Isolation and identification of diisopropylnaphthalene isomers in the alkylation products of naphthalene

GC analysis of diisopropylnaphthalene (DIPN) isomers is presented. Naphthalene was repeatedly alkylated with propylene over an amorphous aluminosilicate catalyst under different preparation conditions, and then pure isomers or at least DIPN fractions enriched in individual isomers were isolated from the alkylates and analysed using GC–MS, IR and NMR techniques. Eight of the ten possible isomers appeared in the chromatograms; seven of them (1,3-, 1,4-, 1,5-, 1,6-, 1,7-, 2,6- and 2,7-) were separated and identified, while the eighth one was indirectly proved to be 2,3-DIPN. The remaining two isomers (1,2- and 1,8-DIPN) were not found in the products.