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Probing the Carbonyl Functionality of a Petroleum Resin and Asphaltene through Oximation and Schiff Base Formation in Conjunction with N-15 NMR.

Thorn KA, Cox LG - PLoS ONE (2015)

Bottom Line: In this study, the carbonyl functionalities of the resin and asphaltene fractions from a light aliphatic crude oil that is the source of groundwater contamination at the long term USGS study site near Bemidji, Minnesota, have been examined through reaction with 15N-labeled hydroxylamine and aniline in conjunction with analysis by solid and liquid state 15N NMR.Anilinohydroquinone adducts provided evidence for quinones.In a solid state cross polarization/magic angle spinning (CP/MAS) 15N NMR spectrum recorded on the underivatized asphaltene as a control, carbazole and pyrrole-like nitrogens were the major naturally abundant nitrogens detected.

View Article: PubMed Central - PubMed

Affiliation: U.S. Geological Survey, Denver Federal Center, MS 408, Denver, Colorado, 80225-0046, United States of America.

ABSTRACT
Despite recent advances in spectroscopic techniques, there is uncertainty regarding the nature of the carbonyl groups in the asphaltene and resin fractions of crude oil, information necessary for an understanding of the physical properties and environmental fate of these materials. Carbonyl and hydroxyl group functionalities are not observed in natural abundance 13C nuclear magnetic resonance (NMR) spectra of asphaltenes and resins and therefore require spin labeling techniques for detection. In this study, the carbonyl functionalities of the resin and asphaltene fractions from a light aliphatic crude oil that is the source of groundwater contamination at the long term USGS study site near Bemidji, Minnesota, have been examined through reaction with 15N-labeled hydroxylamine and aniline in conjunction with analysis by solid and liquid state 15N NMR. Ketone groups were revealed through 15N NMR detection of their oxime and Schiff base derivatives, and esters through their hydroxamic acid derivatives. Anilinohydroquinone adducts provided evidence for quinones. Some possible configurations of the ketone groups in the resin and asphaltene fractions can be inferred from a consideration of the likely reactions that lead to heterocyclic condensation products with aniline and to the Beckmann reaction products from the initially formed oximes. These include aromatic ketones and ketones adjacent to quaternary carbon centers, β-hydroxyketones, β-diketones, and β-ketoesters. In a solid state cross polarization/magic angle spinning (CP/MAS) 15N NMR spectrum recorded on the underivatized asphaltene as a control, carbazole and pyrrole-like nitrogens were the major naturally abundant nitrogens detected.

No MeSH data available.


Related in: MedlinePlus

Liquid-state DEPT N-15 NMR spectra of asphaltene and resin derivatized with 15N-labeled aniline.LB = line broadening.
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pone.0142452.g014: Liquid-state DEPT N-15 NMR spectra of asphaltene and resin derivatized with 15N-labeled aniline.LB = line broadening.

Mentions: The DEPT 15N NMR spectra of the asphaltene and resin fractions reacted with aniline show only nitrogens directly bonded to protons (Fig 14). Prominent anilinohydroquinone peaks are present at 81.5 ppm and 80.4 ppm in the asphaltene and resin, respectively. Several discrete peaks are resolved in the liquid spectra, superimposed upon the three main regions, from approximately 60 to 95 ppm, 95 to 115 ppm, and 115 to 145 ppm, corresponding to the anilinohydroquinone, anilinoquinone and heterocyclic nitrogens, respectively. The sharp peaks, at 100.0, 105.3, 130.6 and 134.0 ppm in the resin and 100.0 and 134.0 ppm in the asphaltene, likely represent aniline adducts of a specific constituent that occurs at relatively high concentration in the fractions. The presence of the anilinohydroquinone peak in the resin provides evidence for the occurrence of quinones in this fraction. Interestingly, the resin shows a greater proportion of heterocyclic nitrogens than the asphaltene. This may possibly be explained by the greater aliphatic carbon content, and by implication, greater activated methylene carbon content of the resin compared to the asphaltene. The configurations of carbonyl groups that condense with aniline to form indoles and quinolones in the Bischler and CLK reactions contain activated methylene carbons (Fig 12).


