Fuming sulfuric acid, with

Isoquinoline-5-Sulfonic Acid. Add 221 g reagent grade isoquinoline to 183 g of coned sulfuric acid. The resulting product is broken into small lumps and added to 561 g of 65% fuming sulfuric acid, with swirling, in a dry ice chloroform bath to keep the temp below 40°. After complete... 

Other THF polymerization processes that have been disclosed in papers and patents, but which do not appear to be in commercial use in the 1990s, include catalysis by boron trifluoride complexes in combination with other cocatalysts (241—245), modified montmorriHonite day (246—248) or modified metal oxide composites (249), rare-earth catalysts (250), triflate salts (164), and sulfuric acid or fuming sulfuric acid with cocatalysts (237,251—255). 

For this reason the potency of a nitric-sulfuric acid mixture can be considerably increased by using fuming nitric and fuming sulfuric acids. With such mixtures nitration of relatively unreactive compounds can be achieved. For example, 4-nitromethylbenzene is far less reactive than methylbenzene, but when heated with an excess of nitric acid in fuming sulfuric acid, it can be converted successively to 2,4-dinitromethylbenzene and to 2,4,6-trinitro methylbenzene (TNT) ... 

Dimethyl sulfate is produced by acting on fuming. sulfuric acid with methyl alcohol and distilling in vacuo. Before Uie war it was used in industry as a methylating agent for amines and phenols and as a reagent for detecting coal-tar oils. 

Derivation By treating sulfur trioxide or fuming sulfuric acid with hydrochloric acid. 

Reaction of CCl with SO 3, or wth fuming sulfuric acid with an SO 3 content of greater than 45%, proceeds according to Equation (5.13) [1591,1231] ... 

Ammonium sulfamate may be prepared by the reaction of sulfur trioxide with liquid ammonia, or by the neutralisation of sulfamic acid (made by the reaction of fuming sulfuric acid with urea) with ammonia (Cupery and Tanberg, 1942 Sasaki et al 1968). 

Electrophilic substitution is a straightforward way to functionalize polyaniline. Substitution of sulfonic acid groups on the backbone of polyaniline, as shown in Figure 2.2, was first introduced by Epstein et al. [39] in the very first report of self-doped water soluble polyaniline. Their synthetic method involved the sulfonation of polyaniline using fuming sulfuric acid. The emeraldine base form of polyaniline (0.5 g) was dissolved in 40 mL of fuming sulfuric acid with constant stirring. 

Alkyl selenazoles have been sulfonated. Thus 2,4-dimethylselenazole with fuming sulfuric acid (5% SO3) at 100°C gives 2.4-dimethy -5-sulfonylselenazole [m.p. 238 C (decomp.) (26)], which is relatively unstable. decomposing to give metallic selenium. 

Polyaniline (PANI) can be formed by electrochemical oxidation of aniline in aqueous acid, or by polymerization of aniline using an aqueous solution of ammonium thiosulfate and hydrochloric acid. This polymer is finding increasing use as a "transparent electrode" in semiconducting devices. To improve processibiHty, a large number of substituted polyanilines have been prepared. The sulfonated form of PANI is water soluble, and can be prepared by treatment of PANI with fuming sulfuric acid (31). A variety of other soluble substituted AJ-alkylsulfonic acid self-doped derivatives have been synthesized that possess moderate conductivity and allow facile preparation of spincoated thin films (32). 

Tetrahydrofuran is polymerized to poly(tetramethylene glycol) with fuming sulfuric acid and potassium biduoride (29). 

Make acid yields coumaUc acid when treated with fuming sulfuric acid (19). Similar treatment of malic acid in the presence of phenol and substituted phenols is a facile method of synthesi2ing coumarins that are substituted in the aromatic nucleus (20,21) (see Coumarin). Similar reactions take place with thiophenol and substituted thiophenols, yielding, among other compounds, a red dye (22) (see Dyes and dye intermediates). Oxidation of an aqueous solution of malic acid with hydrogen peroxide (qv) cataly2ed by ferrous ions yields oxalacetic acid (23). If this oxidation is performed in the presence of chromium, ferric, or titanium ions, or mixtures of these, the product is tartaric acid (24). Chlorals react with malic acid in the presence of sulfuric acid or other acidic catalysts to produce 4-ketodioxolones (25,26). 

In the reaction of arulinium sulfate [542-16-5] with fuming sulfuric acid, the major products are m- and -aminoben2enesulfonic acid with less than 2% of the ortho isomer. With excess concentrated sulfuric acid (96.8—99.9%) at 60—100°C, the sulfate salt gives mainly the ortho and para isomers of the sulfonic acid (42). 

