Sulfuric acid dilution heat

Phenolphthalein. Alophen, Ex-Lax, Feen-a-Miat, Modane, and Phenolax are trade names for phenolphthaleia [77-09-8] (3,3-bis(4-hydroxyphen5l)-l-(3ff)-l isobensofuranone) (10). It is a white or faintiy yellowish white crystalline powder, odorless and stable ia air, and practically iasoluble ia water one gram is soluble ia 15 mL alcohol and 100 mL diethyl ether. Phenolphthaleia may be prepared by mixing phenol, phthaHc anhydride, and sulfuric acid, and heating at 120°C for 10—12 h. The product is extracted with boiling water, then the residue dissolved ia dilute sodium hydroxide solution, filtered, and precipitated with acid. 

C. Thymoquinone.—The wet aminothymol thus prepared is immediately dissolved in no cc. of concentrated sulfuric acid diluted to 4 1. and contained in a 12-I. flask. To this solution is added 150 g. of sodium nitrite (2.18 moles), in 5-10-g. portions, with shaking after each addition. The resulting mixture is heated to 60° on a steam bath, with occasional shaking, for half an hour (Note 5), and is then distilled in a current of steam, by means of the apparatus described in Org. Syn. 2, 80 (Note 6). All the thymoquinone passes over with the first 3 1. of distillate it solidifies on cooling, and is filtered with suction (Note 7), washed, and dried at room temperature. The yield is 80-87 g. (73-80 per cent of the theoretical amount) of bright yellow crystals, melting at 43-45° (Note 8). 

In a 2-1. flask are placed 375 g. of commercial sodium dichromate, 225 cc. of water, and 300 g. of dichlorohydrin (b. p. 68-75°/i4 mm.). The flask is set in a water bath and equipped with a thermometer and mechanical stirrer. The contents are vigorously stirred, and 450 g. of sulfuric acid, diluted with 115 g. of water, are introduced during the course of seven to eight hours. It is convenient to add the acid at ten-minute intervals. The temperature is kept between 20° and 250 during the entire reaction this is accomplished by adding a little ice to the water bath from time to time. The stirring is continued for sixteen to seventeen hours after all the acid has been added as there is very little heat evolved during this part of the reaction, the water bath may be allowed to come to room temperature. 

In a recent document [25] presenting techniques adopted by the French for pollution prevention, a new process modification for steam segregation and recycle in phosphoric acid production is described. As shown in Figure 9, raw water from the sludge/fluorine separation system is recycled to the heat-exchange system of the sulfuric acid dilution unit and the wastewater used in plaster manufacture. Furthermore, decanted supernatant from the phosphogypsum deposit pond is recycled for treatment in the water filtration unit. The claim was that this process modification permits an important reduction in pollution by... 

Insoluble polystyrene crosslinked with divinylbenzene can easily be converted by sulfonation to a usable ion exchanger. For this purpose a mixture of 0.2 g of silver sulfate and 150 ml of concentrated sulfuric acid are heated to 80-90 °C in a 500 ml threenecked flask fitted with stirrer, reflux condenser, and thermometer. 20 g of a bead polymer of styrene and divinylbenzene (see Example 3-41) are then introduced with stirring the temperature climbs spontaneously to 100-105 °C.The mixture is maintained at 100 C for 3 h,then cooled to room temperature and allowed to stand for some hours. Next the contents of the flask are poured into a 11 conical flask that contains about 500 ml of 50% sulfuric acid. After cooling, the mixture is diluted with distilled water, and the gold-brown colored beads are filtered off on a sintered glass filter and washed copiously with water. 

Inflammable air from the solution of metals in acids had been observed and commented on for at least a hundred years, but only after the attention of chemists had been directed toward gases generally did a systematic study appear. Cavendish obtained the inflammable air by dissolving zinc, iron, and tin in dilute vitriolic acid or in spirit of salt. The same metals also dissolved readily in nitrous (nitric) acid, and in concentrated vitriolic (sulfuric) acid with heat, but the resulting airs were not at all inflammable. He interpreted these reactions as follows ... 

