Drying and ‘water, removal

Sohds in divided form, such as powders, pellets, and lumps, are heated and/or cooled in chemical processing for a variety of objectives such as solidification or fusing (Sec. 11), drying and water removal (Sec. 20), solvent recoveiy (Secs. 13 and 20), sublimation (Sec. 17), chemical reactions (Sec. 20), and oxidation. For process and mechanical-design considerations, see the referenced sections. 

Molecular sieves are used in a variety of fuel processing applications. Uses include drying and water removal from fuel, product purification, hydrocarbon separation and catalysis. Molecular sieves are composed of sodium and calcium aluminosilicate crystals which have been produced from natural or synthetic zeolite compounds. The crystals are dehydrated through heating and are processed to ensure that pore sizes are tightly controlled. 

Dissolve 1 g. of the secondary amine in 3-5 ml. of dilute hydrochloric acid or of alcohol (in the latter case, add 1 ml. of concentrated hydrochloric acid). Cool to about 5° and add 4-5 ml. of 10 per cent, sodium nitrite solution, and allow to stand for 5 minutes. Add 10 ml. of water, transfer to a small separatory funnel and extract the oil with about 20 ml. of ether. Wash the ethereal extract successively with water, dilute sodium hydroxide solution and water. Remove the ether on a previously warmed water bath no flames should be present in the vicinity. Apply Liebermann s nitroso reaction to the residual oil or solid thus. Place 1 drop or 0 01-0 02 g. of the nitroso compovmd in a dry test-tube, add 0 05 g. of phenol and warm together for 20 seconds cool, and add 1 ml. of concentrated sulphuric acid. An intense green (or greenish-blue) colouration will be developed, which changes to pale red upon pouring into 30-50 ml. of cold water the colour becomes deep blue or green upon adding excess of sodium hydroxide solution. 

If the compound itself is desired, the salt is dissolved in water and the solution saturated with a mild alkali such as potassium carbonate. The product is then extracted with chloroform, dried, and after removal of the chloroform, distilled. 

Warm to dissolve 1.5 g 2,3-dihydro-LSD in 5 ml acetone, 40 ml water and 40 ml saturated NaHC03. Cool to 20° and add all at once with vigorous stirring 2.46 g potassium nitro-sodisulfonate dissolved in 90 ml water and 10 ml saturated NaHC03. After 1 minute, extract 7 times with ethylacetate, wash the combined extracts with water, dry and carefully remove solvent to get a mixture of 12-OH-LSD, LSD and starting material which can be chromatographed to give about 0.2 g 12-OH-LSD. 

Nonfat dry milk has only its fat and water removed. Federal standards of identity in the United States and FAO/WHO allow a maximum of 5% moisture and not more than 1.5% milk fat (FDA 1981A FAO 1973). 

A high quality of oxygen and water removal is more easily maintained. Attainment of 10 4 torr vacuum may require several hours for large cells, but it is a simple matter to maintain routinely less than a 1 ppm level of oxygen (we have successfully maintained less than 0.1 ppm oxygen as determined with a Chemtrix model 30 oxygen meter) in the inert atmosphere of the dry box. 

The final process of solvent removal, known as drying, can be conducted by two methods "air-dry and "water-dry . There is also a "continuous air-dry method , which is used in conjunction with "water-dry method ... 

Lastly, besides inconsistency in the polymer and additives, there may be fortuitous differences between mixes of what supposedly is the same composition—such as the water content changing between summer and winter (or by night and day under some climatic conditions). Thus, provision must be made for drying and the removal of other volatiles, and (especially if the processing is by batches and components are held in store at intermediate stages) drying may be required at more than one point in the manufacture. 

The product from Step 1 was added to a mixture of 400 g 85% H3PO4 and 650 g P2O5 then heated to 90-95 °C 4 hours. The mixture was hydrolyzed with water, extracted with diethyl ether, and a 65% yield of crude product isolated. The material was purified by dissolving in 100 ml HO Ac, 100 ml water and 10 ml concentrated HCl and refluxing overnight. After neutralization, drying, and solvent removal the product was isolated in 64% yield. 

Radiostearic acid was adsorbed from n-hex-adecane onto mica and thin vapor-deposited films of iron, gold, and copper that had been exposed to dry and water-saturated helium or air. Adsorption was measured directly and continuously by a recently developed technique. The mica substrate showed essentially zero adsorption. None of the metals adsorbed more than one stable compact monolayer. Iron and gold showed a large difference in adsorption in dry helium or air, but adsorbed about the same amoxmt, 0.2 to 0.5 monolayer, when exposed to either wet helium or air. Copper adsorbed 0.3 to 0.7 monolayer in all atmospheres except wet air, in which it showed a weak adsorption of nine monolayers rinsing with hexaiie removed all but one monolayer. 

For solvents more volatile than water (e.g. methanol, acetone) fractionation may serve the double purpose of drying and simultaneously removing less volatile impurities and colour bodies. It will also remove any diacetone alcohol or dimethyl ether which may be formed during processing. 

In adsorption chromatography (NPLC), control of the water content in solvents is important. In some cases, it is preferred to mix known amounts of dry and water saturated solvents together in order to know or control the percentage of water saturation. On the other hand, addition of activated molecular sieve beads (4 A or 5 A) to the solvent storage bottle clearly improves their purity and reduces the water content, hnpiu ities, in addition to water, can often be removed by adsorption methods, particularly frontal analysis, which is utiHzed often in LC. 

The appropriate diethyl ester (22 mmol) was dissolved in 40 ml of 6N HCl and 10 ml of water and refluxed for 4 h. Evaporation in vacuo and addition of benzene (200 ml) followed by refluxing and water removal with a Dean-Stark trap gave a suspension which was filtered and dried under vacuum to produce the hygroscopic hydrochloride salt. 

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