Tantalum is not resistant to substances that can react with the protective oxide layer. The most aggressive chemicals are hydrofluoric acid and acidic solutions containing fluoride. Fuming sulfuric acid, concentrated sulfuric acid above 175°C, and hot concentrated aLkaU solutions destroy the oxide layer and, therefore, cause the metal to corrode. In these cases, the corrosion process occurs because the passivating oxide layer is destroyed and the underlying tantalum reacts with even mild oxidising agents present in the system. 

Toluenesulfonic Acid. Toluene reacts readily with fuming sulfuric acid to yield toluene—sulfonic acid. By proper control of conditions, /)i7n7-toluenesulfonic acid is obtained. The primary use is for conversion, by fusion with NaOH, to i ra-cresol. The resulting high purity i7n -cresol is then alkylated with isobutylene to produce 2 (i-dii-tert-huty -para-cmso (BHT), which is used as an antioxidant in foods, gasoline, and mbber. Mixed cresols can be obtained by alkylation of phenol and by isolation from certain petroleum and coal-tar process streams. 

Sulfonation. Benzene is converted iato benzenesulfonic acid [98-11-3] C H SO, upon reaction with fuming sulfuric acid (oleum) or chlorosulfonic acid. y -Benzenedisulfonic acid [98-48-6] CgHgS20, is prepared by reaction of benzene-sulfonic acid with oleum for 8 h at 85°C. Often under these conditions, appreciable quantities ofT -benzenedisulfonic acid [31375-02-7] are produced. 1,3,5-Benzenetrisulfonic acid [617-99-2] C H S Og, is produced by heating the disulfonic acid with oleum at 230°C (21). 

Modem plants manufacture chlorosulfuric acid by direct union of equimolar quantities of sulfur trioxide and dry hydrogen chloride gas. The reaction takes place spontaneously with evolution of a large quantity of heat. Heat removal is necessary to maintain the temperature at 50—80°C and thus minimize unwanted side reactions. The sulfur trioxide may be in the form of 100% Hquid or gas, as obtained from boiling oleum, ie, fuming sulfuric acid, or may be present as a dilute gaseous mixture as obtained direcdy from a contact sulfuric acid plant (24). The hydrogen chloride gas can be in the form of 100% gas or in a diluted form. 

Sulfonation. Fuming sulfuric acid reacts with coumarin to give coumarin-6-sulfonic acid [27279-86-3] at moderate temperature and coumarin-3,6-disulfonic acid [69089-38-9] at higher temperature. 

The reconcentration of dilute (50—60%) sulfuric acid is one of the more costly operations in the manufacture of ethanol by this process. An acid reboiler, followed by a two-stage vacuum evaporation system, raises acid concentration to about 90%. The 90% acid is then brought to 96—98% strength by fortification with 103% oleum (fuming sulfuric acid). 

The best laboratory synthesis of thymine (947) is probably from 3-methylmalic acid (945) which gives 2-formylpropionic acid (946 R = H) in situ by decarboxylation and oxidation in fuming sulfuric acid prior to condensation with urea (46JA912) a similar method from ethyl 2-formylpropionate (946 R = Et) is also described (68IZV918). 

Materials that are corrosion resistant to the expected cathodic polarization qualify as impressed current cathodes. Austenitic CrNi steels are used with strong acids. The oleum (i.e., fuming sulfuric acid) and concentrated sulfuric acid tanks used in sulfonating alkanes and in the neutralization of sulfonic acids are anodi-cally protected using platinized brass as cathodes [15]. Lead cathodes are used to protect titanium heat exchangers in rayon spinning baths [16]. 

A mixture of either bromine or iodine and sulfur trioxide reacts with either tetrafluoroethylene or chlorotrifluoroethylene to produce an intermediate, which, when treated with fuming sulfuric acid, yields a difluorohaloacetyl fluoride [2] (equation 2) 1,1,2-Trichlorotrifluoroethane can be used as a solvent. 

Perfluoroindene and 3-chloroperfluoroindene both react with fuming sulfuric acid [27] However, whereas the former gives only heptafluoro-l-indanone-2-sul-fonic acid (equation 29), the latter yields both this product and 3-chloropenta-fluoromdanone (equation 30). 

When treated with fuming sulfuric acid and then with water, decafluoro-cyclohepta-1,4-diene gives hexafluoro-l,5-dihydroxy-8-oxabicyclo(3 2 l)octan-3-one rather than octafluorocyclohepta-2,6-dienone, which is a probable intermediate [28] (equation 31)... 

Methyl 2-methoxy-2-polyfluoroalkyl-2-fluoroacetates, generated from poly-fluoroalkyltrifluoroethylene oxides and methanol, give, on heating with concentrated or fuming sulfuric acid, methyl polyfluoroalkylglyoxylates [29] (equation 32). 

Perfluorohexamethylbenzene is converted to perfluoropentamethylbenzoic acid by sequential treatment with sodium methoxide, then concentrated sulfuric acid, and finally fuming sulfuric acid [37] (equation 38). The intermediate methyl ortho ester and methyl ester of the acid can be isolated... 

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