Chemical derivatization of Athabasca oil sand asphaltene for analysis of hydroxyl and carboxyl groups via nuclear magnetic resonance spectroscopy

Desando, M. A.

doi:10.1016/s0016-2361(02)00040-6

Cited by 28 publications

(17 citation statements)

References 52 publications

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“…This voxel space can be readily expanded to higher dimensions by including complementary data, like those derived from genomic and proteomic analyses [ 84 , 131 – 134 ] or by recognising selective chemical reaction products [ 135 – 140 ]. Degradative approaches to the characterisation of complex systems produce limited amounts of unambiguously identifiable small molecules but lose crucial linkage information.…”

Section: Information Transfer In Organic Structural Spectroscopy and mentioning

confidence: 99%

High-precision frequency measurements: indispensable tools at the core of the molecular-level analysis of complex systems

Hertkorn¹,

et al. 2007

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This perspective article provides an assessment of the state-of-the-art in the molecular-resolution analysis of complex organic materials. These materials can be divided into biomolecules in complex mixtures (which are amenable to successful separation into unambiguously defined molecular fractions) and complex nonrepetitive materials (which cannot be purified in the conventional sense because they are even more intricate). Molecular-level analyses of these complex systems critically depend on the integrated use of high-performance separation, high-resolution organic structural spectroscopy and mathematical data treatment. At present, only high-precision frequency-derived data exhibit sufficient resolution to overcome the otherwise common and detrimental effects of intrinsic averaging, which deteriorate spectral resolution to the degree of bulk-level rather than molecular-resolution analysis. High-precision frequency measurements are integral to the two most influential organic structural spectroscopic methods for the investigation of complex materials-NMR spectroscopy (which provides unsurpassed detail on close-range molecular order) and FTICR mass spectrometry (which provides unrivalled resolution)-and they can be translated into isotope-specific molecular-resolution data of unprecedented significance and richness. The quality of this standalone de novo molecularlevel resolution data is of unparalleled mechanistic relevance and is sufficient to fundamentally advance our understanding of the structures and functions of complex biomolecular mixtures and nonrepetitive complex materials, such as natural organic matter (NOM), aerosols, and soil, plant and microbial extracts, all of which are currently poorly amenable to meaningful target analysis. The discrete analytical volumetric pixel space that is presently available to describe complex systems (defined by NMR, FT mass spectrometry and separation technologies) is in the range of 10 8-14 voxels, and is therefore capable of providing the necessary detail for a meaningful molecular-level analysis of very complex mixtures. Nonrepetitive complex materials exhibit mass spectral signatures in which the signal intensity often follows the number of chemically feasible isomers. This suggests that even the most strongly resolved FTICR mass spectra of complex materials represent simplified (e.g. isomer-filtered) projections of structural space.

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Section: Information Transfer In Organic Structural Spectroscopy and mentioning

confidence: 99%

High-precision frequency measurements: indispensable tools at the core of the molecular-level analysis of complex systems

Hertkorn¹,

et al. 2007

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“…It is because the number of methylene groups on the aromatic structure side chains in asphaltene B is higher than that in asphaltene A, indicating more protons connecting to α carbon in the aromatic ring. It consists of the ratio of CH 2 /CH 3 analyzed from the FTIR spectra. On the basis of the above analysis results and known asphaltene structure models, − the structure parameters and supposed molecular structures of both asphaltenes were deduced and shown in Table S2 of the Supporting Information and Figure . Both asphaltenes are “continental model”, with polycyclic aromatic hydrocarbons as the core and surrounded by alkane chains.…”

Section: Results and Discussionmentioning

confidence: 99%

Effect of Aromatic Pendants in a Maleic Anhydride-co-Octadecene Polymer on the Precipitation of Asphaltenes Extracted from Heavy Crude Oil

