Stirred slurry

Secondary Chlorides With a low-boiling chloride such as 2-chlorobutane, a stirred slurry of 30 g (0.61 mole) of sodium cyanide in 150 ml of dimethyl sulfoxide is heated to 90° with a heating mantle, and 0.5 mole of the chloride is slowly added over a period of 30 minutes. The temperature of the refluxing reaction mixture slowly increases as nitrile is formed. Refluxing continues as the temperature slowly rises to 150° after 3 hours reaction time. The flask is then cooled and the reaction mixture is worked up in the same way as for the primary nitriles. With 2-chlorooctane, the sodium cyanide-dimethyl sulfoxide slurry is heated to 130° and 0.5 mole of the chloride added. The reaction mixture is maintained at 135-145° for 1 hour, then cooled, and the product is isolated as above. Examples are given in Table 16.1. 

To a stirred slurry of 35 mg (0.87 mmol) of sodium hydride in 5 mL of THF under a nitrogen atmosphere at OX is added 225 mg (0.80 mmol) of ethyl [4-oxo-1-(2-propenyl)-2-cyclohexenyl]methylpropanedioatein 3 mL of THF. After the evolution of hydrogen ceases the cooling bath is removed and the mixture is stirred for 2.5 h at 25 °C. The mixture is poured into cold 0.1 N aq HCI and then extracted three times with 10 mL of CH2n2. The combined extracts are washed with aq NaHCO, and water. After drying and evaporation of the solvent the crude product is recrystallized yield 197 mg (87%) mp 83-84 C (diethyl ether). 

In the second class, the particles are suspended in the liquid phase. Momentum may be transferred to the particles in different ways, and it is possible to distinguish between bubble-column slurry reactors (in which particles are suspended by bubble movement), stirred-slurry reactors (in which particles are suspended by bubble movement and mechanical stirring), and gas-liquid fluidized reactors (in which particles are suspended by bubble movement and cocurrent liquid flow). 

Hydrogenation of unsaturated fats and fatty oils is one of the oldest heterogeneous catalytic processes of industrial significance, and is carried out exclusively by gas-liquid-particle operation, the vaporization of the fats being impracticable. Stirred-slurry operation is the normal mode of operation, the suspended catalyst being finely divided by Raney nickel (B2). 

In stirred-slurry reactors, momentum is transferred to the liquid phase by mechanical stirring as well as by the movement of gas bubbles. Small particles are used in most cases, and the operation is usually carried out in tank reactors with low height-to-diameter ratios. The operation is in widespread use for processes involving liquid reactants, either batchwise or continuous— for example, for the batchwise hydrogenation of fats as referred to in Section II. 

Stirred-slurry reactors are of considerable industrial importance in batch-wise processing. The catalytic hydrogenation of fats and fatty acids is an example of a process that is carried out almost exclusively in mechanically stirred slurry reactors. The operation is of less significance with respect to continuous processing. 

Liquid residence-time distributions in mechanically stirred gas-liquid-solid operations have apparently not been studied as such. It seems a safe assumption that these systems under normal operating conditions may be considered as perfectly mixed vessels. Van de Vusse (V3) have discussed some aspects of liquid flow in stirred slurry reactors. 

Among the earlier studies of reaction kinetics in mechanically stirred slurry reactors may be noted the papers of Davis et al. (D3), Price and Schiewitz (P5), and Littman and Bliss (L6). The latter investigated the hydrogenation of toluene catalyzed by Raney-nickel with a view to establishing the mechanism of the reaction and reaction orders, the study being a typical example of the application of mechanically stirred reactors for investigations of chemical kinetics in the absence of mass-transfer effects. 

Gas holdup may be of the same magnitude in the various operations, although for bubble-columns, the presence of electrolytes or surface-active agents appears to be a condition for high gas holdup. The gas residence-time distribution resembles that of a perfect mixer in the stirred-slurry operation, and comes close to piston flow in the others. 

The liquid residence-time distribution is close to plug flow in trickle-flow operation and corresponds to perfect mixing in the stirred-slurry operation, whereas the other types of bubble-flow operation are characterized by residence-time distributions between these extremes. 

