Stirrers mechanical

Homogenisation with respect to temperature This effectively means that if conditions are to be adiabatic (or nearly so), the outer layers of the mixture which are in contact with the vessel and the gas phase must be mixed with the bulk so effectively that no important temperature difference persists. If a reaction mixture is to be kept isothermal, the stirring must be even more effective, and there is a danger that the stirrer mechanism may dissipate so much energy that the heat generated in the solution becomes appreciable. 

The oxidation reactions were performed in a glass batch reactor, equipped with magnetic stirrer (mechanic for L-sorbose oxidation), reflux condenser and thermometer. The reaction conditions are summarized in Table I. Before reaction the catalyst was pre-reduced in situ in a nitrogen atmosphere ( 20 min) with the alcohol reactant in 30-40 ml alkaline water (and dodecylbenzenesulfonic acid sodium salt detergent for water-insoluble reactants). The reactor worked in a mass transfer limited regime, controlled by the air flow rate (7.5-20 cm3min 1) and the mixing rate (1500-1800 min 1). The reactions were followed by GO or HPLC analysis. 

In the screen tests, each coagulant or flocculant is added to the beaker samples of representative slurry or hquor in a dropwise fashion, while the sample is mixed with a spatula, stirrer, or 3-6 jar stirrer mechanism. The amount of coagulant or flocculant required to initiate floe particle formation is noted along with relevant notes as to the size of the floe, capture of fines, resultant liquor clarity, and stabihty of the floe structure. The dosage is typically noted in g/t solids if the sample is primarily solids (thickener design), or in mg/L liquor if the sample is primarily for clarification and the solids concentration is low. 

A thermostated water bath A submersible stirrer mechanism with a cell stand... 

Any calorimeter with a suitable mixing device and designed for use with liquids can be applied to determine heats of solution, dilution, or mixing. To obtain good precision in the determination of heats of solution requires careful attention to detail in the construction of the calorimeter. The dissolution of a solid can sometimes be a relatively slow process and requires efficient and uniform stirring. Substantial experimental precautions are ordinarily made to ensure that heat input from the stirrer mechanism is minimized. 

The seals on this piston were made of 0-rings and a Teflon guide attached to the top of the piston permitted it to move smoothly inside the main body. The stirrer mechanism consists of four two-bladed fans along the stirrer stem. A small magnet is fitted into the lower end of the stirrer stem and the stirrer is... 

Multi-necked flasks. Fig. II, 1, 8, a, illustrates a typical threenecked flask. This has numerous applications in organic chemistry for many operations, the central aperture carries a mechanical stirrer, and the two side apertures a dropping funnel and a reflux condenser respectively. 

Hydriodic acid. A 1-5 litre three-necked flask is charged with a mixture of 480 g. of iodine and 600 ml. of water. The central aperture is fitted with a stopper carrying an efficient mechanical stirrer leading... 

Cuprous cyanide solution. The most satisfactory method is to dissolve the cuprous cyanide (1 mol) in a solution of technical sodium cyanide (2 5-2-6 mols in 600 ml. of water). If it is desired to avoid the preparation of solid cuprous cyanide, the following procedure may be adopted. Cuprous chloride, prepared from 125 g. of copper sulphate crystals as described under 1 above, is suspended in 200 ml. of water contained in a 1-litre round-bottomed flask, which is fitted with a mechanical stirrer. A solution of 65 g. of technical sodium cyanide (96-98 per cent.) in 100 ml. of water is added and the mixture is stirred. The cuprous chloride passes into solution with considerable evolution of heat. As the cuprous cyanide is usually emplo3 ed in some modification of the diazo reaction, it is usual to cool the resulting solution in ice. 

Dichlorobutane. Place 22-5g. of redistilled 1 4-butanediol and 3 ml. of dry pyridine in a 500 ml. three necked flask fitted with a reflux condenser, mechanical stirrer and thermometer. Immerse the flask in an ice bath. Add 116 g. (71 ml.) of redistilled thionyl chloride dropwise fix>m a dropping funnel (inserted into the top of the condenser) to the vigorously stirred mixture at such a rate that the temperature remains at 5-10°. When the addition is complete, remove the ice bath, keep the mixture overnight, and then reflux for 3 hours. Cool, add ice water cautiously and extract with ether. Wash the ethereal extract successively with 10 per cent sodium bicarbonate solution and water, dry with anhydrous magnesium sulphate and distil. Collect the 1 4-dichloro-butane at 55-5-56-5°/14 mm. the yield is 35 g. The b.p. under atmospheric pressure is 154 155°. 

