Mechanism of 1-acetyl-2-methoxynaphthalene isomerisation over a HBEA zeolite

Over HBEA, liquid phase acetylation of 2-methoxynaphthalene (2-MN) by aceti c anhydride leads directly to 1-acetyl-2-methoxynaphthalene (I), to 2-acety l-6-methoxynaphthalene (II), and to a small amount of 1-acetyl-7-methoxynap hthalene (III). At a long contact time, isomer I undergoes deacylation into 2-MN and isomerisation into II and III. Isomerisation of I is much faster in the presence of 2-MN than in its absence, which suggests that this react ion occurs through an intermolecular transacylation mechanism. The transfor mation of isomer I with a deuterated methoxy group (OCD3) in the presence o f 2-MN shows that isomer II results only from this mechanism whereas an int ramolecular mechanism participates also in the formation of isomer III. (C) 2000 Academic Press.