Simple distillation Hickman head

This experiment can also be performed using a Hickman head, although it is not as easy to monitor the volume of distillate. To perform a simple distillation, refer to Technique 14, Figure 14.7B. For a fractional distillation, see Technique 15, Figure 15.2. For both distillations, use a 10-mL round-bottom flask and a Hickman head with a side port (Technique 14, Figure 14.4B). Attach a water-cooled condenser on top of the Hickman head. It is helpful to tilt the apparatus slightly (5-10 degrees) in the direction of the side port so that the liquid in the reservoir of the Hickman head will flow toward the side port. 

A basic apparatus similar to the one shown in Figure 16.1 may be used for microscale vacuum distillations. As is the case for simple distillation, this apparatus uses the Hickman head as a means to reduce the length of the vapor path. The major difference to be found when comparing this assembly to one for simple distillation (Technique 14, Figure 14.8) is that the opening to the atmosphere has been replaced by a connection to a vacuum source (top right-hand side). The usual sources of vacuum are the aspirator (Technique 8, Section 8.5), a mechanical vacuum pump, or a "house" vacuum line (one piped directly to the laboratory bench). The aspirator is probably the simplest of these sources and the vacuum source most likely to be available. However, if pressures below 10-20 mm Hg are required, a vacuum pump must be used. 

The Hickman still head (Fig. 3.14) is ideally suited for simple distillations.This system has a 14/10 I male joint for connection to conical vids or round-bottom... 

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. 

Microscale spinning-band distillation apparatus (Fig. 5.11) can achieve nearly 12 theoretical plates and are simple enough to be used in the instructional laboratory. This stiU has a Teflon band that fits closely inside an insulated glass tube. The Teflon band has spiral grooves which, when the band is spun (1000-1500 rpm), rapidly return condensed vapor to the distillation pot. A powerful extension of this apparatus uses a short spinning band inside a modified Hickman stiU head (see Fig. 3.15). These stills are called Hickman-Hinkle stills 4-cm Hickman-Hinkle columns can have more than 10 theoretical plates. The commercially available 2.5-cm version is rated at 6 theoretical plates. Experiments [3C] and [3D] involve fractional distillation with spinning-band columns. 

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