THE NATURE AND FATE OF NATURAL RESINS IN THE GEOSPHERE - VIII - NMR AND PY-GC-MS CHARACTERIZATION OF SOLUBLE LABDANOID POLYMERS, ISOLATED FROM HOLOCENE CLASS-I RESINS
Dj. Clifford et al., THE NATURE AND FATE OF NATURAL RESINS IN THE GEOSPHERE - VIII - NMR AND PY-GC-MS CHARACTERIZATION OF SOLUBLE LABDANOID POLYMERS, ISOLATED FROM HOLOCENE CLASS-I RESINS, Organic geochemistry, 27(7-8), 1997, pp. 449-464
Soluble polylabdanoids isolated by sequential solvent extraction have
been characterized by liquid-state C-13- and H-1 NMR and C-13-H-1 HMQC
(heteronuclear correlation) NMR spectroscopy in addition to solid-sta
te NMR and Py-GC-MS techniques. Two Holocene resins originating from S
antander, Colombia and Mombasa, Kenya were analyzed. Soluble polymers
were isolated by extraction with a 1:1 (v/v) methylene chloride-methan
ol mixture following sequential extractions with methylene chloride an
d methanol. The molecular weight of polymer extracts was shown by GPC
analyses to exceed that of non-polymeric occluded terpenoids. Py-GC-MS
, solid-state C-13 CP/MAS and C-13 cross-polarization/depolarization N
MR spectroscopy results indicated that chemical compositions of solubl
e polymers isolated from immature resins are highly representative of
the structure of corresponding insoluble polymers, i.e. polylabdatrien
es. These data provide evidence for cross-linking or cyclization of si
de-chain olefinic carbons during or shortly after polymerization. Gene
rally, the characterization of soluble resin polymers by liquid-state
NMR spectroscopy has proven to be an excellent means for investigating
the maturation mechanism of polylabdanoid resinites, and has potentia
l for furthering the application of Class I resinites as geothermal in
dicators. (C) 1997 Elsevier Science Ltd. All rights reserved.