Rinsing precipitate

Filter off the rinsed precipitate on a Buchner funnel and dry it at a temperature not exceeding 100 °C. What is produced if the salt is roasted without the access of air ... 

B) Cunningham and Dove [324] obtained similar results to earlier workers [35] on filtered and hydrocarbon-rinsed precipitates from TiC / Al(n-Pr)3 with or without anisole present. The work included experiments at low Al/Ti ratios (0.2/1). The main effect of anisole was to increase the amount of aluminium in the filtrate at low Al/Ti ratios and to reduce somewhat the Cl/Ti ratio in the precipitate. Perry et al. [325] show, clearly, however, that thoroughly washed precipitates lose virtually all their aluminium to the solvent, so this question may simply be one of efficiency of washing. 

Rinse the walls of the flask with a httle water and complete the reaction by heating the mixture (which consists of two layers and a precipitate of sodium chloride) on a boiling water bath for 15 minutes with vigorous mechanical stirring. Pour the hot reaction mixture into 1500 ml. of glacial acetic acid contained in a 4-htre round-bottomed flask rinse the flask with 250 ml. of acetic acid. Cool the solution in an ice bath to 5° (11), stir mechanically, and add a solution of 125 g. of sodium nitrite in 250 ml. 

The distillate was dissolved in a mixture of 350 ml of dry diethyl ether and 45 g of dry triethylamine (dried over powdered KQH). Trimethylchlorosilane (45 g) was added in 20 min with cooling at about 10°C. After standing for 1 h at room temperature the precipitate was sucked off on a dry sintered-glass funnel and rinsed with pentane. The filtrate was concentrated in a water-pump vacuum- The small amount of salt which precipitated during this operation was removed by a second suction filtration. Subsequent distillation afforded the trimethyl silyl ether, b.p. 100°C/15 mmHg, 1.4330, in 944 yield. 

KO-tert.-C H9-riO-te . -C4H9 was rapidly Sucked off through a sirtered-glass funnel and the precipitate on the filter was rinsed with pentane. The greater part of the pentane and TUF was distilled off from the filtrate through a 30-cm Vigreux column... 

A sample containing 60 mg of Mg + will generate approximately 600 mg, or 0.6 g, of MgNH4P04 6H2O. This is a substantial amount of precipitate to work with during the filtration step. Large quantities of precipitate may be difficult to filter and difficult to adequately rinse free of impurities. 

This is done for the same reason that precipitation is carried out in an ammonical solution using dilute ammonia minimizes solubility losses when rinsing the precipitate. 

Sohd, water-soluble a-hydroxycarboxyhc acid and oxaUc acid titanium complexes can be formed by reaction of the acid and a tetraaLkyl titanate in an inert solvent, such as acetone or heptane. The precipitated complex is filtered, rinsed with solvent, and dried to give an amorphous white soHd, which is water- and alcohol—water-soluble (81,82). 

Soil Leaching. Soil leaching or acid extraction uses acid to solubilize metals for removal from soils, a technique akin to that ia the mining industry. After extraction with an acid such as hydrochloric, sulfuric, or nitric, the soil is separated from the acid, rinsed with water to remove excess acid and metals, dewatered, and neutralized. The acid is regenerated and recycled back to the process. The extracted metals can be precipitated and recovered. 

In a 5-I. round-bottom flask fitted with a reflux condenser, a mechanical stirrer (Note i) and a i-l. separatory funnel, is placed 2800 cc. of absolute ethyl alcohol (Note 2), and to this is added 125 g. (5.4 moles) of sodium over a period of one to two hours. The stirrer is started and the mixture allowed to cool to room temperature (Note 3), and a mixture of 730 g. (5 moles) of ethyl oxalate (Note 4) and 290 g. (5 moles) of acetone (Note 5) is added slowly over a period of two to three hours. At first a white precipitate forms this is followed by a yellow precipitate that darkens as the reaction proceeds and later turns yellow again. The temperature rises to about 40. Toward the end the mixture becomes so thick that stirring is difficult. Stirring is continued for one hour after the addition of the oxalate and acetone mixture. The yellow sodium salt is filtered by suction on two 20-cm. Buchner funnels (Note 6). The reaction flask is rinsed with 200 cc. of absolute ethyl alcohol, which is then used to wash the salt. The filtrate is turbid as a rule, but there is not enough sodium salt in suspension or solution to warrant recovery. 

The crude ketal from the Birch reduction is dissolved in a mixture of 700 ml ethyl acetate, 1260 ml absolute ethanol and 31.5 ml water. To this solution is added 198 ml of 0.01 Mp-toluenesulfonic acid in absolute ethanol. (Methanol cannot be substituted for the ethanol nor can denatured ethanol containing methanol be used. In the presence of methanol, the diethyl ketal forms the mixed methyl ethyl ketal at C-17 and this mixed ketal hydrolyzes at a much slower rate than does the diethyl ketal.) The mixture is stirred at room temperature under nitrogen for 10 min and 56 ml of 10% potassium bicarbonate solution is added to neutralize the toluenesulfonic acid. The organic solvents are removed in a rotary vacuum evaporator and water is added as the organic solvents distill. When all of the organic solvents have been distilled, the granular precipitate of 1,4-dihydroestrone 3- methyl ether is collected on a filter and washed well with cold water. The solid is sucked dry and is dissolved in 800 ml of methyl ethyl ketone. To this solution is added 1600 ml of 1 1 methanol-water mixture and the resulting mixture is cooled in an ice bath for 1 hr. The solid is collected, rinsed with cold methanol-water (1 1), air-dried, and finally dried in a vacuum oven at 60° yield, 71.5 g (81 % based on estrone methyl ether actually carried into the Birch reduction as the ketal) mp 139-141°, reported mp 141-141.5°. The material has an enol ether assay of 99%, a residual aromatics content of 0.6% and a 19-norandrost-5(10)-ene-3,17-dione content of 0.5% (from hydrolysis of the 3-enol ether). It contains less than 0.1 % of 17-ol and only a trace of ketal formed by addition of ethanol to the 3-enol ether. 

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