Aromatics

Abstract

A start is made with the family of the para-dihalobenzenes, including the key system p-dichlorobenzene + p-dibromobenzene. Special attention is given to the melting behaviour of mixed materials prepared by zone levelling. The family of the dihalobenzenes is followed by the group of the 2-R-substituted naphthalenes which includes naphthalene itself (R = H), and the substances with R = F, Cl, Br, SH, CH3, and OH. It appears that the naphthalene group falls apart into two structural subfamilies. Furthermore, evidence is given of an extra attractive effect between substituted methyl and substituted halogen. In addition, a number of stand-alone systems are discussed, on the basis of which afore-mentioned phenomena are further illustrated. One of these systems is trans-azobenzene + trans-stilbene for which the outcome of lattice energy calculations is also presented.