Filtration aspirator

In a 2-1. three-necked round-bottomed flask, fitted with an efficient sealed stirrer and a reflux condenser capped by a drying tube, are placed the dried anisyl chloride (Notes 2 and 3), 73.6 g. (1.5 moles) of finely powdered sodium cyanide, 10 g. of sodium iodide, and 500 ml. of dry acetone (Note 4). The heterogeneous reaction mixture is heated under reflux with -sngorous stirring for 16-20 hours, then cooled and filtered with suction. The solid on the filter is washed with 200 ml. of acetone and discarded (Note 5). The combined filtrates are distilled to remove the acetone. The residual oil is taken up in 300 ml. of benzene and washed with three 100-ml. portions of hot water. The benzene solution is dried over anhydrous sodium sulfate for about 15 minutes, and the solvent is removed by distillation at the reduced pressure of the water aspirator (Note 6). The residual -methoxyphenyl-acetonitrile is purified by distillation under reduced pressure through an 8-in. Vigreux column b.p. 94—97°/0.3 mm. 1.5285-1.5291. The yield is 109-119 g., or 74-81% based on anisyl alcohol (Notes 7 and 8). 

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 %). 

To a freshly prepared solution of 11.3 g. (0.10 mole) of hydrox-ylamine-O-sulfonic acid (Note 1) in 64 ml. of cold water there is added 24 ml. (24 g., 0.30 mole) of pyridine (Note 2). The mixture is heated at about 90° on a steam bath for 20 minutes. It is then cooled to room temperature with stirring, and 13.8 g. (0.10 mole) of potassium carbonate is added. The water and excess pyridine are removed from the mixture by heating it at 30-40° in a rotatory evaporator in conjunction with a water aspirator. The residue is treated with 120 ml. of ethanol, and the insoluble precipitate of potassium sulfate is removed by filtration. 

Pyridinecarboxaldehyde (nicotinaldehyde) was supplied by Aldrich-Europe, Beerse, Belgium. The checkers purified this reagent by fractional distillation, b.p. 95-97° (15 mm.). The submitters stress that 3-pyridinecarboxaldehyde should be completely free from contamination by the acid. They stirred 150 g. of the aldehyde with 100 g. of potassium carbonate and 300 ml. of ethanol for 12 hours, filtered the suspended solid, and fractionally distilled the filtrate through a 30-cm. Vigreux column using a water aspirator. However, the checkers found that the recovery of aldehyde from this procedure was very low, and recommend vacuum distillation instead. 3-Pyridinecarboxaldehyde is a powerful skin irritant and should be handled with protective gloves. 

In figure 7 a procedure was described for aspirating a sample from a capillary tube and simultaneously adding zinc sulfate and barium hydroxide solutions in order to produce a Somogyi filtrate. Aliquots of the supernatant are suitable for assay for glucose and urea by various procedures. The reason for this is the fact that zinc hydroxide precipitates uric acid, creatinine and other substances, such as low molecular polypeptides, along with the proteins, so that there results a solution which is clear with relatively few components. 

The solution is cooled to room temperature and is washed with a few milliliters of benzene into a single-necked flask. The solvent is removed with a rotary evaporator connected to a water aspirator vacuum gentle heat is supplied from a steam bath. The residue is cooled to room temperature before air is admitted. About 200 ml. of hexane is added and stirred with the residue to extract most of the carborane. The brownish tar which remains undissolved is allowed to settle and the solution is decanted. A second extraction of the tar with 40 ml. of hexane converts the residue to a solid which is removed by filtration. The solid is washed on the filter with an additional 40 ml. of hexane. The combined hexane extracts are filtered and then washed in a separatory funnel with four 100-ml. portions of a chilled aqueous 10% sodium hydroxide solution, followed by four 100-ml. portions of water. After the yellow hexane solution has been dried over anhydrous magnesium sulfate and filtered, the solvent is removed by use of a rotary evaporator connected to a water aspirator. The carborane is washed with a small amount of pentane into a 300-ml. single-necked flask which is attached to an alembic column as pictured in Fig. 13. 

