Hydroxyl derivatives of 5-CQA and their complexes with water

• 5-CQA forms two diastereomeric aqueous adducts in its water solution. • 5-CQA aqueous adducts decompose and isomerize in their water solution. • Each 5-CQA aqueous adduct is able to form two hydrates. • Each hydrate of 5-CQA aqueous adducts consists of two 5-CQA-OH and two H 2 O molecules. Although the addition of water without a catalyst to α,β-unsaturated carbonyl compounds is unlikely, the results presented in this paper show that this is not necessarily the case with. 5-CQA. The obtained results demonstrate that 5-CQA forms two diastereomeric hydroxyl derivatives, 5-CQA-OH-1 and 5-CQA-OH-2, which are products of water addition to the. 5-CQA molecule via Michael addition. Each of the hydroxyl derivatives of 5-CQA slowly isomerizes and decomposes in aqueous solution. However, after the evaporation of water from their aqueous solutions, they exist in the form of two hydrates, each consisting of two. 5-CQA-OH molecules and two H 2 O molecules.