Sulfuric acid reaction with benzene

Cyanide and thiocyanate anions in aqueous solution can be determined as cyanogen bromide after reaction with bromine [686]. The thiocyanate anion can be quantitatively determined in the presence of cyanide by adding an excess of formaldehyde solution to the sample, which converts the cyanide ion to the unreactive cyanohydrin. The detection limits for the cyanide and thiocyanate anions were less than 0.01 ppm with an electron-capture detector. Iodine in acid solution reacts with acetone to form monoiodoacetone, which can be detected at high sensitivity with an electron-capture detector [687]. The reaction is specific for iodine, iodide being determined after oxidation with iodate. The nitrate anion can be determined in aqueous solution after conversion to nitrobenzene by reaction with benzene in the presence of sulfuric acid [688,689]. The detection limit for the nitrate anion was less than 0.1 ppm. The nitrite anion can be determined after oxidation to nitrate with potassium permanganate. Nitrite can be determined directly by alkylation with an alkaline solution of pentafluorobenzyl bromide [690]. The yield of derivative was about 80t.with a detection limit of 0.46 ng in 0.1 ml of aqueous sample. Pentafluorobenzyl p-toluenesulfonate has been used to derivatize carboxylate and phenolate anions and to simultaneously derivatize bromide, iodide, cyanide, thiocyanate, nitrite, nitrate and sulfide in a two-phase system using tetrapentylammonium cWoride as a phase transfer catalyst [691]. Detection limits wer Hi the ppm range. 

The reaction of various A-tosylated a-amino acids (94) with benzene in concentrated sulfuric acid yielded diphenyl derivatives (95)." The mechanism proposed for the reaction (Scheme 9) involves initial protonation of the carboxyl group to give (96), which suffers decarbonylation to the A-tosyliminium salt (97). This reactive electrophile (97) interacts with benzene to give a monophenyl compound (98) which, via a Friedel-Crafts reaction, interacts with another molecule of benzene to yield the diphenyl compound (95)." Toluene and p-xylene reacted analogously to yield diarylated products. 

In Table 1.3.2 a method for the analysis of nitrates and nitrites for a wide variety of samples is given Aqueous nitrate ions are converted to nitrobenzene by reaction with benzene in the presence of concentrated sulfuric acid as catalyst. The special methods for the different materials are described. To stabilize samples against bacterial action, which can reduce nitrate concentrations, phenylmercuric acetate is added after collection ° Other inorganic compounds in the trace levels for gas-chromatographic determination are, for example, water and carbon monoxide, which were determined in organic solvents or air in the ppb-range ... 

CHLORINE FLUORIDE OXIDE (7616-94-6) Noncombustible, but many chemical reactions can cause fire and explosions. A powerful oxidizer. Reacts violently with reducing materials, alcohols, alkalis, amines, anilines, benzene, butyl-amine, calcium hydride, calcium acetylide, charcoal, combustible materials, ethers, hydrazine, hydrogen sulfide, finely divided metals, nitric oxide, olefins, orgtinic substances, potassium cyanide, potassium thiocyanate, sodium, strontium hydride, sulfur, sulfur dichloride, sulfuric acid. Incompatible with hydrogen sulfide, potassium thiocyanate, vinylidene chloride. Forms heat-, friction-, and shock-sensitive explosives with calcium hydride, nitrogenous bases, isopropylamine. Attacks some plastics, rubber, and coatings. 

Subsequently, MBH adducts were successfully utilized as novel stereodefined electrophiles in the Friedel-Crafts reaction with benzene in the presence of a Lewis acid " and sulfuric acid, leading to the stereoselective synthesis of (Z)- and ( )-functionalized trisubstituted alkenes. Notably, MBH adducts obtained from acrylonitrile provide high (Z)-stereoselectivities, while adducts derived from methyl acrylate and aromatic aldehydes give high ( )-stereo-selectivities. When the MBH adducts drived from methyl acrylate and aliphatic aldehydes were involved in the Friedel-Crafts reaction, no significant stereoselectivity was observed (Scheme 3.29). 

