scholarly journals Oxidation of dibenzothiophene as a model substrate for the removal of organic sulphur from fossil fuels by iron(III) ions generated from pyrite by Acidithiobacillus ferrooxidans

2007 ◽  
Vol 72 (6) ◽  
pp. 533-537 ◽  
Author(s):  
Vladimir Beskoski ◽  
Valerija Matic ◽  
Jelena Milic ◽  
Dejan Godjevac ◽  
Boris Mandic ◽  
...  
Keyword(s):  
Acidithiobacillus Ferrooxidans ◽  
Fossil Fuels ◽  
Model Compound ◽  
Reaction Products ◽  
Dibenzothiophene Sulfone ◽  
Organic Sulphur ◽  
Indirect Mechanism ◽  
Abiotic Oxidation ◽  
Basic Hypothesis

Within this paper a new idea for the removal of organically bonded sulphur from fossil fuels is discussed. Dibenzothiophene (DBT) was used as a model compound of organicmolecules containing sulphur. This form of (bio)desulphurization was performed by an indirect mechanism in which iron(III) ions generated from pyrite by Acidithiobacillus ferrooxidans performed the abiotic oxidation. The obtained reaction products, dibenzothiopene sulfoxide and dibenzothiophene sulfone, are more soluble in water than the basic substrate and the obtained results confirmed the basic hypothesis and give the possibility of continuing the experiments related to application of this (bio)desulphurization process. .

scholarly journals Study of the Synchrotron Photoionization Oxidation of Alpha-Angelica Lactone (AAL) Initiated by O(3P) at 298, 550, and 700 K

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4070
Author(s):  
Golbon Rezaei ◽  
Giovanni Meloni
Keyword(s):  
Atomic Oxygen ◽  
Fossil Fuels ◽  
Reaction Products ◽  
Photoionization Mass Spectrometry ◽  
Natural Substances ◽  
Primary Products ◽  
Major Reaction ◽  
Angelica Lactone ◽  
Significant Attention

In recent years, biofuels have been receiving significant attention because of their potential for decreasing carbon emissions and providing a long-term renewable solution to unsustainable fossil fuels. Currently, lactones are some of the alternatives being produced. Many lactones occur in a range of natural substances and have many advantages over bioethanol. In this study, the oxidation of alpha-angelica lactone initiated by ground-state atomic oxygen, O(3P), was studied at 298, 550, and 700 K using synchrotron radiation coupled with multiplexed photoionization mass spectrometry at the Lawrence Berkeley National Lab (LBNL). Photoionization spectra and kinetic time traces were measured to identify the primary products. Ketene, acetaldehyde, methyl vinyl ketone, methylglyoxal, dimethyl glyoxal, and 5-methyl-2,4-furandione were characterized as major reaction products, with ketene being the most abundant at all three temperatures. Possible reaction pathways for the formation of the observed primary products were computed using the CBS–QB3 composite method.

Reaction kinetics of strong nucleophiles with a dimeric non-phenolic lignin model compound with α-carbonyl functionality (adleron) in aqueous alkali solution

Holzforschung ◽  
2016 ◽  
Vol 70 (9) ◽  
pp. 811-818 ◽  
Author(s):  
Olesya Fearon ◽  
Susanna Kuitunen ◽  
Tapani Vuorinen
Keyword(s):  
Hydrogen Sulfide ◽  
Model Compound ◽  
Degradation Kinetics ◽  
Reaction Products ◽  
Lignin Model Compound ◽  
Vis Spectroscopy ◽  
Soda Pulping ◽  
Lignin Model ◽  
Kinetics Of ◽  
Sulfite Ion

Abstract The degradation kinetics of a non-phenolic lignin model compound with α-carbonyl functionality (adlerone) has been studied by varying temperature and concentrations of sodium hydroxide, sodium hydrogen sulfide, and sodium sulfite. The kinetics of adlerone degradation and formation of its reaction products were monitored by UV-Vis spectroscopy and their structures were analyzed by GC/MS. The two step degradation of adlerone was studied in two separate experimental setups. In the first alkali catalyzed step, adlerone is converted to a β-elimination product that reacts further in the second step with hydrogen sulfide or sulfite ion. The Arrhenius kinetic parameters were derived by the KinFit software. The activation energy for the 1st step was 69.1 kJ mol-1, and for the 2nd step with sulfide 42.4 kJ mol-1 and with sulfite ion 35.8 kJ mol-1. The reaction mechanisms presented are in line with those published earlier: β-ether bonds of structures having α-carbonyl functionality do not cleave under soda pulping conditions, whereas in kraft and sulfite pulping the cleavage of β-ether bonds proceeds via nucleophile attack and addition. The combination of hydroxyl and sulfite ions gives the fastest cleavage of β-ether bonds in non-phenolic lignin structures with the α-carbonyl functionality.

