Fuming sulfuric acid, with aromatic compounds

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). 

The aliphatic iodine derivatives are usually prepared by reaction of an alcohol with hydroiodic acid or phosphorus triiodide by reaction of iodine, an alcohol, and red phosphorus addition of iodine monochloride, monobromide, or iodine to an olefin replacement reaction by heating the chlorine or bromine compound with an alkali iodide in a suitable solvent and the reaction of triphenyl phosphite with methyl iodide and an alcohol. The aromatic iodine derivatives are prepared by reacting iodine and the aromatic system with oxidizing agents such as nitric acid, fuming sulfuric acid, or mercuric oxide. 

BiscMorome Uition. Electron-poor tetrasubstitutcd aromatic compounds such as nitromesitylene (1) are bischloromethylated when treated with chloromethyl methyl ether and 60% fuming sulfuric acid. ... 

This is a powerful sulfonating agent approximately equivalent in strength to fuming sulfuric acid. Treatment of an aromatic compound with an equimolar amount of the reagent yields the corresponding sulfonic acid (31), but when an excess of chlorosulfonic... 

The reaction of an aromatic compound with chlorosulfonic acid (44) (one molar equivalent) in an inert solvent, e.g. chloroform, can be used to prepare aromatic sulfonic acids (Scheme 23). Chlorosulfonic acid is a powerful sulfonating agent approximately equivalent to fuming sulfuric acid (oleum), and care must be taken with this reagent to avoid the formation of sulfones or sulfonyl chlorides (see p. 103).5 Aliphatic or benzylic sulfonic acids can be obtained in good yields... 

Furthermore the effect of the reaction mixture upon the molecule being substituted must also be considered. It is well known that an aromatic amine is converted into a substituted ammonium ion in acidic media and that this is the species which is actually responsible for the meta orienta-tion frequently observed (p. 9). It is often forgotten, however, that many compounds other than amines are bases in strong acid solution so that the species undergoing substitution may actually be a cation. p Tolyl carbonate, for example, is nitrated principally in the ortho position with fuming nitric acid but in the meta position in a mixture of fuming nitric and fuming sulfuric acid 6... 

Aromatic amines, Sulfuric acid Nielsen, A. T. etal., J. Org. Chem., 1980, 45, 2341-2347 The acid, prepared from 90-98% hydrogen peroxide and oleum or 100% sulfuric acid, is one of the most powerful known oxidants and its use for oxidising aromatic amines to nitro compounds has been studied. Some mono- di- and tri-amines are destroyed exothermically with violent fume-off. Precautions for use are detailed. 

Certain deactivated aromatic compounds can be sulfonated only with fuming rather than concentrated sulfuric acid ... 

Mixtures with sulfur or sulfuric acid (used in commercial reactions) may explode if heated to 120°C. Initiation temperature depends on the quality of the dinitronaphthalene. When heated to decomposition it emits toxic fumes of NOx. See also NITRO COMPOUNDS of AROMATIC HYDROCARBONS. 

DOT CLASSIFICATION 6.1 Label Poison SAFETY PROFILE Poison by ingestion, intravenous, and intraperitoneal routes. Moderately toxic by intramuscular route. Mutation data reported. Acute symptoms of exposure are headache, nausea, vomiting, weakness and stupor, cyanosis and methemoglobinemia. Chronic exposure can cause liver damage. Experimental reproductive effects. Combustible when exposed to heat or flame. See NITRATES for explosion and disaster hazards. To fight fire, use water spray or mist, foam, dry chemical, CO2. Vigorous reaction with sulfuric acid above 200°C. Reaction with sodium hydroxide at 130°C under pressure may produce the explosive sodium-4-nitrophenoxide. When heated to decomposition it emits toxic fumes of NOx. See also m-NITROANILINE, o-NITROANILINE, NITRO COMPOUNDS OF AROMATIC HYDROCARBONS, and ANILINE DYES. 

From the aromatic nitro compound with concentrated or fuming nitric acid and sulfuric acid For directions and examples see Cheronis, pp 580, 627, Shriner, p 249, Vogel, pp 526,527 From fuming nitric acid in acetic acid or acetic anhydride... 

SAFETY PROFILE A skin and severe eye irritant. Decomposes violendy at about 200°. Mixture with siolfuric acid + sulfur trioxide may explode above 150°C. When heated to decomposition it emits toxic fumes of SOx and NO. See also NITRO COMPOUNDS OF AROMATIC HYDROCARBONS and SULFONATES. 

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