Sulfuric acid, dilute Acetates, CH3COO- Evolution of acetic acid (vinegar-like odor) concentrated sulfuric acid also evolves sulfur dioxide under mild heating... 

The amount of reduction of the chromium may be determined by oxidizing aliquot portions of the above solution and determining the total chromium content. The oxidation is effected by acidifying the sample with 10% sulfuric acid and heating nearly to boiling. A small crystal of silver nitrate and approximately 2 g. of ammonium peroxydisul-fate are added for every 50 ml. of solution. The treated solution is evaporated to one-half its former volume, cooled, apd diluted to 50 ml. The remainder of the procedure is the same as that used for hexavalent chromium. 

Assay With the aid of about 25 mL of water, transfer about 125 mg of sample, accurately weighed, into a 300-mL Erlen-meyer flask. Add 50.0 mL of 0.5 N potassium dichromate, mix, then carefully add 100 mL of sulfuric acid, and heat to boiling. Remove the mixture from the heat, allow it to stand at room temperature for 15 min, cool it in a water bath, and transfer it into a 250-mL volumetric flask. Dilute almost to volume with water, cool to 25°, then dilute to volume with water, and mix. Titrate a 50.0-mL aliquot with 0.1 iV ferrous ammonium sulfate, using 2 or 3 drops of orthophenanthroline TS as the indicator, and record the volume required, in milliliters, as S. Perform a blank determination (see General Provisions), and record the volume of 0.1 N ferrous ammonium sulfate required, in milliliters, as B. Calculate the percent cellulose in the sample by the formula... 

Standard Preparations Dissolve 338.5 mg of mercuric chloride, in about 200 mL of water in a 250-mL volumetric flask, add 14 mL of 1 2 sulfuric acid, dilute to volume with water, and mix. Pipet 10.0 mL of this solution into a 1000-mL volumetric flask containing about 800 mL of water and 56 mL of 1 2 sulfuric acid, dilute to volume with water, and mix. Pipet 10.0 mL of the second solution into a second 1000-mL volumetric flask containing 800 mL of water and 56 mL of 1 2 sulfuric acid, dilute to volume with water, and mix. Each milliliter of this diluted stock solution contains 0.1 pig of mercury. Pipet 1.25, 2.50, 5.00, 7.50, and 10.00 mL of the last solution (equivalent to 0.125, 0.250, 0.500, 0.750, and 1.00 ptg of mercury, respectively) into five separate 150-mL beakers. Add 25 mL of aqua regia to each beaker, cover with watch glasses, heat just to boiling, simmer for about 5 min, and cool to room temperature. Transfer the solutions into separate 250-mL volumetric flasks, dilute to volume with water, and mix. Transfer a 50.0-mL aliquot from each solution into five separate 150-mL beakers, and add 1.0 mL of 1 5 sulfuric acid and 1.0 mL of a filtered solution of 1 25 potassium permanganate solution to each. Heat the solutions just to boiling, simmer for about 5 min, and cool. 

Transfer 20 mL of sample into a 500-mL separator, add a solution of 20 g of sodium hydroxide in 50 mL of water, stopper the separator, and wrap it securely in a towel for protection against the heat of the reaction. Shake the mixture vigorously for about 5 min, cautiously opening the stopcock from time to time to permit the escape of air. Continue shaking the mixture vigorously until a homogeneous liquid results, then distill, and collect about 25 mL of the distillate. Add 1 drop of dilute phosphoric acid (1 20) and 1 drop of a 1 20 solution of potassium permanganate to 1 drop of the distillate. Mix, allow to stand for 1 min, and add, drop wise, a 1 20 solution of sodium bisulfite until the color disappears. If a brown color remains, add 1 drop of the dilute phosphoric acid. Add to the colorless solution 5 mL of a freshly prepared 1 2000 solution of chromotropic acid in 75% sulfuric acid, and heat on a steam bath for 10 min at 60°. No violet color appears. 

