Production of potassium hydroxide

Chlorine from Potassium Hydroxide Manufacture. One of the coproducts during the electrolytic production of potassium hydroxide employing mercury and membrane ceHs is chlorine. The combined name plate capacity for caustic potash during 1988 totaled 325,000 t/yr and growth of U.S. demand was expected to be steady at 2% through 1990 (68). 

The production of sodium hydroxide by electrolysis has been described in sufficient detail, and this procedure serves equally well for the production of potassium hydroxide. 

The ratio of values Wt and W in percents indicates the total energy (power) efficiency of the electrolysis. The efficiency of the production of potassium hydroxide is calculated analogously. 

Figure 1.9. Schematic representation of EG40 electrolytic production of potassium hydroxide (KOH) eluent (courtesy of Dionex Corp).

Industrial-grade and chemical-grade potassium chloride are used mainly for the electrolytic production of potassium hydroxide. Other important uses include the production of drilling fluids for the oil industry, aluminum smelting, metal plating, production of various potassium compounds, and appli-... 

A smaller quantity of activated carbon is used for separation of organic impurities from solutions in the production of potassium hydroxide, alums, and soda ash in order to obtain high quality products. Activated carbon filters are also lied for the purification of ram-... 

Caustic potash is considerably more expensive than caustic soda because the feedstock is refined, crystalline potassium chloride. Hence it is only used when it has a particular advantage, and the production of potassium hydroxide is only 2—3% that of sodium hydroxide. Potassium hydroxide can be produced by each of the electrolytic routes described in Section 3.3 above the only major difference is that the potassium chloride electrolyte is always recycled, the solution leaving the cell being resaturated and passed back to the cell. 

Most of the chemical-grade potash is used for production of potassium hydroxide. Potassium hydroxide ... 

Production. Today, potassium hydroxide is manufactured almost exclusively by potassium chloride electrolysis. The diaphragm, mercury, and membrane processes are all suitable for the production of potassium hydroxide, but the mercury process is preferred because it yields a chemically pure 50 % potassium hydroxide solution. 

Undecylenic acid (or 10-undecenoic acid) (I), a comparatively inexpensive commercial product obtained from castor oil, reacts with bromine in dry carbon tetrachloride to give 10 11-dibromoundecoic acid (II), which upon heating with a concentrated solution of potassium hydroxide yields 10-niidecynoic acid (III) ... 

Alkali AletalIodides. Potassium iodide [7681-11-0] KI, mol wt 166.02, mp 686°C, 76.45% I, forms colorless cubic crystals, which are soluble in water, ethanol, methanol, and acetone. KI is used in animal feeds, catalysts, photographic chemicals, for sanitation, and for radiation treatment of radiation poisoning resulting from nuclear accidents. Potassium iodide is prepared by reaction of potassium hydroxide and iodine, from HI and KHCO, or by electrolytic processes (107,108). The product is purified by crystallization from water (see also Feeds and feed additives Photography). 

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. 

A solution of the ketol diacetate (15 g, 0.028 mole) in toluene (200 ml) is dried by concentration to 150 ml at normal pressure. The solution is cooled to room temperature and then added with vigorous stirring to a solution of calcium turnings (4.2 g, 0.11 g-atom) in liquid ammonia (500 ml). The addition is made in 5 min, the mixture is stirred for a further 3 min, and excess calcium is then destroyed by the dropwise addition of bromobenzene ca. 4 ml). Water (5 ml) is added cautiously and the ammonia is allowed to evaporate. The toluene is removed by distillation on a steam-bath under reduced pressure and methanol (200 ml) is added to the residue, followed by a solution of potassium hydroxide (5 g) in water (10 ml). The mixture is boiled for 1 hr, water (50 ml) is added, and the mixture is warmed on the steam bath for 30 min in order to coagulate the product. Water (250 ml) and acetic acid (15 ml) are added, the mixture is cooled and the product filtered, washed thoroughly with water and dried to give 12.3 g of crude 11-ketotigogenin, mp 209-218° Md, -31°. 

Either the iodo carbamate (96) or the iodo amine salt (94) from above can be converted to the aziridine by refluxing about 2.5 g of the respective product in 100 ml of ethanol which contains 10 ml of water and 10 g of potassium hydroxide for ca. 2 hr. The aziridine is then isolated by pouring the basic reaction mixture into 250 ml water and extracting with 200 ml ether. The ether extract is washed several times with water and dried (MgS04). Evaporation of the ether on a steam bath yields 2j5,3j5-iminocholestane (95, 25-95 %) as a clear oil which solidifies on standing mp 103-105°. This aziridine is not easily crystallized. 

Androst-4-ene-3,17,19-trione (0.23g) is added to a precooled solution of 0.23 g of potassium hydroxide in a mixture of 1 ml of water and 5 ml of methanol. The reaction mixture is stirred at 5-10° under nitrogen for 3 hr, diluted with benzene (30 ml) and washed with water (2 x 10 ml). The aqueous layer is reextracted with benzene and the benzene solution dried and evaporated. The crude crystalline product is filtered through 8 g of Merck silicagel and eluted with benzene-ethyl acetate (9 1) to yield 0.19 g of 19-norandrostenedione (88%) mp 169-171° 141° (CHCI3). 

The crude diol (47)(3.8 g) is dissolved in 160 ml of methanol, mixed with 4 g of potassium hydroxide in 10 ml of water and 20 ml of methanol, and warmed under nitrogen for 5 min. Acetic acid (4 ml) is added and the solution is poured into an aqueous solution of sodium chloride. The product is extracted 3 times with ethyl acetate and the extracts are washed with 10% sodium bicarbonate and then with water. The solvent is removed by distillation and the residue is recrystallized from acetone-petroleum ether to give 1.85 g of (48) mp 275-277°. 

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