P. Moreau et al., SELECTIVE DIALKYLATION OF NAPHTHALENE WITH HINDERED ALKYLATING-AGENTSOVER HM AND HY ZEOLITES UNDER LIQUID-PHASE CONDITIONS, Catalysis today, 31(1-2), 1996, pp. 11-17
Liquid-phase alkylation of naphthalene with cyclohexyl derivatives as
alkylating agents has been studied over HM and HY zeolites. The reacti
on can be carried out efficiently over HY zeolites, for which high con
versions and good selectivities in 2,6- and 2,7-dicyclohexyl naphthale
nes (DCN) are obtained after very short reaction times. The ratio 2,6-
DCN/2,7-DCN is near to 1, as in the case of the isopropylation reactio
n over the same catalysts. Such a result is in agreement with the valu
es of critical diameters of 2,6- and 2,7-dicyclohexyl and diisopropyl
naphthalenes, calculated by molecular mechanics. The 2,6-dicyclohexyl-
naphthalene is a crystalline compound which is easily separated from t
he reaction mixture by crystallization, which constitutes an interesti
ng advantage of cyclohexylation in comparison with isopropylation.