Vacuum pumps aspirator

Lift out DNA on glass pipet and transfer to smaller Duran. Wash 3 times with ethanol at room temperature by vigorous shaking and water vacuum pump aspiration of the ethanol. Make sure DNA spreads out in ethanol to ensure complete penetration of ethanol. 

A well-defined volume of the gaseous sample is directed towards the flow manifold, where it interacts with a liquid medium, and the chem-iluminometric determination of nitrous acid in an indoor environment [18] is a good example. A calibrated vacuum pump aspirated the volume of air through a diffusion scrubber and the membrane-separated analyte was collected into a buffered stream that directed it towards an 8-port injection valve after passing a de-bubbler, the analyte zone was directed towards the detector. With this approach, a 120 pp tv detection limit was attained. The characteristics, potential and limitations of analytical procedures involving diffusion scrubbers and other devices for gas sampling aimed at in-line flow-based determinations have been discussed elsewhere [19]. 

Vacuum Sources. A vacuum is used to draw the sample through the collection device. Motor- or hand-driven vacuum pumps, aspirators, and automobile vacuums are commonly used. When vacuum devices are being used to draw samples through a filter, in which pressure loss may build up during sampling (e.g., as the filter becomes partially clogged), it is recommended that some constant-flow device be attached. 

The fluid dehvery in an air-spray system can be pressure or suction fed. In a pressure-fed system, the fluid is brought to the atomizer under positive pressure generated with an external pump, a gas pressure over the coating material in a tank, or an elevation head. In a suction system, the annular flow of air around the fluid tip generates sufficient vacuum to aspirate the coating material from a container through a fluid tube and into the air stream. In this case, the paint supply is normally located in a small cup attached to the spray device to keep the elevation differential and frictional pressure drop in the fluid-supply tube small. 

Pump manufacturers express vacuum in aspirated feet of water in a ver r -i (0 psia = -33.9 feet of water). The pharmaceutical and chemical indue r Pascals (100,000 Pascals = atmospheric pressure) and the term TO C. conglomeration of values and conversion n, causes confusion. In ( ... 

A solution of 30 g (0.1 mole) of 17j5-hydroxy-5a-androstan-3-one (androstano-lone), 20 ml of pyrrolidine and 200 ml of benzene is heated at reflux temperature for 2.5 hr under a Bidwell-Sterling water trap. The benzene solution is evaporated to dryness in a rotating evaporator connected to a water aspirator. The white cake which remains is broken up and dried further by immersing the flask in a water bath at 60-75° and evacuating the flask with a mechanical vacuum pump. After 0.5 hr the solid cake is broken up again and dried for another 0.5 hr at 60-75°. The enamine (9) obtained should smell only faintly of pyrrolidine. 

Beakers 10 to 1000-ml. volumetric flasks 1-ml. volumetric pipet, serological pipet steam bath vacuum desiccator vacuum pump and water aspirator are also required. 

Considerable dissolved hydrogen chloride is liberated at this point and passes into the water aspirator. A mechanical vacuum pump should not be used at this stage because it would be damaged by corrosion. 

B. Pyridine-N-oxide. The acetic acid solution is evaporated on the steam bath under the pressure of a water aspirator, and the residue (180-190 g.) is distilled at a pressure of 1 mm. or less in an apparatus suitable for collecting a solid distillate (Note 5). The vacuum pump must be protected with a Dry Ice trap capable of holding about 60 ml. of acetic acid, which distils as the pyridine-N-oxide acetate dissociates at low pressure. Heat is provided by an oil bath, the temperature of which is not allowed to rise above 130° (Note 6). The product is collected at 100-105°/1 mm. (95-98°/0.5 mm.). The yield is 103-110 g. (78-83%) of colorless solid, m.p. 65-66° (sealed capillary). The base is deliquescent and must be stoppered immediately. 

A 1-1., three-necked, round-bottomed flask equipped with a Trubore stirrer, a pressure-equalizing dropping funnel, and a reflux condenser with a drying tube is charged with 350 ml. of acetonitrile (Note 1) and 106.4 g. (0.41 mole) of triphenylphos-phine (Note 2). The flask is cooled in an ice-water bath (Note 3), and 64 g. (0.40 mole) of bromine is added dropwise over a period of ca. 15-20 minutes (Notes 4 and 5). The ice-water bath is removed, and a solution of 54 g. (0.40 mole) of cinnamyl alcohol in 50 mi. of acetonitrile is added in portions over a period of 5-10 minutes with continued stirring (Note 6). The solvent is removed by distillation with the use of a water aspirator (30-40 mm.) and an oil bath until the bath temperature reaches 120°. The water aspirator is replaced by a vacuum pump and the water-cooled condenser with an air condenser, and the distillation is continued with rapid stirring (Notes 7, 8, and 9). Most of the product (Note 10) distills at 91-98° (2-4 mm.), and about 59 g. of product crystallizes in the receiving flask (63-75% yield) (Note 11). 

