Effects of Solvent Polarity on the Reaction of Aldehydesand Ketones with a Hydrazide-Bound Scavenger Resin

摘要

Polymer-supported reagents have been extensively studied and used in various applications, such as condensation reactions and multiple component reactions. This paper examines the reactions between a solid-functionalized resin, named Amb15-Iso, and aldehydes and ketones that have been solubilized in different solvents. The reactions between these molecules and a hydrazide (isoniazid) in both neutral and acidic media were also studied. The results showed that the solvent polarity influenced the kinetics of the reaction and the yields of carbonyl compounds that were captured by the resin, particularly, for less-reactive molecules. The reactions using the resin were faster than those using free isoniazid in solution, likely because the acidic sites remaining in the resin can catalyze the reaction, increasing the rate of capture. A high dependence on the presence of acidic compounds and the rate of the reaction was observed, in which trifluoroacetic acid was used to catalyze the reaction between the tested molecules and isoniazid in solution. The differential reactivities of the examined ketones and aldehydes in these condensationreactions demonstrate that the resin can provide selective criteria,preferentially scavenging aldehydes from solution. While benzaldehydereacted quite quickly with the resin, acetophenone barely had anyreaction and remained in solution.