Biotransformations of Turpentine Constituents: Oxygenation and Esterification

This thesis describes methods to obtain value–added compounds from TMPturpentine obtained from the spruce, Picea abies. The methodology focuses on biotransformations using two approaches: an oxygenation approach (i.e. oxygenation of terpene hydrocarbons by cell cultures) and an esterification approach (i.e. lipase-catalysed transesterification of vinyl acetate with terpene alcohols, and a further fractionation of the TMP-turpentine). The main constituents of the turpentine, α-pinene, β-pinene and limonene, were subjected to a P. abies suspension culture. Allylic oxidation formed the major products for α-pinene and β-pinene, which were further oxidised to their respective aldehyde or ketone. One of the minor products from α-pinene, cisverbenol, was not only transformed into verbenone but also isomerised to transverbenol. Limonene gave limonene-(1,2)-epoxide as the major product. Fractionation of monoterpenes is accomplished through physical separation methods, chromatography and distillation, and lipase-catalysed transesterification of vinyl acetate with terpene alcohols. The esters of myrtenol and trans-pinocarveol were separated from the more slowly reacting alcohols such as borneol and carveol by use of a combination of the Mucor miehei lipase and Candida antarctica lipase A as catalysts. Furthermore, the non-reacting tertiary terpene alcohols were separated from the reacting alcohols in a single step by Candida antarctica lipase A. Lipase-catalysed (Candida antarctica lipase B and Pseudomonas cepacia lipase) transesterification of vinyl acetate with sterically hindered secondary alcohols unexpectedly yielded hemiacetals or hemiacetal esters. The reaction conditions required to obtain these side products have been studied.