Kinetic investigation into the phogochemical oxidation of benzothiophene in seawater showed that photo-oxidation rates of benzothiophene were influenced by the medium,pH,heary metal ion,dissolved oxygen,and light inte...Kinetic investigation into the phogochemical oxidation of benzothiophene in seawater showed that photo-oxidation rates of benzothiophene were influenced by the medium,pH,heary metal ion,dissolved oxygen,and light intensity.The photo-oxidation of benzothiophene followed the first order reaction law, with the rate constants ranging from 1.21×10 -5 /s to 5.38×10 -5 /s.An interesting observation was that the presence of Hg 2+ could markedly enhance the photo-oxidation rate of benzothiophene in seawater;and that the photo-oxidation rate of benzothiophene increased with light intensity.The effect of oxygen on the rate constant for benzothiophene photolysis was also observed.Compared with purging with nitrogen,purging seawater with oxygen evidently increased the photolysis rate of benzothiophene. Based on this observation,a benzothiophene photo-oxidation mechanism including singlet oxygen (O 2 1 Δ g) was suggested.Two photolysis products of benzothiophene were identified.The photolysis of benzothiophene is considered to be important in the removal of this compound in seawater.展开更多
Using density functional theory(DFT) combined with nonequilibrium Green's function investigates the electron-transport properties of several molecular junctions based on the PBTDT-CH=NH molecule, which is modified ...Using density functional theory(DFT) combined with nonequilibrium Green's function investigates the electron-transport properties of several molecular junctions based on the PBTDT-CH=NH molecule, which is modified by one to four alkyl groups forming PBTDT-(CH2)nCH=NH. The electronic structures of the isolated molecules(thiol-ended PBTDT-(CH2)nCH=N) have been investigated before the electron-transport calculations are performed. The asymmetric current-voltage characteristics have been obtained for the molecular junctions. Rectifying performance of Au/S-PBTDT-CH=N-S/Au molecular junction can be regulated by introducing alkyl chain. The N3 molecular junction exhibits the best rectifying effect. Its maximum rectifying ratio is 878, which is 80 times more than that of the molecular junction based on the original N molecular junction. The current-voltage(I-V) curves of all the sandwich systems in this work are illustrated by transmission spectra and molecular projection density analysis.展开更多
This work yielded an improved method for extracting and analysing benzothiophene in marine sediment.The detation limit was 0.05 ng S of benzothiophene, with precision of 8%. Benzothiophene was found in Nansha Islands ...This work yielded an improved method for extracting and analysing benzothiophene in marine sediment.The detation limit was 0.05 ng S of benzothiophene, with precision of 8%. Benzothiophene was found in Nansha Islands sea area sediments and ranged from 1.1 -6.8 ng per gram dry sediment. Its concentration was closely correlated to hte organic carbon content in the sediment.Several source processes of benzohtiophene are discussed in this paper.展开更多
The sorption behavior of benzothiophene on marine sediments treated by different procedures was studied. Linear sorption isotherms were found for sorption of benzothiophene by no treatment and NaOAC-HOAC treatment sed...The sorption behavior of benzothiophene on marine sediments treated by different procedures was studied. Linear sorption isotherms were found for sorption of benzothiophene by no treatment and NaOAC-HOAC treatment sediments. The ediment treated by NaOAC-HOAC exhibited obviously larger Kp value for benzothiophene. The observed Koc value was basically consistent with the value predicted from the benzothiophene solubility in water. Nonlinear isotherms were observed for adsorption of benzothiophene on the sediments treated by H2O2 and could be described by the Freundlich equation.展开更多
Deep eutectic solvents(DESs)1-butyl-3-methylimidazolium bromide-polyalcohol([Bmim]Br-polyalcohol)were synthesized from[Bmim]Br and polyalcohol such as ethylene glycol(EG),propylene glycol(PG),glycerol(GL)at a molar ra...Deep eutectic solvents(DESs)1-butyl-3-methylimidazolium bromide-polyalcohol([Bmim]Br-polyalcohol)were synthesized from[Bmim]Br and polyalcohol such as ethylene glycol(EG),propylene glycol(PG),glycerol(GL)at a molar ratio of 1:2.[Bmim]Br-2propylene glycol([Bmim]Br-2PG)was characterized with FT-IR spectroscopy and 1H NMR.The removal of benzothiophene(BT)from model oil was investigated by extraction with DES[Bmim]Br-2PG.The results showed that an extraction efficiency as high as 54.1%could be achieved with the solvent in one-stage extraction at 30℃in 30 min with a DES/oil mass ratio of 1:1.Deep desulfurization was realized after five-stage extraction,and sulfur content in model oil was reduced to less than 10μg/g.The used[Bmim]Br-2PG DES was regenerated and showed an extraction efficiency of 50.5%within four recycles.展开更多
