Potassium hydroxide Subject

The cmde phthaUc anhydride is subjected to a thermal pretreatment or heat soak at atmospheric pressure to complete dehydration of traces of phthahc acid and to convert color bodies to higher boiling compounds that can be removed by distillation. The addition of chemicals during the heat soak promotes condensation reactions and shortens the time required for them. Use of potassium hydroxide and sodium nitrate, carbonate, bicarbonate, sulfate, or borate has been patented (30). Purification is by continuous vacuum distillation, as shown by two columns in Figure 1. The most troublesome impurity is phthahde (l(3)-isobenzofuranone), which is stmcturaHy similar to phthahc anhydride. Reactor and recovery conditions must be carefully chosen to minimize phthahde contamination (31). Phthahde [87-41-2] is also reduced by adding potassium hydroxide during the heat soak (30). 

Mitsubishi Chemical Industries, Ltd. practiced a Henkel II technology starting with toluene to produce benzoic acid. Reaction of benzoic acid with potassium hydroxide resulted in potassium benzoate, which was subjected to a disproportionation reaction to produce dipotassium terephthalate and benzene. Dipotassium terephthalate reacted with sulfuric acid, and the resulting terephthahc acid was recovered by filtration and drying (65,66). Here, dipotassium sulfate was the by-product. 

Manufacture. A limited, amount of natural cinnamyl alcohol is produced by the alkaline hydrolysis of the cinnamyl cinnamate present in Styrax Oil. Thus treatment of the essential oil with alcohoHc potassium hydroxide Hberates cinnamyl alcohol of reasonable purity which is then subjected to distillation. This product is sometimes preferred in fine fragrance perfumery because it contains trace impurities that have a rounding effect in finished formulations. 

A solution containing 741 g (5.0 mols) of 1-phenyl-2-propylidenylhydrazine, 300 g (5.0 mols) of glacial acetic acid and 900 cc of absolute ethanol was subjected to hydrogenation at 1,875 psi of hydrogen in the presence of 10 gof platinum oxide catalyst and at a temperature of 30°C to 50°C (variation due to exothermic reaction). The catalyst was removed by filtration and the solvent and acetic acid were distilled. The residue was taken up In water and made strongly alkaline by the addition of solid potassium hydroxide. The alkaline mixture was extracted with ether and the ether extracts dried with potassium carbonate. The product was collected by fractional distillation, BP B5°C (0.30 mm) yield 512 g (68%). 

Procedure. Dissolve 0.1 g of the sample in 10 mL purified methanol and transfer 1.0 mL of this solution to a stoppered test-tube. Add 1.0 mL of solution A and one drop of concentrated hydrochloric acid, then place the stoppered tube in a beaker of boiling water for 5 minutes. Cool, and then add 5.0 mL of the potassium hydroxide solution. Measure the absorbance of the solution at 480 nm (blue-green filter) against a blank obtained by subjecting 1.0mL of purified methanol to the above procedure. 

When 2-methoxy-l,6-methano[10]annulene 32 was subjected to a cyclopropana-tion with diazomethane and cuprous chloride as catalyst reaction occurred preferentially at the 5,6-, 6,7- and/or 1,10-bonds and the adducts spontaneously underwent disrotatory opening yielding the corresponding methoxybicyclo[5.4.1]dodecapen-taenes. Hydride abstraction with triphenylmethyl fluoroborate was performed on the mixture and the ions 33 and 34 so produced were treated with dilute aqueous potassium hydroxide. The annulenones 13 and 14 were then separated by chromatography. 

The simplicity of the two-phase modification of the Gabriel synthesis of primary amines, via the N-alkylation of potassium phthalimide, makes the procedure considerably more convenient than the traditional method, which normally requires the use of anhydrous dipolar aprolic solvents. The reaction can be conducted under solid liquid conditions using potassium hydroxide in toluene [25], or with preformed potassium phthalimide [26, 27] (cf ref. 28). As is normal for acylation reactions, relatively mild conditions are required for the preparation of the A-ethoxycarbonyl derivative [29], whereas a reaction temperature of 100°C is generally used for N-alkylation (Table 5.16). The reaction time for the soliddiquid two-phase system can be reduced dramatically with retention of the high yields, when the reaction mixture is subjected to microwave irradiation [30]. 

By the beginning of the nineteenth century, caustic soda (sodium hydroxide) and caustic potash (potassium hydroxide) had come to be very widely used in chemical laboratories. Both substances were thought to be elements no one had ever broken them down into their chemical components. Nevertheless, Davy began to wonder if they might not turn out to be compounds after all, so he decided to subject them to electrolysis to see what happened. Realizing that the more powerful the batteries used, the better the chances of success, he had an assistant connect together all the batteries that the institution possessed. He then dissolved some caustic potash in water and passed an electrical current through the solution. 

To a stirred solution of 10 gm (0.040 mole) of m-iodonitrobenzene in 100 ml of ethanol is added 16 gm (0.30 mole) of potassium hydroxide. The mixture is then heated to reflux for 1 hr. After this, the reaction mixture is subjected to steam distillation. The distillation residue is then extracted with boiling benzene. After cooling, the benzene layer is separated and evaporated to dryness. Yield 5.9 gm (60 %), m.p. (after recrystallization from ethanol-benzene) 120°-121°C. 

A similar mechanism is thought to be involved when functionalized dihalocyclopropanes are treated with sodium alkoxides as well as thiophenolates or subjected to the influence of potassium hydroxide in methanol. 

