Recrystallization filter flask

At the completion of the reaction acidify the solution with 20.0 mL of 10% hydrochloric acid (check with litmus paper) and then reduce the volume to one-half by removing the ethanol either by distillation or evaporation on a rotary evaporator. Cool the solution in an ice bath until no more product crystallizes, then collect it by vacuum filtration on the Buchner funnel. Empty the filter flask and then wash unreacted n-butyldiethyl malonate (detected by its odor) from the crystals with ligroin, press it dry, and then recrystallize the product from boiling water... 

To 100 mL of crude, vacuum-distilled H(tod) in a 1-L filter flask containing a magnetic stirring bar is added 100 mL of methanol. To a separate beaker containing 200 mL of distilled water is added 40 g of copper(II) acetate hydrate. This solution is stirred and heated to just below the boiling point, and, while hot, is filtered directly into the stirred methanolic H(tod) solution. The resulting mixture is allowed to stand for four hours, after which the solid that forms is collected by suction filtration and washed with cold (4°) methanol (two x 10 mL). Recrystallization from hexane gives a purple powder. Anal. Calcd. for Cu(C H,A)2 Cu, 14.77 C, 61.44 H, 8.91. Found Cu, 14.47 C, 61.48 H, 8.89. 

Transfer the filter cake to an Erlenmeyer flask and recrystallize the crude product from 95% ethanol. Allow the residual solution to cool slowly to room temperature then cool it to 0 °C in an ice-water bath. Isolate the crystalline product by vacuum filtration. Wash the product with a little ice-cold95% ethanol, allowing the washes to drain into the filter flask with the mother liquors. Transfer the product to a watchglass or a piece of filter paper for air-drying. 

Use of the Hirsch Funnel. The standard filtration system for collecting products purified by recrystallization in the microscale laboratory is vacuum (suction) ffltration with an 11-mm Hirsch funnel. Many reaction products that do not require recrystallization can also be collected directly by vacuum filtration. The Hirsch funnel (Fig.5.23a) is composed of a ceramic cone with a circular flat bed perforated with small holes. The diameter of the bed is covered by a flat piece of filter paper of the same diameter. The funnel is sealed into a filter flask with a Neoprene adapter (Fig. 5.23b). Plastic and glass varieties of this funnel that have a polyethylene or glass frit are now available. It is stfll advisable to use the filter paper disk with these funnels to prevent the frit from clogging or becoming discolored. Regardless of the type of fflter used, always wet the filter paper disk with the solvent being used in the crystallization and then apply the vacuum. This ensures that the filter paper disk is firmly seated on the bed of the filter. 

The indicator was prepared by the method of Oiehl and Einhorn. A solution of 5 g of sodium hydroxide in 50 mL of water and 40 ml of ethanol is prepared in a 250-mL Erlenmeyer flask. To this is added a solution of 1.64 ml (0.025 mol, 1.45 g) of acetone in 6.3 mL (0.050 mol, 5.6 g) of freshly distilled cinnamaldehyde (Note 1). This mixture is stirred thoroughly at room temperature for 30 min. The resulting voluminous yellow precipitate is filtered with suction, washed with 100 mL of water, and dried, affording 6.5 g of l,9-diphenylnona-l,3,6,8-tetraen-5-one. Recrystallization from 200 mL of hot 9511 ethanol gives 3.5 g of yellow crystals, mp 142-143 C (lit mp 142°C). This indicator is also available from Aldrich Chemical Co. 

