Fenske helices

Supplied inter alia by the Hydronyl S fndicate Ltd. tuch as Fenske helices are described in S tion 11,17. 

To the cooled mixture 6N hydrochloric acid is added drop wise with stirring, until no solid remains. The organic layer is separated, washed four times with 30-ml. portions of water (Note 6), dried over powdered calcium chloride (Note 7), and distilled through a 1 X 15 cm. column packed with Fenske helices (Note 8). The yield of benzene is 5.5-6.5 g. (70-83%), b.p. 80-82°, n20d 1.5007. The fraction boiling at 82-180° contains no unreacted chlorobenzene (Notes 9, 10, 11). 

Supplied inter alia by the Hydronyl Syndicate Ltd. More expensive column packings, such as Fenske helices, are described in SMtion 11,17. 

Isolation of Volatiles. An aliquot of blended pulp (1.2 kg) was diluted with distilled water (700 mL) in a 3-L three-neck flask and vacuum distilled (25-30°C/l mm Hg). Distillation continued for 2.5 to 3 h yielding approximately 500 mL of distillate which was collected in two liquid nitrogen cooled traps. A total of 3.6 kg of fruit pulp was distilled in three batches. The distillates were combined and immediately frozen until use. The combined distillate was extracted in 250 mL batches for 20 h with 60 mL trichloro-fluoromethane (Freon 11, b p 23.8°C) using a continuous liquid-liquid extractor. The trichlorofluoromethane was distilled through a 120 x 1.3 cm glass distillation column, packed with Fenske helices, prior to use. Each extract was carefully concentrated to approximately 100 pL by distillation of solvent using a Vigreux column (16 cm), and a maximum pot temperature of 30°C. 

It was an obvious step also to make such helices of glass (Fenske helices). The writer carried out some tests on closely-wound glass spirals of 4x4x0.3 and 7 X 7 X 0.3 mm at atmospheric pressure with benzene-CXH mixture and obtained the results shown in Table 71. They are available as both single and multi-turn helices. 

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