Sulfones trioxide

IS reversible but can be driven to completion by several techniques Removing the water formed m the reaction for example allows benzene sulfonic acid to be obtained m vir tually quantitative yield When a solution of sulfur trioxide m sulfuric acid is used as the sulfonatmg agent the rate of sulfonation is much faster and the equilibrium is dis placed entirely to the side of products according to the equation... 

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)... 

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. 

Sulfonation. Maleic anhydride is sulfonated to a-sulfomaleic anhydride [40336-85-4] (30) with sulfur trioxide [7446-11-9] (112,113). Uses for this monomer have not been pubHshed. 

Commercially, sulfonation is carried out by the classic method with sulfuric acid. Modem reactors are glass-lined older equipment was made from cast iron or coated with enamel Processes often use chlorosulfonic acid or sulfur trioxide to minimi2e the need of excess sulfuric acid. Improved analytical methods have contributed to the success of process optimi2ation (9—12). 

The older methods have been replaced by methods which require less, if any, excess sulfuric acid.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). 

Sulfation and Sulfonation. a-Olefin reactions involving the introduction of sulfur-containing functional groups have commercial importance. As with many derivatives of olefins, several of these products have appHcations in the area of surfactants (qv) and detergents. Typical sulfur reagents utilized in these processes include sulfuric acid, oleum, chlorosulfonic acid, sulfur trioxide, and sodium bisulfite. 

Detergent All late. In the 1940s, sodium dodecylben2ene sulfonate [25155-30-0] (DDES) produced by the alkylation of ben2ene with propylene tetramer followed by sulfonation with oleum [8014-95-7] (H2SO4 mixture with sulfur trioxide) or sulfur trioxide and then neutrali2ation... 

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). 

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. 

Sulfation is defined as any process of introducing an SO group into an organic compound to produce the characteristic C—OSO configuration. Typically, sulfation of alcohols utilizes chlorosulfuric acid or sulfur trioxide reagents. Unlike the sulfonates, which show remarkable stability even after prolonged heat, sulfated products are unstable toward acid hydrolysis. Hence, alcohol sulfuric esters are immediately neutralized after sulfation in order to preserve a high sulfation yield. 

By 1987, sulfur trioxide reagent use in the United States exceeded that of oleum for sulfonation. Sulfur trioxide source is divided between Hquid SO and in situ sulfur burning. The latter is integrated into sulfonation production faciUties. 

Sulfur trioxide reactivity can also be moderated through the use of SO adducts. The reactivity of such complexes is inversely proportional to their stabihty, and consequentiy they can be selected for a wide variety of conditions. Whereas moderating SO reactivity by adducting agents is generally beneficial, the agents add cost and may contribute to odor and possible toxicity problems in derived products. CeUulosic material has been sulfated with SO.—trimethyl amine adduct in aqueous media at 0 to 5°C (16). Sulfur trioxide—triethyl phosphate has been used to sulfonate alkenes to the corresponding alkene sulfonate (17). Sulfur trioxide—pyridine adduct sulfates oleyl alcohol with no attack of the double bond (18). 

Benzene. The reaction of sulfur trioxide and ben2ene in an inert solvent is very fast at low temperatures. Yields of 90% ben2enesulfonic acid can be expected. Increased yields of about 95% can be reali2ed when the solvent is sulfur dioxide. In contrast, the use of concentrated sulfuric acid causes the sulfonation reaction to reach reflux equiUbrium after almost 30 hours at only an 80% yield. The by-product is water, which dilutes the sulfuric acid estabhshing an equiUbrium. 

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. 

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). 

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). 

Sulfonic acids may be subjected to a variety of transformation conditions, as shown in Figure 2. Sulfonic acids can be used to produce sulfonic anhydrides by treatment with a dehydrating agent, such as thionyl chloride [7719-09-7J. This transformation is also accomphshed using phosphoms pentoxide [1314-56-3J. Sulfonic anhydrides, particulady aromatic sulfonic anhydrides, are often produced in situ during sulfonation with sulfur trioxide. Under dehydrating conditions, sulfonic acids react with substituted aromatic compounds to give sulfone derivatives. 

Sulfur dioxide is usefiil as a solvent for sulfur trioxide in sulfonation reactions for example, in the large-scale production of alkylbenzenesulfonate surfactant (329). A newer use for sulfur dioxide is in cyanide detoxification in connection with cyanide leaching of precious metals from mine dumps. 

