Sulfuric acid, concentrated

Example 2.5 tert-Butyl hydrogen sulfate is required as an intermediate in a reaction sequence. This can be produced by the reaction between isobutylene and moderately concentrated sulfuric acid ... 

Using a batch reactor, a constant concentration of sulfuric acid can be maintained by adding concentrated sulfuric acid as the reaction progresses, i.e., semi-batch operation. Good temperature control of such systems can be maintained, as we shall discuss later. 

Carbonizable substances (paraffin) NFT 60-134 ASTM D 612 Coloration after treatment in concentrated sulfuric acid... 

To be able to prepare and study these elusive species in stable form, acids billions of times stronger than concentrated sulfuric acid were needed (so called superacids). Some substituted carbocations, however, are remarkably stable and are even present in nature. You may be surprised to learn that the fine red wine we drank tonight contained carbocations which are responsible for the red color of this natural 12% or so alcoholic solution. I hope you enjoyed it as much as I did. 

The literature states that if one uses ice cold, concentrated sulfuric acid on a terminal alkene (a.k.a. allylbenzene) an alcohol (OH) intermediate will form Markovnikoviy on the secondary carbon (don t ask). What does this mean Let s take an example. Say one has some elemi oil and wants that elemicin that is in it. What one can do is chili, say, 500mLs of the oil to freezing and do the same for about 100-200mLs of concentrated sulfuric acid (at least 90% cone.). Next, one just mixes the two together for about 5 min. What will happen is that the cold H2SO4 will make a hydrogen... 

If the chemist wants to know whether her final product is bromo-safrole and not just a bunch of unreacted safrole there is a simple little test she can do. Safrole is soluble (will dissolve in) cold concentrated sulfuric acid. But bromosafrole is insoluble in it. So the chemist can take a shot glass full of straight-from-the-bottle 96% H2SO4 and place it in the freezer until it s ice cold. Then she takes it out and drops a few drops of mystery product into it. If the oil dissolves then the stuff is unreacted safrole. If the oil drops to the bottom and does not dissolve it s the goods. 

With brisk stirring 75mL Everclear (ethanol) is poured into the reaction flask then 75mL concentrated sulfuric acid is slowly added until incorporated. The rest of the distillation apparatus is connected and the solution slowly heated to about 140°C. Next, 150mL Everclear is dripped in slowly so as to match the approximate distillation output that one can see condensing over into the collection flask. The temperature must remain between 140-150 C. After all the ethanol has been added (which should have taken approximately 90 min) the distillate that has collected is washed with 5% NaOH solution then with water (remember that the ether will form the top layer here). The ether can then be dried through sodium sulfate and used or can be distilled to purify. 

That numerous 2-amino-5-nitrothiazole derivatives exhibit antiamebic, antihistomonal, antitrichomonal, and antischistosomal properties (see Section VI.2) explains the large number of nitration reactions reported. Nitration in a mixture of concentrated nitric and concentrated sulfuric acids IS among the most common experimental methods (16, 27, 58, 374-377). 

An interesting set of results was obtained by Burmistrov et al, (242. 444-448) when they studied the reaction of 2-aminothiazole and derivatives with various alcohols in concentrated sulfuric acid (see Section III.l.Cl. 

The cyclization of a-thiocyanatoketones (183) in aqueous acid, concentrated sulfuric acid in acetic acid and water, or alkaline solution leads to 2-hydroxythiazoles after dilution in water. 

Arylthiazoles were prepared either from w-formaminoaceto-phenones and phosphorus pentasulfide in 70% yield (47, 641) or by treating thioformaminoketones with concentrated sulfuric acid in water (344). Thioformaminoacetophenone itself was obtained by the action of potassium dithioformate on aminoacetophenone (251). 

Hydration of alkenes by this method however is limited to monosubstituted alkenes and disubstituted alkenes of the type RCH=CHR Disubstituted alkenes of the type R2C=CH2 along with trisubstituted and tetrasubstituted alkenes do not form alkyl hydrogen sulfates under these conditions but instead react m a more complicated way with concentrated sulfuric acid (to be discussed m Section 6 21)... 

