Solids washing

Tlie time required to reduce the solubles in a slurry to a desired level is a function of the feed solids concentration. The qrtimum washing concentration can be determined from tlie slurry s filtration characteristics. 

As the first stage is run, informatiou is automatically recorded (with a data logger) concerning temperature, torque and filtrate weights. Thus, in one run filtrate rates can be obtained as a function of solids concentration. 

Pdndpal types of filteriiig centrifoges are suspended batch machines, automatic short-cycle batch machines and continuous cmiveyor centrifuges. In suspended centrifoges, the filter medium is usually canvas or a similar fabric, or woven metal cloth. Automatic machines employ fine metal screens. The filter medium in conveyor centrifoges is usually (he slotted wall of the bowl itself. 

The theory of constant-pressure filtration may approximately be applied to filtration in a cenhifoge. The following are assumed  

Effects of gravity and changes in the liquid kinetic energy arc negligible. 

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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°). 

Dissolve 1 g. of the ketomethylene compound and 1 1 g. or 2 2 g. of pure benzaldehyde (according as to whether the compound may be regarded as RCOCHjR or as RCHjCOCHjR ) in about 10 ml. of rectified (or methylated) spirit, add 0 5 ml. of 5.N -sodium hydroxide solution, shake and allow the mixture to stand for about an hour at room temperature. The benzylidene derivative usually crystallises out or will do so upon scratching the walls of the vessel with a glass rod. Filter off the solid, wash it with a little cold alcohol, and recrystallise it from absolute alcohol (or absolute industrial spirit). 

In a 50-100 ml. conical flask place a solution of 0 -5 g. of glucose in 5 ml. of water, 12-15 ml. of 10 per cent, sodium hydroxide solution and 1 ml. of benzoyl chloride, cork tightly, and shake until the odour of benzoyl chloride has disappeared and a crystalline (frequently sticky) soUd has separated. Filter oflF the solid, wash it with a Uttle water, and recrystaUise it from ethyl or n-butyl alcohol. (If the product is sticky, it should be removed, and spread on a porous tile before recrystaUisation.) Glucose pentabenzoate has m.p. 179°. Fructose pentabenzoate, m.p. 78-79°, may be similarly prepared. 

Benzoylindoline (223 g, l.Omol) was dissolved in CH2CI2 (2.23 1) and Mn02 (261 g, 3.0 mol. Diamond"Shamrock grade M) was added. The mixture was heated at reflux and agitated for 18 h. The reaction mixture was filtered and the solid washed with hot CH2CI2 (200ml). Evaporation of the solvent left 7-benzoylindole. 

Washing of Solids. Washing is a process designed to replace the mother liquor in the solids stream with a wash Hquid. The growing importance of this process is due to demands for increased purity of the products combined with the increasingly poorer raw materials available. Washing often may represent a dominant portion of the installation cost because it is usually multistaged and often countercurrent. 

Froiii C. Tcholjano loiis, H. Thciscn, and R. Eliasscn, Solid Wash s Enai-niaoina Piincijdos mu Mnnnainiuail Issvas, McCraw -Hill, New York, 1977. 

PIcollnIc aldehyde (4). BenzenesuHonyl chlonde (6 92 g, 40 mmol) was added with stirring to a chilled solution ol picollnic hydrazide 2 (4 62 g, 33 mmol) in pyndlne (3S mL). After l h the solvent was removed In vacuum, the residue stirred with water, liliered and the solid washed with EtOH and EtzO to afford 10 5 g ol 3 (100%), mp 202-203°C... 

B. Extraction with Ether (Note 10).—The solid mixture is transferred to a 2-1. flask and shaken ten minutes with 750 cc. of ether. The ether solution is decanted through a suction filter and the solid thrown onto the filter and pressed dry. The solid is then returned to the flask and shaken with 400 cc. of ether, d his mixture is filtered by suction and the solid washed twice on the filter with 250 cc. portions of ether. Each portion is allowed to drain through the filter several times while the solid is kept... 

