Fractionating-column packing, glass

Note 1). The mixture is heated with a mantle with stirring for 32 hr under a 50-cm fractionating column packed with 5-nm glass beads and topped by a Dean-Stark trap. The reaction mixture is then distilled through the packed column. The fraction which boils at 120 -126°C is collected. The yield is 86.0-87.3 g (77-78%) of 2,2-dimethyl-4-pentenal (1) as a clear, colorless oil, n 1.4216 (Note 2). 

Separation of the hexachlorodisiloxane (b.p. 137°) from unreacted silicon tetrachloride is accomplished by distillation. A 40-cm. fractionating column packed with glass helixes and provided with a heating jacket is suitable. The distillation is started cautiously since much dissolved chlorine is expelled initially. Care. Use a fume hood ) Silicon tetrachloride (b.p. 57°) will pass up the column with little or no heat applied to the jacket. When the bulk of the tetrachloride has passed over, the heat to the flask and the column jacket is increased carefully so that distillation continues steadily. The product passing over at 135 to 138° is collected and redistilled if desired. The recovered silicon tetrachloride may be recirculated. 

Benzylamine [I00-46-9J M 107.2, b 178 /742mm, 185 /768mm, d 0.981, n 1.5392, pK 9.33. Dried with NaOH or KOH, then distd under N2, through a column packed with glass helices, taking the middle fraction. Has also been distd from zinc dust under reduced pressure. 

HCl, water, 10% aqueous NaHS03, and then water. Dried with CaCl2, Na2S04 or anhydrous K2CO3, and fractionally distd through a Im column packed with glass helices. 

Fractionally distd through a 4-ft column packed with glass helices. Ppted as its oxalate from diethyl ether soln. After crystn from 95% EtOH, the salt was decomposed with aqueous saturated NaOH, and the free base was distd, dried over BaO and redistd [McBride and Kruse 7 Am Chem Soc 79 572 1957]. Distn and storage should be under nitrogen. 

Steam distd from a soln containing 1-2 equivalents of 20% H2SO4 until about 10% of the base had been carried over with the non-basic impurities, then the acid soln was made alkaline, and the base separated, dried with NaOH and fractionally distd twice. Dried with Na and fractionally distd through a Todd column packed with glass helices (see p. 174). 

Dried with molecular sieves for 2days, then distd under reduced pressure through a column packed with glass helices. Fractionally crystd by partial freezing and the solid portion was vac distd. 

Phenyl trimethylsilylmethyl sulfide 196.4, b 48 /0.04mm, 113-115 /12mm, 158.5 /52mm, d" " 0.9671, Hq 1.5380. If the sample is suspect then add H2O, wash with 10% aqueous NaOH, H2O again, dry (anhydrous CaCl2) and fractionally distil through a 2ft column packed with glass helices. [J Am Chem Soc 76 3713 1954.]... 

The term porosity refers to the fraction of the medium that contains the voids. When a fluid is passed over the medium, the fraction of the medium (i.e., the pores) that contributes to the flow is referred to as the effective porosity of the media. In a general sense, porous media are classified as either unconsolidated and consolidated and/or as ordered and random. Examples of unconsolidated media are sand, glass beads, catalyst pellets, column packing materials, soil, gravel and packing such as charcoal. 

Setups for simple and fractional distillation at atmospheric pressure are shown (Fig. A3.13). A 30-cm Vigreux column (Fig. A3.13b) is convenient if the components boil at least 50° apart at atmospheric pressure. For better separation, a column packed with glass helices is suitable. All columns employed in fractional distillation should be wrapped or jacketed to minimize heat loss. 

The material which is collected is redistilled through a 90-cm. vacuum-jacketed column packed with glass beads (5 mm.) using a 1 10 reflux ratio. The fraction, b.p. 80-100°, is redistilled through the same column to give 353-386 g. (77-84%) of di-chloromethyl methyl ether, b.p. 82-85.5°, 20d 1.4303 (Note 5). 

The system is evacuated to a pressure of 5-10 mm., and the tube is heated to 700°, measured at the center of the heated zone. 2-Chloro-2,3,3-trifluorocycIobutyl acetate is admitted at the rate of 10-20 g. per hour. From 70 g. (0.35 mole) of the cyclobutyl acetate there is obtained 62-68 g. of mixed solid and liquid condensate (Note 10). Fractionation through a 30-cm. column packed with glass helices affords 30-35 g. (60-70%) of 1-chloro-1,4,4-trifluorobutadiene (Note 11), b.p. 50-51°, 1-3870 18-22... 

Piperidine obtained from Eastman Kodak was fractionated through a 90-cm. column packed with glass helices, and the fraction distilling at 105° was used for this work. This material contained approximately 0.36 wt.% of pyridine as indicated by vapor phase chromatography and ultraviolet analysis. 

The fractions may be analyzed by gas chromatography for absence of solvent. For gas chromatographic analysis a 300 cm. by 0.3 cm. glass column packed with XE-60 (1.5% vjjw) coated on Chromosorb G AW DCMS (80/100 mesh) was employed. 

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