Introduction to Mass Spectra Interpretation: Organic Chemistry

Lebedev, A. T.

doi:10.1002/9780470395813.ch5

Cited by 10 publications

(9 citation statements)

References 25 publications

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“…However, due to their close relationship with other plant matter constituents, the above compounds predominate in the pyrolysis products at 150–250 °C ( Figure 6 b). At the same time, the ion with m / z = 60 (HOCHCHOH + ) observed in Figure 6 a is known to be the most intense marker ion in the mass spectra of carbohydrate pyrolysis products and is usually detected already at 150 °C [ 37 , 38 ].…”

Section: Resultsmentioning

confidence: 99%

Rice Husk Research: From Environmental Pollutant to a Promising Source of Organo-Mineral Raw Materials

Satbaev¹,

Yefremova

Zharmenov

et al. 2021

Materials

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Rice husk is a large-tonnage waste left from rice production. It is not subject to humification and therefore becomes a serious environmental pollutant. Due to the presence of two essential elements—carbon and silicon—in its composition, rice husk is a promising organo-mineral raw material. The known methods for processing of rice husk are associated with the formation of even more aggressive waste. The creation of a waste-free technology for processing this plant material requires a detailed study. Rice husk of yzylorda oblast was studied using IR, SEM, TA, TPD-MS, EPR, and TEM methods. It was determined that under a temperature up to 500 °C, the ligno-carbohydrate component of rice husk decomposes almost completely. Three main peaks are recorded during the decomposition: hemicellulose at 200 °C, cellulose at 265 °C, and lignin at 350–360 °C. This process is endothermic. However, above of 300 °C the exothermic reactions associated with the formation of new substances and condensation processes in the solid residue begin to prevail. This explains the increase in the concentration of paramagnetic centers (PMCs) in products of rice husk carbonization in the range of up to 450 °C. Further increase in temperature leads to a decrease in the number of PMCs as a result of carbon graphite-like structures formation. The silicon–carbon product of rice husk carbonization (nanocomposite) is formed by interconnected nanoscale particles of carbon and silicon dioxide, the modification of which depends on the temperature of carbonization. The obtained data allow management of the rice husk utilization process while manufacturing products in demand based on ecofriendly technologies.

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Section: Resultsmentioning

confidence: 99%

Rice Husk Research: From Environmental Pollutant to a Promising Source of Organo-Mineral Raw Materials

Satbaev¹,

Yefremova

Zharmenov

et al. 2021

Materials

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“…In view of the “soft” desorption/ionization of the sample provided by LDI-TOF mass spectrometry, which avoids destructive fragmentation of the compounds, we have resorted to this technique to ascertain the presence of dimeric species in our samples and have chosen the Eu III samples for their typical isotopic distribution. Interpretation of these spectra was made using the general rules of fragmentation of lanthanide β-diketonates described for other mass-spectrometry techniques .…”

Section: Resultsmentioning

confidence: 99%

Role of the Ancillary Ligand N,N-Dimethylaminoethanol in the Sensitization of Eu^III and Tb^III Luminescence in Dimeric β-Diketonates

