Affinity support, scale

Liquid-liquid extraction is a basic process already applied as a large-scale method. Usually, it does not require highly sophisticated devices, being very attractive for the preparative-scale separation of enantiomers. In this case, a chiral selector must be added to one of the liquid phases. This principle is common to some of the separation techniques described previously, such as CCC, CPC or supported-liquid membranes. In all of these, partition of the enantiomers of a mixture takes place thanks to their different affinity for the chiral additive in a given system of solvents. 

In the chromatography technique, proteins bind differentially to solid matix supports or media with various functional groups to provide hydrophobic, ion-exchange, and affinity interactions. Some of the matrices used for intermediate purification that provide sufficient flow rate for large-scale purification are listed in Table 4.13. Some of the functional groups attached to matrix supports and examples of proteins purified by these matrix supports are fisted in Table 4.14. The chromatography technique should provide high capacity and selectivity. The matrix material must withstand multiple purification cycles with minimum loss of efficiency. 

Wang and Charles Han calculated the electron affinities of aldehydes and ketones by using the parameterized Huckel theory. Eight parameters were used to calculate the electron affinities of 16 compounds with a deviation of only 0.05 eV. However, some of the data were not published until the 1970s [35]. By measuring relative electron capture coefficients and scaling to the acetophenone data, more precise electron affinities could be obtained. This was further support for the validity of the ECD model. M. J. S. Dewar reproduced the experimental electron affinities of aromatic hydrocarbons using the MINDO/3 method and calculated Ea from reduction potentials [36]. 

The electron affinities of the chlorobenzene isomers have been determined by scaling half-wave reduction potentials [22], With higher gas phase values higher values are obtained from reduction potentials. These are compared to the ECD and CURES-EC values in Table 11.9. The CURES-EC-calculated values for the above compounds support experimental quantities and suggest that the Ea of all halogenated benzenes can be calculated. The CURES-EC values are listed in Table 11.10. The Ea... 

The electron affinities of several chlorinated biphenyls and chlorinated naphthalenes have been determined from half-wave reduction potentials [22]. The electron affinity of 1-C1 naphthalene measured in the ECD has been used to scale the values for the other chloronaphthalens. The solution energy differences were set to the same value, 2.05(5) eV, for compounds with the same number of chlorine atoms up to three chlorines. For four or more chlorines up to the fully chlorinated naphthalene the mddG is 1.95(5) eV. For the fully chlorinated compound the mddG is 1.85(5) eV. This gives for Ea a range of 0.3 to 1.57 eV or 0.2 eV/Cl atom from naphthalene to the fully chlorinated naphthalene. The CURES-EC calculations support these values. They are given in Table 11.11. 

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