Sulfuric acid concentrated fuming

Other substances. The concentrations of acids and bases and alkalis could be listed as follows acetic acid > 25% concentration, hydrochloric acid > 25% concentration, nitric acid > 20% concentration, chromic acid, hydrofluoric acid, perchloric acid > 10% concentration, sulfuric acid > 15% concentration, fuming sulfuric acid, ammonium hydroxide > 35% by weight of gas, potassium hydroxide (caustic potash), sodium hydroxide > 5% concentration, aluminum chloride, bromine, phosphorous trichloride, potassium bifluoride, sodium hypochlorite > 10% concentration, and zinc chloride. 

That means that any bottle of sulfuric acid will have some SO3 in it. At room temperature, SO3 is a gas, and it is possible to add extra SO3 gas to sulfuric acid (which shifts the equilibrium). When we do this, we call the mixturesulfuric acid. So, from now on, whenever you see concentrated, fuming sulfuric acid, you should realize that we are talking about SO3 as the reagent. 

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. 

In some processes the reactant bases are too weak to be protonated significantly except in the presence of very strong acids such as fuming sulfuric acid or a mixture of concentrated sulfuric and nitric acids, ie, mixed acid. Nitration of toluene, for example, requires such solutions two Hquid phases are present in the reactor. 

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). 

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]. 

Dilute nitric acid or sulfuric acid in place of concentrated fuming nitric acid or oleum (SO3 solution in sulfuric acid)... 

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... 

The acid is prepared by sulfonation of nitrobenzene with oleum, and the reaction product consists essentially of a hot solution of the acid in sulfuric acid. A completed 270 1 batch exploded violently after hot storage at 150C for several hours. An exotherm develops at 145°C, and the acid is known to decompose at 200 C [ 1], A similar incident arose from water leaking from a cooling coil into the fuming sulfuric acid reaction medium, which caused an exotherm to over 150°C and subsequent violent decomposition [2], Detailed examination of the thermal decomposition of the acid shows that it is much slower for the isolated acid than for the reaction mass, and that the concentration of sulfur trioxide in the oleum used for sulfonation bears... 

The most common way to modify aromatic polymers for application as a PEM is to employ electrophilic aromatic sulfonation. Aromatic polymers are easily sulfonated using concentrated sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, or sulfur trioxide (or complexs thereof). Postmodification reactions are usually restricted due to their lack of precise control over the degree and location of functionalization, the possibility of side reactions, or degradation of the polymer backbone. Regardless, this area of PEM synthesis has received much attention and may be the source of emerging products such as sulfonated Victrex poly (ether ether ketone). 

Sulfonated poly(4-substituted benzoyl-1,4-phenylene) homopolymers and copolymers using concentrated sulfuric acid or fuming sulfuric acid have been shown to form sulfonated polymers with variable degrees of sulfonation. To improve film formation of the sulfonated polyphenylenes, multiblock copolymers have been synthesized by reacting a more flexible poly(arylene ether sulfone) with sulfonated poly-phenylenes. ... 

Poly(phthalazinone ether ketone)s (PPEKs) were synthesized by the reaction of the polymer in mixtures of 95—98% concentrated sulfuric acid and 27— 33% fuming sulfuric acid in the absence of other solvents. A general reaction scheme is given in Figure 30. The mixed solvent systems of sulfuric acid... 

Sulfonate 42 was nitrated with a mixture of concentrated nitric and fuming sulfuric acids to give nitro 5-sulfonate 43 (Eq. 10) (95JFC). 

Tellurium metal, its alloys, minerals or the teUurides may be dissolved in warm concentrated sulfuric acid or cold fuming sulfuric acid to form a red color, the intensity of which is proportional to the tellurium content in the substance. When this red solution is poured into water, black elemental tellurium metal precipitates out of solution. Oxidized tellurium does not respond to this test. 

In fuming sulfuric acid the electrophile may be H3S2O7 or, at concentrations higher than 104%, H2S4Oi3 (H2S04 + 3 SO3).91 Sulfur trioxide itself may also act as the electrophile in aprotic solvents.90 On the basis of a second-order rate dependence on S03 the primary sulfonation product was suggested to be an arenepyrosulfonic acid intermediate (7) that is converted in secondary sulfonation steps into the product ... 

This acid, approximately 30 per cent sulfur trioxide, is made by mixing 500 g. each of fuming sulfuric acid containing 60 per cent free sulfur trioxLde and concentrated sulfuric acid (sp. gr. 1.84) 500 cc. of this mixture is used. 

Benzo[6]thiophene 1,1-dioxides have been made by cyclization procedures (Section 3.15.3.1.7). Homologs of acetophenone cyclize on treatment with chlorosulfonic acid to give 2-substituted 3-chlorobenzo[6]thiophene 1,1-dioxides (equation 86). Similarly 1,1-diaryl-1-propenes in concentrated sulfuric acid gave 2-methyl-3-arylbenzo[6]thiophene 1,1-dioxides (65JOC2840). Friedel-Crafts cyclization of l,l-diphenylethylene-2-sulfonyl chloride gave 3-phenylbenzo[6]thiophene 1,1-dioxide (equation 87) (59JA2000). Treatment of various biphenyl derivatives with fuming sulfuric acid forms the dibenzothiophene 5,5-dioxides (Section 3.15.3.1.7). 

Substitution of the sulfonic acid (—S03H) group for a hydrogen of an aromatic hydrocarbon can be carried out. by heating the hydrocarbon with a slight excess of concentrated or fuming sulfuric acid ... 

Some investigators have used concentrated instead of fuming sulfuric acid for the condensation, but the yield is usually low and the product is always colored bright yellow by some impurity which cannot be removed by crystallization. 

Acetone dicarboxylic acid was first obtained by the action of concentrated sulfuric acid upon citric acid.1 It has been made also by the gradual decomposition of a mixture of lime and sucrose.2 The most satisfactory method, however, for producing this substance, is by the action of fuming sulfuric acid upon citric acid. Details of this preparation have been modified a number of times with the intention of improving the yield.3... 

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