Role of various types of shape-selectivity in catalysis, exemplified by diisopropylnaphthalene isomers

Robert BRZOZOWSKI* – Industrial Chemistry Research Institute, Warsaw, Poland
Please cite as: CHEMIK 2016, 70, 5, 310–317

Reactions of diisopropylnaphthalene (DIPN) synthesis are excellent examples how we can control isomeric composition of the product by exploiting shape-selectivity phenomenon and selecting proper reaction conditions. Moreover, these reactions are excellent examples illustrating main types of shape selectivity, such as substrate selectivity, product selectivity or transition state selectivity and also they prove an important role of the external surface of crystals and pore entrances.

A mixture of DIPN isomers can be obtained e.g. by alkylation of naphthalene with propylene. Scheme of the reaction is shown in Figure 1. Initially naphthalene is alkylated to monoisopropylnaphthalene (IPN) and aromatic nucleus is preferentially alkylated in alpha-position to give 1-IPN. 2-IPN isomer is mainly formed by 1-IPN isomerization. It is caused by the fact that 1-IPN is kinetically preferred but 2-IPN is thermodynamically more stable. In the second step of the reaction IPN is alkylated to give DIPN isomers mixture.

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