Synthesis of Alkoxylated Phenolic Resins Containing an Acetyl Group and Their Functionalization by Grignard Reaction

Abstract

We successfully synthesized acetyl group-containing phenolic resins as novel reactive polymers. The addition-condensation of 2,4,6-trimethoxyacetophenone (1) with an equimolar amount of formaldehyde catalyzed by 12mol/L HCl aq. proceeded homogeneously without side reactions to give polymer 3 (Mn 4800, Mw/Mn 1.3) in 32% yield. The FT-IR, 1H NMR and 13C NMR spectra of 3 revealed that it had arylene-methylene units on the polymer backbones. The terpolymerization from 1, 1,3,5-trimethoxybenzene (2) and formaldehyde was also carried out. When the feed ratio of 1 to 2 was 1:1, the content of 1 in the obtained polymer, 4, was found to be 25% by the 1H NMR spectrum; hence, the reactivity of 1 was lower than that of 2. The reactions of 4 with Grignard reagents were carried out to evaluate the reactivity of acetyl groups in the obtained polymers. Their reactions proceeded at some parts of acetyl groups, so 4 can be applied as novel reactive phenolic resins. From thermogravimetric analyses, thermal stabilities of the functionalized polymers (6a-6d) are similar to that of 4, so it is expected that 4 have characters not only of the phenolic resins but also of the reactive polymers.