Synthesis of cyclic α-pinane carbonate - a potential monomer for bio-based polymers

This work reports the first known synthesis of alpha-pinane carbonate from an alpha-pinene derivative. Pinane carbonate is potentially useful as a monomer for poly(pinane carbonate), which would be a sustainable bio-based polymer. alpha-Pinene is a major waste product from the pulp and paper industries and the most naturally abundant monoterpene in turpentine oil. alpha-Pinene is routinely converted to pinene oxide and pinanediol, but no study has yet demonstrated the conversion of pinanediol into alpha-pinane carbonate. Here, alpha-pinane carbonate was synthesised via carboxylation of alpha-pinanediol with dimethyl carbonate under base catalysis using triazabicyclodecene guanidine (TBD). 81.1 +/- 2.8% alpha-pinane carbonate yield was achieved at 98.7% purity. The produced alpha-pinane carbonate was a white crystalline solid with a melting point of 86 degrees C. It was characterised using FTIR, NMR, GCMS and a quadrupole time-of-flight (QTOF) mass spectrometer. The FTIR exhibited a C=O peak at 1794 cm(-1) confirming the presence of a cyclic carbonate. GCMS showed that the alpha-pinane carbonate fragments with loss of CO2, forming pinene epoxide. Base hydrolysis of the alpha-pinane carbonate using NaOH/ethanol/water regenerated the pinanediol with formations of Na2CO3.