In a 3-I. round-bottomed flask are placed 500 cc. (400 g., 8.7 moles) of absolute alcohol which has been saturated in the cold with hydrochloric acid gas (Note i), 870 cc. (6S0 g., 20 moles) of 96 per cent alcohol (Note 2) and 70 g. (1.03 moles) of methyleneaminoacetonitrile (Note 3). This mixture is refluxed on a steam bath for three hours (Note 4). During the refluxing, ammonium chloride separates. After the reaction is complete, the hot alcohol solution is filtered with suction and the filtrate cooled, thus allowing the glycine ester hydrochloride to separate out in fine white needles. The product is filtered with suction, sucked as dry as possible on the filter, and then allowed to dry in the air. The yield is about no g. The alcohol from the filtrate is distilled (Note 5) until about one-third of its volume is left and again cooled and a second crop of crystals is obtained. The total yield of product, m.p. 142-143, varies from 125 to 129 g. (89-91 per cent of the theoretical amount). If a very pure product is desired, it may be recrystallized from absolute alcohol. 

B. Diethyl aminomalonate hydrochloride. The crude diethyl aminomalonate is diluted with 80 ml. of dry ether and filtered to remove a small amount of white solid. The filtrate is collected in a 250-ml. Erlenmeyer flask and cooled in an ice bath. Dry hydrogen chloride is passed just over the solution while it is being stirred mechanically (Note 6). The fine white crystals which precipitate are collected by suction filtration and washed three times with a total of 60 ml. of dry ether (Note 7). The filtrate and washings are treated again with hydrogen chloride, and a second crop of diethyl aminomalonate hydrochloride is collected and washed as before. This process is repeated until no further precipitation results from passing hydrogen chloride into the solution. A total of 16.5-17.4 g. (78-82% yield based on diethyl malonate) of diethyl aminomalonate hydrochloride, m.p. 162-163°, is obtained. Recrystallization from alcohol-ether affords a purer product, 164-165°. 

Hydroxyandrosta-4,6-dien-3-one. A suspension of 42 g of crude androsta-4,6-diene-3j ,17j -diol in 2000 ml of chloroform is treated with 250 g of activated, manganese dioxide. The mixture is then shaken vigorously for 15 min in a stoppered flask. The mixture is filtered and the manganese dioxide washed well with chloroform in order to elute material which initially remains adsorbed on the solid phase. The filtrate is concentrated to a pale yellow, crystalline residue. Recrystallization from acetonitrile gives 38 g (90%) of 17/ -hydroxyandrosta-4,6-dien-3-one as plates mp 211-214°. 

The dry tosylhydrazone (20 g, 45.5 mmol) is dissolved in 750 ml of 1,2-dimethoxyethane (freshly distilled from lithium aluminum hydride) in a flame-dried 1 liter round bottom flask fitted with a 240 ml addition funnel, a drierite tube and a magnetic stirrer. A 2.05 M ether solution of methyllithium (130 ml, Alfa Inorganics, Inc.—Caution to avoid the mineral oil impurity the methyllithium solution is decanted from a cold solution which contains a precipitate) is placed in the dropping funnel and added over a 60 min period. The temperature of the reaction mixture increases to ca. 35° during the addition however, no cooling precautions are required. The highly colored reaction mixture is stirred for 7 hr and then poured into 1.5 liters of ice water. The flocculent precipitate is digested for 12 hr at room temperature to speed the filtration. After filtration the filter cake is washed with 500 ml water and dried under vacuum at 50° for several hr. The androsta-5,16-dien-3l5-ol is obtained in ca. 70% yield after recrystallization from methanol mp 138-139°. 

A mixture of the epoxide ca. 5 mmol), sodium azide (6 g, activated by the method of Smith) and 0.25 ml of concentrated sulfuric acid in 70 ml of dimethyl sulfoxide is heated in a flask fitted with a reflux condenser and a drierite tube on a steam bath for 30-40 hr. (Caution carry out reaction in a hood.) The dark reaction mixture is poured into 500 ml of ice water and the product may be filtered, if solid, and washed well with water or extracted with ether and washed with sodium bicarbonate and the water. The crude azido alcohols are usually recrystallized from methanol. 

