Fractionating columns semi-micro

Fractional Distillation. Fractional distillation on a semi-micro scale can be carried out satisfactorily with the fractionating column shown in Fig. 39. The column is 10 cm. long and is filled with pieces... 

Fractionally distd through a Widmer column as a mobile liquid and redistilled with a Claisen flask or through a semi-micro column (Gould, Holzman and Neiman AC 20 361 1948. NB It has a strong characteristic disagreeable odour dectectable at low concentrations and causes headaches on prolonged exposure. [IR Cope and Estes JACS 72 1128 1950 UV Cope and Baumgardner JACS 78 2812 7956]. 

A short-path distillation procedure may be used in situations where a simple distillation is required, as purification from non-volatile components/fractional distillation with a Kugelrohr apparatus is difficult. A water-jacketed, semi-micro distillation apparatus is illustrated in Figure 1.7. Heating can either be achieved with the aid of an oil-bath, an isomantle, or a flame (Caution ensure that there are no flammable solvents nearby). For larger scale distillations, a round-bottomed flask should be attached to a distillation column, a still-head, and condenser. The column used in the distillation is variable, and may be either a Vigreux column or a column packed with glass helices. 

The simple Hickman still is used with an O-ring compression cap to carry out semi-micro simple or crude fractional distillations. The Hickman-Hinkle spinning band still uses a 3-cm fractionating column and routinely develops between five and six theoretical plates. The Hickman-Hinkle still is currently available with 14/10 I joints and can be conveniently operated with the 14/10 I 3- and 5-mL conical vials (see Figs. 3.1, 3.3, and 3.7). The still head is also available with an optional sidearm collection port. 

Column dimensions Different column dimensions are available. Most common are analytical SEC columns with an inner diameter between 0.7 and 0.8 cm and a length of 25-30 cm. Columns of 60 cm are still available but rarely used. Preparative columns with the same length but a larger diameter (up to several centimeters) allow to fractionate larger sample amounts. (Semi)micro-columns with... 

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