Adamantane acetic acid [4942-47-6] M 194.3, m 136 , pK jtDissolve in hot N NaOH, treat with charcoal, filter and acidify. Collect solid, wash with H2O, dry and recryst from MeOH. [Chem Ber 92 1629 1959.]... 

Dissolve in H2O by adding Et3N to form the salt and while hot acidify, cool and pour into a large volume of H2O. Filter off the solid, wash with H2O, dry over P2O5 in vacuum. [Nefken And Teser J Am Chem Soc 83 1263 1961 Fieser 1 485 1976 Nefkens et al. Reel Trav Chim Payx-Bas 81 683 1962] The O-acetyl derivative has m 178-180° (from EtOH). 

Naphthalene-l-sulfonyl chloride [85-46-1] M 226.7, m 64-67°, 68°, b 147.S°/0.9mm, 147.S°/13mm. If the IR indicates the presence of OH then treat with an equal weight of PCI5 and heat at ca 100° for 3h, cool and pour into ice + H2O, stir well and filter off the solid. Wash the solid with cold H2O and dry the solid in a vacuum desiccator over P2O5 + solid KOH. Extract the solid with pet ether (b 40-60°) filter off any insoluble solid and cool. Collect the crystalline sulfonyl chloride and recryst from pet ether or C6H6 pet ether. If large quantities are available then it can be distd under high vacuum. [Fierz-Davaid and Weissenbach Helv Chim Acta 3 2312 1920.] The sulfonamide has m 150° (from EtOH or H2O). 

M 436.6, m 175-176 . Recrystallise from toluene (light yellow solid), wash with Et20 and dry in a vacuum. [Helv Chim Acta 70 1001 1987.]... 

The material is filtered and the residual solid washed twice with 50-ml. portions of low-boiling petroleum ether. The combined filtrates are concentrated and distilled through a short packed column to yield 190-205 g. (76-82%) of 2,2,5,5-tetra-methyltetrahydro-3-ketofuran b.p. 149-151°, d 1-4180. 

The flask was cooled before opening, excess methyl bromide removed by filtration, and the white solid washed thoroughly with dry ether. The yield of crude scopolamine methyl bromide was 80 g (94% yield 93.5% over-all yield). 

If the substance is unaffected by exposure to the air, it may be weighed on a watch glass, or in a disposable plastic container. The weighing funnel (Fig. 3.8) is very useful, particularly when the solid is to be transferred to a flask having weighed the solid into the scoop-shaped end which is flattened so that it will stand on the balance pan, the narrow end is inserted into the neck of the flask and the solid washed into the flask with a stream of water from a wash bottle. 

N(w), is the amount of wash liquor used divided by the amount of liquor in the cake at the start of washing. Note that in practice results do not improve beyond about N(w)=3, fine solids wash better than coarse sohds, and that less than 10% fraction of original hquor remaining in the cake is seldom achieved. Understanding this general pattern will result in a scaleup with either a reslurry step and a second filtration, or the use of a filter like a Rosenmund that can reslurry the cake internally, and filter and wash again. 

The slurry was filtered and the solid washed with heptane (25 mL). 

Method D (EtO)2PHO (6.9 g, 50 mmol) in CC14 (10 ml or 30 ml when an amine salt is used) is added dropwise with stirring to the amine or amine salt (50 mmol), KHCO, (10 g), and TBA-Br (0.8 g, 2.5 mmol) in CH2C12 (40 ml) at 10-15°C. The reaction is exothermic and requires external cooling. The mixture is stirred at 15-20°C for 2 h (4 h for the amine salt) and then allowed to stand at room temperature for 12 h. The mixture is filtered and the solid washed with CH2C12 (2 x 25 ml). The combined organic solutions are evaporated to yield the phosphorylated amine. 

