Heats and Temperatures of Transition of Some Aromatic Liquid Crystal-Forming Materials

The heats and temperatures of transitions were measured for five pure compounds which were known or expected to form mesophases or liquid crystals. The five compounds were N-(p-cyanobenzal)-p-anisidine, p-(4-cyanobenzalamino)-cinnamic acid-active amyl ester, N, N'-tereph-thalylidene-di-p-toluidine, p-acetoxy-cinnamic acid, and p-[N-(p-methoxy-benzylidine)-amino]-phenyl acetate. Temperatures of transition for the compounds are reported here for the first time using a well-calibrated differential thermal analyzer. Heats of transitions for the compounds have not been previously reported. They were measured here by differential scanning calorimetry. Tests were made for phase reversibility of the multiple transitions and the possible changes in heats and temperatures of transition with sample origin, i.e., solvent or melt crystallized.