Isopropylation of 2-naphthol over mesoporous silicoaluminophosphate-37 (MESO-SAPO-37): the effect of bond dissociation energy on product distribution

Abstract

The vapor phase isopropylation of 2-naphthol (2-NP) with isopropyl alcohol (IPA) in the presence of recently developed mesoporous silicoaluminophosphate assembled from a microporous SAPO-37 precursor (MESO-SAPO-37) was investigated. The bond dissociation energy calculation revealed that the reaction proceeds by O-alkylation followed by rearrangment into C-alkylated products. The presence of a phenolic hydroxyl group facilitates o- and p-directing (1- and 6-positions of 2-NP) and favors 1- and 6-isopropyl-2-naphthols as the major products. The moderately acidic MESO-SAPO-37 showed a maximum 2-NP conversion of 60% achieved with a selectivity of 60% for 6-isopropyl-2-naphthol (6-IP-2-NP) under optimum reaction conditions (T = 250 °C, WHSV = 9.4 h⁻¹ and a 2-NP : IPA ratio of 1 : 20).