The methods used to purify the solvents were as follows. The early batches of ethanol were subjected to a somewhat lengthy series of fractionations involving successive treatment with sulfuric acid, silver nitrate and potassium hydroxide, and aluminium-mercury couple. However, the following simple procedure was found to give equally good results. Three grams of potassium hydroxide pellets were rinsed with ethanol to remove surface impurities and added to 3 liters of boiling ethanol. The ethanol was then immediately fractionated and the middle 50% collected. The n-hexane and the isopentane were purified by ex-... 

The aldehydes and ketones formed in this reaction are subject tn secondary oooden ation reactions, and so the isolation of product nor molly is difficult. However, the reaction of potassium hydroxide in... 

Concentrated sulfuric acid (0.316 mol) was added over lh to dimethyl sulfide (0.316 mol), the temperature of the reaction mixture being kept below 30°C. Methanol (0.156 mol) was then added over 30 min with the temperature below 35°C. After the mixture had been stirred for 5h, t-BuOH (0.048 mol) was added to it followed by potassium hydroxide (0.58 mol) in 10 equal aliquots over 2.5 h. Benzaldehyde (0.15 mol) was added after the seventh KOH aliquot0 and an alkaline pH had been achieved. The mixture was stirred at room temperature for 12 h and subjected to conventional pentane/aqueous work-up. Styrene oxide was isolated in a 55% yield. 

Di(p-tolyl)isoxazole (61) is also sufficiently stable to alkali to be subjected to the Anil Synthesis. Thus, with benzalaniline in the presence of potassium hydroxide, the expected 3,5-di(stilben-4-yl)isoxazole (62) is formed. 

A. Stock found that the m.p. of phosphorus depends on the rate of heating and in contradistinction to A. Smits and H. L. de Leeuw, A. Stock and E. Stamm did not find the m.p. of yellow phosphorus to be altered by heating it to 100° followed by rapid cooling. Molten phosphorus is easily obtained as an under-cooled liquid, even at temp. 40° below its m.p. A. Bellani, and H. Rose noted that contact with solid phosphorus causes an immediate solidification of the under-cooled liquid. The phenomenon is particularly marked with phosphorus which has been boiled under an aq. or alcoholic soln. of potassium hydroxide. Observations on this subject were made by T. de Grotthus, J. B. Kallhofert, A. Schrotter, F. P. Venable and A. W. Belden, P. Heinrich, J. W. Retgers, and D. Gernez. The last-named also measured the velocity of crystallization of the under-cooled liquid—vide supra. 

The acid-catalysed reaction of a dicarboxylic acid with an excess of alcohol yields the diester. However, the process may be adapted to prepare acid esters of dicarboxylic acids by using molar proportions of the diacid and alcohol (e.g. methyl hydrogen adipate, Expt 5.147). Alternatively the acid ester may be prepared by subjecting the diester to controlled partial hydrolysis with one molar proportion of potassium hydroxide. 

The reaction may alternatively be carried out by boiling the benzaldehyde vigorously under reflux for 2 hours with a solution of 20 g of potassium hydroxide in 90 ml of water, and then working up the cooled reaction mixture as described above. Reaction is normally complete under these conditions the extent of the reaction may be determined by subjecting the crude ether extract, before the latter is washed with bisulphite solution, to g.l.c. analysis on a 1.5 m column of Chromosorb W with 10 per cent of Carbowax as the stationary phase, at 156 °C with a nitrogen flow rate of 40ml per minute. The retention times of benzaldehyde and benzyl alcohol are approximately 2.7 and 9.7 minutes respectively. 

Dogrukol-Ak et al. [55] determined omeprazole in pharmaceutical preparations by a TLC densitometric method. Pellets from eneric coated capsules were finely powdered and dissolved in ethanolic 0.05 M potassium hydroxide with sonication. Four microliters of the solution was subjected to TLC on a silica gel FG254 plates with chloroform-methanol-25% ammonia (97.5 2.5 1) as mobile phase and densitometric detection of omeprazole (Rf = 0.46) at 302 nm. Calibration graphs were linear for 0.42—1.68 jug omeprazole the detection limit was 25 ng. In the determination of omeprazole in 20 mg Omeprazit, Omeprol, and Losec capsules, the found amounts were 20.2, 20.3, and 19.8 mg omeprazole, respectively, with corresponding RSD 1.9,1.8, and 1.6% (n = 8). The results agree with those of UV spectrophotometry. 

The following procedures were reported for the assay of Melphalan Tablets (a) hydrolysis with aqueous potassium hydroxide under reflux and potentiometric titration of the liberated chloride ions with silver nitrate in the presence of nitric acid. (Corrections for "ionisable chlorine" are made by titrating under the same conditions a sample that is not subjected to hydrolysis [25,46].) (b)... 

In 135 ml THF was dissolved 3.03 g of a 3,5-dinitrobenzoyl derivative of (-)-3-acetoxymethyl-7,8-difluoro-2,3-dihydro-4H-[l,4]benzoxazine, and 135 ml of ethanol and 30 ml of 1.0 N potassium hydroxide were added to the solution. After 30 min 3 ml of acetic acid was added thereto for neutralization. The mixture was concentrated. The solid was subjected to column chromatography using 40 g of silica gel and eluted with chloroform/methanol to obtain 1.17 g of (-)-7,8-difluoro-2,3-dihydro-3-hydroxymethyl-4H-[l,4]benzoxazine [a]D22 = -14.1° (c = 1.80, CHCI3). 

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