Intramolecular Aldol Condensation ofα- Oxo Ketene Dibenzylthioacetals: A Facile Route to Substituted Thiophenes

A new method for the synthesis of substituted thiophenes was through intramolecular aldol condensation ofα-oxo ketene dibenzylthioacetals.All products were confirmed with IR, 1 H NMR and elemental analysis.

Oxidation of Thiophenes over Silica Gel in Hydrogen Peroxide/Formic Acid System

Thiophene C4H4S and 3-methylthiophene3-MC4H4S are typical thiophenenic sulfur compounds that exist in fluid catalytic cracking FCC gasoline. Oxidation of C4H4S and 3-MC4H4S were conducted in hydrogen peroxide H2O2 and formic acid system over a series of silica gel loaded with metal oxide. The silica gel loaded with copper and cobalt 1:1 oxide was found very active for the model compound oxidation using H2O2formic acid, while the silica gel unloaded with metal oxide was less active. The sulfur removal rate of thiophenes was dif- ferent as solvent was changed. And the conversation of C4H4S and 3-MC4H4S was improved at higher temperature, but reduced when olefin was added. The sulfur removal rate of model sulfur compounds was enhanced when the phase transfer catalyst emulsifier polyethylene glycol octyl phenyl ether or tetrabutylammonium bromideTBAB was added. The sulfur removal rate of simulated gasoline containing 524μg·ml-1 sulfur reached 90%. Interestingly, in a H2O2 and formic acid system with the addition of TBAB, a bromine substitution trend appeared in the oxidation of thiophenes, suggesting the influence of TBAB.

The Reaction of 2-Amino-4,5,6,7-tetrahydrobenzo[<i>b</i>]thiophenes with Benzoyl-Isothiocyanate: Synthesis of Annulated Thiophene Derivatives and Their Antitumor Evaluations

The reaction of the tetrahydrobenzo[b]thiophene derivatives 1a,b with benzoylisothiocyanate (2) afforded the thiourea derivatives 3a,b. Cyclization of the latter products gave the annulated products 4a,b. Compounds 3a,b reacted with either hydrazine hydrate (5a) or phenyl hydrazine (5b) afforded compounds 7a-d which underwent cyclization for compounds 7a,c afforded compound 9. On the other hand compounds 4a,b reacted with either hydrazine hydrate (5a) or phenyl hydrazine (5b) afforded compounds 6a-d a second pathway was applied to synthesize compound 6c which underwent cyclization afforded compound 9. Also compounds 4a,b reacted with either phenacyl bromide (10) afforded compounds 11a,b or ethylchloroacetae (12) compounds 13a,b were produced. The latter products reacted with each hydrazine hydrate (5a) and phenyl hydrazine (5b) afforded compounds 14a-d. Their antitumor activities were tested using three different cell lines.

Synthesis of 3-Methylthio-benzo[b]furans/Thiophenes via Intramolecular Cyclization of 2-Alkynylanisoles/Sulfides Mediated by DMSO/DMSO-d_(6) and SOCl_(2)

Main observation and conclusion The reaction of 2-alkynylanisoles/sulfides with SOCl_(2) and DMSO was conducted to conveniently furnish the biologically interesting 3-(methylthio)-benzo[b]furans/thiophenes via intramolecular cyclization.DMSO acts as a solvent as well as a sulfur source and can also be replaced with DMSO-d_(6),enabling the incorporation of the SCD3 moiety of DMSO-d_(6) to the 3-position of the heterocyclic frameworks.

The design and synthesis of fused thiophenes and their applications in organic field-effect transistors

Fused thiophenes refer to oligothienoacenes in which several thiophenes are coupled together via twoor multi-positions and their derivatives. The synthesized organic semiconductors based on fused thiophenes exhibit excellent field effect properties due to their efficient intermolecular S…S interactions and π…π stacking. The performances of organic field-effect transistors (OFETs) depend not only on the materials but also on the devices. Such factors which influence the device performances as device structures, fabrication technologies and interface engineering are extensively investigated based on the fused thiophenes. Searching for new organic semiconductors and improving the device fabrication technologies are two major issues in the development of OFETs.

Synthesis of 2-Benzylthio-5-phenyl-3,4-disubstituted Thiophenes by Intramolecular Condensation of α-Oxo Ketene Dibenzyl^thioacetals

A facile route to 2-benzylthio-5-phenyl-3,4-disubstituted thiophenes was described. Catalyzed by sodium hydroxide, the title compounds were synthesized in moderate to good yields simply from the intramolecular aldol type condensation of α-oxo ketene dibenzylthioacetals. The chemical selectivity for this annulation reaction was studied and discussed.

