Addition of sulfuric acid

FIGURE 6 8 Mechanism of addition of sulfuric acid to propene... 

Write a structural formula for the compound formed on elec trophilic addition of sulfuric acid to cyclohexene (step 1 in the two step transfer mation shown in the preceding equation)... 

Reaction of carboxylate ion with nitrophenyl sulfites gives the carboxylate -nitrophenyl esters. If the -nitrophenyl sulfite is unsymmethcal (02NCgH40S(0)0R, where R is ethyl or phenyl), carboxylate attacks the -nitrophenyl side (69). Some amino acids react with methyl and benzyl sulfites in the presence of -toluenesulfonic acid to give methyl and benzyl esters of the amino acids as -toluenesulfonate salts (70). With alcohols, the conversion of henzil to a monoacetal upon addition of sulfuric acid to the henzil in methanol and dimethyl sulfite proceeds in high yield (71). 

The principal vanadium-bearing ores are generally cmshed, ground, screened, and mixed with a sodium salt, eg, NaCl or Na2C02- This mixture is roasted at ca 850°C and the oxides are converted to water-soluble sodium metavanadate, NaVO. The vanadium is extracted by leaching with water and precipitates at pH 2—3 as sodium hexavanadate, Na V O, a red cake, by the addition of sulfuric acid. This is then fused at 700°C to yield a dense black product which is sold as technical-grade vanadium pentoxide. This product contains a minimum of 86 wt % V20 and a maximum of 6—10 wt % Na20. 

For solvent extraction of pentavalent vanadium as a decavanadate anion, the leach solution is acidified to ca pH 3 by addition of sulfuric acid. Vanadium is extracted in about four countercurrent mixer—settler stages by a 3—5 wt % solution of a tertiary alkyl amine in kerosene. The organic solvent is stripped by a soda-ash or ammonium hydroxide solution, and addition of ammoniacal salts to the rich vanadium strip Hquor yields ammonium metavanadate. A small part of the metavanadate is marketed in that form and some is decomposed at a carefully controlled low temperature to make air-dried or fine granular pentoxide, but most is converted to fused pentoxide by thermal decomposition at ca 450°C, melting at 900°C, then chilling and flaking. 

For solvent extraction of a tetravalent vanadium oxyvanadium cation, the leach solution is acidified to ca pH 1.6—2.0 by addition of sulfuric acid, and the redox potential is adjusted to —250 mV by heating and reaction with iron powder. Vanadium is extracted from the blue solution in ca six countercurrent mixer—settler stages by a kerosene solution of 5—6 wt % di-2-ethyIhexyl phosphoric acid (EHPA) and 3 wt % tributyl phosphate (TBP). The organic solvent is stripped by a 15 wt % sulfuric acid solution. The rich strip Hquor containing ca 50—65 g V20 /L is oxidized batchwise initially at pH 0.3 by addition of sodium chlorate then it is heated to 70°C and agitated during the addition of NH to raise the pH to 0.6. Vanadium pentoxide of 98—99% grade precipitates, is removed by filtration, and then is fused and flaked. 

Commercial manufacture of methyl bromide is generally based on the reaction of hydrogen bromide with methanol. For laboratory preparation, the addition of sulfuric acid to sodium bromide and methanol has been used (80). Another method involves the treatment of bromine with a reducing agent, such as phosphoms or sulfur dioxide, to generate hydrogen bromide (81). 

In the known absence of bromoform, iodoform, chloral, and other halogenated methanes, the formation of phenyhsonitrile with aniline provides a simple and faidy sensitive but nonspecific test for the presence of chloroform, the carbylamine test. Phenyhsonitrile formation is the identification test given in the British Pharmacopoeia. A small quantity of resorcinol and caustic soda solution (10% concentration) added to chloroform results in the appearance of a yellowish red color, fluorescing yeUow-green. When 0.5 mL of a 5% thymol solution is boiled with a drop of chloroform and a small quantity of potassium hydroxide solution, a yellow color with a reddish sheen develops the addition of sulfuric acid causes a change to brilliant violet, which, diluted with water, finally changes to blue (33). 

The primary Cr—O bonded species is cbromium (VT) oxide, CrO, which is better known as chromic acid [1115-74-5], the commercial and common name. This compound also has the aliases chromic trioxide and chromic acid anhydride and shows some similarity to SO. The crystals consist of infinite chains of vertex-shared CrO tetrahedra and are obtained as an orange-red precipitate from the addition of sulfuric acid to the potassium or sodium dichromate(VI). Completely dry CrO is very dark red to red purple, but the compound is deflquescent and even traces of water give the normal mby red color. Cbromium (VT) oxide is a very powerful oxidi2er and contact with oxidi2able organic compounds may cause fires or explosions. 