Cyclamate is about 30 times (8% sucrose solution sweetness equivalence) more potent than sugar. Its bitter aftertaste is minor compared to saccharin and acesulfame-K. The mixture of cyclamate and saccharin, especially in a 10 1 ratio, imparts both a more rounded taste and a 10—20% synergy. Cyclamate (6) is manufactured by sulfonation of cyclohexylamine (7). Many reagents can be used, including sulfamic acid, salts of sulfamic acid, and sulfur trioxide (74—77). 

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. 

According to Figure 3, hydroperoxides are reduced to alcohols, and the sulfide group is oxidized to protonic and Lewis acids by a series of stoichiometric reactions. The sulfinic acid (21), sulfonic acid (23), sulfur trioxide, and sulfuric acid are capable of catalyzing the decomposition of hydroperoxides to nonradical species. 

Appropriate pyrido[2,3-d]pyrimidin-5-ones with formyl groups in the 6-position have been oxiized to piromidic (68) and pipemidic (69) acids, or to intermediates for these, using moist silver oxide, chromium trioxide (potassium dichromate), potassium permanganate or, alternatively, sodium chlorite/hydroxylamine-O-sulfonic acid. 6-Acetyl groups have been similarly oxidized using sodium hypobromite in aqueous dioxane, whilst 2-acetyl groups give dimethylaminomethylene derivatives en route to 2-pyrazolylpyrido[2,3-d]pyrimidines. 

Both pyrrole and furan can be sulfonated in the 2-position by treatment with the pyridine-sulfur trioxide complex (Scheme 14). Furan can be further sulfonated by this reagent to give the 2,5-disulfonate. 

In contrast to thiazoles, certain isothiazoles and benzisothiazoles have been directly oxidized to sulfoxides and sulfones. 4,5-Diphenyl-l,2,3-thiadiazole is converted by peracid into the trioxide (146). Although 1,2,5-thiadiazole 1,1-dioxides are known, they cannot be prepared in good yield by direct oxidation, which usually gives sulfate ion analogous to the results obtained with 1,2,4- and 1,3,4-thiadiazoles (68AHC 9)107). 

Alkyl-5-acetamidoisothiazoles are nitrosated at the 4-position by nitrosylsulfuric acid (78JOC4154). Isothiazoles are sulfonated at the 4-position using either oleum or sulfur trioxide <72AHQ14)1). 

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. ... 

The conversion of cyclic sulfides to sulfones is accompbshed by more energetic oxidations. Perhalogenated thiolanes [106] and 1,3-dithietanes [107] are oxidized to sulfones and disulfones, respectively, by a mixture of chromium trioxide and nitric acid (equation 98) The same reagent converts 2,4-dichloro-2,4-bis(tnfluoromethyl)-l,3-dif/u cto cs to disulfone derivatives [107], whereas trifluoromethaneperoxysulfonic acid converts the starting compound to a sul-fone-sulfoxide derivative [2(equation 99). 

Most of the material presented in this section are reactions of sulfur trioxide. This compound is ambivalent and frequently forms a carbon-sulfur bond (true sulfonation), but it can form a carbon-oxygen bond as well. Examples of both types of bonding are included... 

Sulfonation of the aromatic ring of l, 2, 2 -trifluorostyrene below 0 C does not give satisfactory yields with chlorosulfonic acid or a sulfur trioxide-dioxane complex Tar forms on heating In contrast, under similar conditions ipso substitution IS facile at the position of a trialkylsilyl or -stannyl group Thus, 4-trimethyl-silyl-T 2, 2 D-trifluorostyrene affords the corresponding trimethylsilyl sulfonate [20] (equation 9)... 

A one-pot synthesis of alkyl perfluoroalkyl ketones has been developed. Phosphoranes, generated in situ, are acylated with a perfluoroacyl anhydnde, and the resultmg phosphonium salts are hydrolyzed with alkali [4S (equation 48) Hydrolysis of a carbon-sulfur bond in 2-chloro-2,4,4-trifluoro-1,3-dithietane-S-trioxide, which can be obtained from 2,2,4,4-tetrachloro-l,3-dithietane by fluor-mation with antimony trifluoride followed by selective oxidations, opens the nng to produce 2-chloro-1,1,2-trifluorodimethyl sulfone [49] (equation 49)... 

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