Synthesis of Chiral 2,5-Bis(oxazolinyl)thiophenes and Their Application as Chiral Shift Reagents for 1,1′-Bi-2-naphthol

A series of C_2-symmetrical chiral 2,5-bis(4'-alkyloxazolin-2-yl) thiophenes(thiobox) have been synthesized from thiophene-2,5-dicarboxylic acid by sequential amidation with achiral ethanolamine, conversion of hydroxyl to chloro group, and base-promoted oxazoline ringformation. As demonstrated by (-)-2,5-bis[4'-(S)-isopropyloxazolin-2'-yl] thiophene, these thioboxsystems exhibited remarkable chirality recognition of 1,1'-bi-2-naphthol giving rise to pronouncedshifts in the ~1H NMR signals of the latter axial chiral compound at the positions of C-3, C-4, C-5,and C-8.

Synthesis of Functionalized Thiophenes by Four-component Reactions of 1,3-Thiazolidinedione, Aromatic Aldehydes, Cyanoacetamide and Cyclic Secondary Amines

The polysubstituted thiophene derivatives were conveniently prepared by the four-component reactions of 1,3-thiazolidinedione, aromatic aldehydes, cyanoacetamide and cyclic secondary amines such as pyrrolidine, mor- pholine and piperidine. The reaction mechanism is believed to involve domino reactions of Knoevenagel condensation, Michael addition, ring-opening and recyclization of 1,3-thiazolidinedione.

Synthesis of tetrasubstituted thiophenes from pyridinium 1,4-zwitterionic thiolates and modified activated alkynes

Pyridinium 1,4-zwitterionic thiolates were applied to a formal [3+2] annulation reaction with modified activated alkynes, affording various tetrasubstituted thiophenes with aryl, alkenyl, alkyl or silyl group at the special position. The structural modification of alkyne substrates enabled the synthesis of diverse thiophenes to be achieved using the pyridinium 1,4-zwitterionic thiolates as the sulfur-containing building blocks. This approach is metal-free and catalyst-free.

Preparation of ZIF-8@PEBAX/PVDF nanocomposite membrane by the combination of self-assembly and in-situ growth for removing thiophene from the model gasoline

Metal-organic frameworks(MOFs)have gained attention in the development of MOFs/polymer hybrid membranes for pervaporation.However,the agglomeration of MOFs particles and interfacial defects limit its further application.In this study,we present a novel approach to fabricate a ZIF-8@PEBAX/PVDF nanocomposite membrane for removing thiophene from the model gasoline by combination of selfassembly and in-situ growth.Firstly,a PVDF supporting membrane was modified to have a negative charge.Next,positively charged zinc ions were attracted onto the negatively charged PVDF supporting membrane through electrostatic interaction.Afterwards,the Zinc ions deposited PVDF membrane was immersed into dimethylimidazole solution to form a uniform ZIF-8 layer.Finally,the ZIF-8 layer was coated with poly(ether-block-amide)(PEBAX)using the pouring method.Experimental results showed that the separating efficiency of the ZIF-8@PEBAX/PVDF nanocomposite membrane was improved significantly compared to that of pristine PEBAX membrane.The optimal permeation flux and enrichment factor of membrane were 27.80 kg(m^(2)h)^(-1)and 6.9,respectively.

Orientational Separation of Sulfur in Petroleum Coke by Alkali Calcining and Reflux Washing

The application of high-sulfur petroleum coke after desulfurization in aluminum electrolysis anodes is an important development trend. However, removing sulfur from high-sulfur petroleum coke is still a significant challenge.This study proposes alkali calcining and reflux washing to examine the impacts of temperature, particle size, the mass ratio of Na_(2)CO_(3) to NaOH, and total sodium addition on the desulfurization efficiency and mechanism. The results show that the desulfurization rate increases with increasing temperature, increasing total sodium content, and decreasing particle size. The addition of alkali can significantly reduce the opening-ring reaction temperature of thiophene and convert organic sulfur into inorganic sulfur(Na_(2)S). Three washing methods were compared, and reflux washing was selected to separate inorganic sulfur(Na_(2)S) from calcined petroleum coke. The sulfur content in petroleum coke decreased from 7.29% to 1.90%, with a desulfurization rate of 80.13% under optimal conditions. The petroleum coke was analyzed before and after desulfurization using X-Ray diffraction(XRD), Scanning Electron Microscopy(SEM), Infrared Spectroscopy(IR), Thermogravimetric Analysis and Differential Scanning Calorimetry(TG-DSC), Gaschromatography-mass Spectrometry(GC-MS). The results show that thiophene and benzothiophene in petroleum coke are decomposed and converted into octane and ethyl cyclohexane. These new observations are expected to provide further understanding and guidance for the utilization of highsulfur petroleum coke.

硅胶催化双氧水甲酸氧化噻吩类化合物的研究

Thiophene (C4H4S) and 3-methylthiophene(3-MC4H4S) are typical thiophenenic sulfur compounds that exist in fluid catalytic cracking (FCC) gasoline. Oxidation of C4H4S and 3-MC4H4S were conducted in hydrogen peroxide (H2O2) and formic acid system over a series of silica gel loaded with metal oxide. The silica gel loaded with copper and cobalt (1:1) oxide was found very active for the model compound oxidation using H2O2/formic acid, while the silica gel unloaded with metal oxide was less active. The sulfur removal rate of thiophenes was different as solvent was changed. And the conversation of C4H4S and 3-MC4H4S was improved at higher temperature,but reduced when olefin was added. The sulfur removal rate of model sulfur compounds was enhanced when the phase transfer catalyst emulsifier polyethylene glycol octyl phenyl ether or tetrabutylammonium bromide(TBAB)in a H2O2 and formic acid system with the addition of TBAB, a bromine substitution trend appeared in the oxidation of thiophenes, suggesting the influence of TBAB.

