Why Does the Weak Leaving Group Hydroxyl in Products of the Aldol Condensation Leave Easily
XU Jia-Xi1**, MA Yuan2
1. College of Chemistry, Beijing University of Chemical Technology, Beijing 100029, China; 2. Department of Chemistry, Tsinghua University, Beijing 100084, China
Abstract The hydroxyl group in alcohols is a weak leaving group. It can leave easily only after protonation with acids or formation of complexes with Lewis acids, or transformation into their sulfonates. It cannot depart under basic conditions. However, β-hydroxyaldehydes and ketones, the products of the Aldol condensation, can leave their hydroxyl group to realize dehydration under basic conditions, generating α,β-unsaturated aldehydes and ketones. These differences in dehydration of alcohols frequently cause students’ confusion. This article rationally explains the differences of these two classes of dehydrations of alcohols through analyses of their reaction mechanisms and stereoelectronic effect in the dehydrations (eliminations). It would provide a deeper understanding for students.
XU Jia-Xi, MA Yuan. Why Does the Weak Leaving Group Hydroxyl in Products of the Aldol Condensation Leave Easily[J]. Chinese Journal of Chemical Education, 2024, 45(4): 121-123.
