Vanillin Based Polymers: VI. Poly (hydrovanilloin-furfural) and Poly (hydrovanilloin-5-hydroxymethylfurfural).

Renewable resources based polymers provides a sustainable alternative to petroleum derived polymeric materials. As a part of our series on synthesis of vanillin based renewable polymers, we report the synthesis of poly(hydrovanilloin-furfural) [poly(HVL-Fur)] and poly(hydrovanilloin–5-hydromethylfurfural) [poly(HVL-5-HMF)]. Vanillin was dimerized to a mixtures of meso/DL-hydrovanilloins with 94% meso product by electrochemical reductive coupling in aqueous sodium hydroxide using lead electrodes in quantitative yield. Then sodium hydroxide catalyzed condensation of hydrovanilloin with furfural in water at 80°C for 72 h was used to synthesize poly(HVL-Fur) with Mw = 8600 g mol⁻¹, PDI = 1.28 in 78% yield. Similarly, condensation of hydrovanilloin with 5-hydroxymethylfurfural at 80°C for 48 h produced poly(HVL-5-HMF) with Mw = 12,100 g mol⁻¹, PDI = 1.27 in 68% yield. poly(HVL-Fur) and poly(HVL-5-HMF) showed similar T_g values of 59°C and 60°C, respectively; whereas melting behaviors are dissimilar with T_m 171°C–173°C and 148°C–182°C, respectively. [ABSTRACT FROM AUTHOR]