The sulfonation of benzene by concentrated sulfuric acid is another reaction that involves the reaction of benzene with an electrophilic species. When benzene reacts with sulfuric acid, it attacks the electrophilic sulfur atom, as shown in the illustration, to give arenium ion intermediate 43. This intermediate loses a proton via the El reaction, but it also loses a molecule of water to give benzenesulfonic acid (44). (See Chapter 16, Section 16.9, for an introduction to sulfonic acids.) Concentrated sulfuric acid reacts with the water byproduct, which effectively removes this product from the reaction, and drive the reaction toward 44. In other words, concentrated sulfuric acid acts as a drying agent. If fuming sulfuric acid (which is simply concentrated sulfuric acid saturated with sulfur trioxide, SO3) is used rather than sulfuric acid, the reaction proceeds faster to give 44 and with fewer problems. This latter reaction depends on the fact that the sulfur atom in SO3 is more electrophilic than the sulfur atom in sulfuric acid. 

Sulfonation with Sulfuric Acid and Sulfur Triozide. Various mechanisms for the reaction of aromatic hydrocarbons or aryl halides with sulfuric acid or with sulfur trioxide have been proposed. Since.the reaction is heterogeneous, it is not favorable for experimental study. Solvents that dissolve sulfuric acid or sulfur trioxide form addition compounds with the reagent hence any conclusion drawn from a homogene ous sulfonation might not be applicable to the ordinary sulfonation. One possibility is that an electrophilic reagent such as sulfur trioxide with its relatively positive sulfur atom or an ion such as HOaS" " in the case of sulfuric acid attacks the negative center of the polarized form of the hydrocarbon, as illustrated for benzene. 

The following reactions were used for the industrially important benzene hexachloride with zinc or, better, magnesium, in glacial acetic acid, benzene hexachloride is dechlorinated to benzene, which can then be detected by the Janovsky or Mohler color reaction (p. 356) (18—20). Also, the test proposed for DDT, i.e., nitration and the reaction of the nitro compoimds formed with methanolic sodium hydroxide, is recommended (21). Other tests recommended are the reaction of DDT with sulfuric acid in acetic acid (22), the reaction with xanthydrol, alkali, and pyridine (23), and the reaction with benzene according to the Friedel-Crafts procedure (24). 

The reaction of benzene with sulfuric acid to produce benzenesulfomc acid... 

Alkali Fusion of /u-Benzenedisulfonic Acid. Even though this process like the previous one is a very ancient one, it is still the main route for the synthesis of resorcinol. It has been described in detail previously and does not seem to have drastically evolved since 1980. It involves the reaction of benzene with sulfuric acid to form y -benzenedisulfonic acid which is then converted to its disulfonate sodium salt by treatment with sodium sulfite. In a second step, this salt is heated to 350°C in the presence of sodium hydroxide yielding the sodium resorcinate and sodium sulfite. 

Mitsubishi Chemical Industries, Ltd. practiced a Henkel II technology starting with toluene to produce benzoic acid. Reaction of benzoic acid with potassium hydroxide resulted in potassium benzoate, which was subjected to a disproportionation reaction to produce dipotassium terephthalate and benzene. Dipotassium terephthalate reacted with sulfuric acid, and the resulting terephthahc acid was recovered by filtration and drying (65,66). Here, dipotassium sulfate was the by-product. 

Friedel-Grafts Reaction. Until quite recently, the manufacture of anthraquiaone ia the United States was by the Friedel-Crafts reaction benzene [71-43-2] and phthaUc anhydride [85-44-9] condense ia the preseace of anhydrous aluminum chloride to give o-benzoylbenzoic acid [85-52-9] which, on treatment with concentrated sulfuric acid, is converted iato anthraquiaoae ia high yields and purity (33). 

Reactions other than those of the nucleophilic reactivity of alkyl sulfates iavolve reactions with hydrocarbons, thermal degradation, sulfonation, halogenation of the alkyl groups, and reduction of the sulfate groups. Aromatic hydrocarbons, eg, benzene and naphthalene, react with alkyl sulfates when cataly2ed by aluminum chloride to give Fhedel-Crafts-type alkylation product mixtures (59). Isobutane is readily alkylated by a dipropyl sulfate mixture from the reaction of propylene ia propane with sulfuric acid (60). 

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