Moisture by distillation

A solution of 2 grams of A -19-norandrosten-3,17-dione and 0.4 gram of pyridine hydrochloride in 50 cc of benzene free of thiophene was made free of moisture by distilling a small portion 4 cc of absolute alcohol and 4 cc of ethyl orthoformate were added and the mixture was refluxed during 3 hours. 5 cc of the mixture were then distilled and after adding an additional 4 cc of ethyl orthoformate the refluxing was continued for 2 hours longer. The mixture was evaporated to dryness under vacuum and the residue was taken up in ether, washed, dried and evaporated to dryness. The residue was crystallized from... 

A solution of 2 grams of A4-19-norandrosten-3,17-dione and 0.4 gram of pyridine hydrochloride in 50 cc of benzene free of thiophene was made free of moisture by distilling a small portion 4 cc of absolute alcohol and 4 cc of ethyl orthoformate were added and the mixture was refluxed during 3 hours. 

Another method is to determine the moisture by distillation with toluene or xylene in a Dean and Stark apparatus (p. 803), adding 10 g of lump resin, stearic acid, or anhydrous barium chloride to prevent frothing. 

The direct measurement of moisture by distillation with an immiscible solvent is of wide application and is of considerable use in pharmaceutical analysis, particularly when gravimetric determination is interfered with by the presence of other volatile matter or by decomposition of the substance. The method is rapid and has been shown to be capable of considerable accuracy. Water of hydration is removed by this method. 

The moisture present in commercial benzene may be conveniently removed by distilling oS about one-tenth of the liquid the first fraction contains all the moisture. It is generally unnecessary to distU the remaining liquid before use unless the technical benzene is suspected of being highly impure. 

Iodine monochlorlde may be prepared as follows. Pass dry chlorine into 127 g. of iodine contained in a 125 ml. distilling flask until the weight has increased by 34-6 g. The chlorine should be led in at or below the surface of the iodine whilst the flask is gently shaken it is essential to have an excess of iodine. Distil the iodine chloride in an ordinary distillation apparatus use a filter flask, protected from atmospheric moisture by a calcium chloride (or cotton wool) guard tube, as a receiver. Collect the fraction b.p. 97-105° the jdeld is 140 g. Preserve the iodine monochloride in a dry, glass-stoppered bottle. 

Chelated titanates are made simply by mixing the chelating agent with TYZOR TPT or another alkoxide. The Hberated alcohol is usually left in the product to maintain the products fluidity. It may, however, be removed by distillation if desirable. Organic titanates are normally shipped in 208-L dmms, totes, cylinders, or tank tmcks. Most titanates are moisture-sensitive and must be handled with care, preferably under dry nitrogen. 

The quaHty of the feedstock is important since it affects not only the product quaHty but the rate of hydrogenation. Some of the impurities that affect the rate are sulfur, phosphoms, haHdes, polyethylene, and moisture. Impurities are usually removed by clay treatment or by distillation (30). 

Dried with CaH2, then passed through a column of silica gel to remove oleFinic impurities and fractionally distd. Freed from peroxides and moisture by refluxing with sodium, then distilling from LiAlH4. Alternatively, peroxides can be removed by treatment with aqueous ferrous sulfate and sodium bisulfate, followed by solid KOH, and fractional distn from sodium. 

Methyl-dibenzo[b,fl azepine (4.1 g), N-diethylaminoborane (1.7 g) and freshly distilled toluene (150 cc) are introduced into a 500 cc three-neck flask equipped with a dropping funnel and a condenser, and protected against moisture by a calcium chloride guard tube. The solution Is heated under reflux (110°C) for 22 hours under a nitrogen atmosphere and then cooled. A 2N aqueous sodium hydroxide solution (33 cc) is then run in followed by an... 

Virtually identical results (within 0.1%) were obtained by distillations with toluene and benzene, and by the DeBruyn method. It is surprising to note from Figure 8 that constant values for moisture were obtained at the high distillation temperatures of 80° and... 

Figure 8. Determination of Moisture in Corn by Distillation Methods (28)...

Ibid, E170 (Electrolytic Hygrometer Method) Ibid, E171-L to E172-L (Moisture Determination in Propellants and Explosives by Distillation Method) Ibid, E172-L to E173-L (Moisture Determination in Propellants and Explosives by the Karl Fischer Method)... 

Styrene monomer was purified by vacuum distillation over CaHi. Inhibitor in styrene was removed using activated alumina. N-heptane was purified by distillation over sodium to remove tire trace of residual moisture. The purified slyreaie and n-heptane were stored over activated alumina under nitrogen blanket. Et[Ind]2ZrCl2 Strem Chem.), MAO (modified methylaluminoxane, type 3A, Akzo Novel) wee used without fiirtha" purification. 

Tetrahydrofuran from E. I. du Pont de Nemours and Company can be dried conveniently by adding to it lithium aluminum hydride in small portions until no further reaction (evolution of hydrogen) ensues. After the mixture has been stirred for a few minutes, most of the tetrahydrofuran is distilled from it with stirring (to prevent bumping) (Note 3), and collected in a receiver protected from moisture by a calcium chloride tube. 

Benzene is conveniently dried by slowly distilling about 20% of it and cooling the residue with protection from atmospheric moisture by use of a calcium chloride tube. 

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