Isolation and Identification of Two Novel Condensed
Aromatic Lactones from Zhundong Subbituminous Coal
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Abstract
Zhundong subbituminous coal was extracted
with isometric carbon
disulfide (CDS) and acetone mixed solvent (IMCDSAMS) to obtain the
extract (E<sub>M</sub>). E<sub>M</sub> was fractionated with petroleum
ether (PE), CDS, methanol, acetone, IMCDSAMS, and tetrahydrofuran
to obtain the sub-extracts 1–6 (E<sub>S1</sub>–E<sub>S6</sub>), respectively. E<sub>S2</sub> was sequentially eluted with
PE and 30, 50, and 70% CDS/PE mixed solvents through a silica-gel-packed
column to obtain eluted fractions 1–4 (EF<sub>1</sub>–EF<sub>4</sub>). A series of condensed aromatic lactones (CALs) were detected
in EF<sub>4</sub>. Among them, 5<i>H</i>-phenanthro[1,10,9-<i>cde</i>]chromen-5-one and 4<i>H</i>-benzo[5,10]anthra[1,9,8-<i>cdef</i>]chromen-4-one were further isolated as nearly pure
compounds by gelatin column chromatography and identified by gas chromatography/mass
spectrometry, atmospheric solid analysis probe/time-of-flight mass
spectrometry, Fourier transform infrared spectrometry, <sup>1</sup>H nuclear magnetic resonance spectrometry, and <sup>1</sup>H–<sup>1</sup>H correlation spectrometry. Main fragmental ions in the mass
spectrum of each CAL are formed by successive losses of <i>m</i>/<i>z</i> 28 (CO) and 29 (−CHO) from the molecular
ion. An effective way to isolate CALs from low-rank coals was provided
in this paper