The vacuum adapter is connected to a vacuum source, either a vacuum pump or a water aspirator. Real live vacuum pumps are expensive and rare and not usually found in the undergraduate organic laboratory. If you can get to use one, that s excellent. See your instructor for the details. The water aspirator is used lots, so read up on it. 

After this period, the dropping funnel and the vacuum takeoff are replaced by the short-path distillation assembly shown in Figure 2. The system is protected by a Drierite tube and the benzene is distilled under reduced pressure (water aspirator). After the benzene is removed, the benzene-containing receiver is replaced with a clean, dry flask, and the system is connected to an eflScient vacuum pump. The pressure in the system is reduced to 0.02 mm., and the flask is immersed deeply in an oil bath (Figure 2) heated to about 200°. After about 1 ml. of fluid forerun is collected, the diethylaluminum cyanide distils at 162° (0.02 mm.) (Note 7) and is collected in a tared 200-ml. receiver by heating the side arm and the adaptor with a stream of hot air or an infrared lamp (Note 8). After all the distillate is collected in the receiver (Note 9), dry nitrogen is admitted to the evacuated apparatus and the receiver is stoppered and weighed. Diethylaluminum cyanide is obtained usually as a pale yellow syrup (Note 10) in 60-80% yield (26.7-35.6 g.) (Note 11). 

To a stirred solution (0 °C) of 10 mmol of (- )-(S)-a-(methoxymethyI)benzenccthanamine dissolved in 30 mL of benzene (previously washed with concentrated sulfuric acid and distilled) are added 10 mmol of the pure aldehyde. An immediate cloudiness usually results on addition of the aldehyde. The mixture is allowed to warm to r.t. and 15 g of anhyd Na2S04 are added. After stirring the mixture an additional 30-40 min, it is filtered and the Na2S04 washed thoroughly with dry diethyl ether. The solvent is removed by evaporation, first with aspirator pressure and then with the vacuum pump (0.5 Torr) to generally furnish 9.5-10 mmol of the aldimine as a colorless oil. The aldimines are dissolved in THF (0.4 M) and stored at — 20 to — 30 °C. Attempts to store the aldimines as neat liquids results in deterioration. As solutions, the aldimines can be conveniently transferred via syringe to reaction vessels. 

Rotary evaporator with vacuum pump or water aspirator, 40°C... 

Rotary evaporator with water aspirator or vacuum pump, 40°C water bath... 

Place the filtered proanthocyanidin extract into an appropriately sized round-bottom flask and remove acetone on a rotary evaporator equipped with a water aspirator or vacuum pump, at 40°C. 

Better yields are obtained at low pressures (preferably below 5 mm.) because of more efficient sublimation of coumalic acid. The submitters report that a water aspirator could be used with crude (unrecrystallized) coumalic acid to avoid damage to the vacuum pump by untrapped corrosive vapors, and that yields of a-pyrone averaged 45% in this modification. The checkers used a mechanical pump with an efficient sodium hydroxide trap in all runs. 

The apparatus routinely used in this laboratory for the manual synthesis of peptides consists of a flask attached to a glass manifold that can support up to four sintered funnels, thereby permitting the simultaneous synthesis of up to four peptides. The side arm of the flask is attached to a vacuum pump to allow for solvents to be aspirated from each funnel. The manifold also contains valves... 

Remove DMF from the swollen resin in the glass sinter filter funnel by aspiration using the vacuum pump and add the activated amino acid solution. Stir with a spatula and incubate at room temperature for 30-45 min, stirring occasionally. 

The goal of vacuum filtration is usually to remove liquids from a solid to obtain a solid that is dry. An aspirator or a vacuum pump is used to provide suction though a rubber tube to a filter trap. The trap is attached to a filter flask (show to the right) by a second rubber tube. The filter flask is an Erlenmeyer flask with a thick wall and a hose barb for the vacuum tube. Filter flasks are used to filter material using a Buchner funnel (shown to the right) or a smaller Hirsch funnel. These porcelain or plastic funnels hold a circular piece of filter paper. A single-hole rubber stopper supports the funnel in the flask while maintaining suction. 

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