Theoretical studies on a series of oligobenzothiophenes were carded out with the AM 1 and DFT methods. Based on B3LYP/6-31G(D) optimized geometries, the electronic spectra, IR spectra and NMR spectra of the oligomer...Theoretical studies on a series of oligobenzothiophenes were carded out with the AM 1 and DFT methods. Based on B3LYP/6-31G(D) optimized geometries, the electronic spectra, IR spectra and NMR spectra of the oligomers were calculated by INDO/CIS, AM1 and B3LYP/6-31G(D) methods, respectively. The energy gaps decrease, and the absorption in elec- tronic spectra exhibits a red-shift as polymerization increases. The IR frequencies are little affected by the polymerization and substituents. The ^13C chemical shifts are changed to be upfield since the electron-donating groups increase the electron density of carbon atoms but remain unchanged with the increase of polymerization.展开更多
The release and control of sulfur species in the pyrolysis of fossil fuels and solid wastes have attracted attention worldwide.Particularly,thiophene derivatives are important intermediates for the sulfur gas release ...The release and control of sulfur species in the pyrolysis of fossil fuels and solid wastes have attracted attention worldwide.Particularly,thiophene derivatives are important intermediates for the sulfur gas release from organic sulfur,but the underlying migration mechanisms remain unclear.Herein,the mechanism of sulfur migration during the release of sulfur-containing radicals in benzothiophene pyrolysis was explored through quantum chemistry modeling.The C_(1)-to-C_(2)H-transfer has the lowest energy barrier of 269.9 kJ·mol-1 and the highest rate constant at low temperatures,while the elevated temperature is beneficial for C−S bond homolysis.2-Ethynylbenzenethiol is the key intermediate for the formation of S and SH radicals with the overall energy barriers of 408.0 and 498.7 kJ·mol-1 in favorable pathways.The generation of CS radicals is relatively difficult because of the high energy barrier(551.8 kJ·mol-1).However,it can be significantly promoted by high temperatures,where the rate constant exceeds that for S radical generation above 930°C.Consequently,the strong competitiveness of S and SH radicals results in abundant H2 S during benzothiophene pyrolysis,and the high temperature is more beneficial for CS2 generation from CS radicals.This study lays a foundation for elucidating sulfur migration mechanisms and furthering the development of pyrolysis techniques.展开更多
3-CF3 S substituted thioflavones and benzothiophenes were achieved via the reactions of AgSCF3 with methylthiolated alkynones and alkynylthioanisoles,respectively,promoted by persulfate.This protocol possesses good fu...3-CF3 S substituted thioflavones and benzothiophenes were achieved via the reactions of AgSCF3 with methylthiolated alkynones and alkynylthioanisoles,respectively,promoted by persulfate.This protocol possesses good functional group tolerance and high yields.Mechanistic studies suggested that a classic two-step radical process was involved,which includes addition of CF3 S radical to triple bond and cyclization with SMe moiety.展开更多
In this work,the effect of the textural property of activated carbons on desorption activation energy and adsorption capacity for benzothiophene(BT)was investigated.BET surface areas and the textural parameters of thr...In this work,the effect of the textural property of activated carbons on desorption activation energy and adsorption capacity for benzothiophene(BT)was investigated.BET surface areas and the textural parameters of three kinds of the activated carbons,namely SY-6,SY-13 and SY-19,were measured with an ASAP 2010 instrument.The desorption activation energies of BT on the activated carbons were determined by temperature-programmed desorption(TPD).Static adsorption experiments were carried out to determine the isotherms of BT on the activated carbons.The influence of the textural property of the activated carbons on desorption activation energy and the adsorption capacity for BT was discussed.Results showed that the BET surface areas of the activated carbons,SY-6,SY-13 and SY-19 were 1106,1070 and 689 m2·g^(-1),respectively,and their average pore diameters were 1.96,2.58 and 2.16 nm,respectively.The TPD results indicated that the desorption activation energy of BT on the activated carbons,SY-6,SY-19 and SY-13 were 58.84,53.02 and 42.57 KJ/mol,respectively.The isotherms showed that the amount of BT adsorbed on the activated carbons followed the order of SY-6>SY-19>SY-13.The smaller the average pore diameter of the activated carbon,the stronger its adsorption for BT and the higher the activation energy required for BT desorption on its surface.The Freundlich adsorption isotherm model can be properly used to formulate the adsorption behavior of BT on the activated carbons.展开更多
