Solid-liquid equilibria (SLE) of N,N,N',N'-tetramethylethylenediamine, 1,4-dimethylpiperazine and N,N-dimethylaniline + n-heptane or cyclohexane mixtures were measured by a static method. It was found that all systems are simple eutectic systems. Group contribution models have proved fairly successful in predicting SLE, however, the presence of intramolecular effects (ring effect, proximity effect) renders the widely used empirical methods quite inaccurate. However, in this work, the experimental phase diagrams compared satisfactorily with group contribution models (DISQUAC) and also modified UNIFAC (Dortmund version) predictions.