Study on the Formation of Ethyl Levulinate from Wheat Straw Based on a Model Compound

2020 ◽  
Vol 14 (2) ◽  
pp. 273-279
Author(s):  
Zhiyong Chen ◽  
Qian Guan ◽  
Haiyan Xu ◽  
Tingzhou Lei ◽  
Lu Lin ◽  
...  
Keyword(s):  
Reaction Time ◽  
Wheat Straw ◽  
Microcrystalline Cellulose ◽  
Model Compound ◽  
Cellulose Degradation ◽  
Biomass Conversion ◽  
Reaction Products ◽  
Model Compounds ◽  
Ethyl Levulinate ◽  
Change Trend

Glucose and microcrystalline cellulose were selected as model compounds to investigate the formation of ethyl levulinate (EL). Optimal glucose and microcrystalline cellulose transformation conditions resulted in yields of 41.05 wt.% and 38.56 wt.% for EL, 0.73 wt.% and 2.63 wt.% for ethyl-glucoside (EG), 0.42 wt.% and 0.36 wt.% for 5-hydroxymethylfurfural (HMF), and 2.18 wt.% and 2.16 wt.% for 5-ethoxy methyl furfural (EMF), respectively. Increasing the reaction time and temperature resulted in an optimized yield of EL. These increases also resulted in decreased EG and EMF yield, and the change trend of HMF was not significant. EMF, HMF, and EG are intermediates in the formation of EL. Finally, we concluded that biomass conversion occurs first through cellulose degradation to glucose followed by the production of EG through alcoholysis and hydrolysis and dehydration of the reaction products to produce EL.

Liquefaction Mechanism of β-O-4 Lignin Model Compound in the Presence of Phenol under Acid Catalysis. Part 1. Identification of the Reaction Products

Holzforschung ◽  
2001 ◽  
Vol 55 (6) ◽  
pp. 617-624 ◽  
Author(s):  
L. Lin ◽  
Y. Yao ◽  
N. Shiraishi
Keyword(s):  
High Performance ◽  
Model Compound ◽  
Structural Characteristics ◽  
Main Reaction ◽  
Reaction Products ◽  
Lignin Model Compound ◽  
H Nmr ◽  
Lignin Model ◽  
Oxalic Acids ◽  
C Nmr

Summary Guaiacylglycerol-β-guaiacyl ether (GG) was used as a lignin model compound to study the liquefaction reaction mechanism of lignin in the presence of phenol under the catalysis of several typical acids such as sulfuric, phosphoric and oxalic acids. The reaction products were isolated by silicagel column chromatography and high performance liquid chromatography (HPLC). The structures of the obtained compounds were identified by means of GC-MS, 1H-NMR, 13C-NMR, 1H-1H COSY, HMBC and HMQC. As a result, about 30 compounds were obtained as the main reaction products. It was found that their structural characteristics were significantly different from those yielded at the non-catalyzed liquefaction (Lin et al. 1997a), and independent on the acid species. The dominant products were guaiacylglycerol-α-phenyl-β-guaiacyl ethers, followed by guaiacol, triphenylethanes, diphenylmethanes, benzocyclobutanes and phenylcoumarans. The structural characteristics and yields of these main reaction products indicated that condensation between phenol and GG in its C-α and further cleavages in both the β-O-4 linkage and Cβ–Cγ bonding could be the dominant reaction pathways.

The Chemistry of Vulcanization. VII. Role of Zinc Butyrate in the Reaction of Diphenylmethane, Sulfur and 2-Mercaptobenzothiazole

1960 ◽  
Vol 33 (1) ◽  
pp. 217-228 ◽  
Author(s):  
Jitsuo Tsurugi ◽  
Haruko Fukuda
Keyword(s):  
Zinc Oxide ◽  
Kinetic Study ◽  
Butyric Acid ◽  
Model Compound ◽  
Reaction System ◽  
The Other ◽  
Zinc Salt ◽  
Reaction Products ◽  
Molecular Dispersion