1, 2 - bis(3-Methylbenzo[b]thiophen-2-yl)cycloalkene derivatives 3a, 3b and 1 - (2-methylbenzo[b]thiophen - 3 - yl) - 2 - (3 - methylbenzo[b]thiophen - 2 - yl)cyclohexene 9 were synthesized. The obtained compounds exh...1, 2 - bis(3-Methylbenzo[b]thiophen-2-yl)cycloalkene derivatives 3a, 3b and 1 - (2-methylbenzo[b]thiophen - 3 - yl) - 2 - (3 - methylbenzo[b]thiophen - 2 - yl)cyclohexene 9 were synthesized. The obtained compounds exhibited photochromic property and the absorption bands of the colored forms 4a, 4b and 10 centered between 360-440 nm thus possessing the sensitivity at the wavelength of the newly developed InGaN diode laser.展开更多
Solid adsorbents Cu+- 13X and Cu+-13X loaded with La element were prepared by ion-exchange method. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterize the structure of the pr...Solid adsorbents Cu+- 13X and Cu+-13X loaded with La element were prepared by ion-exchange method. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterize the structure of the prepared zeolite. Adsorption of thiophene with differ- ent groups over the two adsorbents was investigated by static adsorption equilibrium and kinetic test. Static equilibrium data were correlated based on the Langmuir model and the modified Langmuir model. Kinetic data were fitted very well by Crank diffusion model. The results re- vealed that the adsorption capacity of single component over the Cu+-13X loaded with La element increased about 10% as compared to the non-doped Cu+-13X. Fitting results of ηi and De illustrated that loading of the La element into zeolite could change the interaction force be- tween binary components. The kinetic test showed that the competitive adsorption became moderate, and thus resulted in the improvement of the total desulfiarization capacity. Keywords: rare earths; static adsorption; kinetic adsorption; thiophene; 3-methylthiophene; 2,5-dimethvlthiophene; benzothiophene展开更多
A convenient synthetic route to 2-heteroaryl-3-hydroxybenzo[b]thiophene derivatives via K_(2)CO_(3)-promoted multicomponent cycliza-tion between o-halogenated benzaldehyde,2-methylquinolines and sulfur powder has been...A convenient synthetic route to 2-heteroaryl-3-hydroxybenzo[b]thiophene derivatives via K_(2)CO_(3)-promoted multicomponent cycliza-tion between o-halogenated benzaldehyde,2-methylquinolines and sulfur powder has been demonstrated.This reaction is performed smoothly under simple conditions to give the corresponding products in moderate to good yields.The resultant 3-hydroxybenzo[b]thiophenes have been proved to be versatile building blocks in a range of transition-metal-catalyzed cross-coupling reactions.展开更多
文摘Kinetic investigation into the phogochemical oxidation of benzothiophene in seawater showed that photo-oxidation rates of benzothiophene were influenced by the medium,pH,heary metal ion,dissolved oxygen,and light intensity.The photo-oxidation of benzothiophene followed the first order reaction law, with the rate constants ranging from 1.21×10 -5 /s to 5.38×10 -5 /s.An interesting observation was that the presence of Hg 2+ could markedly enhance the photo-oxidation rate of benzothiophene in seawater;and that the photo-oxidation rate of benzothiophene increased with light intensity.The effect of oxygen on the rate constant for benzothiophene photolysis was also observed.Compared with purging with nitrogen,purging seawater with oxygen evidently increased the photolysis rate of benzothiophene. Based on this observation,a benzothiophene photo-oxidation mechanism including singlet oxygen (O 2 1 Δ g) was suggested.Two photolysis products of benzothiophene were identified.The photolysis of benzothiophene is considered to be important in the removal of this compound in seawater.
基金supported by the National Natural Science Foundation of China(21401023)
文摘Using density functional theory(DFT) combined with nonequilibrium Green's function investigates the electron-transport properties of several molecular junctions based on the PBTDT-CH=NH molecule, which is modified by one to four alkyl groups forming PBTDT-(CH2)nCH=NH. The electronic structures of the isolated molecules(thiol-ended PBTDT-(CH2)nCH=N) have been investigated before the electron-transport calculations are performed. The asymmetric current-voltage characteristics have been obtained for the molecular junctions. Rectifying performance of Au/S-PBTDT-CH=N-S/Au molecular junction can be regulated by introducing alkyl chain. The N3 molecular junction exhibits the best rectifying effect. Its maximum rectifying ratio is 878, which is 80 times more than that of the molecular junction based on the original N molecular junction. The current-voltage(I-V) curves of all the sandwich systems in this work are illustrated by transmission spectra and molecular projection density analysis.
