Potassium hydroxide removal

Saturate the distillate with sodium chloride (ca. 8 g.) and extract four times with 5 ml. portions of ether. Dry the combined ethereal extracts with a little anhydrous potassium carbonate or a few pellets of potassium hydroxide. Remove the ether (Fig. 11,13, 4), using a 20-25 ml. distilling flask. When all... 

The potassium hydroxide removes carbon dioxide from the apparatus by the reaction... 

Assay Determine as directed under Phenols, Appendix VI, using a measure of filtered sample prepared as follows Shake a suitable quantity of sample with 2% powdered tartaric acid for about 2 min, and filter. Modify the test by heating the flask in a boiling water bath for 10 min after shaking the sample with 1 N potassium hydroxide. Remove from the boiling water bath, cool, and proceed as directed. 

Potassium hydroxide [1, 935-937, before references]. Lawrence et al.10 charged Carius tubes with an ether-methanol solution of methyl levopimarate (1) and 5 mole percent of potassium hydroxide, removed the solvent under reduced pressure, sealed... 

Construction of the oxazine ring of 783 was achieved by cyanation of the 4-amino-4-ethoxycarbonyl-pyrrol-3-yl C-nucleoside 337 with cyanogen bromide, followed by hydrolysis and cyclization of the ester cyanamide 782 with methanolic potassium hydroxide. Removal of the sugar-protective ketal group gave 783, which possessed immunostimulant properties [85TL5785 86JAP(K)86/260094] (Scheme 205). 

Nickel/potassium hydroxide Removal of bromine blocking groups... 

When iron or other heavy metals are present in any appreciable concentration, they should be precipitated with potassium carbonate or potassium hydroxide, removed by filtration, and the sample subsequently neutralised before the sulphates are determined. 

Sodium and potassium hydroxides. The use of these efficient reagents is generally confined to the drying of amines (soda lime, barium oxide and quicklime may also be employed) potassium hydroxide is somewhat superior to the sodium compound. Much of the water may be first removed by shaking with a concentrated solution of the alkali hydroxide. They react with many organic compounds (e.g., acids, phenols, esters and amides) in the presence of water, and are also soluble in certain organic liquids so that their use as desiccants is very limited... 

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. 

Hydrolysis (or saponification) of n-butyl acetate. Boil 4-5 g. of n-butyl acetate (Section 111,95) with 50 ml. of 10 per cent, sodium hydroxide solution under reflux until the odour of the ester can no longer be detected (about 1 hour). Set the condenser for downward distiUation and coUect the first 10 ml. of distillate. Saturate it with potassium carbonate, aUow to stand for 5 minutes, and withdraw all the Uquid into a small pipette or dropper pipette. AUow the lower layer of carbonate solution to run slowly into a test-tube, and place the upper layer into a small test-tube or weighing bottle. Dry the alcohol with about one quarter of its buUr of anhydrous potassium carbonate. Remove the alcohol with a dropper pipette and divide it into two parts use one portion for the determination of the b.p. by the Siwoloboff method (Section 11,12) and convert the other portion into the 3 5-dinitrobenzoate (Section III, 27) and determine the m.p. 

Boil 2 g. of the ester with 30 ml. of 10 per cent, sodium or potassium hydroxide solution under reflux for at least 1 hour. If the alcohol formed is water (or alkali) soluble, the completion of the hydrolysis will be indicated by the disappearance of the ester layer. Distil ofiF the liquid through the same condenser and collect the first 3-5 ml. of distillate. If a distinct la3 er separates on standing (or upon saturation of half the distillate with potassium carbonate), remove this layer with a capillary dropper, dry it with a little anhydrous potassium carbonate or anhydrous calcium sulphate, and determine the b.p. by the SiwoloboflF method... 

