Sulfuric acid, fuming Replacement

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. 

Analogous Sulfonations. Exactly the same method can be used for sulfonating p-nitrochlorobenzene, p-nitrotoluene, o-m trochlorobenzene, chlorobenzene, and many other compounds. On the other hand, it is usually not possible to sulfonate dinitaro compounds in this way. Dinitrochlorobenzene and dinitrotoluene are decomposed explosively by treatment with fuming sulfuric acid. If dinitrochloro-benzenesulfoitic acid is to be prepared, for example, one starts with p-nitrochloro-benzene/ This is sulfonated, as described previously, and the sulfonic acid is converted to dinitrochlorobenzenesulfonic acid by treatment with mixed acid (50 50 sulfuric and nitric acids) at low temperatures. This product yields, on replacement of the chlorine by —OH and partial reduction, 4-nitro-2-aminophenol-6-sulfonic acid (nitro acid III), which is used in preparing chrome dyes. 

The standard method of nitration uses a mixture of concentrated nitric acid and concentrated sulfuric acid, but when stronger conditions are required, fuming nitric acid can replace the concentrated reagent. For example, benzene is readily nitrated by mixed acid, but nitration of nitrobenzene requires fuming nitric acid in concentrated sulfuric acid (Scheme 7.1). 

Zenno and Mizutani55 extended this synthesis by treating N-(p-nitro-phenethyl)acetamide (73) with fuming sulfuric acid to give 3,4-dihydro-7-nitro-2W-1,2-benzothiazine 1,1-dioxide (74) in good overall yield (Eq. 17). After reduction and diazotization, the nitro group in 74 could be replaced with a variety of other functional groups (vide infra). 

Procedure Fill the gas developer under the fume hood with sulfuric acid and sodium chloride. Dropping the acid onto the solid salt develops a gas and fills the cylinder through air replacement. First check the gas with a damp universal indicator paper, place a little water and shake, test the solution with indicator paper. 

Accidents can be very expensive, not just in plant replacement costs, but also compensation to victims (as well as lost profits from lost sales). When operators at General Chemical s Richmond, California, plant overheated a railroad tank car, a safety relief valve sent fuming sulfuric acid over the area. More than 20,000 people sought medical treatment. Five freeways and several rapid-transit stations closed. A fund of 92.8 million dollars has been set up to compensate the victims.149 A re-... 

Fibers (6) of p-phenylene oxadiazole/N-methyl hydrazide copolymers were prepared by polymerization of terephthalic acid (TA), dimethyl terephthalate (DMT) and hydrazine sulfate in fuming sulfuric acid (Oleum) and "reaction spinning" of the resulting polymer solution into aqueous sulfuric acid. Replacement of some of the dimethyl terephthalate used with dimethyl isophthalate (DMI) allowed the preparation of p-/m-phenylene oxadiazole/ N-methyl hydrazide copolymers. In the polymerization, a p-/m-phenylene oxadiazole polymer is formed which is methylated during the reaction ... 

Elimination of toxic reagents and intermediates [via novel catalysis] ...Anhydrous hydrofluoric and fuming sulfuric acids are used as catalysts throughout the chemical and petroleum industry. Replacing these materials with safe, solid catalysts could have a profound positive impact on industry. 

In the case of sulfonation of benzene, one or more hydrogen atoms are replaced by the sulfonic acid group. (-SO3H). Sulfonation of benzene with fuming sulfuric acid H2S0 + SO3) yields benzenesulfonic acid. 

Sulfamic acid, NH2SO3H, is an ammonoaquosulfuric acid in which one of the hydroxyl groups of sulfuric acid has been replaced by the isosteric amido group. It is prepared commercially by the interaction of fuming sulfuric acid and urea. This method is not readily adaptable to laboratory preparation on a small scale. Consequently, the sulfur dioxide-hydroxylamine reaction is recom-mended.H Sulfamic acid may also be obtained by the action of sulfur dioxide upon certain compounds which yield hydroxylamine such as acetoxime. The recommended procedures are modifications of older processes and involve the use of sulfur dioxide under pressure upon aqueous solutions of hydroxylammonium salts and compounds yielding hydroxylamine. 

The free hydroxyl groups of the anhydro alditols may be replaced by chlorine through treatment with phosphorus pentachloride, or thionyl chloride and pyridine. In this manner, l,4 3,6-dianhydro-D-mannitol ( isomannide ) yields an exceptionally stable dichlorodideoxy derivative which is unaffected by fused potassium hydroxide, phosphorus pentachloride at 125°, sodium amalgam, or zinc and dilute sulfuric acid 96). Fuming... 

Gel silicon electrolyte was introduced in battery design to eliminate spilling and the need for constant maintenance. A gel battery (also known as a gel cell) is a VRLA battery with a gelled electrolyte the sulfuric acid is mixed with silica fume or silica additives, which makes the resulting mass gel-like, stiff, and immobile. Unlike a flooded wet-cell lead-acid battery, these batteries do not need to be kept upright. Gel batteries reduce the electrolyte evaporation and the spillage (and subsequent corrosion issues) common to the wet-cell battery, and they boast greater resistance to extreme temperatures, shock, and vibration. Chemically they are the same as wet (nonsealed) batteries except that the antimony in the lead plates is replaced by calcium. 

The DS increases with prolonging reaction time. Replacing concentrated sulfuric acid with fuming sulfuric acid is also very effective for enhancing the DS. A high value of DS (154%) was achieved as the sulfonation was conducted in fuming sulfuric acid (20% SO3) at 80°C for 5 h [10],... 

When selenophene-2-aldehyde or its diacetate is sulfonated with dioxane-sulfur trioxide, 5-sulfoselenophene-2-aldehyde is formed. The 2-carboxylic acid with oleum gives 5-sulfoselenophene-2-car-boxylic acid containing an admixture ( 20%) of the 4-sulfo isomer. The sulfo group is readily replaced by nitro by the action of fuming nitric acid.51... 

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