Probing the Carbonyl Functionality of a Petroleum Resin and Asphaltene through Oximation and Schiff Base Formation in Conjunction with N-15 NMR.

Thorn KA, Cox LG - PLoS ONE (2015)

Liquid-state DEPT N-15 NMR spectra of asphaltene and resin derivatized with 15N-labeled aniline.LB = line broadening.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4640887&req=5

pone.0142452.g014: Liquid-state DEPT N-15 NMR spectra of asphaltene and resin derivatized with 15N-labeled aniline.LB = line broadening.
Mentions: The DEPT 15N NMR spectra of the asphaltene and resin fractions reacted with aniline show only nitrogens directly bonded to protons (Fig 14). Prominent anilinohydroquinone peaks are present at 81.5 ppm and 80.4 ppm in the asphaltene and resin, respectively. Several discrete peaks are resolved in the liquid spectra, superimposed upon the three main regions, from approximately 60 to 95 ppm, 95 to 115 ppm, and 115 to 145 ppm, corresponding to the anilinohydroquinone, anilinoquinone and heterocyclic nitrogens, respectively. The sharp peaks, at 100.0, 105.3, 130.6 and 134.0 ppm in the resin and 100.0 and 134.0 ppm in the asphaltene, likely represent aniline adducts of a specific constituent that occurs at relatively high concentration in the fractions. The presence of the anilinohydroquinone peak in the resin provides evidence for the occurrence of quinones in this fraction. Interestingly, the resin shows a greater proportion of heterocyclic nitrogens than the asphaltene. This may possibly be explained by the greater aliphatic carbon content, and by implication, greater activated methylene carbon content of the resin compared to the asphaltene. The configurations of carbonyl groups that condense with aniline to form indoles and quinolones in the Bischler and CLK reactions contain activated methylene carbons (Fig 12).

Bottom Line: In this study, the carbonyl functionalities of the resin and asphaltene fractions from a light aliphatic crude oil that is the source of groundwater contamination at the long term USGS study site near Bemidji, Minnesota, have been examined through reaction with 15N-labeled hydroxylamine and aniline in conjunction with analysis by solid and liquid state 15N NMR.Anilinohydroquinone adducts provided evidence for quinones.In a solid state cross polarization/magic angle spinning (CP/MAS) 15N NMR spectrum recorded on the underivatized asphaltene as a control, carbazole and pyrrole-like nitrogens were the major naturally abundant nitrogens detected.

View Article: PubMed Central - PubMed

Affiliation: U.S. Geological Survey, Denver Federal Center, MS 408, Denver, Colorado, 80225-0046, United States of America.

ABSTRACT
Despite recent advances in spectroscopic techniques, there is uncertainty regarding the nature of the carbonyl groups in the asphaltene and resin fractions of crude oil, information necessary for an understanding of the physical properties and environmental fate of these materials. Carbonyl and hydroxyl group functionalities are not observed in natural abundance 13C nuclear magnetic resonance (NMR) spectra of asphaltenes and resins and therefore require spin labeling techniques for detection. In this study, the carbonyl functionalities of the resin and asphaltene fractions from a light aliphatic crude oil that is the source of groundwater contamination at the long term USGS study site near Bemidji, Minnesota, have been examined through reaction with 15N-labeled hydroxylamine and aniline in conjunction with analysis by solid and liquid state 15N NMR. Ketone groups were revealed through 15N NMR detection of their oxime and Schiff base derivatives, and esters through their hydroxamic acid derivatives. Anilinohydroquinone adducts provided evidence for quinones. Some possible configurations of the ketone groups in the resin and asphaltene fractions can be inferred from a consideration of the likely reactions that lead to heterocyclic condensation products with aniline and to the Beckmann reaction products from the initially formed oximes. These include aromatic ketones and ketones adjacent to quaternary carbon centers, β-hydroxyketones, β-diketones, and β-ketoesters. In a solid state cross polarization/magic angle spinning (CP/MAS) 15N NMR spectrum recorded on the underivatized asphaltene as a control, carbazole and pyrrole-like nitrogens were the major naturally abundant nitrogens detected.

No MeSH data available.


Related in: MedlinePlus