Dioitroanthraquiaoae and 1,8-dinitroanthraquinone can also be prepared by nitration of anthraquiaone ia coaceatrated nitric acid (70). The 1,5-isomer can then be easily separated from the reaction mixture by filtration, since 1,8- or other isomers than 1,5-dinitroanthraquinone are completely dissolved in concentrated nitric acid. However, this process is unsuitable for industrial production for safety reasons the mixture of dinitroanthraquiaone and concentrated nitric acid forms a detonation mixture (71). Addition of sulfuric acid makes it possible to work outside the detonation area. 

The rapid addition of sulfuric acid is made to give finely divided barium sulfate. 

It is convenient to titrate the suspended barium salt with 18 N sulfuric acid (approx. 12-14 ml.) to a pH. of 1.5 using a pH meter. After removal of the barium sulfate the slight excess of sulfate ion may be precipitated using barium chloride solution. The end point is taken when several drops of filtrate show no turbidity either upon addition of sulfuric acid or barium chloride solution. 

Salts of other metals are obtained by metathesis, and aqueous solutions of the corresponding acids are obtained by controlled addition of sulfuric acid to the barium salts ... 

A portion (950 ml) of the rich eluate was adjusted to pH 6.0 by the addition of sulfuric acid. Ultrawet K (7.0 g) in 70 ml water was added slowly to the neutralized eluate to precipitate kanamycin B dodecylbenzenesulfonate which was collected by filtration after adding filter-aid (Dicalite). The cake was washed with water and extracted with 100 ml methanol. After filtering and washing with methanol, sulfuric acid was added to the filtrate until no more kanamycin B sulfate precipitated. After addition of an equal volume of acetone to provide more complete precipitation, the kanamycin B sulfate was collected by filtration, washed with methanol and dried in vacuo at 50°C. 

The contents of the tube were then acidified to pH 2 by the addition of sulfuric acid and centrifuged. Examination of the supernatant liquid by paper chromatography employing the methods of 8ohonos et al. Antibiotics Annual (1953-4, page 49), demonstrates the presence of 7-chloro-6-demethyltetracycline, 7-chlorotetracycline and tetracycline. 

The culture broth (about 1,100 gallons in volume) is adjusted to pH 9.5 with 40% sodium hydroxide solution and is filtered to remove the mycelium, the filtration being assisted by use of 3% of Hyflo Super-Cel, a filter aid, (sold by Johns-IVlanville Company). The clear filtrate is extracted with amyl acetate in a Podbielniak extractor using a ratio of 1 volume of amyl acetate to 6 volumes of clarified broth. The amyl acetate extract is in turn extracted batchwise with water brought to about pH 5 by the addition of sulfuric acid. Two... 

The addition of sulfuric acid will probably produce a slight precipitate, but this may be ignored if the original treatment with hydrochloric acid was properly carried out. 

Paste mixing means the addition of sulfuric acid and water. The result is a fairly stiff paste with a density between 1.1 and 1.4gcm 3 containing 8-12wt% of lead sulfate. The water content of thus mix determines the porosity of the active material achievable later (cf. "curing" below). In the paste, a mixture of lead sulfate and basic lead sulfate is formed (cf. Table 1). In the usual mixing process between room temperature and 50 °C, tribasic lead sulfate is formed. The generation of the tetrabasic... 

Nitration vs side-chain oxidation of toluene in dilute MA was investigated by Namba et al (Ref 69). They found that addition of sulfuric acid accelerated both reactions but nitration more than oxidation. Addition of water to the MA favors oxidation as does an increase in reaction temp... 

A further improvement involves the essentially simultaneous synthesis and extrn of Petrin from the reaction mixt. Methylene chloride solvent is added to the PE/nitric acid mixt before the addition of sulfuric acid. After adding the sulfuric acid the solvent is removed, and fresh solvent is added and removed several times. 

The addition of sulfuric acid requires ca. 1 hour. Occasional swirling of the Erlenmeyer flask is recommended for smooth generation of methyl nitrite. 

Contact of acetylene with the cone, acid in presence of mercury salts forms trini-tromethane, explosive above its m.p., 15°C. Subsequent addition of sulfuric acid produces tetranitromethane, a powerful oxidant of limited stability, in high yield. See Trinitromethane, also Tetranitromethane... 

A safe method of preparing 5-nitro-2-methylbenzimidazole involves preliminaiy addition of the heterocycle to nitric acid (d 1.40) with subsequent addition of sulfuric acid, keeping the temperature below 110°C. 

Addition of sulfuric acid to the cyano-alcohol caused a vigorous reaction which pressure-ruptured the vessel [1]. This seems likely to have been caused by insufficient cooling to prevent dehydration of the alcohol to methaciylonitrile and lack of inhibitors to prevent exothermic polymerisation of the nitrile [2],... 

Boron or yellow phosphorus explode violently on grinding with lead dioxide, while red phosphorus ignites [1]. Mixtures with sulfur ignite on grinding or addition of sulfuric acid [2], An initiating mixture of silicon and lead dioxide (2 1) attains a temperature around 1100°C after ignition by a small flame [3],... 

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