Kieselguhr water filters

Diatomaceous earth (Celite 535 or 545, Hyflo Super-cel, Dicalite, Kieselguhr) is purified before use by washing with 3M hydrochloric acid, then water, or it is made into a slurry with hot water, filtered at the pump and washed with water at 50° until the filtrate is no longer alkaline to litmus. Organic materials can be removed by repeated extraction at 50° with methanol or chloroform, followed by washing with methanol, filtering and drying at 90-100°. 

A solution of S-iodomethyl-6a,9a-difluoro-lip-hydroxy-16a-methyl-3-oxo-17a-propionyloxyandrosta-l,4-diene-17p-carbothioate (310 mg) in acetonitrile (10 ml) was stirred with silver fluoride (947 mg) for 3 days at room temperature in the dark. Ethyl acetate (100 ml) was added and the mixture was filtered through kieselguhr. The filtrate was washed successively with 2 N hydrochloric acid, water, saturated brine, then dried. The solvent was removed and the residue was subjected to column chromatography in chloroform then chloroform-acetone (19 1). The product was eluted with ethyl acetate and crystallised on concentration of the solution to give S-fluoromethyl 6a,9a-difluoro-lip-hydroxy-16a-methyl-3-oxo-17a-propionyloxyandrosta-l,4-diene-17p-carbothioate (0.075 g) melting point 272-273°C (dec.), [a]D= +30° (c 0.35). 

Dissolve the copper(ll) nitrate solid (6.0 g) in water (300 mL) in a 1 L conical flask containing a stirrer bead and add a solution of the 3,7-dithianonane-1,9-diamine (5.0 g) in methanol (50 mL) slowly. Warm (to 50°C) and stir for 1 h. Cool and filter through Kieselguhr (or an alternative filter aid) under suction to yield a dark purple filtrate. 

The oil was dissolved in 45 ml THF and added to a mixture of 10% palladium on carbon (0.50 g) and 5.82 ml 2,6-lutidine in 30 ml THF, then hydrogenated 4 days at 2 atm hydrogen. The mixture was then filtered through a kieselguhr pad, the filtrate concentrated, and a solid isolated. The solid was then dissolved in 20 ml DMF and treated with 4.53 ml ethyl cyanoacetate and sulfur (1.36 g), then stirred 2 hours at 50°C. The mixture was then treated with 300 ml water and 50 ml brine and extracted three times with 300 ml diethyl ether. The extracts were dried with MgS04 and concentrated. The residue was purified by chromatography with silica using diethyl ether/hexane, 2 3, and ll.OOg product isolated. 

The oxidation reaction is interrupted by the addition of 10 ml of ethanol. After 10 min, the manganese dioxide is filtered off through a layer of water-washed fumed silica ( Kieselguhr , Fluka AG Switzerland) and washed with a small amount of sodium bicarbonate (1% solution). The aqueous phase is extracted with 2 x 50 ml of diethyl ether, the ether in turn is extracted with 15 ml of sodium bicarbonate (1% solution) and, after adjustment of the pH to 6.5 with 9M sulfuric acid, the combined aqueous extracts are evaporated to a small volume (30 ml). 

For partial hydrolysis of the amorphous glycosides, a mixture of 10 g. of glycosides obtained as above, 5 g. of crude enzyme and 700 cc. of water is allowed to stand at pH 5.6 at 37 for nine days. The mixture is treated with 5 volumes of alcohol, filtered through kieselguhr, and concentrated to a small volume under reduced pressure. The residue is extracted with chloroform. The chloroform-soluble glycosides (4.3 g.) are crystallized from methanol, yielding a first crop (2.1 g.) of a mixture of glycosides and crude emicymarin (0.55 g.) from the mother liquors. After repeated crystallization from methanol, emicymarin forms rosettes of stout needles which sinter at 160 and melt at about 207 . The value of Qalo for the anhydrous substance is - -12.8 (c. 2.5, absolute alcohol). 

Formation of indoles by intramolecular Wittig reaction A suspension of 119 (500 mg) in toluene (25 mL) and DMF (5 mL) was distilled until approximately 5 mL of distillate had been collected. KOtBu (134 mg, 1.2 mmol) was then added and the mixture was heated under reflux for 45 min. After cooling, the mixture was acidified with 2 n HCl, filtered through kieselguhr, and the polymer was washed extensively with CH2CI2. The filtrate was washed with water and brine, dried (Na2SO4), and concentrated to dryness to yield 120 (135 mg, 78%). 

Digest for six hours at very gentle heat, place in a steam jacketed still, add another 5 gallons water, and distill slowly for 2 hours with partial reflux until all the alcohol is driven over. Rectify the raw distillate to 35% alcohol by volume and filter clear over Kieselguhr to remove terpenes. Clean still and then rectify the filtered distillate to 58 gallons, 60% alcohol by volume. 

The flask is cooled to 0° with crushed ice (Note 9), and 150 ml. of dichloromethane is added with stirring. The reaction mixture is then poured into a 2-1. beaker containing 500 ml. of water and 500 ml. of crushed ice. Material remaining in the flask is rinsed into the beaker with 10 ml. of dichloromethane, and the mixture is stirred thoroughly, further salts being precipitated, until the ice just melts. The mixture is then filtered into a cooled filter flask under reduced pressure through a sintered or Buchner funnel and a kieselguhr filter-aid cake (Note 10). The beaker and filter cake are... 

Both solutions were heated to boiling, and Solution 2 (containing the kieselguhr) was poured as rapidly as possible into Solution 1. This was then heated to boiling for one minute and filtered. The catalyst cake was washed six to eight times with a total of 20 liters of boiling distilled water (until alkali free), dried at 110°C., and granulated. 

Nickel nitrate hexahydrate (58 g) is dissolved in distilled water (80 ml) and rubbed in a mortar with kieselguhr (previously extracted with hydrochloric acid) until, after 30-60 min the mixture flows like a heavy oil. It is then added slowly to a solution of ammonium carbonate monohydrate (34 g) in distilled water (200 ml) the precipitate is filtered off under suction, washed in two portions with water (100 ml), and dried at 110°. Shortly before use, this material is reduced at 450° for 1 hour in a stream of hydrogen (10-15 ml/min). 

Reaction mixtures containing higher alkyl bromides are first filtered through glass wool or kieselguhr, and then diluted with water. The crude bromide is separated in a separatory funnel. 

The most common filter aid employed is kieselguhr (diatomaceous earth). This comprises the fossils or skeletons of fresh or salt water algae known as diatoms (Figure 11.1). The highly porous nature of the particles enables effective liquid flow but also entrapment of particles. Other types of filter aid that are commonly used include perlite (volcanic glass) and cellulose fibres. However, the porous internal structure of the diatoms makes them more effective than the alternatives. 

Kieselguhr prepared as follows 500 g Kiesel-guhr stirred with 3 1 hydrochloric acid (1 2) for 2 h, decanted, filtered by suction, and repeated 3 times. For decanting wash with water until chlorides are eliminated, dry at I00°C, and sift through sieve No. 200 ASTM. A slurry of 40 g of Kieselguhr is made with 80 ml of aq. 5% EDTA neutralized to pH 7.5 or 9.0 with 20% sodium hydroxide. A 0.3-mm coating is made, dried at room temperature for 1 h and then at 100°C for 1 h... 

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