Stirred-slurry operation, 120-123 holdup, axial dispersion, 122-123 mass transfer, 120-122 reactors, 80 Subcooling, 236-238 inlet, 261 Subreactors, 363 Sulfite-oxidation, 300-301 Summerfield, combustion equation, 44-43 Surface-active agents, 327-333 experiment, 327-329 theory, 329-333... 

To a stirred slurry of copper(i) cyanide (110 mmol) in THF (100 ml), cooled to 0 °C, was added a solution of dimethylphenylsilyl lithium (220 mmol, 1.3 m in THF), and the mixture was stirred at 0°C for a further 30min. After cooling to —78°C, a solution of methyl cinnamate (100mmol) in THF (50 ml) was added, and stirring was continued at —78°Cfor6h. At this time, iodomethane (300 mmol) (CAUTION—CANCER SUSPECT AGENT) was added, and the mixture allowed to warm to ambient temperature with... 

Base-induced elimination (2). KH (5 g, 40% dispersion in oil, 60 mmol) was washed with hexane. To a stirred slurry of the residue in THF (50ml) was added the above alcohol (50 mmol) within a few minutes, hydrogen evolution was complete. The mixture was stirred for 6h at ambient temperature, and then carefully poured on to ice-cold saturated ammonium... 

Methyl 4-chlorobenzoate (13.65 g, SOmmol) was added in one portion to a stirred slurry of potassium trimethylsilanolate 97 (10.26 g, 80 mmol) in 500 mb dry ether at ambient temperature, under N2. After 4h the white slurry is filtered under N2, washed with ether, and dried under a stream of N2 to afford 13.1 g (84%) analytically pure potassium 4-chlorobenzoate [119] (Scheme 4.62). 

Filter, recrystallize the precipitate from boiling water and dry to get the dioxindole (III). To a stirred slurry of 1.9 g lithium aluminum hydride in 100 ml dry ether add 4.3 g (111) in 120 ml dry benzene and reflux four hours. Cool and carefully add a little water. When bubbling stops, filter and dry, evaporate in vacuum the organic layer to get (IV). 

This is a rapid, convenient procedure. If trimethoxybenzyl alcohol is used in place of p-anisyl alcohol, mescaline will result. Shake 100 g p-anisyl alcohol (or 0.72 moles analog) with 500 ml concentrated HCI for 2 minutes. Wash the organic phase with water, 5% NaHC03 and water, and then add over 40 minutes to a stirred slurry of 49 g NaCN in 400 ml dimethylsulfoxide with ice water cooling to keep temperature at 35-40°. After completing addition, remove cooling bath, stir for 90 minutes and then add to 300 ml water. Separate the small upper layer and extract the aqueous-DMSO layer... 

B. Fluoromethyl phenyl sulfone (2). To a 3-L, three-necked, round-bottomed flask, equipped with an overhead stirrer, thermometer, and 1-L addition funnel with sidearm are added Oxone (221.0 g, 0.36 mol) (Note 9) and water (700 mL). The mixture is cooled to 5°C and a solution of the crude fluoromethyl phenyl sulfide (1) in methanol (700 mL) is placed in the addition funnel and added in a slow stream to the stirring slurry. After addition of the sulfide, the reaction mixture is stirred at room temperature for 4 hr, (Note 10) and the methanol is removed on a rotary evaporator at 40°C. The remaining solution is extracted with methylene chloride (2 x 500 mL). The combined organic layers are dried over magnesium sulfate, concentrated to ca. 150 mL, filtered through a plug of silica gel (230-400 mesh, 300 mL, 10 x 6.5 cm), and washed with an additional 500 mL of methylene chloride (Note 11). The colorless filtrate is concentrated and the resulting oil or solid is dried under vacuum (0.1 mm) at room temperature to provide 29 g of crude fluoromethyl phenyl sulfone (2) as a solid... 

Pentane is added as a diluent in order to obtain an easily stirred slurry. Amounts varying from 100 to 250 ml. per mole of olefin have been used with no appreciable change in yield of product. 

