Spectroscopic and thermal characterization of chemically modified 10,12-pentacosadiynoic acid (PCDA) and its sodium salt (PCDA-Na)

Sodium 10,12-pentacosadiynoate (PCDA-Na) was synthesized from 10,12-pentacosadiynoic acid (PCDA) using Na₂CO₃ (1:2) and NaOH (1:1) routes. Comprehensive characterization by FT-IR, PXRD, DSC, TGA, and elemental analysis confirmed salt formation. FT-IR revealed Δν = 146 cm⁻¹ for ionic COO⁻, PXRD showed 44% crystallite size increase, and TGA identified decarboxylation (33.6%) followed by diacetylene decomposition (36.2%). These findings establish PCDA-Na as a thermally robust (stable to 195 °C) PDA precursor with enhanced crystallinity, addressing the gap in alkali metal diacetyleneate thermal-structure relationships for sensor applications.