Selective Synthesis of Monoesters of Itaconic Acid with Broad Substrate Scope: Biobased Alternatives to Acrylic Acid?

摘要

Over the last few years, there has been an increasing interest to identify biobased alternatives to acrylic acid in UV-curing materials. In this respect, itaconic acid has drawn considerable attention, due to its structural similarity. However, the second acid group in the molecule limits its use in many applications, as undesired side reactions can occur. One solution is the use of monoesters of itaconic acid to mimic the properties of acrylic acid. However, to date, no general applicable and straightforward synthetic protocol has been reported. Herein, the synthesis of a variety of monoesters of itaconic acid is presented. The methodology tolerates a broad substrate scope, is highly efficient, and does not suffer from tedious purification steps; therefore it can be applied on large scale. In the next step, the monoesters were reacted with epoxidized soybean oil to produce biobased UV-curing oligomers. The influence of the different monoesters on the properties of the functionalized vegetable oils, such as viscosity as well as the reactivity toward UV-light induced radical cross-linking, was studied. In addition, these findings were compared with those of acrylated soybean oil. Despite the lower rate of polymerization of the itaconic acid-based oligomers, the double bond conversion was higher in some cases. In addition, the viscosity was found to be lower in comparison to that of the acrylic acid-derived compound, making these novel monoesters promising alternatives to the petrochemical-based acrylic acid.