Add 78.5 g of the above benzoate in 300 ml of ether to a stirred suspension of 19 g lithium aluminum hydride in 200 ml of ether at such a rate as to give gentle reflux. After the addition, reflux for 2V2 hours, then cool. Add 50 ml of wet ether and 100 ml dilute sulfuric acid. Evaporate the ether extract in vacuo to get about 60 g of 3,5-dimethoxybenzyl alcohol and recrystallize with ether-pentane. To a cooled, stirred slurry of CrOs and 250 ml pyridine, add 8.4 g of the above alcohol in 25 ml pyridine and after the addition let stand at room temp for 1 hour. Add 60 ml of methanol, let stand 2 hours, and dilute with 500 ml of 5% NaOH and 500 ml ether. Extract the aqueous layer with ether and wash the combined ether layers with water (500 ml), then three 500 ml of 5% sulfuric acid, again with 500 ml water, and then 200 ml saturated NaCl. Dry and evaporate in vacuo to get 7 g 3,5-dimethoxybenzaldehyde. (This benzaldehyde is not much more suspicious to the DEA than the LAH used to make it. It may be cheaper for you to buy than to make.)... 

Immerse amine slides in a stirred slurry of cyanuric chloride (12.7 g/L) and sodium carbonate (25g/L) in hexane at 4°C for 1 hr with sonication rinse with hexane air dry. 

The stirred sodium hydride suspension is cooled by an external ice-water bath and the jacket of the addition funnel is cooled in a dry ice-isopropyl alcohol bath. Into the addition funnel is introduced 275 g (4.16 mol) of neat, freshly distilled cyclopentadiene (Note 5). The cyclopentadiene is added rapidly, dropwise over 30-40 min to the stirred slurry Caution Avoid exoeee foaming) (Note 6). After the addition is complete, the cooling bath is removed and the solution is stirred for 1 hr at room temperature. 

Slurry tank hydrogenation. Predict the conversion of glucose to sorbitol in a stirred slurry reactor using pure hydrogen gas at 200 atm and 150°C. The catalyst used is porous Raney nickel, and under these conditions Brahme and Doraiswamy, lEC/PDD, 15,130 (1976) report that the reaction proceeds as follows ... 

In a well-ventilated hood, to a vigorously stirred dispersion of 29 gm (0.12 mole) of 5,5-diphenyl-2-6xazolidone in 200 ml of dried pyridine maintained between 10° and 15°C is added, over a 20-min period, 28 ml of a solution of 4.8 A nitrosyl chloride (0.13 mole) in acetic anhydride. Stirring is continued for an additional 5 min. Then the deep-red mixture is poured into a stirred slurry of 250 gm of ice and water. 

B. N,N, N"-Tris(p-tolysulfonyl)diethylenetriamine-N,N"-disodium salt (2). A 3-1., three-necked, round-bottomed flask is equipped with a mechanical stirrer, reflux condenser, and addition funnel. In the flask are placed 11. of absolute ethanol and 425 g. (0.75 mole) of triamine 1 under nitrogen. The stirred slurry is heated to reflux, the heat source is removed, and 1000 ml. of 1.5N sodium ethoxide solution (Note 2) is added through the addition funnel as rapidly as possible. The solution is then decanted from any undissolved residue into an Erlenmeyer flask. The disodium salt 2, which crystallizes on standing overnight, is filtered under nitrogen, washed with absolute ethanol, and dried in a vacuum oven at 100°. The yield is 400-440 g. (87-96%). 

A large filter area is recommended. A 1-cm layer of Celite is pressed on a sintered-glass funnel (6 cm x 17 cm). The Celite is dried in an oven at 120°C for 12 hr. A 6-mm Teflon tube is used to connect the flask and the filter funnel through the septa, and the stirred slurry is then transferred to the funnel with the aid of nitrogen pressure. Inner pressure of the receiver flask and the funnel Is leaked through oil bubblers. The... 

In the third section an extensive writing on two types of slurry catalytic reactors is proposed Bubble Slurry Column Reactors (BSCR) and Mechanically Stirred Slurry Reactors (MSSR). All the variables relevant in the design and for the scale-up and the scale-down of slurry catalytic reactors are discussed particularly from the point of view of hydrodynamics and mass transfer. Two examples of application are included at the end of the section. 

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