Terpenoids INDEX

G.l.c. papers of interest include the classification of 22 acyclic monoterpenoid alcohols according to retention indexes, resolution of cyclic ketones [e.g. ( )-menthone, ( )-isomenthone] as diethyl (+)-tartrate acetals, and the use of lanthanide shift reagents to resolve non-terpenoid racemic epoxides.The occurrence and prevention of monoterpenoid hydrocarbon isomerization during silica gel chromatography has been examined and the separation of monoterpenoids and sesquiterpenoids by gel permeation chromatography is reported. Monoterpenoid hydrocarbons have been selectively extracted from essential oils using dimethylsilicone. ... 

Collins Ferrier, Monosaccharides, their Chemistry and Roles in Natural Products, Chichester J. Wiley Sons 1995 Czygan (ed.). Pigments in Plants, 2. edition, Berlin Akademie-Verl. 1980 Conolly Hill, Dictionary of Terpenoids, 3 Vol. (Vol. 1 Mono- and Ses-quiterpenoids, Vol. 2 Di- and higher Terpenoids, Vol. 3 indexes), London Chapman Hall 1991... 

Modern analytical techniques can provide accurate and precise profiles of plant and insect cuticular waxes as well as terpenoids. For structural studies the most effective procedures are those based on a combination of mass spectra and GC retention index data. 

The use of diode-array detection is limited because many of the terpenoids do not have chromophores for the UV region. Refractive index, evaporative light scattering detectors (ELSD), or low-UV detectors can overcome, to a certain extent, this problem. However, the refractive index detector... 

Most terpenoids are optically active and have a bigger refractive index (Rl) because of asymmetric carbon atoms in their molecules. Terpenoids commoidy are hydrophobic, but their solubility can be improved through the addition of polar groups. 

Terpenoids can be analyzed by the usual methods. For the volatile members of the family, gas chromatography-mass spectrometry (gc-ms) is a particularly useful tool. In laboratories (e.g., those in the major fragrance companies), which are accustomed to analyzing mixtures of volatile terpenoids, gc-ms is the major analytical technique employed and such laboratories will have extensive libraries of mass spectra of terpenoids to assist in this. However, the mass spectral fragmentation patterns of closely related terpenoids are often so similar as to render definitive identification by ms alone, impossible. For these materials and those for which there is no reference (e.g., compounds newly isolated from nature), nuclear magnetic resonance (nmr) spectroscopy is the analytical tool of choice. Physical techniques, e.g., density, refractive index, and optical rotation, are relatively inexpensive and prove useful in quality control. 

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