Menthone 1,2-glycerol ketal is synthesized by the condensation of the carbonyl group of menthone with the hydroxyl group of glycerol under acid catalysis to form a hemiketal. The resulting hemiketal is unstable and will directly condense with the unreacted hydroxyl group of glycerol to form Menthone 1,2-glycerol ketal and one molecule of water. This process is reversible, so timely removal of water from the reaction system can significantly improve the reaction efficiency. The synthetic route of Menthone 1,2-glycerol ketal is shown in Figure 1.
Figure 1 Synthetic route of Menthone 1,2-glycerol ketal (6-isopropyl-9-methyl-1,4-dioxospiro[4,5]decane-2-methanol)
In addition, menthone will also condense with the hydroxyl group on Menthone 1,2-glycerol ketal to form a polymer.
This reaction is thermodynamically driven; as temperature increases, the polymer content increases significantly, indicating it is a byproduct of the synthesis of Menthone 1,2-glycerol ketal.
