Sulfur trioxide preparation

Sodium fluorosulfate may be prepared by the action of fluorosulfuric acid on powdered, ignited sodium chloride (13) or of sulfur trioxide on sodium fluoride (48). In general, the alkah metal fluorosulfates may be prepared from the ammonium salt by evaporating a solution containing that salt and an alkah metal hydroxide (77). The solubiUties of some Group 1 and 2 fluorosulfates in fluorosulfuric acid have been deterrnined (93). 

Currently, the commercially important methods of preparations of perfluorkiated sulfonic acid derivatives are electrochemical fluotination and sulfur trioxide addition to tetrafluoroethylene with subsequent ring opening. 

Bitumen Ionomers. Moisture-resistant asphalts (qv) have been prepared by reaction of metal oxides with acid-functionalized bitumens (75). Maleic anhydride or sulfur trioxide/trimethylamine complexes have been used successfully for introduction of acid groups into asphaltic bitumens. 

Hexafluoro-2,5-dihydrofuran [24849-02-3] is distilled into sulfur trioxide [7446-11-9] at 25°C. Addition of trimethyl borate [121-43-7] initiates a reaction which upon heating and distillation leads to a 53% yield of difluoromaleic anhydride. Dichloromaleic anhydride [1122-17-4] can be prepared with 92% selectivity by oxidation of hexachloro-1,3-butadiene with SO in the presence of iodine-containing molecules (65). Passing vaporized... 

During calcination, water is removed at temperatures between 200 and 300°C sulfur trioxide is removed at temperatures between 480 and 800°C. At about 480°C the crystals of Ti02 are being formed and continue to grow with increasing temperature. To prepare the anatase pigment, the final calcination temperature of the hydrolysate prepared in the presence of anatase seeds should reach about 800—850°C. 

Sulfosahcyhc acid is prepared by heating 10 parts of sahcyhc acid with 50 parts of concentrated sulfuric acid, by chlorosulfonation of sahcyhc acid and subsequent hydrolysis of the acid chloride, or by sulfonation with hquid sulfur trioxide in tetrachloroethylene. It is used as an intermediate in the production of dyestuffs, grease additives, catalysts, and surfactants. It is also useful as a colorimetric reagent for ferric iron and as a reagent for albumin. Table 9 shows the physical properties of sahcyhc acid derivatives. 

Selenium trioxide, SeO, is white, crystalline, and hygroscopic. It can be prepared by the action of sulfur trioxide on potassium selenate or of phosphorous pentoxide on selenic acid. It forms selenic acid when dissolved in water. The pure trioxide is soluble in a number of organic solvents. A solution in Hquid sulfur dioxide is a selenonating agent. It is stable in very dry atmospheres at room temperature and on heating it decomposes first to selenium pentoxide [12293-89-9] and then to selenium dioxide. 

Sulfamic acid [5329-14-6] (amidosulfuric acid), HSO2NH2, molecular weight 97.09, is a monobasic, inorganic, dry acid and the monoamide of sulfuric acid. Sulfamic acid is produced and sold in the form of water-soluble crystals. This acid was known and prepared in laboratories for nearly a hundred years before it became a commercially available product. The first preparation of this acid occurred around 1836 (1). Later work resulted in identification and preparation of sulfamic acid in its pure form (2). In 1936, a practical process which became the basis for commercial preparation was developed (3,4). This process, involving the reaction of urea with sulfur trioxide and sulfuric acid, continues to be the main method for production of sulfamic acid. 

Dyes, Dye Intermediates, and Naphthalene. Several thousand different synthetic dyes are known, having a total worldwide consumption of 298 million kg/yr (see Dyes AND dye intermediates). Many dyes contain some form of sulfonate as —SO H, —SO Na, or —SO2NH2. Acid dyes, solvent dyes, basic dyes, disperse dyes, fiber-reactive dyes, and vat dyes can have one or more sulfonic acid groups incorporated into their molecular stmcture. The raw materials used for the manufacture of dyes are mainly aromatic hydrocarbons (67—74) and include ben2ene, toluene, naphthalene, anthracene, pyrene, phenol (qv), pyridine, and carba2ole. Anthraquinone sulfonic acid is an important dye intermediate and is prepared by sulfonation of anthraquinone using sulfur trioxide and sulfuric acid. 