文摘This work yielded an improved method for extracting and analysing benzothiophene in marine sediment.The detation limit was 0.05 ng S of benzothiophene, with precision of 8%. Benzothiophene was found in Nansha Islands sea area sediments and ranged from 1.1 -6.8 ng per gram dry sediment. Its concentration was closely correlated to hte organic carbon content in the sediment.Several source processes of benzohtiophene are discussed in this paper.
文摘The sorption behavior of benzothiophene on marine sediments treated by different procedures was studied. Linear sorption isotherms were found for sorption of benzothiophene by no treatment and NaOAC-HOAC treatment sediments. The ediment treated by NaOAC-HOAC exhibited obviously larger Kp value for benzothiophene. The observed Koc value was basically consistent with the value predicted from the benzothiophene solubility in water. Nonlinear isotherms were observed for adsorption of benzothiophene on the sediments treated by H2O2 and could be described by the Freundlich equation.
基金The authors are grateful for financial support from the Doctoral Scientific Research Foundation of Liaoning Shihua University(2019×JJ-006).
文摘Deep eutectic solvents(DESs)1-butyl-3-methylimidazolium bromide-polyalcohol([Bmim]Br-polyalcohol)were synthesized from[Bmim]Br and polyalcohol such as ethylene glycol(EG),propylene glycol(PG),glycerol(GL)at a molar ratio of 1:2.[Bmim]Br-2propylene glycol([Bmim]Br-2PG)was characterized with FT-IR spectroscopy and 1H NMR.The removal of benzothiophene(BT)from model oil was investigated by extraction with DES[Bmim]Br-2PG.The results showed that an extraction efficiency as high as 54.1%could be achieved with the solvent in one-stage extraction at 30℃in 30 min with a DES/oil mass ratio of 1:1.Deep desulfurization was realized after five-stage extraction,and sulfur content in model oil was reduced to less than 10μg/g.The used[Bmim]Br-2PG DES was regenerated and showed an extraction efficiency of 50.5%within four recycles.
文摘Theoretical studies on a series of oligobenzothiophenes were carded out with the AM 1 and DFT methods. Based on B3LYP/6-31G(D) optimized geometries, the electronic spectra, IR spectra and NMR spectra of the oligomers were calculated by INDO/CIS, AM1 and B3LYP/6-31G(D) methods, respectively. The energy gaps decrease, and the absorption in elec- tronic spectra exhibits a red-shift as polymerization increases. The IR frequencies are little affected by the polymerization and substituents. The ^13C chemical shifts are changed to be upfield since the electron-donating groups increase the electron density of carbon atoms but remain unchanged with the increase of polymerization.
基金the National Natural Science Foundation of China(Grant Nos.52006069,51922040,51821004)Fundamental Research Funds for the Central Universities(Grant No.2020MS020)Hunan Science and Technology Planning Project(Grant No.2020RC5008)for financial support.
文摘The release and control of sulfur species in the pyrolysis of fossil fuels and solid wastes have attracted attention worldwide.Particularly,thiophene derivatives are important intermediates for the sulfur gas release from organic sulfur,but the underlying migration mechanisms remain unclear.Herein,the mechanism of sulfur migration during the release of sulfur-containing radicals in benzothiophene pyrolysis was explored through quantum chemistry modeling.The C_(1)-to-C_(2)H-transfer has the lowest energy barrier of 269.9 kJ·mol-1 and the highest rate constant at low temperatures,while the elevated temperature is beneficial for C−S bond homolysis.2-Ethynylbenzenethiol is the key intermediate for the formation of S and SH radicals with the overall energy barriers of 408.0 and 498.7 kJ·mol-1 in favorable pathways.The generation of CS radicals is relatively difficult because of the high energy barrier(551.8 kJ·mol-1).However,it can be significantly promoted by high temperatures,where the rate constant exceeds that for S radical generation above 930°C.Consequently,the strong competitiveness of S and SH radicals results in abundant H2 S during benzothiophene pyrolysis,and the high temperature is more beneficial for CS2 generation from CS radicals.This study lays a foundation for elucidating sulfur migration mechanisms and furthering the development of pyrolysis techniques.
