Salt-free filters

For waters with much less than 0.5 mg/L SPM, the amount of material obtainable from the typical 0.5-2 L sample volume is insufficient for subsequent precise and accurate TE analyses. Off-line processing of the much larger volumes of water then necessary becomes very laborious and should be replaced by on-line filtration from appropriate samplers (Fig. 12-30). To this end, the filter holder is attached to the drain spigot, and the necessary additional pressure is applied via the sampler s air-vent. The suspended particulate matter is collected by filtering all the water held by the sampler. To remove the seasalt from the loaded filters, the on-line filter holder is disconnected from the sampler and attached to a plastic syringe. Manually, two 20 mL portions of high-purity distilled water are drained through the filters. The further treatment of the loaded, salt-free filters is identical to the procedure applied to filters obtained by off-line filtration. 

Slurries of free-filtering sohds that are difficult to suspend are sometimes filtered on a top-feed drum filter or filter-diyer. An example application is in the production of table salt. An alternative for slurries of extremely coarse, dense solids is the internal drum filter. In the chemical-process industiy both top-feed and internal drums (which are described briefly by Emmett in Schweitzer, op. cit., p. 4-41) have largely been displaced by the horizontal vacuum filter (q.v). 

The amine (Imol) is added to a solution of anhydrous zinc chloride (Imol) in concentrated hydrochloric acid (42mL) in ethanol (200mL, or less depending on the solubility of the double salt). The solution is stirred for Ih and the precipitated salt is filtered off and recrystallised from ethanol. The free base is recovered by adding excess of 5-ION NaOH (to dissolve the zinc hydroxide that separates) and is steam distilled. Mercuric chloride in hot water can be used instead of zinc chloride and the salt is crystallised from 1% hydrochloric acid. Other double salts have been used, e.g. cuprous salts, but are not as convenient as the above salts. 

In order to complete the reaction, heating at 50°C is carried out for 3 hours. After cooling, one liter of benzene is added and the reaction mixture is stirred, then washed salt-free with water. The benzene solution is dried over anhydrous sodium sulfate, filtered and concentrated by evaporation giving 167 g crude 1-(o-chlorophenylbisphenylmethyl)-imidazole. By recrystallization from acetone, 115 g (= 71% of the theory) of pure 1-(o-chlorophenyl-bisphenylmethyD-imidazole of MP 154° to 156°C are obtained. 

To a stirred suspension of 5 parts of N-(4-chlorophenyl)-N-(4-piperidinyl)benzeneacetamide, 5 parts of sodium carbonate, a few crystals of potassium iodide in 200 parts of butanol is added dropwise 4 parts of 2-bromopropane at room temperature. After the addition is complete, the whole is stirred and refluxed for 20 hours. Then the second portion of 4 parts of 2-bromopropane is added and stirring and refluxing is continued for another 19 hours. The reaction mixture is cooled, filtered and the filtrate is evaporated. From the oily free bese, the hydrochloride salt is prepared in the conventional manner in 1,1 -oxybisethane and 2-propanone. The precipitated solid salt is filtered off and crystallized from a mixture of 2-propanone and 2-propanol, yielding 2 parts of N-(4-chlorophenyl)-N-[1-(1-methylethyl)-4-piperidinyl] benzeneacetamide hydrochloride melting point 263°C. 

No. 41 or 541 filter paper. Wash the precipitate first with warm, dilute hydrochloric acid (approx. 0.5M), and then with hot water until free from chlorides. Pour the filtrate and washings into the original dish, evaporate to dryness on the steam bath, and heat in an air oven at 100-110 °C for 1 hour. Moisten the residue with 5 mL concentrated hydrochloric acid, add 75 mL water, warm to extract soluble salts, and filter through a fresh, but smaller, filter paper. Wash with warm dilute hydrochloric acid (approx. 0.1M), and finally with a little hot water. Fold up the moist filters, and place them in a weighed platinum crucible. Dry the paper with a small flame, char the paper, and burn off the carbon over a low flame take care that none of the fine powder is blown away. When all the carbon has been oxidised, cover the crucible, and heat for an hour at the full temperature of a Meker-type burner in order to complete the dehydration. Allow to cool in a desiccator, and weigh. Repeat the ignition, etc., until the weight is constant. 

To a solution of l. 47 g (0.03 mol) of sodium cyanide and 4.73 g (0.03 mol) of (-)-(.S)-x-methylbenzylamine hydrochloride in 5 mL of cold water is added 1 g (8.3 mmol) of free ( - )-(.S )-a-mcthylbcnzylaininc in 200 mL of CHjOH. 1.32 g (0.03 mol) of acetaldehyde is added at 0°C and the clear solution is kept at r.t. for five days. After evaporation of the solvent in vacuo, the residue is dissolved in 50 mL of 1 N HC1 and the solution is extracted twice with diethyl ether. After addition of 12 N HCl to adjust the acid concentration to approximately 5 N, the solution is retluxed for 6 h. The HCl is evaporated in vacuo and the residue is dried over sodium hydroxide. The crude. V-x-methylbenzylalaninc hydrochloride is dissolved in 200 mL of 50% ethanol and the pH is adjusted to 6.0 with NaHCOj. To this solution, 3.5 g of palladium hydroxide is added. After hydrogenolysis for 10 h, the catalyst is filtered off and washed with hot water. The filtrate is concentrated to 30%, and the pH is adjusted to 1 with dilute IIC1. The solution is evaporated to dryness and the alanine hydrochloride is extracted with three 20-inL portions of absolute ethanol. After cooling overnight at — 50°C, the precipitated salt is filtered. Pyridine is added to the alcoholic solution to precipitate crude alanine, which is dissolved in 2.5 mL of water. The pH is adjusted with pyridine to 5.5-6.0, and 10 mL of absolute ethanol arc added yield 0.45 g (17% over four steps) mp 290 C [a] 7 + 13.13 (0 = 2.32. 6 N IICi). 