The reaction flask is allowed to cool and the condenser, stirrer, and nitrogen inlet are removed. To the solution is added 100 ml. of absolute ethanol, and a brisk stream of carbon dioxide is passed through the solution to precipitate the excess potassium hydroxide as potassium carbonate. Sufficient carbon dioxide to precipitate the excess potassium hydroxide is conveniently obtained from about 150 g. of Dry Ice. The Dry Ice is powdered and placed in a stoppered 500-ml. filter flask with a line leading into the reaction solution. The insoluble potassium carbonate is filtered and washed with four 50-ml. portions of absolute ethanol. The combined filtrate and washings are evaporated to dryness on a rotary evaporator using a water aspirator vacuum and heat from a steam bath. This yields a solid or semisolid cake containing some residual potassium carbonate. 

Willis 93) extracted lead directly from 200 ml of urine with APDC into 1.5 ml of methyl-n-amyl ketone. He was able to determine as little as 0.02 ppm of lead. Kopito and Shwachman 141>, on the other hand, co-precipitate the lead from urine with bismuth nitrate by adding ammonia. The precipitated bismuth hydroxide is dissolved in acid and this solution is aspirated. Coprecipitation of the lead is not quantitative, and so standards should be prepared in the same manner. It should be possible to employ this procedure with protein free filtrates of blood without the necessity of close pH control. 

A. Oximinomalononitrile. Malononitrile (Note 1) (25 g., 0.38 mole) is dissolved in a mixture of 20 ml. of water and 100 ml. of acetic acid in a 1-1. round-bottomed flask equipped with a stirrer, a thermometer, and a powder funnel. The solution is cooled to —10° with a dry ice-acetone bath, and 50 g. (0.72 mole) of granulated sodium nitrite is added in approximately 2-g. portions over a 30-minute period while the temperature is maintained at 0° to —10°. After the addition is complete a wet ice bath is used to maintain the temperature below 5° while the mixture is stirred for 4 hours. Four hundred milliliters of tetrahydrofuran (Note 2) and 400 ml. of ether are added in separate portions, and the mixture is stored at —40° overnight. The mixture is filtered rapidly, and the solid is washed with a mixture of 200 ml. of tetrahydrofuran (Note 2) and 200 ml. of ether. The filtrate and washings are combined and concentrated by distillation to a volume of 250 ml. by the use of a water aspirator and a bath at 40° (Note 3). This solution of oximinomalononitrile is used directly in the next step. 

The flask is cooled in an ice bath, and the precipitate is filtered onto a large Buchner funnel and washed well with ether (Note 6). Ether is distilled from the yellow-brown filtrate at atmospheric pressure, and /-butyl alcohol is distilled under reduced pressure at 40°. Distillation of the residue through a 10-cm. Vigreux column at the water aspirator gives, after a small forerun (ca. 20 ml.), the product as a colorless liquid, b.p. 70-73° (10-12 mm.) yield 268 g. (81%) (Notes 7, 8, and 9). This becomes brown on standing. 

The Pd-C catalyst was then removed by filtration through Celite in a sintered glass funnel with the aid of a water aspirator. The filtration was completed by rinsing the packing with 95% ethanol (75 mL). Attention due to the pyrophoric properties of hydrogen-saturated palladium, it is important to keep the filter plug under a layer of ethanol. 

The aluminates were removed by filtration through a sintered glass funnel with the aid of the water aspirator. The filtration was completed by rinsing the packing with tetrahydrofuran (75 mL). 

Sometimes you ll need a vacuum for special work like vacuum distillation and vacuum filtration as with the Buchner funnel. An inexpensive source of vacuum is the water aspirator (Fig. 47). 

Every year I run a chem lab and when someone is doing a vacuum filtration, suddenly I ll hear a scream and a moan of anguish, as water backs up into someone s filtration system. Usually there s not much damage, since the filtrate in the suction flask is generally thrown out. For vacuum distillations, however, this suck-back is disaster. It happens whenever there s a pressure drop on the water line big enough to cause the flow to decrease so that there is a greater vacuum in the system than in the aspirator. Water, being water, flows into the system. Disaster. 

The precipitate of triphenylphosphine oxide is filtered and washed with 50 ml. of pentane. The solvent is removed from the combined filtrate at the rotary evaporator under water aspirator pressure at room temperature. Distillation of the residue through a 2-cm. Vigreux column attached to a short-path distillation apparatus (Note 4) provides 13.0-14.0 g. (75-81%) of geranyl chloride, b.p. 47-49° (0.4 mm.), w2Sd = 1.4794 (Note 5). 

Aspirator filtration through a pad of Celite was beneficial to prevent small particulate matter from clogging the fritted funnel. However, it was necessary to break up the pad of Celite to allow for effective filtration. 

---