Soft and hard acidity in ion-exchanged Y zeolites: rearrangement of 2-bromopropiophenone ethylene acetal to 2-hydroxyethyl 2-phenylpropanoate

The rearrangement of the cyclic ethylene acetal of 2-bromopropiophenone to 2-hydroxyethyl 2-phenylpropanoate is catalysed by zinc exchanged Y zeolites with higher activity than the conventional ZnCl2; hydrolysis of the acetal moiety owing to the Brønsted acid sites is one of the major side reactions, while the competitive formation of 5-methyl-6-phenyl-2,3-dihydro-1,4-dioxine increases with the softness of the Lewis acid centres.