Unlike the addition of concentrated sulfuric acid to form alkyl hydrogen sulfates this reaction is carried out m a dilute acid medium A 50% water/sulfuric acid solution is often used yielding the alcohol directly without the necessity of a separate hydrolysis step Markovmkov s rule is followed... 

Dimerization in concentrated sulfuric acid occurs mainly with those alkenes that form tertiary carbocations In some cases reaction conditions can be developed that favor the formation of higher molecular weight polymers Because these reactions proceed by way of carbocation intermediates the process is referred to as cationic polymerization We made special mention m Section 5 1 of the enormous volume of ethylene and propene production in the petrochemical industry The accompanying box summarizes the principal uses of these alkenes Most of the ethylene is converted to polyethylene, a high molecular weight polymer of ethylene Polyethylene cannot be prepared by cationic polymerization but is the simplest example of a polymer that is produced on a large scale by free radical polymerization... 

Alkenes react with sulfuric acid to form alkyl hydrogen sulfates A proton and a hydrogen sulfate ion add to the double bond in accordance with Markovnikov s rule Alkenes that yield tertiary carboca tions on protonation tend to polymerize in concentrated sulfuric acid (Section 6 21)... 

Sulfonation Treatment of benzene with hot concentrated sulfuric acid gives benzenesulfonic acid A sulfonic acid group (—SO2OH) replaces one of the ring hydrogens... 

Among the variety of electrophilic species present m concentrated sulfuric acid sulfur tnoxide (Figure 12 4) is probably the actual electrophile m aromatic sulfonation We can represent the mechanism of sulfonation of benzene by sulfur tnoxide by the sequence of steps shown m Figure 12 5... 

Sulfonation (Section 12 4) Sulfonic acids are formed when aromatic compounds are treated with sources of sulfur trioxide These sources can be concentrated sulfuric acid (for very reactive arenes) or solutions of sulfur trioxide in sulfuric acid (for ben zene and arenes less reactive than ben zene)... 

Sulfonation Heating a phenol with concentrated sulfuric acid causes sulfonation of the ring... 

Organic matter Hot concentrated sulfuric acid plus a few drops of sodium or potassium nitrate solution. 

Aluminous and siliceous residues A 2% hydrofluoric acid solution followed by concentrated sulfuric acid rinse immediately with distilled water followed by a few milliliters of acetone. Repeat rinsing until all trace of acid is removed. 

Xanthenes date from 1871 when von Bayer synthesized fluorescein (5) by the condensation of two moles of resorcinol with one mole of phthaUc anhydride in the presence of concentrated sulfuric acid (1). 

The amide group is readily hydrolyzed to acrylic acid, and this reaction is kinetically faster in base than in acid solutions (5,32,33). However, hydrolysis of N-alkyl derivatives proceeds at slower rates. The presence of an electron-with-drawing group on nitrogen not only facilitates hydrolysis but also affects the polymerization behavior of these derivatives (34,35). With concentrated sulfuric acid, acrylamide forms acrylamide sulfate salt, the intermediate of the former sulfuric acid process for producing acrylamide commercially. Further reaction of the salt with alcohols produces acrylate esters (5). In strongly alkaline anhydrous solutions a potassium salt can be formed by reaction with potassium / /-butoxide in tert-huty alcohol at room temperature (36). 

At room temperature, PET is resistant to organic and moderate strength mineral acids. At elevated temperatures, PET strength loss in moderate strength acids can be appreciable. Strong acids such as concentrated sulfuric acid dissolve and depolymerize PET. 

Anhydrous aluminum triduotide, A1F., is a white crystalline soHd. Physical properties are Hsted ia Table 2. Aluminum duotide is spatingly soluble ia water (0.4%) and iasoluble ia dilute mineral acids as well as organic acids at ambient temperatures, but when heated with concentrated sulfuric acid, HF is hberated, and with strong alkah solutions, aluminates are formed. A1F. is slowly attacked by fused alkahes with the formation of soluble metal duotides and aluminate. A series of double salts with the duotides of many metals and with ammonium ion can be made by precipitation or by soHd-state reactions. 