et al. 2008

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Two types of dimeric complexes [Ln2(hfa)6(mu2-O(CH2)2NHMe2)2] and [Ln(thd)2(mu2,eta2-O(CH2)2NMe2)]2 (Ln = YIII, EuIII, GdIII, TbIII, TmIII, LuIII; hfa- = hexafluoroacetylacetonato, thd- = dipivaloylmethanato) are obtained by reacting [Ln(hfa)3(H2O)2] and [Ln(thd)3], respectively, with N,N-dimethylaminoethanol in toluene and are fully characterized. X-ray single crystal analysis performed for the TbIII compounds confirms their dimeric structure. The coordination mode of N,N-dimethylaminoethanol depends on the nature of the beta-diketonate. In [Tb2(hfa)6(mu2-O(CH2)2NHMe2)2], eight-coordinate TbIII ions adopt distorted square antiprismatic coordination environments and are O-bridged by two zwitterionic N,N-dimethylaminoethanol ligands with a Tb1...Tb2 separation of 3.684(1) A. In [Tb(thd)2(mu2,eta2-O(CH2)2NMe2)]2, the N,N-dimethylaminoethanol acts as chelating-bridging O,N-donor anion and the TbIII ions are seven-coordinate; the Tb1...Tb1A separation amounts to 3.735(2) A within centrosymmetric dimers. The dimeric complexes are thermally stable up to 180 degrees C, as shown by thermogravimetric analysis, and their volatility is sufficient for quantitative sublimation under reduced pressure. The EuIII and TbIII dimers display metal-centered luminescence, particularly [Eu2(hfa)6(O(CH2)2NHMe2)2] (quantum yield Q(L)Ln = 58%) and [Tb(thd)2(O(CH2)2NMe2)]2 (32%). Consideration of energy migration paths within the dimers, based on the study of both pure and EuIII- or TbIII-doped (0.01-0.1 mol %) LuIII analogues, leads to the conclusion that both the beta-diketone and N,N-dimethylaminoethanol ligands contribute significantly to the sensitization process of the EuIII luminescence. The ancillary ligand increases considerably the luminescence of [Eu2(hfa)6(O(CH2)2NHMe2)2], compared to [Ln(hfa)3(H2O)2], through the formation of intra-ligand states while it is detrimental to TbIII luminescence in both beta-diketonates. Thin films of the most luminescent compound [Eu2(hfa)6(O(CH2)2NHMe2)2] obtained by vacuum sublimation display photophysical properties analogous to those of the solid-state sample, thus opening perspectives for applications in electroluminescent devices.

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“…Compound identification was performed by mass spectra comparison with the database available in the Xcalibur software. For compounds not identified by the software, usually high C number aliphatics and aromatics, the homologous ion series for organic compounds reported by Lebedev 16 and the National Institute of Standards and Technology webbook 17 were used as references. After identification, pyrolysis products were classified and grouped by C number and chemical class.…”

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

Effect of Temperature and Vapor Residence Time on the Micropyrolysis Products of Waste High Density Polyethylene

Gracida-Alvarez

Mitchell

Sacramento-Rivero

et al. 2018

Ind. Eng. Chem. Res.

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Thermal degradation of plastics is a promising technology for addressing the waste management issues of landfill disposal, while obtaining useful products. Primary thermal degradation of polymers usually yields a large quantity of high molecular weight compounds with a limited applicability, making necessary a secondary degradation to improve the product quality. In this study, pyrolysis vapors from waste high density polyethylene (HDPE) were subjected to secondary degradation by varying the temperature and vapor residence time (VRT) in the reaction zone of a new two-stage micropyrolysis reactor (TSMR) attached to a commercial micropyrolysis unit. Temperature and VRT variations showed a strong effect on the product distribution, with low temperature (625 °C) and short VRT (1.4 s) producing a wide range of gases and liquid products and with high temperature (675 °C) and long VRT (5.6 s) producing mostly hydrocarbon gases and mono- and polyaromatics. The results showed a good agreement with previously reported product distributions for larger-scale pyrolysis reactors and were well explained by known degradation mechanisms.

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Introduction to Mass Spectra Interpretation: Organic Chemistry

Cited by 10 publications

References 25 publications

Rice Husk Research: From Environmental Pollutant to a Promising Source of Organo-Mineral Raw Materials

Rice Husk Research: From Environmental Pollutant to a Promising Source of Organo-Mineral Raw Materials

Role of the Ancillary Ligand N,N-Dimethylaminoethanol in the Sensitization of Eu^III and Tb^III Luminescence in Dimeric β-Diketonates

Effect of Temperature and Vapor Residence Time on the Micropyrolysis Products of Waste High Density Polyethylene

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Introduction to Mass Spectra Interpretation: Organic Chemistry

Cited by 10 publications

References 25 publications

Rice Husk Research: From Environmental Pollutant to a Promising Source of Organo-Mineral Raw Materials

Rice Husk Research: From Environmental Pollutant to a Promising Source of Organo-Mineral Raw Materials

Role of the Ancillary Ligand N,N-Dimethylaminoethanol in the Sensitization of EuIII and TbIII Luminescence in Dimeric β-Diketonates

Effect of Temperature and Vapor Residence Time on the Micropyrolysis Products of Waste High Density Polyethylene

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Role of the Ancillary Ligand N,N-Dimethylaminoethanol in the Sensitization of Eu^III and Tb^III Luminescence in Dimeric β-Diketonates