Abstract In previous Parts of this series, the accelerating mechanism of thiazole type accelerators, namely, 2-mercaptobenzothiazole (MBT), 2,2′-benzothiazolyl disulfide (MBTS) and zinc salt of 2-mercaptobenzothiazole (ZMBT) in the absence of zinc oxide or zinc soap, was investigated with diphenylmethane (DPM) as a model compound of rubber hydrocarbon. The significance of DPM as a model was discussed in some of the earlier papers. Parts IV, V and VI of this series indicated that 2-mercaptobenzothiazolyl radical generated from accelerators splits the sulfur ring, and that the processes by which accelerators generate the radical differ with each other according to their types. These results were obtained in the absence of zinc oxide or zinc soap. The present study will report the role of zinc butyrate in the reaction involving DPM, sulfur and MBT. Experience in the industry indicates that zinc oxide (or zinc soap) is indispensable to the thiazole type accelerators and that the efficiency of zinc oxide or soap is more prominent in MBT than in MBTS or ZMBT. The results obtained in the previous papers also suggest that zinc oxide or soap may have an influence on the rate at which the accelerator generates 2-mercaptobenzothiazolyl radical, since it is shown in Parts IV, V and VI that the radical has an accelerating effect. Therefore, it may be considered that zinc oxide or zinc soap activates MBT more effectively than does the other thiazole type accelerators in order to produce this radical. As will be seen later in this study, interaction of MBT with zinc butyrate in the absence of sulfur produces ZMBT and butyric acid. The ZMBT will interact with sulfur and generate the 2-mercaptobenzothiazolyl radical as reported in Part VI. The zinc salt thus formed will be dispersed in a state of molecular dispersion in the reaction system, while the same compound prepared in Part VI was not dissolved in DPM even at the reaction temperatures. In this respect the former is considered more effective than the latter. In order to verify the above assumptions the reaction involving DPM, sulfur and MBT in the presence of zinc butyrate were investigated. The reaction products and mechanism were compared with those in the absence of zinc soap. Since zinc butyrate is soluble in the reaction system at the reaction temperatures, a kinetic study also was carried out and compared with that in the absence of zinc soap.

The Chemistry of Vulcanization. I. Diphenylmethane as a Model of Rubber Hydrocarbon for Its Reaction with Sulfur

1958 ◽  
Vol 31 (4) ◽  
pp. 762-786 ◽  
Author(s):  
Jitsuo Tsurugi
Keyword(s):  
Reaction Mechanism ◽  
Model Compound ◽  
Chemical Investigation ◽  
Hydrocarbon Radical ◽  
Reaction Products ◽  
Primary Reaction ◽  
Secondary Product ◽  
Model Compounds ◽  
Vast Number ◽  
Produce Water

Abstract Following the discovery of vulcanization of rubber by Goodyear, a vast number of experiments and speculations have been carried out, but the final clarification of the mechanism of vulcanization and acceleration has remained unsettled. Overemphasis of physical and technological criteria in the investigation of vulcanization may have contributed to the failure to attach importance to the purely chemical investigation. In fact rubber vulcanizates defy chemical investigation because they are insoluble and infusible. However, in 1947 Farmer and collaborators, using olefinic substances such as cyclohexene, dihydromyrcene and squalene as model compounds, proposed a new theory on the vulcanization of rubber by sulfur. According to them α-methylenic hydrogen adjacent to olefinic double bonds is attacked by sulfur, and a hydrocarbon radical is formed. Then this radical couples with the diradical ⋅Sx⋅ and this leads to polysulfides as primary reaction products. Farmer's theory laid the ground work for the chemical investigation of vulcanization but the reaction of olefins with sulfur is too complex to indicate the reaction mechanism. Diphenylmethane (DPM) contains α-methylenic hydrogen (to a benzene ring) and may be expected to react with relative readiness. Moreover the reaction of DPM with molecular oxygen is already reported to produce water, diphenylmethyl hydroperoxide, tetraphenylethane and benzophenone. It is expected then that when DPM reacts with sulfur, it should give the thio analogs of these compounds. Since the reaction and reaction products of sulfur with DPM are considerably less complex than those with olefinic substances, the reaction mechanism should be elucidated by using the simpler hydrocarbon as a model compound. Comparative studies of the reaction with and without accelerator will present the key to the mechanism and theory of acceleration. As fundamental studies of rubber vulcanization as well as acceleration the following are the two objects of this paper. The first is the reaction mechanism of DPM with sulfur at 180° C and the second is the pyrolysis of the primary product (dibenzhydryl polysulfide) to the secondary product (thiobenzophenone) at the same temperature. Investigations on the reaction of DPM with sulfur in the presence of accelerators will be reported in other papers of this series.

