Glass helices

However, where small quantities of liquids are involved, a column filled with glass helices will probably give the best results and the cost will not be unduly high. Rings in stainless steel and other metals can be purchased in sizes from to i. ... 

Fig. II, 17, 2 illustrates a fractional distillation unit f for use with glass helices. The column is provided with an electrically-heated jacket the resistance shown in the Figure may be replaced by a variable transformer. The still head is of the total-condensation variable take-off type aU the vapour at the top of the column is condensed, a portion of the condensate is returned to the column by means of the special stopcock (permitting of...

The packing for the other columns consists of 4 mm. glass helices. 

The checkers found that the distillate contained 15-30% butyraldehyde (as monitored by NMR), which depended upon the efficiency of the distillation, A 10-cm column packed with glass helices was the most efficient, hut the yield of distilled product dropped drastically. 

A Vigieux-type column 60 cm. in length and 2 cm. in outside diameter was used for the fractionation. The submitters state that they have also used a column of similar dimensions, packed with glass helices, for a fractionation at atmospheric pressure. They recommended the Vigreux column under reduced pressure, as used by the checkers. 

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. 

Washed with 10% (vol) aqueous H2SO4 (three times), 10% aqueous KOH (three times), and then with water until neutral. Dried with MgS04 and fractionally distd from CaH2 through a glass helices-packed column under reduced pressure. 

Chlorotoluene [95-49-8] M 126.6, b 159 , d 1.083, n 1.5255. Dried for several days with CaCl2, then distd from Na using a glass helices-packed column. 

Crotyl bromide [29576-14-5] M 135.0, b 103-105 /740mm, n s 1.4792. Dried with MgS04, CaC03 mixture. Fractionally distd through an all-glass Todd column. [Todd column. A column (which may be a Dufton type, fitted with a Monel metal rod and spiral, or a Hempel type, fitted with glass helices) which is surrounded by an open heating jacket so that the temperature can be adjusted to be close to the distillation temperature (Todd Ind Eng Chem (Anal Ed) 17 175 1945)]. 

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. 

Epoxybutane [106-88-7] M 72.1, b 66.4-66.6 , d 0.837, n 1.3841. Dried with CaS04, and fractionally distd through a long (126cm) glass helices-packed column. The first fraction contains a water azeotrope. 

Furfurylamine (2-aminomethylfuran) [617-89-0] M 97.1, b 142.5-143°/735mm, d 1.059, n 1.489, pK3 8.89. Distd under nitrogen from KOH through a column packed with glass helices. 

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. 

Refluxed with sodium wire, then fractionally distd twice through a Fenske (glass helices packing) column. 

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