Potassium hydroxide impurities

This type of extraction depends upon the use of a reagent which reacts chemically with the compound to be extracted, and is generally employed either to remove small amounts of impurities in an organic compound or to separate the components of a mixture. Examples of such reagents include dilute (5 per cent.) aqueous sodium or potassium hydroxide solution, 5 or 10 per cent, sodium carbonate solution, saturated sodium bicarbonate solution (ca. 5 per cent.), dilute hydrochloric or sulphuric acid, and concentrated sulphuric acid. 

Manufacture. Commercial KF is manufactured from potassium hydroxide and hydrofluoric acid followed by drying ia a spray dryer or flaking from a heated dmm. The KF assay is typically 97—99% impurities are KF 2H20 and either potassium carbonate or potassium bifluoride. The 1992 price of... 

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). 

Analytical and Test Methods. The acid number of terephthahc acid discussed above is a titration of a sample dissolved in pyridine, using a sodium or potassium hydroxide titrant. However, specifications on certain impurities are so strict that this test caimot, as a practical matter, be failed. Its use has been discontinued by some manufacturers. 

Potassium Carbonate. Except for small amounts produced by obsolete processes, eg, the leaching of wood ashes and the Engel-Precht process, potassium carbonate is produced by the carbonation, ie, via reaction with carbon dioxide, of potassium hydroxide. Potassium carbonate is available commercially as a concentrated solution containing ca 47 wt % K CO or in granular crystalline form containing 99.5 wt % K CO. Impurities are small amounts of sodium and chloride plus trace amounts (<2 ppm) of heavy metals such as lead. Heavy metals are a concern because potassium carbonate is used in the production of chocolate intended for human consumption. 

Chemical Processing. Activated carbon consumption in a variety of chemical processing appHcations is about 8% of the total (74). The activated carbon removes impurities to achieve high quaHty. For example, organic contaminants are removed from solution in the production of alum, soda ash, and potassium hydroxide (82). Other apphcations include the manufacture of dyestuffs, glycols, amines, organic acids, urea, hydrochloric acid, and phosphoric acid (83). 

Potassium chromate is prepared by the reaction of potassium dichromate and potassium hydroxide. Sulfates are the most difficult impurity to remove, because potassium sulfate and potassium chromate are isomorphic. 

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. 

Preparation of Diethylphenylacetic Acid 46 grams of the foregoing nitrile was added to 140 ml ethylene glycol containing 36 grams potassium hydroxide and the mixture refluxed with stirring for about 20 hours. The mixture was diluted with water, extracted with light petroleum (8P 60° to 80°C) to remove traces of impurities and then acidified to yield diethylphenylacetic acid which was recrystallized from dilute ethanol (40% v/v ethanol in water). 

After 30 minutes the solid sulfinic acid is separated on a fritted-glass filter. The sulfinic acid is dissolved from the filter by a mixture of 750 ml. of ether and 750 ml, of methylene chloride. The solution is dried over calcium chloride and evaporated to dryness under reduced pressure (bath temperature 25°) (Note 5). The residue is suspended in 50 ml. of water, and small portions of dilute ammonia are added to the well-stirred suspension until it has a pH of 9 (Note 6). Insoluble impurities are separated by filtration, and 2-nitrobenzenesulfinic acid is precipitated from the filtrate by adding 5-ml. portions of 6N hydrochloric acid with cooling the sulfinic acid precipitated by each portion of acid is separately collected on a Buchner funnel (Note 7). The acid, a pale yellow solid, is dried on a clay plate in a vacuum desiccator over potassium hydroxide pellets, m.p. 120-125° (dec.), weight 9.4-14.9 g. (50-80%). If the 2-nitrobenzenesulfinic acid is to be used for the hydrogenation of the next step high purity is required, and it is generally advisable to reprecipitate the acid once more in the same way (Note 8). 

Calcein solution. Dissolve sufficient calcein, or its disodium salt, in the minimum amount of 0.40M potassium hydroxide solution and dilute with water to give a concentration of 60 mg L"1 in a graduated flask. A small amount of EDTA solution (about 1.0 mL of 0.03M for every 100 mL calcein solution) may be needed in the calcein solution to achieve balancing of the blank on the fluorimeter. This is only necessary in those cases in which the potassium hydroxide used is found to contain a small amount of calcium impurity. 