A solution of 200 g. (1.03 moles) of a-methyl-d-mannoside (Org. Syn. Coll. Vol. 1, 1st Ed. (1932), p. 362 2nd Ed. (1941), p. 371) in 3.2 1. of 2 N sulfuric acid (178 cc. concentrated sulfuric acid diluted to 3.2 1.) is steam-distilled from a 5-1. flask for one hour. The flask is heated externally during this time so that the volume of the solution remains constant. The mixture is transferred to a 2- or 3-gal. crock, 10 g. of decolorizing charcoal (Norite) is added, and the solution is rapidly stirred while it is neutralized (litmus) by the addition of barium carbonate (Note 1). 

To 0.5 g of dry 2-acetylamino-1,4-naphthoquinone (5) contained in a 25-mL Erlenmeyer flask add 2 mL of concentrated sulfuric acid and heat the mixture on the steam bath with swirling to promote rapid solution (1-2 min). After 5 min cool the deep red solution, dilute extensively with water, and collect the precipitated product wash it with water and crystallize the moist sample (dry weight about 0.4 g) from alcohol or alcohol-water red needles, mp 206°C. 

Properties White to yellow, crystalline powder. D 7.56, decomposes on heating. Soluble in hot sulfuric acid, dilute nitric acid slightly soluble in water. 

Chromic acid attacks the alkaloids only very slowly. Jowett (30) recovered isopilocarpine unchanged after it had been treated with chromic acid at room temperature for several days, and Pinner and Schwarz (39) found that heating on the water bath for 7 days was necessary for the complete oxidation of this base with excess chromic acid the products were not examined. A solution of pilocarpine in dilute sulfuric acid, on heating with chromic acid, consumed four atomic proportions of oxygen in 6 hours, giving 50-60 % of an acid, pilocarpoic acid (37, 39), and a trace of a second product, C8H10O2N2 or C8Hi202N2, which was not further examined ammonia, methylamine and carbon dioxide were not formed in the oxidation. 

A mixture of one gm allocryptopine, 2 gm phloroglucinol, and 10 nil o8% sulfuric acid was heated to boiling and then digested on the steam bath for 1 hour (longer heating is disadvantageous). The diluted, cooled, and filtered solution was exhausted with ether, basified with ammonia, and extracted with chloroform. The residue from the latter in methanol was methylated in methanol with excess diazoinethane and the resulting nonphenolic base isolated in the normal way. Its solution in dry ether was clarified with charcoal, evaporated to a small volume, and allowed to evaporate further at room temperature. The brilliant, colorless stout prisms which separated melted sharply at 175 either alone or in admixture wdth muramine. When recrystallized from methanol it melted at 175 -176°. The yield of purified base was 25 mg. 

Nitrites are oxidized by permanganate ions in acidic medium with the formation of nitrate ions. The determination consists of a back titration. The nitrite solution is progressively added into the solution of permanganate ions in excess. The medium consists of a diluted sulfuric acid solution heated at 50°C since the reaction is slow. It is... 

In a typical process where ammonia is reacted with sulfuric acid, this heat of reaction is augmented by the heat of dilution of sulfuric acid from 60° B6 (77.6%) to 7% which amounts to 15,000 Btu/lb mole. The total heat effect is, therefore, 101,000 Btu/lb mole of ammonium sulfate. 

Regeneration can be accomplished by washing the adsorbent with water to produce a dilute solution of sulfuric acid or heating to reduce the sulfuric acid to SO2, which can then be converted to concoitrated sulfuric acid or sulfur. The reduction reaction can be represented by the following equation ... 

Acetic anhydride adds to acetaldehyde in the presence of dilute acid to form ethyUdene diacetate [542-10-9], boron fluoride also catalyzes the reaction (78). Ethyfldene diacetate decomposes to the anhydride and aldehyde at temperatures of 220—268°C and initial pressures of 14.6—21.3 kPa (110—160 mm Hg) (79), or upon heating to 150°C in the presence of a zinc chloride catalyst (80). Acetone (qv) [67-64-1] has been prepared in 90% yield by heating an aqueous solution of acetaldehyde to 410°C in the presence of a catalyst (81). Active methylene groups condense acetaldehyde. The reaction of isobutfyene/715-11-7] and aqueous solutions of acetaldehyde in the presence of 1—2% sulfuric acid yields alkyl-y -dioxanes 2,4,4,6-tetramethyl-y -dioxane [5182-37-6] is produced in yields up to 90% (82). 

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. 

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