Pumps water

The high-pressure water supply service is employed for the operation of the ordinary filter pump, which finds so many applications in the laboratory. A typical all metal filter pump is illustrated in Fig. 11, 21, 1. It is an advantage to have a non-return valve fitted in the side arm to prevent sucking back if the water is turned off or if the water pressure is suddenly reduced. Theoretically, an efficient filter pump should reduce the pressure in a system to a value equal to the vapour pressure of the water at the temperature of the water of the supply mains. In practice this pressure is rarely attained (it is usually 4 10 mm. higher) because of the leakage of air into the apparatus and the higher temperature of the laboratory. The vapour pressures of water at 5°, 10°, 15°, 20° and 25° are respectively 6-5, 9-2,12-8, 17 5 and 23 8 mm. respectively. It is evident that the vacuum obtained with a water pump will vary considerably with the temperature of the water and therefore with the season of the year in any case a really good vacuum cannot be produced by a filter pump. 

---

The P-scan System 4 can be configured in many ways, dependent on the application. Figure 1 shows a basic system configuration. The P-scan processor (PSP-4) controls the scanner and the water pump. Scarmer operation on site is performed from the remote control unit, as an alternative to the control from the computer. The PSP-4 also includes the ultrasonic system. 

This type of filtration is almost invariably performed with the aid of a Buchner flask and funnel, by means of which a rapid and almost complete separation can be obtained. The Buchner flask A (Fig. 4) consists of a simple thick-walled conical flask with a short side-arm for connection to a water-pump. Into the neck of the flask is fitted the Buchner funnel B which consists usually of a cylindrical porcelain funnel, the bed of which is pierced by a... 

The latter is connected above to a water-condenser and below to a flask which contains a liquid of appropriate boiling-point. The inner tube is connected to a water-pump. A more satisfactory pistol (Fig. 48(B)) consists of a wide glass tube A closed at each end by ground-glass caps. 

Add 15 g, of chloroacetic acid to 300 ml. of aqueous ammonia solution d, o-88o) contained in a 750 ml. conical flask. (The manipulation of the concentrated ammonia should preferably be carried out in a fume-cupboard, and great care taken to avoid ammonia fumes.) Cork the flask loosely and set aside overnight at room temperature. Now concentrate the solution to about 30 ml. by distillation under reduced pressure. For this purpose, place the solution in a suitable distilling-flask with some fragments of unglazed porcelain, fit a capillary tube to the neck of the flask, and connect the flask through a water-condenser and receiver to a water-pump then heat the flask carefully on a water-bath. Make the concentrated solution up to 40 ml. by the addition of water, filter, and then add 250 ml. of methanol. Cool the solution in ice-water, stir well, and set aside for ca. I hour, when the precipitation of the glycine will be complete. 

Place 80 g, of hydroxylamine sulphate (or 68-5 g. of the hydrochloride), 25 g. of hydrated sodium acetate, and 100 ml. of water in a 500 ml. flask fitted with a stirrer and a reflux water-condenser, and heat the stirred solution to 55-60°. Run in 35 g (42 nil,) of -hexyl methyl ketone, and continue the heating and vigorous stirring for ij hours. (The mixture can conveniently be set aside overnight after this stage.) Extract the oily oxime from the cold mixture twice with ether. Wash the united ethereal extract once with a small quantity of water, and dry it with sodium sulphate. Then distil off the ether from the filtered extract, preferably using a distillation flask of type shown in Fig. 41 (p. 65) and of ca, 50 ml, capacity, the extract being run in as fast as the ether distils, and then fractionally distil the oxime at water-pump pressure. Collect the liquid ketoxime, b.p. 110-111713 mm. Yield, 30-32 g. 

Chill the concentrated solution of the amine hydrochloride in ice-water, and then cautiously with stirring add an excess of 20% aqueous sodium hydroxide solution to liberate the amine. Pour the mixture into a separating-funnel, and rinse out the flask or basin with ether into the funnel. Extract the mixture twice with ether (2 X25 ml.). Dry the united ether extracts over flake or powdered sodium hydroxide, preferably overnight. Distil the dry filtered extract from an apparatus similar to that used for the oxime when the ether has been removed, distil the amine slowly under water-pump pressure, using a capillary tube having a soda-lime guard - tube to ensure that only dry air free from carbon dioxide passes through the liquid. Collect the amine, b.p. 59-61°/12 mm. at atmospheric pressure it has b.p. 163-164°. Yield, 18 g. 