Next, a series of runs was conducted to determine the effect of various alkali metal hydroxide additions along with the sponge nickel catalyst. The 50 wt. % sodium hydroxide and 50 wt. % potassium hydroxide caustic solution used in the initial test was replaced with an aqueous solution of the alkali metal hydroxide at the level indicated in Table 2. After the reaction number of cycles indicated in Table 2, a sample was removed for analysis. The conditions and results are shown in Table 2. The results reported in Table 2 show the level of 2° Amine in the product from the final cycle. The level of NPA in all of the mns was comparable to the level observed in the initial test. No significant levels of other impurities were detected. 

During investigation of elfect of 1% of added impurities on the thermal explosion temperature of TNT (297°C), it was found that fresh red lead, sodium carbonate and potassium hydroxide reduced the explosion temperatures to 192, 218, and 192°C, respectively. 

Feuer and co-workers extended their studies to the alkaline nitration of a,Nitration with potassium ferf-butoxide and amyl nitrate in THF at —30 °C yields the corresponding dipotassium salt of the a,nitronate salts from these reactions are isolated via methanol-induced precipitation from the aqueous reaction liquors, a process which also separates the product from impurities. These salts undergo hydrolysis on treatment with aqueous potassium hydroxide, and subsequent acidification yields the corresponding Q, y-dinitroalkane. This route has been used to synthesize 1,4-dinitrobutane (27) from apidonitrile (95) in 30 % overall yield. 

Tetramethylpiperidine, furnished by Aldrich Chemical Company, Inc., Fluka A G, and ICN Life Sciences Group, is sometimes contaminated with traces of water, hydrazine, and/or 2,2,6,6-tetramethyl-4-piperidone. These impurities may be- removed by drying with sodium hydroxide or potassium hydroxide pellets, filtering, and distilling at atmospheric pressure, b.p. 153-154°. The purified amine can be stored indefinitely under a nitrogen atmosphere. 

The selection of raw materials and the method of preparation of the catalyst base are important in determining the final quality of the catalyst. Impregnating almost any iron oxide with potassium hydroxide and drying it will yield a catalyst of some activity, but care must be exercised both in selecting the raw materials and in the method of preparation, if a superior catalyst is to be obtained. Generally, the purer the components the better the catalyst, but substantial quantities of impurities such as silicon dioxide, aluminum oxide, and carbon can be tolerated. Suitable raw materials are obtainable at low cost, and satisfactory methods of preparation are simple and inexpensive. 

The purification of the alkali hydroxides.—Numerous impurities have been reported in commercial sodium and potassium hydroxides. Several have commented on the presence of peroxide, particularly in caustic potash.19 Various salts—carbonate, sulphate, nitrate, nitrite, chloride, and phosphate—as well as alumina, silica, organic matters, and metal oxides—e.g. arsenic, vanadium, iron, etc., have been reported. More or less of the other alkalies may also be present. 

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-... 

An impure sample of potassium ferrate, K2Fe04, may be prepared as follows Dissolve sufficient ferric chloride, FeCl3,6H20, to correspond to 40 g. Fe(OH)3 in 2 1. of hot water and precipitate the hydroxide with potassium hydroxide. Wash the precipitate repeatedly with hot water by decantation until nearly all chlorides have been removed and evaporate the suspended hydroxide to a volume of about 65 cc., bringing it into a porcelain dish that will hold about 250 cc. Break up 25 g. of solid potassium hydroxide into small pieces and add it to the ferric hydroxide, warming the mixture to insure solution. 

The bomb contents are digested with concentrated hydrochloric acid, and material still undissolved is then digested with potassium hydroxide and hydrogen peroxide. A crude separation is made by a sulfide precipitation from the combined digestion solutions. The sulfides are dissolved in aqua regia, the solution is evaporated, and antimony in the residue is reduced to antimony (III) with hydroxylamine hydrochloride. The sample, in ammonium thiocyanate-hydrochloric acid medium, is loaded onto a Dowex 2 column (SCN" form). Arsenic and other impurities are eluted with aliquots of more dilute ammonium thiocyanate-hydrochloric acid solutions. Antimony is eluated with sulfuric acid and fixed in solution by addition of hydrochloric acid. The activity of the solution caused by the 0.56 MeV y-ray of 2.8-day 122Sb is counted. 

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