Potassium hydroxide, anhydrous, preparation

The independent preparation of potassium phthabmide (from a solution of phthalimide in absolute ethanol and potassium hydroxide in 75 per cent, ethanol) may be avoided in many cases by boiling phthalimide with the halide in the presence of anhydrous potassium carbonate. The N-substituted phthalimide (I) is frequently cleav with difficulty this is often facilitated by reaction with hydrazine hydrate to give an intermediate product, which is easily decomposed by hydrochloric acid to 3deld the insoluble hydrazide of phthaUc acid (II) and the primary amine (III) ... 

The free base is liberated from the acid solution with 20% sodium hydroxide solution and taken up in ether. The ether layer is washed with water, saturated with NaCI and then shaken with solid potassium hydroxide. The ether is removed by distillation, 200 parts of benzene added and distilled off. The residue is distilled in vacuo and the fraction 150°-165°C/2 mm is collected and amounts to 433 parts. The hydrochloride salt is prepared by dissolving the free base in anhydrous ether and slowly adding an alcoholic solution of hydrogen chloride. The solid is recrystallized from absolute alcohol-ether mixture or isopro-panol-ether mixture and has a MP of 161°-162°C. 

Preparation of 2-Cyclopropylcarbony/amido-5-Chlorobenzophenone To 400.5 g (1.73 mols) of 2-amino-5-chlorobenzophenone dissolved in 220 g (2.18 mols) of triethylamine and 3.5 liters of tetrahydrofuran is added cautiously 181 g (1.73 mols) of cyclopropane-carboxylic acid chloride. The reaction is refluxed 2 /2 hours and allowed to cool to room temperature. The solvent is then removed under vacuum to obtain 2-cyclopropylcarbonyl-amido-5-chlorobenzophenone as a residue which is dissolved in 1 liter of methylene chloride, washed twice with 5% hydrochloric acid, and then twice with 10% potassium hydroxide. The methylene chloride solution is then dried over anhydrous magnesium sulfate, filtered and the solvent removed under vacuum. The residue is recrystallized from 1,500 ml of methanol, charcoal-treating the hot solution to give 356 g of 2-cyclopropylcarbonylamido-5-chlorobenzophenone, MP 105° to 105.5°C (69% yield). 

A 2-1. three-necked flask is equipped with a stirrer, a 500-ml. dropping funnel protected by a calcium chloride drying tube, and a reflux condenser topped with a potassium hydroxide drying tube. The reaction vessel is cooled in an ice-salt bath and is charged with 500 ml. of dry pentane and 293 g. (6.5 mols) of anhydrous dimethylamine. A solution of 117.2 g. (1 mol) of boron trichloride in 400 ml. of pentane, prepared by passing the gaseous chloride into chilled pentane, is added slowly with... 

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]. 

Anhydrous dipotassium hydrophosphate, K2HPO4, could not be obtained by T. Graham in the solid crystalline condition L. Staudenmaier always obtained a more acid phosphate by crystallization from soln. containing eq. quantities of potassium hydroxide or carbonate and phosphoric acid. No hydrated form has been prepared. E. G. Parker, and J. d Ans and O. Schreiner have studied the conditions under which potassium and sodium salts are formed as solid phases— vide Figs. 86 and 87. E. von Berg prepared dirubidium hydrophosphate,... 

Preparation of Hydrazine. Assemble an apparatus as shown in Fig. 85b. Put an amount of potassium hydroxide into a two-neck flask provided with a reflux condenser such that there is a 2-3-mm layer of hydrazine hydrate over it. Cool the flask in a bath with ice and transfer the previously prepared hydrazine hydrate into it wear eye protection ). Pass a stream of dry nitrogen through the reaction mixture. Carefully heat the flask until the alkali dissolves completely, then cool the flask to room temperature, and, without stopping the nitrogen stream, replace the reflux condenser with a dephlegmator. Assemble an apparatus for fractional distillation (see Fig. 20) and distil off the anhydrous hydrazine in a nitrogen stream at 112-114 °C. 