In a 500 mL Erlenmeyer flask, 1,4-cyclohexanedione (1.12 g) and anhydrous sodium acetate (22 g) were dissolved in glacial acetic acid (60 mL), and the mixture was heated to 115 °C. Benzyl 2,3-dioxobutanoate-2-phenylhydrazone (5.92 g) was mixed with 20 g of zinc dust, and was added slowly to the stirred mixture keeping the temperature between 120-130 °C. Once the addition was complete, the solution was stirred at 100 °C for 30 min. The solution was cooled to 80 °C and poured into 700 mL of ice water with stirring. The residual zinc was washed several times with hot acetic acid and combined with the ice water. The precipitate was filtered and recrystallized from ethanol to give 34... 

The mixture is decanted into an Erlenmeyer flask, the residual green salts are washed with two 15-ml portions of acetone, and the washings are added to the main acetone solution. Cautiously, sodium bicarbonate (approx. 13 g) is added to the solution with swirling until the pH of the reaction mixture is neutral. The suspension is filtered, and the residue is washed with 10-15 ml of acetone. The filtrate is transferred to a round-bottom flask and concentrated on a rotary evaporator under an aspirator while the flask temperature is maintained at about 50°. The flask is cooled and the residue transferred to a separatory funnel, (If solidification occurs, the residue may be dissolved in ether to effect the transfer.) To the funnel is added 100 ml of saturated sodium chloride solution, and the mixture is extracted with two 50-ml portions of ether. The ether extracts are combined, washed with several 5-ml portions of water, dried over anhydrous magnesium sulfate, and filtered into a round-bottom flask. The ether may be distilled away at atmospheric pressure (steam bath) or evaporated on a rotary evaporator. On cooling, the residue should crystallize. If it does not, it may be treated with 5 ml of 30-60° petroleum ether, and crystallization may be induced by cooling and scratching. The crystalline product is collected by filtration and recrystallized from aqueous methanol. 4-r-Butylcyclohexanone has mp 48-49° (yield 60-90 %). 

A three-necked round-bottom flask is fitted with a dropping funnel, a thermometer, and a magnetic stirrer and is heated in a water bath to 30°. Tetralin (1.32 g, 0.01 mole) and 50 ml of 3.5 Anitric acid solution are placed in the flask and brought to temperature. Ceric ammonium nitrate (21.9 g, 0.04 mole) is dissolved in 100 ml of 3.5 N nitric acid, and the solution is added dropwise to the reaction mixture at a rate such that the temperature does not rise and only a pale yellow color is evident in the reaction mixture. At the completion of the reaction (1 to 2 hours), the mixture should be colorless. The solution is cooled to room temperature, diluted with an equal volume of water, and extracted twice with ether. The ether solution is dried with anhydrous sodium sulfate, filtered, and the ether is evaporated. The residue may be distilled to yield a-tetralone (bp 113-11676 mm or 170749 mm) or may be converted directly to the oxime, which is recrystallized from methanol, mp 88-89°. 

In a 100-ml flask is placed a mixture of 19.5 g (0.18 mole) of freshly sublimed, pulverized selenium dioxide, 15 g (0.10 mole) of df/-camphor and 15 ml of acetic anhydride. The flask is fitted with a magnetic stirrer and a condenser, and the mixture is heated to 135° on an oil bath with stirring for 16 hours. After cooling, the mixture is diluted with ether to precipitate selenium, which is then filtered off, and the volatile materials are removed under reduced pressure. The residue is dissolved in ether (200 ml), washed four times with 50-ml portions of water and then washed several times with saturated sodium bicarbonate solution (until the washes are basic). The ether solution is finally washed several times with water, then dried, and the ether is evaporated. The residue may be purified by sublimation at reduced pressure or recrystallized from aqueous ethanol (with clarification by Norit, if necessary). The product is yellow, mp 197-199°. 