Allyl Bromide. Introduce into a 1-litre three-necked flask 250 g. (169 ml.) of 48 per cent, hydrobromic acid and then 75 g. (40-5 ml.) of concentrated sulphuric acid in portions, with shaking Anally add 58 g. (68 ml.) of pure allyl alcohol (Section 111,140). Fit the flask with a separatory funnel, a mechanical stirrer and an efficient condenser (preferably of the double surface type) set for downward distillation connect the flask to the condenser by a wide (6-8 mm.) bent tube. Place 75 g. (40 5 ml.) of concentrated sulphuric acid in the separatory funnel, set the stirrer in motion, and allow the acid to flow slowly into the warm solution. The allyl bromide will distil over (< 30 minutes). Wash the distillate with 5 per cent, sodium carbonate solution, followed by water, dry over anhydrous calcium chloride, and distil from a Claisen flask with a fractionating side arm or through a short column. The yield of allyl bromide, b.p. 69-72°, is 112 g. There is a small high-boiling fraction containing propylene dibromide. 

Alternatively, place the mixture of alcohol and red phosphorus in a 500 ml. three-necked flask fitted with a mechanical stirrer, dropping funnel and double surface condenser. Heat the phosphorus - alcohol mixture to about 250°, and add the bromine whilst stirring vigorously. Work up the reaction product as above. 

In a 1-litre three-necked flask, mounted on a steam bath and provided respectively with a separatory funnel, mechanical stirrer and double surface condenser, place 165 g. of bromoform (96 per cent.). Add 10 ml. of a solution of sodium arsenite made by dissolving 77 g. of A.R. arsenious oxide and 148 g. of A.R. sodium hydroxide in 475 ml. of water. Warm the mixture gently to start the reaction, and introduce the remainder of the sodium arsenite solution during 30-45 minutes at such a rate that the mixture refluxes gently. Subsequently heat the flask on the steam bath for 3-4 hours. Steam distil the reaction mixture (Fig. 11, 41, 1) and separate the lower layer of methylene bromide (79 g.). Extract the aqueous layer with about 100 ml. of ether a further 3 g. of methylene bromide is obtained. Dry with 3-4 g. of anhydrous calcium chloride, and distil from a Claisen flask with fractionating side arm. The methylene bromide boils constantly at 96-97° and is almost colourless. 

In a 1-litre three-necked flask, fitted with a mechanical stirrer, reflux condenser and a thermometer, place 200 g. of iodoform and half of a sodium arsenite solution, prepared from 54-5 g. of A.R. arsenious oxide, 107 g. of A.R. sodium hydroxide and 520 ml. of water. Start the stirrer and heat the flask until the thermometer reads 60-65° maintain the mixture at this temperature during the whole reaction (1). Run in the remainder of the sodium arsenite solution during the course of 15 minutes, and keep the reaction mixture at 60-65° for 1 hour in order to complete the reaction. AUow to cool to about 40-45° (2) and filter with suction from the small amount of solid impurities. Separate the lower layer from the filtrate, dry it with anhydrous calcium chloride, and distil the crude methylene iodide (131 g. this crude product is satisfactory for most purposes) under diminished pressure. Practically all passes over as a light straw-coloured (sometimes brown) liquid at 80°/25 mm. it melts at 6°. Some of the colour may be removed by shaking with silver powder. The small dark residue in the flask solidifies on cooling. 

