The variation in composition and melting point of eutectic mixtures in binary systems formed by acenaphthene with naphthalene homologs is considered. Analysis of the singular points in two ternary systems with acenaphthene-acenaphthene-dibenzofuran-fluorene and acenaphthene-2,7-dimethylnaphthalene-fluorene-indicates their behavior in direct solidification of the acenaphthene fraction. © 2011 Allerton Press, Inc.