Spectroscopic and Thermal Characterization of Sodium 10,12‑pentacosadiynoate (PCDA–Na) Derived from 10,12‑Pentacosadiynoic Acid (PCDA)

Sodium 10,12‑pentacosadiynoate (PCDA–Na) was prepared from 10,12‑pentacosadiynoic acid (PCDA) via conventional solution routes using Na₂CO₃ (1:2) and NaOH (1:1). The product was characterized by Fourier‑transform infrared spectroscopy (FT‑IR), X‑ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). FT‑IR showed disappearance of the broad O–H band of PCDA and the emergence of a carboxylate band, confirming deprotonation. XRD patterns exhibited distinct reflections and reduced FWHM for PCDA–Na relative to PCDA, indicative of enhanced crystallinity. DSC–TGA revealed a defined melting transition and a two‑stage decomposition with final weight loss above 500°C. These findings demonstrate that simple salt formation modulates packing and thermal response of diacetylenic acids, informing the design of thermally robust PDA precursors for sensing applications.