Staircase construction

The series of inclusion compounds formed by 6 differ in the details of their staircase construction and guest inclusion, but their common feature is the PHD interaction involving pairs of opposite enantiomers. Between these step pairs, however, there may be a twofold axis or no symmetry at all. In some examples, such as (6)4-(benzene), there are two independent molecules (A and B) in the asymmetric unit. The staircase structure now contains both A-A and B-B PHD interactions (where indicates the enantiomer of opposite handedness), as illustrated in Figure 4. 

Modified McCabe-Thiele diagrams for acetaldehyde and 2-butanol are shown in Figure 14.28 and 14.29. Note that the staircase construction that represents the trays in the real column does not touch the equilibrium line. The length of each horizontal step compared to the distance from the rather curved operating line to the equilibrium line is a measure of... 

Fig. 2.3.2-9 Balance lines and staircase construction, a) Minimum reflux ratio, infinite plate number, b) Finite reflux ratio, resp. finite plate number, c) Total reflux, minimum plate number.

For V going to infinity the rectification line becomes a diagonal with y = x. In this case, the smallest number of plates is required, as shown by the staircase construction (Figure 2.3.2-9, bottom). 

Fig. 5.9 shows the geometric representation of these balances in the McCabe-Thiele diagram. The distillate composition xP is located at the intersection of the condenser operating line and the operating line of the RD section. By specifying xP, the number of reactive trays can be estimated from the classical staircase construction. From the intersection of the operating line of the column section with that of the reboiler line, the bottom composition is determined. 

The number of stages between feed and effluent is obtained by the usual staircase construction and equals approximately four. The corresponding HETS value is then given by... 

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