Into a 2-litre, three-necked flask, fitted with a separatory funnel, a mechanical stirrer and a reflux condenser, place a hot solution of 200 g. of potassium hydroxide in 200 ml. of water. Stir the solution and add slowly 200 g. of ethyl n-butylmalonate (Section 111,154). A vigorous reaction occurs and the solution refluxes. When all the ester has been added, boil the solution gently for 2-3 hours, i.e., until hydrolysis is complete a test portion should dissolve completely in water. Dilute with 200 ml. of water and distil oflF 200 ml. of liquid in order to ensure the complete removal of the alcohol formed in the hydrolysis (1) it is best to connect the flask by means of a wide delivery tube to a condenser set for downward distillation (compare Fig. II, 41, 1 but with a mercury-sealed stirrer in the centre neck). Replace the separatory funnel and the reflux condenser. 

Benzoyl piperidine. In a 1-litre three-necked flask, equipped with a mechanical stirrer, separatory funnel and a thermometer, place 85 g. (99 ml.) of redistilled piperidine (b.p. 105-108°) and a solution of 53 g. of sodium hydroxide in 400 ml. of water. Stir the mixture and introduce during the course of 1 hour 140 g. (115-5 ml.) of redistilled benzoyl chloride maintain the temperature at 35-40°, Cool to room temperature and extract the benzoyl piperidine with ether. Wash the ethereal solution with a little water to remove any dissolved sodium hydroxide, and dry with anhydrous potassium carbonate. Remove the ether on a water bath and distil the residue under diminished pressure (Fig. II, 20, 1). Collect the benzoyl piperidine at 184—186°/15 mm. it is an almost colourless viscous liquid and crystallises on standing in colourless needles m.p. 46°. The yield is 170 g. 

Benzylatnine. Warm an alcoholic suspension of 118-5 g. of finely-powdered benzyl phthalimide with 25 g. of 100 per cent, hydrazine hydrate (CAUTION corrosive liquid) a white, gelatinous precipitate is produced rapidly. Decompose the latter (when its formation appears complete) by heating with excess of hydrochloric acid on a steam bath. Collect the phthalyl hydrazide which separates by suction filtration, and wash it with a little water. Concentrate the filtrate by distillation to remove alcohol, cool, filter from the small amount of precipitated phthalyl hydrazide, render alkaline with excess of sodium hydroxide solution, and extract the liberated benzylamine with ether. Dry the ethereal solution with potassium hydroxide pellets, remove the solvent (compare Fig. //, 13, 4) on a water bath and finally distil the residue. Collect the benzylamine at 185-187° the 3ueld is 50 g. 

Reduction of A-nitrosomethylaniline. Into a 1 litre round-bottomed flask, fitted with a reflux condenser, place 39 g. of A-nitroso-methylaniline and 75 g. of granulated tin. Add 150 ml. of concentrated hydrochloric acid in portions of 25 ml. (compare Section IV.34) do not add the second portion until the vigorous action produced by the previous portion has subsided, etc. Heat the reaction mixture on a water bath for 45 minutes, and allow to cool. Add cautiously a solution of 135 g. of sodium hydroxide in 175 ml. of water, and steam distil (see Fig. II, 40, 1) collect about 500 ml. of distillate. Saturate the solution with salt, separate the organic layer, extract the aqueous layer with 50 ml. of ether and combine the extract with the organic layer. Dry with anhydrous potassium carbonate, remove the ether on a water bath (compare Fig. II, 13, 4), and distil the residual liquid using an air bath (Fig. II, 5, 3). Collect the pure methylaniline at 193-194° as a colourless liquid. The yield is 23 g. 

Treat 1 g. (1 ml.) of the amine with 4 mols of 10 per cent, sodium or potassium hydroxide solution (say, 20 ml,), and add 1 -5 mols (or 3 g. if the molecular weight is unknown) of benzenesulphonyl or p-toluenesulphonyl chloride in small portions with constant shaking. To remove the excess of acid chloride, either shake vigorously or warm gently. Acidify with dilute hydrochloric acid and filter off the sulphonamide. Recrystallise it from alcohol or dilute alcohol. 

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