Lithium C₁–C₁₂ n‑Alkanoates: Thermal Behavior from −30 °C to 600 °C

The lithium C₁–C₁₂ n-alkanoates (Li-carboxylates) were synthesized, and their thermal behavior was studied over the temperature range t/°C = (−30 to 600). Infrared and Raman spectroscopy indicated that the C₃–C₁₂ Li-carboxylates exist in two different configurations and that these configurations persisted after melting. In both configurations the equivalence of the C–O bonds were retained. Evidence for covalent character of the Li–O bond was found only for lithium methanoate. Solid–solid phase transitions were observed for all C₁–C₁₂ Li-carboxylates, with the exception of lithium butanoate, hexanoate, and octanoate. No liquid crystal phases were found for any of the C₁–C₁₂ Li-carboxylates. These observations were consistent with literature. A previously unreported solid–solid transition at temperature t/°C = (41.3 ± 0.3) with enthalpy ΔH/kJ·kg^–1 = (2.8 ± 0.1) was observed for lithium dodecanoate. The melting points of the C₁–C₂ Li-carboxylates were t/°C = (272 and 283) respectively. For the other Li-carboxylates, the melting points decreased monotonically from t/°C = (331) for lithium propanoate, to t/°C = (227) for lithium dodecanoate. The experimental values for melting point temperature and enthalpy of melting were consistent with literature. Thermal decomposition produced lithium carbonate (Li₂CO₃) as solid residue and took place at t/°C = (380 to 390) for C₁–C₂ Li-carboxylates and t/°C = (450 to 485) for C₃–C₁₂ Li-carboxylates.