Polymer ester condensation, mixed

Esdiweiler s. Clarke Ester condensation s. Dieck-mann cyclization —, mixed, on polymer support 6, 738 suppl. 27... 

The solubility coefficients make interesting contributions to the permeabilities. The solution process of these gas phase permeants can be separated for analysis into two components -condensation and mixing. Table III contains the heats of condensation for the experimental esters. Table III also contains the heats of solution in the polymer films from linear fits of the data in Figures 10 and 15. Finally, Table III contains the heats of mixing for the esters in the films. The heats of mixing were calculated using equation 9. 

The claim that site-separation is achieved in the reactions discussed earlier has been questioned (Crowley and Rapoport, 1976 Neckers, 1978). According to these authors, the Claissen condensation of two molecules of an ester resulting in self-condensation cannot be expected to compete with acylation using acid chlorides or acid anhydrides (more powerful acylating agents). Hence, the formation of mixed ketones as the major product cannot be attributed mainly to site-separation. Furthermore, if site-separation did take place by polymer binding, then why were self-condensation products formed in other reactions The evidence for effective site-separation is contradictory because self-condensation has taken place in some cases and not in others. This difference is better explained in terms of a competitive reaction that takes place in one case and not in the other. 

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