Solution, 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). 

Sulfuric acid. As a 10 to 20% v/v solution, sulfuric acid can be used to clean 300 series SS, as well as other steels and metals, but not galvanized steel or magnesium. The cleaned SS can then be passivated with nitric acid. In practice, sulfuric acid is seldom used, except by specialist cleaning companies, because of its high heat of dilution and terrible burning effect on skin and other tissues. Add acid to 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 ... 

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 Erlenmeyer flask. Add 50.0 mL of 0.5 A potassium dichromate, mix, then carefully add 100 mL of sulfuric acid, and heat to boiling. Remove the flask from the heat, allow the solution to stand at room temperature for 15 min, cool it in a water bath, and transfer the solution to a 250-mL volumetric flask. Dilute with water almost to volume, cool to 25°, dilute to volume with water, and mix. Titrate a 50-mL aliquot with 0.1 A ferrous ammonium sulfate, using 2 or 3 drops of ortho-phenanthroline TS. Perform a blank determination (see General Provisions), and make any necessary correction. Calculate the normality, A, of the ferrous ammonium sulfate solution 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. 

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. 

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. 

To 68 g. (0.5 mole) of aminoguanidine bicarbonate (p. 7) in a 500-ml. round-bottomed flask is added carefully the cold dilute sulfuric acid (0.24 mole), made from 24.5 g. of concentrated acid (sp. gr. 1.84) and 50 ml. of water. After the gas evolution has subsided, the solution is heated for 1 hour on a steam bath and then evaporated to dryness under a pressure of about 15 mm. 

The product Is often used as the acid sulfate which is produced as follows 252.0 g (0.B5 mol) of 0 A-diphenyl-7-dlmethylamlnovaleramide was dissolved in one liter of isopropanol,and 70 ml of concentrated sulfuric acid was added as rapidly as possible. The mixture was heated until clear, then filtered and diluted with 1,500 ml of anhydrous ethyl acetate. The solution was cooled and filtered, and the white crystalline product was dried in vacuo over PjOs. 

The ethyl p-chlorophenoxyisobutyrate may be obtained by heating a mixture of 206 parts of dry p-chlorophenoxyisobutyric acid, 1,000 parts of ethanol and 40 parts of concentrated sulfuric acid under reflux during 5 hours. The aicohol is then distilled off and the residue is diluted with water and extracted with chioroform. The chloroform extract is washed with sodium hydrogen carbonate solution, dried over sodium sulfate and the chloroform removed by distillation. The residue is distilled under reduced pressure and there is obtained ethyl p-chlorophenoxyisobutyrate, BP 148° to 150°C/20 mm. 

A mixture consisting of 8 grams of estriol, 20 grams of succinic acid anhydride and 60 ml of pyridine is heated at 90 C for 4 hours, after which the reaction mixture is poured into water. The aqueous solution is extracted with ether, the ether layer is separated, washed with diluted sulfuric acid and after that with water until neutral, then evaporated to dryness to obtain 14 grams of an amorphous substance. Melting point 82° to 86°C. This drying residue proves to consist of a mixture of estriol disuccinate and estriol monosuccinate, which are separated by repeated crystallization from a mixture of methanol and water. 

A solution of 18 grams of ethyl 2-bromopropionate in 20 ml of tetrahydrofuran is then added to the cooled reaction mixture. After 24 hours at 20°C, the product is hydrolyzed by adding 200 ml of 5 weight percent methanolic sodium hydroxide followed by heating to reflux for 1 hour. The reaction mixture is then diluted with excess 1 N sulfuric acid and extracted with ether. The ether phase Is separated, evaporated to dryness and the residue is recrystallized from acetone-hexane to yield 2-(6-methoxv-2-naphthyl)propionic acid. 

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