基金the National Natural Science Foundation of China(Nos.21991123,21677094)for financial support。
文摘3-CF3 S substituted thioflavones and benzothiophenes were achieved via the reactions of AgSCF3 with methylthiolated alkynones and alkynylthioanisoles,respectively,promoted by persulfate.This protocol possesses good functional group tolerance and high yields.Mechanistic studies suggested that a classic two-step radical process was involved,which includes addition of CF3 S radical to triple bond and cyclization with SMe moiety.
基金the National Natural Science Foundation of China(Grant No.20336020)for financial support.
文摘In this work,the effect of the textural property of activated carbons on desorption activation energy and adsorption capacity for benzothiophene(BT)was investigated.BET surface areas and the textural parameters of three kinds of the activated carbons,namely SY-6,SY-13 and SY-19,were measured with an ASAP 2010 instrument.The desorption activation energies of BT on the activated carbons were determined by temperature-programmed desorption(TPD).Static adsorption experiments were carried out to determine the isotherms of BT on the activated carbons.The influence of the textural property of the activated carbons on desorption activation energy and the adsorption capacity for BT was discussed.Results showed that the BET surface areas of the activated carbons,SY-6,SY-13 and SY-19 were 1106,1070 and 689 m2·g^(-1),respectively,and their average pore diameters were 1.96,2.58 and 2.16 nm,respectively.The TPD results indicated that the desorption activation energy of BT on the activated carbons,SY-6,SY-19 and SY-13 were 58.84,53.02 and 42.57 KJ/mol,respectively.The isotherms showed that the amount of BT adsorbed on the activated carbons followed the order of SY-6>SY-19>SY-13.The smaller the average pore diameter of the activated carbon,the stronger its adsorption for BT and the higher the activation energy required for BT desorption on its surface.The Freundlich adsorption isotherm model can be properly used to formulate the adsorption behavior of BT on the activated carbons.
文摘1, 2 - bis(3-Methylbenzo[b]thiophen-2-yl)cycloalkene derivatives 3a, 3b and 1 - (2-methylbenzo[b]thiophen - 3 - yl) - 2 - (3 - methylbenzo[b]thiophen - 2 - yl)cyclohexene 9 were synthesized. The obtained compounds exhibited photochromic property and the absorption bands of the colored forms 4a, 4b and 10 centered between 360-440 nm thus possessing the sensitivity at the wavelength of the newly developed InGaN diode laser.
基金Project supported by National Natural Science Foundation of China(21176118)
文摘Solid adsorbents Cu+- 13X and Cu+-13X loaded with La element were prepared by ion-exchange method. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterize the structure of the prepared zeolite. Adsorption of thiophene with differ- ent groups over the two adsorbents was investigated by static adsorption equilibrium and kinetic test. Static equilibrium data were correlated based on the Langmuir model and the modified Langmuir model. Kinetic data were fitted very well by Crank diffusion model. The results re- vealed that the adsorption capacity of single component over the Cu+-13X loaded with La element increased about 10% as compared to the non-doped Cu+-13X. Fitting results of ηi and De illustrated that loading of the La element into zeolite could change the interaction force be- tween binary components. The kinetic test showed that the competitive adsorption became moderate, and thus resulted in the improvement of the total desulfiarization capacity. Keywords: rare earths; static adsorption; kinetic adsorption; thiophene; 3-methylthiophene; 2,5-dimethvlthiophene; benzothiophene
基金supported by the National Natural Science Foundation of China(Nos.21871226,21502160,21572194)the Scientific Research Fund of Hunan Provincial Education Department(19B564)+3 种基金the Hunan Provincial Natural Science Foundation of China(No.2020JJ3032)the China Postdoctoral Science Foundation(Nos.2018M632976 and 2019T120709)the Scientific Research Fund of Xiangtan University(No.XDCX2020B110)the Open Fund of Guangdong Provincial Key Laboratory of Lumines-cence from Molecular Aggregates,Guangzhou,510640,China(South China University of Technology,No.2019B030301003).
文摘A convenient synthetic route to 2-heteroaryl-3-hydroxybenzo[b]thiophene derivatives via K_(2)CO_(3)-promoted multicomponent cycliza-tion between o-halogenated benzaldehyde,2-methylquinolines and sulfur powder has been demonstrated.This reaction is performed smoothly under simple conditions to give the corresponding products in moderate to good yields.The resultant 3-hydroxybenzo[b]thiophenes have been proved to be versatile building blocks in a range of transition-metal-catalyzed cross-coupling reactions.