Possibilities to Utilize Species from the Mozambican Forest Biomass for the Production of Essential Oils : Study of Eucalyptus and Pinus Species and Application of Citronellal as Raw Material for Flavour Chemistry

Sammanfattning: This thesis deals partly with the isolation and chemicalanalysis of essential oils from selected Eucalyptus and Pinusspecies grown in Mozambique, and partly with the synthesis ofmore valuable compounds from citronellal isolated fromEucalyptus citriodora Hook oil.More than 60 constituents in the volatile oils wereidentified by gas chromatography and gas chromatography-massspectrometry by comparison with authentic substances andliterature data.The effects of distillation time, age (Eucalyptuscamaldulensis Dehn) and season, for harvesting (E. citriodoraHook) on the yield and the percentage composition of theessential oils were determined. It was found that 60 minuteswas the optimum distillation time required for the isolation ofessential oils from the leaves of Eucalyptus species. The ageof the trees, the harvesting season and the distillation timewere found to be important factors for the composition of theessential oils and for obtaining optimum yields. We showed thatthe yield was highest from the older trees and that the majorvariations in oil composition occurred among the monoterpenehydrocarbons (E. camaldulensis). In general, the highest yieldswere obtained during the warm summer and an increase ofcitronellal content (E. citriodora) was also observed at thatseason.The enantiomeric composition of selected chiral monoterpenehydrocarbons and oxygenated compounds in the essential oil fromE. camaldulensis were briefly investigated. Differences in theratios of (+) to (-) enantiomers of specific compounds werefound in oils from younger and older trees.The synthesis of valuable compounds, hydroxycitronellal andcis/trans-rose oxide, from citronellal were also studied. Thehydroxycitronellal synthesis focused on chemicaltransformations using two approaches. The procedure for thesynthesis of isomeric cis/trans-rose oxide was focused onsynthesizing 3,7-dimethyl-5-octene-1,7-diol and3,7-dimethyl-7-octene-1,6-diol from citronellal by simultaneousphotooxidation and reduction followed by acid catalyzedcyclization.Keywords:Eucalyptus species, Myrtaceae, essential oilcomposition, enantiomeric composition, monoterpene, seasonalvariation, citronellal, photooxidation, acetal, epoxidation,Swern oxidation, hydroxycitronellal, cis/trans-rose oxide.