published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Master / Master of Science

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

No description available.

No abstract, first paragraph of introduction: Simple terpenoids have been known for many centuries as plant constituents whose fragrance commended them to the early investigators. Within this group of naturally-occurring compounds the C15 sesquiterpenes were of particular interest, largely as a result of their relatively high abundance. In 1895, Chapman isolated a new sesquiterpene, humulene (1), from oil of hops and by the preparation of various derivatives distinguished this hydrocarbon, previously called α-caryophyllene, from caryophyllene. The carbon skeleton of this hydrocarbon was established but the placement of the three olefinic bonds proved difficult. The structure was deduced correctly by degradative experiments and the analysis of the nmr spectrum suggested that all the double bonds were endocyclic and had a trans configuration. The structure was confirmed beyond doubt by an X-ray study of the bis-silver nitrate adduct.

A survey to determine the origins of many of the mono- and sesquiterpenoids derived from over 800 species from the Eucalyptus, Leptospermum and Chamelaucium alliances of the family Myrtaceae subfamily Leptospermoideae was undertaken using specially developed small-scale extraction and steam-ditillation techniques (using normal and O-labelled water) coupled with enantioselective gas chromatography. This information was used to indirectly identify potential biosynthetic pathways and accessed how extraction conditions, such as those encountered during a distillation, can alter the oil profiles obtained. Terpenes present in the oils of the Myrtaceae showed a wide range of acid-catalysed solvolysis reactions during distillation and leaf aging thereby altering the biosynthetic history laid down by the plant. Such changes can occur both during leaf aging and distillation. Similarly acid-sensitive sesquiterpenes also undergo acid-solvolysis during leaf aging or distillation. This work identifies the biosynthetic and degradative origins of many of the compounds present in the oils extracted from the Myrtaceae and has found that the composition of an oil, regardless of extractive conditions, should not be considered a true representation of the biosynthetic history of the plant. / Doctor of Philosophy (PhD)(Chemistry)

Thesis (Ph. D.)--University of Kentucky, 2003. / Title from document title page (viewed onJune 1, 2004). Document formatted into pages; contains x, 145 p. : ill. Includes abstract and vita. Includes bibliographical references (p. 126-143).

Thesis (M. Sc.)--University of Hong Kong, 1964. / 2 Offprints in pocket. Typewritten.

Thesis (M. Sc.)--University of Hong Kong, 1968. / Typewritten.

Thesis (M. Sc.)--University of Hong Kong, 1968. / Typewritten.