Phase-transfer catalyzed cyanoethylation of resorcinol–formaldehyde resin: Synthesis and characterization

Abstract

In the current research, a novel cyanoethylated resorcinol–formaldehyde resin (RF-CN) was synthesized through phase-transfer catalysis (PTC) using acrylonitrile. The degree of cyanoethylation (DCE) was optimized through reaction condition manipulation and confirmed by gravimetry analysis, elemental analysis, and FTIR spectroscopy. Solid-state ¹³C NMR also confirmed structural modification through characteristic resonances of the introduced –CN groups. Morphological analysis via SEM displayed conspicuous changes in surface texture and porosity upon modification. Thermogravimetric analysis (TGA) demonstrated enhanced thermal stability of RF-CN through a two-stage degradation profile compared to the single-stage degradation of pure RF. Thermodynamic parameters (ΔG°, ΔH°, and ΔS°) and Van't Hoff analysis attested to the spontaneity and endothermicity of the functionalization under PTC. Kinetic studies via initial rate measurements allowed the estimation of activation energy, testifying to the catalytic efficiency of benzyltriphenyl phosphonium chloride (BTPP) in lowering the energy barrier of the reaction. Further, the versatility of RF-CN as a platform was testified by nucleophilic post-functionalization with hydroxylamine and salicylic acid hydrazide to give amidoxime (AOX-RF) and hydrazidine (SAH-RF) derivatives. The derivatives were characterized neatly by elemental analysis, FTIR, and ¹³C NMR, testifying to successful incorporation. Overall, this study describes a systematic approach to the design of functionalized RF-based sorbents with tunable properties for advanced applications.