For this preparation, the cinnamaldehyde must first be purified by careful redistillation at the water-pump, and a fraction of steady b.p. (e.g., i26°/i5 mm.) collected. 

Assemble in a fume-cupboard the apparatus shown in Fig. 67(A). Place 15 g. of 3,5-dinitrobenzoic acid and 17 g. of phosphorus pentachloride in the flask C, and heat the mixture in an oil-bath for hours. Then reverse the condenser as shown in Fig. 67(B), but replace the calcium chloride tube by a tube leading to a water-pump, the neck of the reaction-flask C being closed with a rubber stopper. Now distil off the phosphorus oxychloride under reduced pressure by heating the flask C in an oil-bath initially at 25-30, increasing this temperature ultimately to 110°. Then cool the flask, when the crude 3,5-dinitro-benzoyl chloride will solidify to a brown crystalline mass. Yield, 16 g., i.e,y almost theoretical. Recrystallise from caibon tetrachloride. The chloride is obtained as colourless crystals, m.p. 66-68°, Yield, 13 g Further recrystallisation of small quantities can be performed using petrol (b.p. 40-60°). The chloride is stable almost indefinitely if kept in a calcium chloride desiccator. 

Fig. 41(A) and (b), p. 65) into which the ethereal extract is allowed to run from a dropping-funnel at approximately the rate at which the solvent is distilling. When the ether has been removed, fit a capillary tube and thermometer, and continue the distillation at water-pump pressure. The diethyl ester of collidine-3,5-dicarboxylic acid (II) distils as a pale golden oil, b.p. i76 178°/i4 mm. Yield, 5 g. from 6 g. of the ester (I). 

The pure quinaldine can now be isolated by either of the following methods, (a) Transfer the acetylated mixture to a Claisen flask (preferably having a short fractionating column below the side-arm) and distil the mixture slowly at water-pump pressure by heating the flask in an oil or silicone bath. The first fraction, of b.p. ca. 50715 mm., contains acetic acid and... 

Assemble an apparatus similar to that used in the prenous experiment, i.e., a 500 ml. conical flask fitted at the neck with a freshly-charged calcium chloride tube, a dropping-funnel, and in addition an outlet-tube joined to the water-pump so that dry air can be drawn through the calcium chloride tube and thence through the conical flask. The purpose of the air-stream is to remove as much as possible of the excess of hydrogen chloride. 

Meanwhile set up the ether distillation apparatus as used in the preparation of triethyl phosphite (p. 308). Distil off the ether and then fractionally distil the residue at water-pump pressure. The di-isopropyl hydrogen phosphite distils at 79Vi4 mm. other b.ps. are 8o°/i5 mm., 82-5°/i7 mm. Yield, 25 g., 89%. 

Now fit the weighed funnel G again to the filter-flask, and attach the Pregl filter-tube K as shown (Fig. 21). Apply 2i gentle suction from the water-pump, and dip the open limb of the tube K just below the surface of the liquid in the Carius tube. Draw off the supernatant liquid a little at a time until rather less than 1 ml. remains. Now gently shake the mixture in the Carius tube, and try to adjust the suction so... 

The pressure is reduced by means of a high capacity water pump, preferably constructed of metal the lowest pressure that can be attained is that of the vapour pressure of water at the particular temperature (for a detailed discussion, see Section 11,21). In winter when the temperature of the water may be 6-8° the vapour pressure of water is 7-8 mm., but in summer when the temperature of the water may reach 22°, the corresponding vapour pressure is 20 mm. Thus the vacuum ... 

In order to carry out a distillation, the apparatus is completely assembled, the water pump turned on to its maximum capacity, and the screw clip on the capillary tube in the Claisen flask adjusted so that a gentle stream of air bubbles through the liquid (see Section 11,19 for details of the preparation of the capillary tube). The barometric pressure is read, and if the resulting vacuum deter mined from the reading on the mano meter is satisfactory (as estimated from the temperature of the tap water), the flask may be heated in an air (Fig. II,... 