Sulfonated polyalkenes were prepared by using a triethyl phosphate—sulfur trioxide complex as the sulfonating reagent along with a solvent at low temperature. Sulfonation takes place at the a-position of the double bond with no cross-linking (222). 

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). 

Chemical Properties. Thionyl chloride chemistry has been reviewed (169—173). Significant inorganic reactions of thionyl chloride include its reactions with sulfur trioxide to form pyrosulfuryl chloride and with hydrogen bromide to form thionyl bromide [507-16-4]. With many metal oxides it forms the corresponding metal chloride plus sulfur dioxide and therefore affords a convenient means for preparing anhydrous metal chlorides. 

Titanium(IV) sulfate can be prepared by the reaction of titanium tetrachloride with sulfur trioxide dissolved in sulfuryl chloride. 

Poly(vinyl nitrate) has been prepared and studied for use in explosives and rocket fuel (104,105). Poly(vinyl alcohol) and sulfur trioxide react to produce poly(vinyl sulfate) (106—111). Poly(vinyl alkane sulfonate)s have been prepared from poly(vinyl alcohol) and alkanesulfonyl chlorides (112—114). In the presence of urea, poly(vinyl alcohol) and phosphoms pentoxide (115) or phosphoric acid (116,117) yield poly(vinyl phosphate)s. 

Arsenic trifluoride (arsenic(III) fluoride), AsF, can be prepared by reaction of arsenic trioxide with a mixture of sulfuric acid and calcium fluoride or even better with fluorosulfonic acid. Chlorine reacts with ice-cold arsenic trifluoride to produce a hygroscopic soHd compound, arsenic dichloride trifluoride [14933-43-8] ASCI2F35 consisting of AsQ. and AsF ions (21). Arsenic trifluoride forms a stable adduct, 2AsF2 SSO, with sulfur trioxide and reacts with nitrosyl fluoride to give nitrosonium hexafluoroarsenate(V) [18535-07-4] [NO][AsFg]. 

The active phase, which is soHd at room temperature, is comprised of mixed potassium and sodium vanadates and pyrosulfates, whereas the support is macroporous siUca, usually in the form of 6—12 mm diameter rings or pellets. The patent Hterature describes a number of ways to prepare the catalyst a typical example contains 7 wt % vanadium pentoxide, 8% potassium added as potassium hydroxide or carbonate, 1% sodium, and 78 wt % siUca, added as diatomaceous earth or siUca gel, formed into rings, and calcined in the presence of sulfur dioxide or sulfur trioxide to convert a portion of the alkah metal salts into various pyrosulfates (81,82). 

Strong dehydrating agents such as phosphorous pentoxide or sulfur trioxide convert chlorosulfuric acid to its anhydride, pyrosulfuryl chloride [7791-27-7] S20 Cl2. Analogous trisulfuryl compounds have been identified in mixtures with sulfur trioxide (3,19). When boiled in the presence of mercury salts or other catalysts, chlorosulfuric acid decomposes quantitatively to sulfuryl chloride and sulfuric acid. The reverse reaction has been claimed as a preparative method (20), but it appears to proceed only under special conditions. Noncatalytic decomposition at temperatures at and above the boiling point also generates sulfuryl chloride, chlorine, sulfur dioxide, and other compounds. 

Other direct methods for the sulfonation of the higher fatty acids are by the use of sulfur trioxide vapor or by the use of chlorosulfonic acid. Indirect methods are also available for the preparation of a-sulfo fatty acids and their salts from an a-bromo fatty acid made by the Hell-Volhard-Zelinsky reaction. The bromo compound may be converted directly to the sodium salt of a sulfonic acid through the Strecker reaction or may be converted to the mercaptan and oxidized to the sulfonate. Sulfonation of the lower fatty acids has been studied by Backer and co-workers. ... 

