Extraction of Organonitrogen Compounds from Five Chinese Coals with Methanol

Extraction of Organonitrogen Compounds from Five Chinese Coals with Methano

Characterization of the Oxygenated Chemicals Produced from Supercritical Methanolysis of Modified Lignites

Lignites are promising as feedstocks for producing value-added oxygenated chemicals (OCs) due to their high contents of oxygen-containing organic species. Two modified lignites were produced from Xiaolongtan lignite and Shengli lignite via sequential ultrasonic extraction and subsequent supercritical methanolysis to produce OCs. Solid-state ¹³C nuclear magnetic resonance analysis reveals the differences in carbon skeleton structures and oxygen-functional groups between the two modified lignites. The molecular compositions of OCs from the methanolysis were characterized with Fourier transform infrared spectrometer (FTIRS), gas chromatograph/mass spectrometer (GC/MS), and negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometer (ESI FTICRMS). Six types of hydrogen bonds and distribution of >CO groups in the OCs were analyzed with FTIRS. Alkylphenols with C₁−C₆ in alkyl group(s) dominate in the GC/MS-detectable organic species and methyl is the major alkyl group. The analysis with high-resolution negative-ion ESI FTICRMS reveals higher-molecular, less volatile, and polar OCs, which are assigned to <i>O</i>₁–<i>O</i>₇ class species, detection of which is difficult with GC/MS. Among the <i>O</i>₁–<i>O</i>₇ class species, <i>O</i>₁–<i>O</i>₃ classes are predominant with double bond equivalent values of 1–17 and carbon numbers of 10–38. They could be acidic OCs, such as arenols, arenediols, alkoxyarenols, and/or arenecarboxylic acids with 1–5 aromatic rings and different alkyl groups, as well as some aliphatic acids. The combination of various advanced analytical techniques should be an ideal approach for characterizing valuable OCs in complex coal-derived liquids

Effect of Ethanolysis on the Structure and Pyrolytic Reactivity of Zhaotong Lignite

Lignite ethanolysis is one of the efficient conversion processes. In our previous study, Zhaotong lignite (ZL) from Southwest China was subjected to ethanolysis to afford an ethanol-soluble portion and ethanolyzed residue (ER). The structural features of ZL and ER were investigated by ruthenium-ion-catalyzed oxidation (RICO) and Fourier transform infrared spectrometry. The pyrolytic reactivities of ZL and ER were examined with a thermogravimetric analyzer and Curie-point pyrolyzer–gas chromatograph/mass spectrometer. The results show that both ZL and ER are rich in −CH₂CH₂– and −CH₂CH₂CH₂– bridged linkages connecting aromatic rings. In comparison to the RICO of ZL, the RICO of ER produced much less long-chain alkanoic and alkanedioic acids, suggesting that long alkylene bridges and alkyl side chains in ZL were largely cleaved via ethanolysis. Interestingly, ZL has a higher condensation degree than ER, which was confirmed by RICO and solid-state ¹³C nuclear magnetic resonance analysis. The result was explained by ethanolysis simulation of lignite-related model compounds using density functional theory. Thermogravimetric analysis of ZL and ER exhibits their different pyrolytic reactivities. According to analysis with a Curie-point pyrolyzer–gas chromatograph/mass spectrometer, significant differences in the distributions of the volatile species from the pyrolyses of ZL and ER were observed. Guaiacols and carbazoles are the most abundant group components from the pyrolyses of ZL and ER, respectively. ZL pyrolysis released much more alkanes and phenolic compounds than ER pyrolysis. The cleavage of C_ar–O bonds significantly proceeded during ZL ethanolysis

Electrochemical-Induced C–N Bond Formation: A New Method to Synthesis (<i>Z</i>)‑Quinazolinone Oximes Using Primary Amines and Quinazolin-4(3<i>H</i>)‑one

A novel and highly selective electrochemical method for the synthesis of diverse quinazolinone oximes via direct electrooxidation of primary amines/C(sp2)–H functionalization of oximes has been developed. The reaction is conducted in an undivided cell under constant current conditions and is oxidant-free, open-air, and eco-friendly. Notably, the protocol shows good functional group tolerance, providing versatile quinazolinone oximes in good yields. Moreover, the mechanism is investigated through control experiments and cyclic voltammogram (CV) experiments

Isolation and Identification of Two Novel Condensed Aromatic Lactones from Zhundong Subbituminous Coal

Zhundong subbituminous coal was extracted with isometric carbon disulfide (CDS) and acetone mixed solvent (IMCDSAMS) to obtain the extract (E_M). E_M was fractionated with petroleum ether (PE), CDS, methanol, acetone, IMCDSAMS, and tetrahydrofuran to obtain the sub-extracts 1–6 (E_S1–E_S6), respectively. E_S2 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 (EF₁–EF₄). A series of condensed aromatic lactones (CALs) were detected in EF₄. 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, ¹H nuclear magnetic resonance spectrometry, and ¹H–¹H 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

Characterization of Biomarkers and Structural Features of Condensed Aromatics in Xianfeng Lignite