The AsF ion is very stable toward hydrolysis in aqueous solution. It is not hydroly2ed by boiling a strongly basic solution almost to dryness (26), although it is hydroly2ed in sulfuric acid (27) or in boiling perchloric acid (26). The hydrolysis of AsF in concentrated sulfuric acid (27) and in base (28) at 193—222°C is first order in AsF . The hydrolysis of AsF in alkaline solution is slower than either PF or SbF . ... 

Olefins are carbonylated in concentrated sulfuric acid at moderate temperatures (0—40°C) and low pressures with formic acid, which serves as the source of carbon monoxide (Koch-Haaf reaction) (187). Liquid hydrogen fluoride, preferably in the presence of boron trifluoride, is an equally good catalyst and solvent system (see Carboxylic acids). 

Hafnium is readily soluble in hydrofluoric acid and is slowly attacked by concentrated sulfuric acid. Hafnium is unaffected by nitric acid in all concentrations. It is resistant to dilute solutions of hydrochloric acid and sulfuric acid. Hafnium is attacked by all mineral acids if traces of fluorides are present. Hafnium is very resistant to attack by alkaUes. 

At room temperature, hafnium dioxide is slowly dissolved by hydrofluoric acid. At elevated temperatures, hafnium dioxide reacts with concentrated sulfuric acid or alkaU bisulfates to form various sulfates, with carbon tetrachloride or with chlorine in the presence of carbon to form hafnium tetrachloride, with alkaline fluorosiUcates to form alkaU fluorohafnates, with alkaUes to form alkaline hafnates, and with carbon above 1500°C to form hafnium carbide. 

Oxides. Two oxides of xenon are known xenon trioxide [13776-58-4], XeO, and xenon tetroxide [12340-14-6], XeO (Table 1). Xenon trioxide is most efftcientiy prepared by the hydrolysis of XeE (47) or by the reaction of XeE with HOPOE2 (48). The XeO molecule has a trigonal pyramidal shape Xe—O, 176(3) pm (49), and XeO is tetrahedral with Xe—O, 173.6(2) pm (50). Xenon tetroxide is prepared by the interaction of concentrated sulfuric acid with sodium or barium perxenate, Na XeO, Ba2XeO ( )- Both oxides are thermodynamically unstable, explosive soHds which must be... 

Iodine dissolves without reaction in concentrated sulfuric acid and with concentrated nitric acid it reacts to form iodine pentoxide (47). Iodine reacts with alkah metal hydroxide solutions to form the corresponding hypoiodite and the rate of the reaction increases with the alkaU concentration and temperature. At 50°C, the reaction is almost instantaneous ... 

Smah concentrations of HI reduce concentrated sulfuric acid to sulfurous acid high concentrations of HI reduce it to hydrogen sulfide (56). 

AH of the [Fe(CN)3] salts maybe considered salts of ferrocyanic acid or tetrahydrogen hexakiscyanoferrate [1712647-5], H4[Fe(CN)3], a strongly acidic, air-sensitive compound. It is soluble in water and alcohol but is insoluble in ether. It can be prepared by precipitation of an etherate by adding ether to a solution of [Fe(CN)3] that was acidified with concentrated sulfuric acid. Removal of the ether of solvation affords a white powder which is stable when dry but slowly turns blue in moist air because of Pmssian Blue formation. 

Industrial Wastewater Treatment. Industrial wastewaters require different treatments depending on their sources. Plating waste contains toxic metals that are precipitated and insolubiHzed with lime (see Electroplating). Iron and other heavy metals are also precipitated from waste-pidde Hquor, which requires acid neutralization. Akin to pickle Hquor is the concentrated sulfuric acid waste, high in iron, that accumulates in smokeless powder ordinance and chemical plants. Lime is also useful in clarifying wastes from textile dyeworks and paper pulp mills and a wide variety of other wastes. Effluents from active and abandoned coal mines also have a high sulfuric acid and iron oxide content because of the presence of pyrite in coal. 

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