Perfluoroallyl fluorosulfate is prepared by the treatment oiperfluoropropene with sulfur tnoxide m the presence of boron catalysts [2, 3, 4, 5, 6, 7] (equation 2) Perfluoroisopropyl allyl ether reacts similarly to give 58% polyfluoroallyl fluorosulfate in a cis/trans ratio of 6 4 [S] Sultones are the exclusive products without catalyst. Polyfluoroolefins such as 2-hydropentafluoropropylene [9], (2,3-dichloropropyl)tri-fluoroethylene [70], perfluoropropene [2, i], perfluoroisopropyl alkenyl ethers [S], and acyclic polyfluoroallyl ethers [77] undergo sulfur trioxidation to regioselectively produce the corresponding P-sultones in high yield... 

Perfluoro-y-butyrolactone can be prepared from 1,4 diiodoperfluorobutane by reaction with turning sulfuric acid (oleum) [7S] (equation 19) The yield depends on the concentration of sulfur trioxide One of the by-products, 4-iodoperfluo-robutyryl fluoride, can be recycled to increase the overall yield of the lactone Pure sulfur trioxide generates only perfluorotetrahydrofuran, the lodo acyl fluoride, and perfluorosuccmyl fluoride... 

Fuming sulfuric acid containing 10-60% sulfur trioxide hydrolyzes perfluoro-Af-alkylcyelic amines to perfluoro-Al-alkyl lactams. Mercuric sulfate acts as a Catalyst [JO, 31] (equation 33). The lactams ate highly reactive and can be used to prepare polymenc films and surfactants... 

Sulfonation with sulfur trioxide, pyridine sulfur trioxide, pyridine bis-sulfur trioxide, and dioxane sulfur trioxide, which are useful sul-fonating agents for acidophobic substances, have been applied to the thiophene seriesd At room temperature the 2-monosulfonic acid (isolated as the barium salt) is obtained in 86% yield. Higher temperatures lead to a disulfonic acid. However, sulfonation with chloro-sulfonic acid appears to be more convenient,as the sulfonyl chloride obtained can be used directly for the preparation of derivatives. 

The last step in the preparation of commercial sulfuric acid is to allow the sulfur trioxide to react with steam ... 

In the literature a number of different techniques for the preparation of a-sulfo fatty acid esters can be found. There is equipment for small-scale and commercial scale sulfonation. Stirton et al. added liquid sulfur trioxide dropwise to the fatty acids dispersed or dissolved in chloroform, carbon tetrachloride, or tetrachoroethylene [44]. The molar ratio of S03/fatty acid was 1.5-1.7 and the reaction temperature was increased to 65 °C in the Final stage of sulfonation. The yield was 75-85% of the dark colored a-sulfonated acid. The esterification of the acid was carried out with either the a-sulfonic acid alone, in which case the free sulfonic acid served as its own catalyst, or with the monosodium salt and a mineral catalyst. 

Pyridinium-1-sulfonate was prepared according to the procedure of Sisler and Audrieth. The submitter reports that this procedure may be conveniently carried out at 5 times the specified scale. The reagent should be dry and used soon after its preparation. The checkers found that a technical grade of pyridinium-1-sulfonate (sulfur trioxide pyridine complex) purchased from Aldrich Chemical Company, Inc., gave substantially lower yields of product. 

A variety of sulfating agents has been used for preparing sulfuric esters of polysaccharides.297 - 303 The methods employed include use of adducts of sulfur trioxide with such aprotic solvents as triethylamine,299 dimethyl... 

Tetrafluorooxathietane-2,2-dioxide (Tetrafluoroethane sultone) [697-18-7] o / I 2c,, so2 cf2 Preparative hazard See Sulfur trioxide Tetralluoroethylene C2F403S... 

The acid is prepared by sulfonation of nitrobenzene with oleum, and the reaction product consists essentially of a hot solution of the acid in sulfuric acid. A completed 270 1 batch exploded violently after hot storage at 150C for several hours. An exotherm develops at 145°C, and the acid is known to decompose at 200 C [ 1], A similar incident arose from water leaking from a cooling coil into the fuming sulfuric acid reaction medium, which caused an exotherm to over 150°C and subsequent violent decomposition [2], Detailed examination of the thermal decomposition of the acid shows that it is much slower for the isolated acid than for the reaction mass, and that the concentration of sulfur trioxide in the oleum used for sulfonation bears... 

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