Potassium Pyrovanadate, K4V207.4lI20, separates out in colourless, transparent crystals when one molecular proportion of vanadium pentoxide is dissolved in two molecular proportions of potassium hydroxide. These lose water when heated, melt, and leave a crystalline mass of the anhydrous salt K4Va07,5 which is deliquescent and melts at 910° C.6 A white, crystalline, xeadily soluble trihydrate, K4V207. SH20, has also been prepared.7... 

Several methods have been developed for preparation of /3 lactose. a-Lactose hydrate has been converted to /3-lactose in nearly quantitative yield by refluxing in methanol containing small amounts of sodium hydroxide (Olano and Rios 1978) ethanol, n-propanol and n-buta-nol were also effective as solvents (Olano 1978). Similarly, a-lactose hydrate was converted to /3-lactose with potassium methoxide or potassium hydroxide as the base (Parrish et al. 1979B). /3-Lactose was also prepared from the anhydrous forms of a-lactose if small amounts of /3-lactose were present (Parrish et al. 1980A). 

B. 2,5-Dimethylmandelic acid. A mixture prepared from 140 g. (0.5 mole) of 2,5-dimethylphenylhydroxymalonic ester and a cold solution of 140 g. of potassium hydroxide in 560 ml. of water in a 1-1. round-bottomed flask is warmed on a steam bath for 5 hours. The alkaline solution is cooled and extracted with one 100-ml. portion of ether to remove any material not soluble in alkali. The alkaline solution is acidified with 300 ml. of concentrated hydrochloric acid and then warmed on a steam bath and stirred for 2 hours (or until there is no further evidence that carbon dioxide is escaping). The mixture is cooled, the oily layer is extracted with ether, the ethereal solution is dried with anhydrous sodium sulfate, and the ether is distilled under partial vacuum (Note 3). The oily residue is crystallized from benzene. The yield of 2,5-dimethyImandelic acid melting at 116.5-117° is 55-63 g. (63-70%) (Note 4). 

Anhydrous dimethylamine may be conveniently prepared by allowing 25% aqueous dimethylamine to drop onto solid potassium hydroxide, the gas evolved being dried by passage over solid potassium hydroxide. 

E. Divers and T. Haga prepared monohydrated triammonium imidodisul-phonate, N(NH4)(NH4S03)2.H20, by the union of ammonia with diammonium imidosulphonate in the presence of water. The ammonia must be in excess or the salt will be decomposed. Cone. aq. ammonia precipitates this salt from a sat. soln. of the diammonium salt, or from a sat. soln. of the sodium salt, but in that case the precipitate is contaminated with the double sodium ammonium salt. Ammonia gas acts similarly and more effectively. The crystalline powder can be recrystallized by cooling a hot cone. soln. of ammonia in a closed vessel. The crystals resemble those of the potassium salt. The clear, lustrous crystals gradually effloresce and become opaque and damp and in a dry ammoniacal atm. over solid potassium hydroxide, the crystals slowly become opaque and anhydrous. WTien heated, the salt partly fuses and passes into the diammonium salt with the loss of both ammonia... 

The diazomethane-ether solutions prepared by all these methods should be dry. If in doubt, it may be dried with potassium hydroxide pellets. The anhydrous ethereal solution may be stored in the fume cupboard in a smooth glass flask or bottle for a day or so at — 70 °C since slow decomposition occurs with liberation of gas, the containing vessel should be protected by a calcium chloride guard-tube. 

To prepare palladium on charcoal (5% Pd), heat a solution of 1.7 g of palladium chloride (1) in 1.7 ml of concentrated hydrochloric acid and 20 ml of water on a water bath for 2 hours or until solution is complete, and add this to a solution of 30 g of sodium acetate trihydrate in 200 ml of water contained in a 500-ml hydrogenation flask. Add 20 g of acid-washed activated charcoal (2) and hydrogenate in an atmospheric hydrogenation apparatus (Fig. 2.63(a)) until absorption ceases. Collect the catalyst on a Buchner funnel and wash it with five 100 ml portions of water and suck as dry as possbile. Dry the catalyst at room temperature (3) over potassium hydroxide pellets or anhydrous calcium chloride in a vacuum desiccator. Powder the catalyst (about 20 g) and store in a tightly stoppered bottle. 

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