Catalytic Oxyfunctionalization of Methyl 10-undecenoate for the Synthesis of Step-Growth Polymers

Abstract

An efficient synthesis strategy for the preparation of two renewable polyesters and one renewable polyamide via catalytic oxyfunctionalization of methyl 10-undecenoate, a castor oil derived platform chemical, is described. The keto-fatty acid methyl ester (keto-FAME) is synthesized applying a cocatalyst-free Wacker oxidation process using a high-pressure reactor system. For this purpose, catalytic amounts of palladium chloride are used in the presence of a dimethylacetamide/water mixture and molecular oxygen as sole reoxidant. The thus derived AB monomers (hydroxy-esters, amine-ester) are synthesized from the obtained keto-FAME through Baeyer–Villiger oxidation and subsequent transesterification, reduction, or reductive amination, respectively. The resulting AB step-growth monomers are then studied in homopolymerizations using 1,5,7-triazabicyclo[4.4.0]dec-5-ene, DBU, and titanium(IV) isopropoxide as transesterification catalyst, yielding polymers with molecular weights (Mn) up to 15 kDa. The polyesters and the polyamide are carefully characterized by FTIR, SEC, 1H-NMR spectroscopy, and differential scanning calorimetry analysis.