Cheng

Zou

et al. 2021

Energy Fuels

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The precipitation and deposition of asphaltenes often cause great troubles to the recovery and transportation of crude oil. Adding polymer inhibitors is an effective approach to prevent asphaltenes from clogging. In this study, maleic anhydrideco-octadecene copolymers with imidazolyl, phenyl, and pyridyl pendants were synthesized. The inhibition behaviors of two extracted asphaltenes in the presence of these copolymers were investigated, which were also identified by the rheological tests of the heavy crude oil sample. The chemical structure of both asphaltenes was analyzed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), elemental analysis, and time-of-flight (TOF) spectrometry. Both asphaltenes A and B have a high aromaticity and low H/C. However, asphaltene B has a much higher aromaticity and polarity than that of asphaltene A. Ultraviolet−visible spectroscopy, turbidity meter, and dynamic light scattering (DLS) were employed to determine the precipitation behaviors of asphaltenes in the absence and presence of copolymers. The influence of intrinsic properties of asphaltenes, polymer concentration, and aromatic group grafting ratio on asphaltene precipitation were also compared. It is found that the initial precipitation point (IPP) of both asphaltenes is increased most by the copolymer containing 2-aminopyridine (PMO-2-P), while the copolymer containing N-(3-aminopropyl)imidazole (PMO-I) shows the worst inhibition performance. It is because that pyridine group has a stronger adsorption capacity with asphaltene than the imidazole group. The effect of various functional groups in copolymers on inhibiting asphaltene precipitation conforms to the following sequence: 2-aminopyridine > aniline > 4aminopyridine > N-(3-aminopropyl)imidazole. It is also found that high polymer concentration and grafting ratio are beneficial to inhibit the asphaltene precipitation. As a result of the π−π conjugation and hydrogen-bonding attractions between the aromatic groups in the copolymers and the asphaltenes, the polymers can be stably adsorbed onto the surface of the asphaltenes and prevent their aggregation.

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“…For those asphaltene samples, including terminal polar groups (i.e., −OH, −SH, −COOH, and −NH 2 ), the hydrogen bonding interactions can be weakened by such reactions as methylation, trifluoroacetylation, trimethylsilylation, and so on. Based on these chemical reactions, Desando and Ripmeester verified the presence of hydroxyl and carboxyl groups in Athabasca oil sand asphaltenes. Regrettably, the aggregation characteristics of the asphaltene reaction products were not studied in their work.…”

Section: Introductionmentioning

confidence: 93%

Impact of Functional Group Methylation on the Disaggregation Trend of Asphaltene: A Combined Experimental and Theoretical Study

et al. 2019

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Asphaltenes have a tendency toward aggregation, leading to a series of problems (e.g., coking) in the field of refining or other oil utilization and making the development of a disaggregation method an urgent need. We employed functional group methylation experiments combined with molecular dynamics simulations and quantum chemical calculations to reveal the disaggregation mechanism of asphaltenes based on the chemical alteration method. Here, the experimental results show that the intersheet distances in the asphaltene aggregate increase after the methylation reaction, and the asphaltene molecules are not prone to reaggregation after methylation, which was demonstrated by an increase in the critical aggregation concentration in toluene. These disaggregation effects can be explained by the theoretical study results; that is, they can be attributed to the reduction of the electrostatic interaction, which is derived from the disappearance of the hydrogen bonds after methylation. However, a thorough disaggregation cannot be achieved only by methylation because the van der Waals force is always the dominant force in both raw and methylated asphaltenes, outweighing the electrostatic force. Asphaltene molecules with very short side chains containing more than one terminal polar group could obtain a better disaggregation effect by the methylation reaction, whereas those with long chains could not. Our results provide the underlying insights for the proposal of an effective method for asphaltene disaggregation to prevent coking.

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Chemical derivatization of Athabasca oil sand asphaltene for analysis of hydroxyl and carboxyl groups via nuclear magnetic resonance spectroscopy

Cited by 28 publications

References 52 publications

High-precision frequency measurements: indispensable tools at the core of the molecular-level analysis of complex systems

High-precision frequency measurements: indispensable tools at the core of the molecular-level analysis of complex systems

Effect of Aromatic Pendants in a Maleic Anhydride-co-Octadecene Polymer on the Precipitation of Asphaltenes Extracted from Heavy Crude Oil

Impact of Functional Group Methylation on the Disaggregation Trend of Asphaltene: A Combined Experimental and Theoretical Study

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