Xianfeng lignite (XL) was sequentially extracted under ultrasonication at room temperature with petroleum ether, carbon disulfide (CDS), methanol, acetone, and isometric CDS/acetone mixed solvent to afford extracts 1–5, respectively. The mixed solvent-inextractable portion was sequentially extracted with cyclohexane, benzene, 1-methylnaphthalene, methanol, and ethanol at 320 °C to afford extracts 6–10, respectively. The extracts were analyzed with a gas chromatography/mass spectrometer (GC/MS) to characterize biomarkers in XL. The biomarkers were significantly enriched in extracts 1 and 6. They can be classified into a series of <i>n</i>-alkanes, isoprenoid alkanes, terpenoids, <i>n</i>-alkenes, methyl alkanones, <i>n</i>-alkylbenzenes, <i>n</i>-alkyltoluenes, and <i>n</i>-alkyl-<i>p</i>-xylenes. The biomarker distributions provided important information on the main origin of organic matter in XL. Related mechanisms for the formation of biomarkers during coalification were discussed. The residue from sequential thermal extraction was subjected to ruthenium-ion-catalyzed oxidation along with subsequent product analyses with GC/MS and direct analysis in a real-time ionization source coupled to a time-of-flight mass spectrometer (DARTIS/TOFMS) to understand its structural features. The results show that the residue is rich in condensed aromatics (CAs) and methyl is the dominant alkyl side chain on aromatic rings. The aromatic rings in the residue are mainly connected by −(CH₂)₃– and −CHCH₃(CH₂)₂–. DARTIS/TOFMS analysis suggests that CAs with alkyl-substituted biphenyl and alkyl-substituted phenylbiphenyl skeletons also exist in the residue. This investigation provides an effective approach for understanding biomarkers and the structural features of the macromolecular network in XL

Structural Characterization of Typical Organic Species in Jincheng No. 15 Anthracite

The structures of typical organic species in Jincheng No. 15 anthracite (J15A) were characterized by solid-state ¹³C nuclear magnetic resonance, X-ray photoelectron spectrometry, X-ray diffraction, and Fourier transform infrared spectrometry in combination with gas chromatography/mass spectrometry and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry analyses of the resulting soluble organic species from ruthenium-ion-catalyzed oxidation (RICO) of J15A. The results show that the typical organic species in J15A are condensed aromatics, along with small amounts of methyl group as the dominant side chain on the condensed aromatic rings (CARs) and methylene linkage connecting the CARs. Every aromatic cluster contains five rings on average, and the substituted degree of each aromatic ring is very low. In addition, J15A is rich in <i>peri</i>-condensed aromatics but poor in <i>cata</i>-condensed aromatics and polyaryls. The oxygen functional groups in J15A include C–O and >CO groups. Pyrrolic nitrogen species and arylthiophenes are the main organic nitrogen and sulfur species in J15A, respectively

Selective Hydrogen Transfer to Anthracene and Its Derivatives over an Activated Carbon

Hydrogenation reactions of three polycyclic arenes (PCAs), that is, anthracene, 9-phenylanthracene (PA), and 9,10-diphenylanthracene (DPA) were carried out under an initial hydrogen pressure of 5 MPa at 300 °C. An activated carbon (AC, a metal-free catalyst), was employed to catalyze the PCA hydroconversions. The results show that the AC can split gaseous hydrogen into atomic form and catalyze monatomic hydrogen transfer to aromatic rings. Interestingly, the AC selectively catalyzed the hydrogenation of the anthracene ring, and prevented the benzene ring from hydrogenation and the C−C linkage from cleavage. The reactivity of the PCAs toward hydrogenation over the AC decreased in the order of anthracene > PA > DPA. The hydrogen-accepting ability and steric hindrance effect are demonstrated to be responsible for the difference in reactivity

Sequential Extraction and Thermal Dissolution of Baiyinhua Lignite in Isometric CS₂/Acetone and Toluene/Methanol Binary Solvents

Baiyinhua lignite (BL) was sequentially extracted and thermally dissolved in isometric CS₂/acetone and toluene/methanol binary solvents to obtain an extract in isometric CS₂/acetone (E_ICA) and a soluble portion (SP) in isometric toluene/methanol (SP_ITM). The yields of E_ICA and SP_ITM are notably higher than the total extract yield from sequential extraction with CS₂ and acetone (or acetone and CS₂) and the total SP yield from sequential thermal dissolution in toluene and methanol (or methanol and toluene), indicating that there exists an obvious synergic effect between CS₂ and acetone during the extraction and between toluene and methanol during the thermal dissolution. E_ICA and SP_ITM mainly consist of hydrocarbons and oxygen-containing organic species, respectively. Little difference in Fourier transform infrared spectroscopy spectra of BL and its extraction residue was observed, while the intensities of absorbances assigned to the phenolic OH, CO, and C–O/C–O–C groups of the thermal dissolution residue are obviously lower than those of BL and its extraction residue. X-ray photoelectron spectroscopy analysis shows that C–O/C–O–C groups in BL remarkably decreased after thermal dissolution, corresponding to the abundant phenols dissolved in SP_ITM. The difference in weight loss between BL and its extraction residue is close to the yield of E_ICA, while the difference in weight loss between extraction and thermal dissolution residues is significantly lower than the yield of SP_ITM

Microwave-Assisted Hydrogen Transfer to Anthracene and Phenanthrene over Pd/C

Microwave-assisted hydrogen transfer to anthracene and phenanthrene over Pd/C was investigated under mild conditions. The effects of reaction temperature, initial hydrogen pressure, and reaction time on the reactant conversions and product selectivities were examined. The results show that the hydrogenations of both reactants proceed at much lower temperature and hydrogen pressure under microwave irradiation than those by conventional heating and that related reactions include both mon- and biatomic hydrogen transfer. The reactivities of both reactants and their products toward hydrogenation and/or dehydrogenation are closely related to super-delocalizability and resonance energy values of the related species