Equip a 1-litre three-necked flask with a powerful mechanical stirrer, a separatory funnel with stem extending to the bottom of the flask, and a thermometer. Cool the flask in a mixture of ice and salt. Place a solution of 95 g. of A.R. sodium nitrite in 375 ml. of water in the flask and stir. When the temperature has fallen to 0° (or slightly below) introduce slowly from the separatory funnel a mixture of 25 ml. of water, 62 5 g. (34 ml.) of concentrated sulphuric acid and 110 g. (135 ml.) of n-amyl alcohol, which has previously been cooled to 0°. The rate of addition must be controlled so that the temperature is maintained at 1° the addition takes 45-60 minutes. AUow the mixture to stand for 1 5 hours and then filter from the precipitated sodium sulphate (1). Separate the upper yellow n-amyl nitrite layer, wash it with a solution containing 1 g. of sodium bicarbonate and 12 5 g. of sodium chloride in 50 ml. of water, and dry it with 5-7 g. of anhydrous magnesium sulphate. The resulting crude n-amyl nitrite (107 g.) is satisfactory for many purposes (2). Upon distillation, it passes over largely at 104° with negligible decomposition. The b.p. under reduced pressure is 29°/40 mm. 

Into a 500 ml. three-necked flask, provided with a mechanical stirrer, a gas inlet tube and a reflux condenser, place 57 g. of anhydrous stannous chloride (Section 11,50,11) and 200 ml. of anhydrous ether. Pass in dry hydrogen chloride gas (Section 11,48,1) until the mixture is saturated and separates into two layers the lower viscous layer consists of stannous chloride dissolved in ethereal hydrogen chloride. Set the stirrer in motion and add 19 5 g. of n-amyl cyanide (Sections III,112 and III,113) through the separatory funnel. Separation of the crystalline aldimine hydrochloride commences after a few minutes continue the stirring for 15 minutes. Filter oflF the crystalline solid, suspend it in about 50 ml. of water and heat under reflux until it is completely hydrolysed. Allow to cool and extract with ether dry the ethereal extract with anhydrous magnesium or calcium sulphate and remove the ether slowly (Fig. II, 13, 4, but with the distilling flask replaced by a Claisen flask with fractionating side arm). Finally, distil the residue and collect the n-hexaldehyde at 127-129°. The yield is 19 g. 

Equip a 1-litre three-necked flask with a mechanical stirrer, a separatory funnel and a thermometer. Place a solution of 47 g. of sodium cyanide (or 62 g. of potassium cyanide) in 200 ml. of water in the flask, and introduce 58 g. (73-5 ml.) of pure acetone. Add slowly from the separatory fumiel, with constant stirring, 334 g. (275 ml.) of 30 per cent, sulphuric acid by weight. Do not allow the temperature to rise above 15-20° add crushed ice, if necessary, to the mixture by momentarily removing the thermometer. After all the acid has been added continue the stirring for 15 minutes. Extract the reaction mixture with three 50 ml. portions of ether, dry the ethereal extracts with anhydrous sodium or magnesium sulphate, remove most of the ether on a water bath and distil the residue rapidly under diminished pressure. The acetone cyanohydrin passes over at 80-82°/15 mm. The yield is 62 g. 

If preferred, a 1 5 litre three-necked flask. equippedropping funnel, mechanical stirrer and leflux condenser, may be used and the obvious modifications of technique introduced. This proaadure is recommended. 

C. Fumaric acid from furfural. Place in a 1-litre three-necked flask, fitted with a reflux condenser, a mechanical stirrer and a thermometer, 112 5 g. of sodium chlorate, 250 ml. of water and 0 -5 g. of vanadium pentoxide catalyst (1), Set the stirrer in motion, heat the flask on an asbestos-centred wire gauze to 70-75°, and add 4 ml. of 50 g. (43 ml.) of technical furfural. As soon as the vigorous reaction commences (2) bvi not before, add the remainder of the furfural through a dropping funnel, inserted into the top of the condenser by means of a grooved cork, at such a rate that the vigorous reaction is maintained (25-30 minutes). Then heat the reaction mixture at 70-75° for 5-6 hours (3) and allow to stand overnight at the laboratory temperature. Filter the crystalline fumaric acid with suction, and wash it with a little cold water (4). Recrystallise the crude fumaric acid from about 300 ml. of iif-hydrochloric acid, and dry the crystals (26 g.) at 100°. The m.p. in a sealed capillary tube is 282-284°. A further recrystaUisation raises the m.p. to 286-287°. 

To prepare methyl n-butyl ketone, add the crude ester (A) or the redistilled ethyl n-propylacetoacetate B) to 1500 ml. of a 5 per cent solution of sodium hydroxide contained in a 4-litre flask equipped with a mechanical stirrer. Continue the stirring at room temperature for... 

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. 

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