A ddH2 0, filtered with 0.45 nm membrane filter and stored dust free and salt free in plastic bottles B 1% gold(III)chloride (tetrachloroauricadd) (w/v) inReagent A C 1% trisodium citrate (w/v) in Reagent A D aquaregia (chloronitrous acid) 1 vol. concentrated HCl+3 vol. concentrated HNO3... 

The hot product from the kiln is quenched in water (e), passed via classifiers and hydroseparators (f) into thickeners (g), filtered on rotary filters (b2), and washed until salt-free. The dried product is ground in high-intensity mills (g) and may undergo organic treatment (with a polyalcohol) depending on the application. 

The ester function was determined by alkaline hydrolysis followed by precipitating the liberated acids as calcium salts. In the present work, samples of 1-1.5 grams were added to 50 ml. of 0.2N aqueous sodium hydroxide and refluxed with continuous stirring under nitrogen for 18-24 hours. After hydrolysis the samples were titrated to a pH of 9 with hydrochloric acid. Then 15 ml. of IN calcium acetate was added, and the sample was stirred rapidly under a stream of nitrogen for 1 hour. The suspension of calcium salt was filtered, washed with dilute base until free of excess calcium acetate as determined by titration with ethylenediaminetetraacetic acid (EDTA), and dried under a stream of nitrogen. Calcium was determined on the dried product. 

Microfilters are used in the electronics industry, principally as final point-of-use filters for ultrapure water. The water is already very pure and almost completely particle- and salt-free, so the only potential problem is contamination in the piping from the central water treatment plant to the device fabrication area. Although fine filters with 0.1 pm pore diameter or less may be used, lifetimes are relatively long. 

The ethyl malonic ester (10 gms.) is hydrolysed by boiling for an hour on the water-bath with strong aqueous potash containing 15 gms. of potash. The product is treated with moderately strong hydrochloric acid till neutral, and the acid is then precipitated as the calcium salt by adding a concentrated solution of calcium chloride. The salt is filtered and decomposed by strong hydrochloric acid and the free ethyl malonic acid extracted with ether. The ether extract deposits crystals on evaporation, and these may be recrystallised from a small quantity of boiling water. Colourless prisms, m.p, 111 5°, Yield, about 5 gms. 

A solution of 36 g. (0.30 mole) of m-xylidine in a solution of 60 g. of concentrated sulfuric acid in 450 ml. of water is diazotized at a temperature below 5° by the addition of a solution of 21 g. (0.30 mole) of sodium nitrite in 60 ml. of water. The resulting solution of the diazonium salt is filtered, and the filtrate is added to a solution of 50 g. (0.30 mole) of potassium iodide in 60 ml. of water. After standing 1 hour at room temperature, the mixture is warmed until evolution of nitrogen ceases, and sufficient solid sodium bisulfite is added to remove the free iodine. The separated oil is removed by extraction with ether, and the ethereal solution is distilled after being washed with 10% aqueous sodium hydroxide and dried with calcium chloride. After removal of the ether by distillation, the residual oil is distilled from solid potassium hydroxide to give 33 g. (47%) of pure iodo compound, b.p. 231-235°. 

Wash the crystalline aminonaphthol hydrochloride into a beaker, stir, add more water, and warm to about 35°C until the salt is dissolved. Filter the solution quickly by suction from a trace of residue and stir in the iron(III) chloride solution. 1,2-Naphthoquinone separates at once as a voluminous precipitate and is collected on a suction filter and washed thoroughly to remove all traces of acid. The yield from pure, salt-free Orange II is usually about 75%. 

Catalysts NaY, REY, H-mordenite were supplied in 1/16 pellets from Strem Chemicals, zeolite A (2 mm pellets) from Merck, the X-type (1/16) zeolite from Grace and the montmorillonite K 10 from Sud-Chetnie (powder). For ion exchange [10], the zeolites were suspended in a 0.5 molar aqueous solution of the appropriate salt and heated to reflux for 2 hours. The exchanged zeolite was filtered, washed salt free with distilled water and dried over night at 80 °C. Activation was carried out in the micro reactor with a stream of dry air (20 ml/min) at 550 °C for 3 hours with the zeolites and at 350 °C in the case of montmorillonite, respectively. 

A solution of the urea derivative (ca. 5 g) in 1 % aq KOH (100 ml.) was heated under reflux for 1 h. After cooling, the precipitated potassium salts were filtered off, and washed several times with hot F.tOH. Water-soluble salts may be decomposed with dil HC1 to obtain the free compounds 19. 

Acylation of alkylidenetriphenylphosphoranes by thiocarboxylic 5-ethyl esters 456 The reactions are carried out in a Schlenk tube, as above. To a boiling solution (which need not be filtered) of a salt-free alkylidenephosphorane (0.022 mole) in anhydrous toluene is added an 5-ethyl thiocarboxylate (0.02 mole), and the mixture is boiled for 18 h. The phosphonium thiolate, that is initially precipitated as an oil, gradually redissolves. If an unfiltered ylide solution was used, the reaction solution must be filtered hot at this stage to remove sodium... 

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