A mechanical device embodying a bellows-sealed needle valve with a lever reduction movement for fine control is shown in Fig. II, 23, 5. The needle is of stainless steel. This fine control valve assembly is useful for pressures ranging from 20 to 100 mm. of mercury when used in conjunction with a good water pump. 

Drawing a stream of air over the surface by inserting a tube, connected to a water pump, above the mixture. 

For alcohols of b.p. below 150°, mix 0- 5 g. of 3-nitrophthalic anhydride (Section VII,19) and 0-5 ml. (0-4 g.) of the dry alcohol in a test-tube fitted with a short condenser, and heat under reflux for 10 minutes after the mixture liquefies. For alcohols boiling above 150°, use the same quantities of reactants, add 5 ml. of dry toluene, heat under reflux until all the anhydride has dissolved and then for 20 minutes more remove the toluene under reduced pressure (suction with water pump). The reaction product usually solidifies upon cooling, particularly upon rubbing with a glass rod and standing. If it does not crystallise, extract it with dilute sodium bicarbonate solution, wash the extract with ether, and acidify. Recrystallise from hot water, or from 30 to 40 per cent, ethanol or from toluene. It may be noted that the m.p. of 3-nitrophthalic acid is 218°. 

Mix 50 ml. of formalin, containing about 37 per cent, of formaldehyde, with 40 ml. of concentrated ammonia solution (sp. gr. 0- 88) in a 200 ml. round-bottomed flask. Insert a two-holed cork or rubber stopper carrying a capillary tube drawn out at the lower end (as for vacuum distillation) and reaching almost to the bottom of the flask, and also a short outlet tube connected through a filter flask to a water pump. Evaporate the contents of the flask as far as possible on a water bath under reduced pressure. Add a further 40 ml. of concentrated ammonia solution and repeat the evaporation. Attach a reflux condenser to the flask, add sufficient absolute ethyl alcohol (about 100 ml.) in small portions to dissolve most of the residue, heat under reflux for a few minutes and filter the hot alcoholic extract, preferably through a hot water fuimel (all flames in the vicinity must be extinguished). When cold, filter the hexamine, wash it with a little absolute alcohol, and dry in the air. The yield is 10 g. Treat the filtrate with an equal volume of dry ether and cool in ice. A fiulher 2 g. of hexamine is obtained. 

For water insoluble aldehydes or ketones, the following alternative procedure may be used. Reflux a mixture of 0-6 g. of the aldehyde or ketone, 0 5 g. of hydroxylamine hydrochloride, 5 ml. of ethanol and 0 5 ml. of pyridine on a water bath for 15-60 minutes. Remove the alcohol either by distillation (water bath) or by evaporation of the hot solution in a stream of air (water pump). Add 5 ml. of water to the cooled residue, cool in an ice bath and stir until the oxime crystallises Filter off the solid, wash it with a little water and dry. Recrystallise from alcohol (95 per cent, or more dilute), benzene, or benzene - light petroleum (b.p. 60-80°). 

Furfuryl acetate. Reflux a mixture of 39 2 g. (34-8 ml.) of redistilled furfuryl alcohol, 48 g. of glacial acetic acid, 150 ml. of benzene and 20 g. of Zeo-Karb 225/H in a 500 ml. bolt-head flask, using the apparatus described under iaoPropyl Lactate. After 3 hours, when the rate of collection of water in the water separator is extremely slow, allow to cool, separate the resin by suction filtration, and wash it with three 15 ml. portions of benzene. Remove the benzene, etc., from the combined filtrate and washings under reduced pressure (water pump) and then collect the crude ester at 74-90°/10 mm. a small sohd residue remains in the flask. Redistil the crude ester from a Claisen flask with fractionating side arm pure furfuryl acetate passes over at 79-80°/17 mm. The yield is 14 -5 g. 

A further 25 g. of cyanoacetamide may be obtained by evaporating the original mother liquor to dryness under reduced pressure (water pump) whilst heating the flask on a steam bath. The residue is dissolved in 50 ml. of hot ethanol, the solution shaken for a few minutes with decolourising carbon, Altered with suction whilst hot, and then cooled in ice. The resulting yellowish amide is recrystallised with the addition of decolourising carbon, if necessary. 

---