Method A Phthalimide (14.7 g, 0.1 mol), powdered KOH (6.7 g, 0.12 mol) and Aliquat (18 g, 25 mmol) in PhMe (25 ml) are stirred at room temperature for 2 h. The alkylating agent (0.1 mmol) is added dropwise and the mixture is then stirred at IOO°C (Table 5.16). The cooled mixture is filtered and the solid washed with Et20 (2 x 25 ml). The organic solutions are evaporated to yield the /V-alkylphthalimide, which is purified by recrystallization from EtOH or by chromatography. 

Bis(p-methoxyphenyl) ditelluride (typicalprocedure To a solution of p-methoxyphenyl-magnesium bromide (prepared from p-bromoanisole (5.82 g, 0.0311 mol) and Mg (1.0 g, 0.042 mol) in THF (20 mL)) is added Te shot (3.81 g, 0.0300 mol) at room temperature. The mixture is stirred under reflux for 3 h and then cooled to 0°C and treated with a sam-rated solution of NH Cl (20 mL vigorous evolution of gas). The mixture is filtered through Celite and the solids washed with saturated solution of NH Cl and ether. The organic phase is washed with brine and dried with Na2S04. Evaporation of the solvent and recrystaUiza-tion from CHClj/petroleum ether affords the pure product (5.16 g (75%) m.p. 57-59°C). 

Acetyl-9-keto 7-methyl-4,5,5a, 6,6a, 7,8,9-octakydroindolo-4,3-quinoline. 24 g of the last product is added to 80 ml of cold acetic anhydride. The mixture is held at 25° for about 5 min, then thoroughly cooled, filtered, and the product (a solid) washed with ether to yield 20,5 g, mp 169-170°. A second crop is obtained by concentrating the mother liquor by evaporation. 

The aged pillaring reagents were heated to 65 C and 325 bentonite, American Colloid Company, whose major constituent is the layered clay mineral, montmorilIonite, was added. There was always a 5-fold excess of aluminum in solution and the volume of solution per gram of clay was always 45 cc/g or more. The reaction was carried out for 2 hours. The slurry was filtered and the solids washed two times with water, dried, sized, and calcined at 500 C for 2 hours in air. 

In a 2-1. round-bottom flask fitted with a reflux condenser and an efficient glass stirrer, are placed 700 cc. of 95 per cent ethyl alcohol, 100 g. of recrystallized p-tolylmercuric chloride (p. 99), and 160 g. of sodium iodide (80 per cent excess). This mixture is boiled with vigorous stirring (Note 2) for fifteen hours the solid does not entirely enter into solution at any time. The mixture is then thoroughly cooled and filtered by suction and the solid washed with water until free of inorganic halide. It is then dried in an air-oven at 40° and recrystallized from 500 cc. of boiling xylene (Note 3). In this way 45-50 g. (78-85 per cent of the theoretical amount) of a product melting at 238° is obtained. 

The KG-60 silica (5g) was treated with 3-mercaptopropyl trimethoxysilane (45 mmol, 8.5 mL) in dry toluene (75 mL) at reflux for 24 h. After coohng the mixture was filtered on Buchner funnel and the solid washed with Soxhlet apparatus for 16 h with a mixture of dichloromethane/diethyl ether (50 mL, 1/1 v/v). 

To a flask containing 12.4 gm (0.037 mole) of l-(a-naphthyl)-l,3-diphenyl-2-propyn-l-ol in 50 ml of dry ether is added 2.0 gm (0.015 mole) of phosphorus trichloride in 10 ml of ether. The solution is stirred at room temperature for 2 hr, filtered, the solid washed with dry ether, and dried to afford 6.5 gm (50 %),... 

M TiCl4 in dry toluene (50 mL) was added slowly to a solution of 2,2,4,4-tetramethylcyclobutane-l,3-dione (0.70 g, 5 mmol) and excess r-BuNH2 (3.66 g, 50 mmol) in dry toluene (100 mL) at — 10°C under N2. The mixture was then allowed to reflux for ca. 20 h. The cooled solution was filtered and the residual solid washed thoroughly with benzene. Concentration of the filtrate and sublimation in vacuo gave the bisimine yield 0.63 g (50%) mp 83-84°C. 

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