To a solution of 1.0 g (0.003 mole) of iridium tetrachloride in 0.5 ml of concentrated hydrochloric acid is added 15 ml of trimethylphosphite. This solution is added to a solution of 7.7 g (0.05 mole) of 4-/-butylcyclohexanone in 160 ml of isopropanol in a 500-ml flask equipped with a reflux condenser. The solution is refluxed for 48 hours, then cooled, and the isopropanol is removed on a rotary evaporator. The residue is diluted with 65 ml of water and extracted four times with 40-ml portions of ether. The extracts are dried with anhydrous magnesium sulfate, filtered, and the ether is removed on the rotary evaporator. The white solid residue is recrystallized from 60 % aqueous ethanol affording cis alcohol of greater than 99% purity, mp 82-83.5°. 

A 500-ml rcund-bottom flask is equipped with a reflux condenser, a gas inlet tube, and a gas outlet leading to a bubbler. The flask is charged with a solution of rhodium (III) chloride trihydrate (2 g) in 70 ml of 95 % ethanol. A solution of triphenylphosphine (12 g, freshly recrystallized from ethanol to remove the oxide) in 350 ml of hot ethanol is added to the flask, and the system is flushed with nitrogen. The mixture is refluxed for 2 hours, following which the hot solution is filtered by suction to obtain the product. The crystalline residue is washed with several small portions of anhydrous ether (50 ml total) affording the deep red crystalline product in about 85% yield. 

A mixture of 100 g (0.6 mole) of 1-morpholino-l-cyclohexene, 28.8 g (0,4 mole) of /3-propiolactone, and 100 ml of chlorobenzene is placed in a 500-ml round-bottom flask fitted with a condenser (drying tube). The mixture is refluxed for 4 hours. The solvent and excess enamine are removed by distillation at aspirator pressure. (The residue may be distilled to afford the pure morpholide, bp 187-18871 rnm, 1.5090.) Basic hydrolysis may be carried out on the undistilled morpholide. To the crude amide is added 400 ml of 10% sodium hydroxide solution. The mixture is cautiously brought to reflux, and refluxing is continued for 2 hours. The cooled reaction mixture is made acidic (pH 4) and is extracted three times with ether. The combined ether extracts are washed twice with 5 % hydrochloric acid solution and twice with water. The ethereal solution is dried (sodium sulfate), then filtered, and the solvent is removed (rotary evaporator). The residue may be recrystallized from petroleum ether-benzene, mp 64°. 

Introduce 33.6 g (0.2 mol) of 1,3 -trimethoxybenzene and 100 ml of chlorobenzene Into a 500 ml three-neck flask with stirrer, hydrochloric acid bubbler and condenser. Stir to dissolve and edd 27.7 g of 4-pyrro idinobutyronitrile (from 4hydrochloric acid gas in for 4 hours. Cool to about 5°C and add 200 cm3 of water, g ir. Decanttheaqueouslayer,wash again with 150cm3 of water. Combine the aqueous layers, drive off the traces of chlorobenzene by distilling 150 cm3 Qf water, and heat under reflux for one hour. Cool and render alkaline by means of 60 ml of sodium hydroxide solution of 36° Baume. Extract twice with 100 ml of ether. Wash the ether with 100 ml of water. Dry the ether over sodium sulfate and slowly run in 50 ml of 5N hydrogen chloride solution in ether, at the boil. Cool in ice. Filter, wash with ether and dry in a vacuum oven. 33.6 g of crude product are obtained. Recrystallize from 200 ml of isopropanol in the presence of 3 SA carbon black. Filter. Wash and dry in a vacuum oven. 

The flask of a Parr hydrogenation apparatus was charged with 10,5 g of 3,3-diphenylpropyl-amine, 7.7 g of cyclohexylacetone, 50 ml methanol and 150 mg of platinum dioxide. Hydrogen at a pressure of 3 atmospheres was introduced and the mixture stirred. Upon absorption of the theoretical amount of hydrogen, stirring is discontinued, the catalyst is filtered off and the solution is evaporated to dryness. The residue is taken up with ether and the hydrochloride is precipitated with HCI in alcoholic solution. The product, as collected on a filter and washed with ether, is recrystallized from isopropanol. Yield 17 g (92.5% of theory). 

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