as 1336 [97]. With... 

Sulfate monoesters can react by dissociative paths, and this is the favored path. Whether such reactions are concerted or involve a very short-lived sulfur trioxide intermediate has been the subject of debate. ° Benkovic and Benkovic reported evidence suggesting that the nucleophile is present (though there is little bond formation) in the transition state for the reaction of amines with p-nitrophenyl sulfate. Alkyl esters of sulfuric or sulfonic acids normally react with C-0 cleavage only when this is disfavored, as in aryl esters, does one see S-0 cleavage. Sulfate diester... 

Taurog et al. [216] showed that contrary to previous suggestions, both iodination and coupling are catalyzed by the oxoferryl porphyrin Tr-cation radical of TPO Compound I and not the oxoferryl protein radical. HRP catalyzed the oxidation of bisulfite to sulfate with the intermediate formation of sulfur trioxide radical anion S03 [217] HPO, MPO, LPO, chloroperoxidase, NADH peroxidase, and methemoglobin oxidized cyanide to cyanyl radical [218],... 

Transformations of Methyl 5-0-Benzyl-2-0-methyl-/3-I)-glueofuranosidurono-6,3-lae-tone (86) to Dimethyl (Z,E)-2-Methoxy-5-(phenylmethoxy)-2,4-hexadienedioatevl (87). ( Elimination employing DBU b oxidation with silver oxide-sodium hydroxide followed by diazomethane esterification c acidic glycoside cleavage, oxidation by dimethyl sulfoxide-acetic anhydride with formation of 5-0-benzyl-2-0-methyI-D-glucaro-1,4 6,3-dilactone, elimination by using DBU, followed by short treatment with diazomethane d elimination by DBU with subsequent diazomethane esterification e sodium borohydride in hexamethylphosphoric triamide 1 catalytic oxidation followed by short treatment with diazomethane " dimethyl sulfoxide-sulfur trioxide-pyridine-triethylamine.150)... 

The material is produced from naphthalene by oleum or sulfur trioxide sulfonation under conditions conducive to the formation of the h sulfonate. Subsequent reaction with formaldehyde leads to polymerization and the sulfonic acid is neutralized with sodium hydroxide [17] or lime. The process is illustrated in Fig. 2.2. The value of n is typically low but conditions are chosen to get a proportion of higher-molecular-weight product as it is believed to be more effective [18]. The quantity of sodium sulfate by-product formed by the neutralization of excess sulfonating reagent will vary depending on the process used, but can be reduced by a subsequent precipitation process using lime [19]. 

One of the first compounds to be introduced to the clinic, aztreonam (40-9), has been produced by total synthesis. Constmction of the chiral azetidone starts with amide formation of L-threonine (40-1) via its acid chloride treatment with ammonia leads to the corresponding amide (40-2). The primary amino group in that product is then protected as its carbobenzyloxy derivative (40-3). Reaction of that product with methanesulfonyl chloride affords the mesylate (40-4). Treatment of that intermediate with the pyridine sulfur trioxide complex leads to the formation of the A -sulfonated amide (40-5). Potassium bicarbonate is sufficiently basic to ionize the very acidic proton on the amide the resulting anion then displaces the adjacent mesylate to form the desired azetidone the product is isolated as its tetrabutyl ammonium salt (40-6). Catalytic hydrogenation over palladium removes the carbobenzyloxy protecting group to afford the free primary amine (40-7). The... 

The degree of conversion to sulfur trioxide is influenced by three factors 1) the amount of sulfur in fuel, b) the amount of excess air used in combustion and, c) the presence of oxidation catalysts. Figure 1 illustrates SO3 formation for coal and oil as a function of excess air used in combustion. More pronounced... 

The direct sulfonation with sulfuric acid discovered by Hanson et al. (18) is more effective. Another method by which the formation of phosphane oxide is strongly inhibited was published in 1995 the use of B(OH)3 in combination with sulfur trioxide hinders the oxidation and offers the possibility to control the number and the position of sulfonate groups (19). 

Fuming sulfuric acid and sulfur trioxide are more reactive than sulfuric acid, frequently leading to polysulfonation. Formation of addition compounds of sulfur trioxide with suitable Lewis bases (nitromethane, pyridine, 1,4-dioxane), however, moderates its reactivity allowing clean monosulfonation. 

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