A review of the occurrence, toxicity,and biodegradation of condensed thiophenes found in petroleum

1998 ◽  
Vol 44 (7) ◽  
pp. 605-622 ◽  
Author(s):  
Kevin G Kropp ◽  
Phillip M Fedorak
Keyword(s):  
Key Words ◽  
Fossil Fuels ◽  
Model Compound ◽  
Microbial Metabolism ◽  
Organosulfur Compounds ◽  
Quantitative Studies ◽  
Detection And Identification ◽  
Laboratory Cultures ◽  
Sulfur Containing ◽  
Key Words Biodegradation

Condensed thiophenes comprise a significant portion of the organosulfur compounds in petroleum and in other products from fossil fuels. Dibenzothiophene (DBT) has served as a model compound in biodegradation studies for over two decades. However, until quite recently, few other organosulfur compounds were studied, and their fates in petroleum-contaminated environments are largely unknown. This paper presents a review of the types of organosulfur compounds found in petroleum and summarizes the scant literature on toxicity studies with condensed thiophenes. Reports on the biodegradation of benzothiophene, alkylbenzothiophenes, DBT, alkylDBTs, and naphthothiophenes are reviewed with a focus on the identification of metabolites detected in laboratory cultures. In addition, recent reports on quantitative studies with DBT and naphtho[2,1-b]thiophene indicate the existence of polar sulfur-containing metabolites that have escaped detection and identification. Key words: biodegradation, condensed thiophenes, dibenzothiophene, microbial metabolism, toxicity.

Chemistry of Various Accelerators in an E-SBR Model Compound

2006 ◽  
Vol 79 (1) ◽  
pp. 1-25 ◽  
Author(s):  
C. C. Pierre ◽  
S. Datta ◽  
R. N. Datta ◽  
A. G. Talma
Keyword(s):  
Reaction Kinetics ◽  
Model Compound ◽  
Reaction Products ◽  
Sulfur Vulcanization ◽  
Analytical Tools

Abstract Sulfur vulcanization was carried out with 5-phenyl hex-2-ene serving as a model of e-SBR. Various accelerators have been used to study and compare the reactivity in a system containing sulfur and activators. Both HPLC and GC-MS analytical tools were used to identify the reaction products. It has been observed that the vulcanization in the presence of N-cyclohexyl-2-benzothiazole sulfenamide (CBS) generates a large amount of 2-marcaptobenzothiazole (MBT), which continuously increases and finally decreases suggesting further participation in vulcanization generating new crosslinks. The sulfenamide, N-cyclohexyl-4,6 dimethyl-2-pyrimidine sulfenamide (CDMPS) behaves different. Although it generates considerable amount of corresponding thiol, (4,6-dimethyl pyrimidine-2-thiol, DMMP) at the beginning of the reaction, no decrease has been observed during the course of further reaction suggesting that the accelerator, DMMP, somehow remains deactivated and therefore no changes in network is feasible. Identical differences exist between bis(2,2′benzothiazyl) disulfide (MBTS) and corresponding bis (4-methyl-2,2′benzothiazyl)disulfide (M-MBTS) in the reaction kinetics.

Liquefaction Mechanism of β-O-4 Lignin Model Compound in the Presence of Phenol under Acid Catalysis. Part 2. Reaction Behaviour and Pathways

Holzforschung ◽  
2001 ◽  
Vol 55 (6) ◽  
pp. 625-630 ◽  
Author(s):  
L. Lin ◽  
S. Nakagame ◽  
Y. Yao ◽  
M. Yoshioka and N. Shiraishi ◽  
N. Shiraishi
Keyword(s):  
High Performance ◽  
Model Compound ◽  
Structural Characteristics ◽  
Gel Permeation Chromatography ◽  
Main Reaction ◽  
Reaction Products ◽  
Reaction Behavior ◽  
Lignin Model Compound ◽  
Lignin Model ◽  
Acid Catalyzed

Summary By means of high performance liquid chromatography (HPLC) and gel permeation chromatography (GPC), the yields of the main reaction products and the polymeric portion formed in the reaction of guaiacylglycerol-β-guaiacyl ether (GG) under various acid-catalyzed conditions were quantified as a function of reaction time. Based on their forming sequence and reaction behavior, as well as their structural characteristics, an acid-catalyzed reaction mechanism of GG with phenol was proposed.

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