Kinetics and Mechanism of the Photo-oxidation of Thiophene by O_2 Adsorbed on Molecular Sieves

Photochemical oxidation of thiophene in n-octane/water extraction system using O2 as oxidant was studied. The reaction mechanism ofthiophene oxidation was proposed. Results obtained here can be used as the reference for the oxidative desulfurization of gasoline because thiophene is one of the main components containing sulfur in fluid catalytic cracking gasoline. Thiophene dissolved in n-octane was photodecomposed and removed into the water phase at ambient temperature and atmospheric pressure. A 500 W high-pressure mercury lamp （main wave length 365 nm, 0.22 kW/m） was used as light source for irradiation, and air was introduced by a gas pump to supply O2. Thiophene can be photo-oxidized to sulfone, oxalic acid, SO4^2-, and CO2. The desulfurization yield of thiophene in n-octane is 58.9% under photo-irradiation for 5 h under the conditions of air flow at 150 mL/min and V（water）：V（n-octane）=1：1. It can be improved to 92.3% by adding 0.15 g zeoliteartificial into 100 mL reaction system, which is the adsorbent for O2 and thiophene. And under such conditions, the photo-oxidation kinetics of thiophene with O2/zeoliteartificial is first-order with an apparent rate constant of 0.5047 h^-1 and a half-time of 1.37 h. The sulfur content can be depressed from 800 μL/L to less than 62 μL/L.

Effects of toluene on thiophene adsorption over NaY and Ce(IV)Y zeolites

Zeolites NaY and Ce（IV）Y were employed as adsorbents to remove organic sulfur compounds from model gasoline （MG） solutions with and without toluene in static adsorption experiments at room temperature （RT） and atmospheric pressure. The adsorbents were characterized by XRD, XRF and pyridine infrared spectrum （IR）. The adsorption experiments show that the desulfurization performance of Ce（IV）Y is much better than that of NaY. The sulfur removal over both NaY and Ce（IV）Y decreases with the increase of toluene concentration in MG, however, the decline tendency on Ce（IV）Y is smooth, and it is steep on NaY. FT-IR spectra of thiophene adsorption indicate that thiophene molecules are mainly adsorbed on NaY via π electron interaction, but on Ce（IV）Y, in addition to the π electron interaction, both Ce^4＋-S direct interaction and protonation of thiophene also play important roles. Toluene molecules are adsorbed on NaY also via π electron interaction. Although the amount of Bronsted acid sites is increased due to the introduction of Ce^4＋ ions into NaY zeolite, it is not found to influence the adsorption mode of toluene over Ce（IV）Y. Compared with NaY zeolite, the improved desulfurization performance over Ce（IV）Y for removing organic sulfur compounds from MG solution, especially those containing large amount of aromatics, may be ascribed to the direct Ce（IV）-S interaction, which is much resistant to the influence resulted from toluene adsorption.

Synthesis of New Schiff Bases Containing Thiophene Moiety

Seven new Schiff bases, which are 4,4,4-trifluo-ro-1-(2-thienyl)-1-butanone-3-Z, Z =-thioseraicarbazone (a); -thiocarbohydrazone (b),-benzoic hydrazone (c), -( o-hydroxyphenyl) imine (d) ,-nicotinic hydrazone (e),-salicylic hydrazone (f), and -(p-fluoro-m-chlorophenyl) imine (g), have been synthesized by reaction of 4, 4, 4-trifluoro-1-(2-thienyl)-1,3-butanedione (TFTBD) with corresponding hy-drazides or anilines, acetic acid or p-toluence sulfonic acid as catalyst, and characterized by Elemental analysis, IR, UV-Vis,1H NMR and MS. The MS spectra confirmed that the -C3=O condensed with primary amino group. Tauto-merism of the compounds is discussed.

Novel MWCNT-Support for Co-Mo Sulfide Catalyst in HDS of Thiophene and HDN of Pyrrole

With home-made multi-walled carbon nanotubes （MWCNTs, simplified as CNTs in later text） as support, CNT-supported Co-Mo-S catalysts, denoted as x%（mass percentage）MoiCoj/CNTs, were prepared. Their catalytic performance for thiophene hydrodesulfurization （HDS） and pyrrole hydrodenitrification （HDN） reactions was studied, and compared with the reference system sup- ported by AC. Over the 7.24%Mo3Co1/CNTs catalyst at reaction condition of 1.5 MPa, 613 K, C4H4S/H2=3.7/96.3（molar ratio） and GHSV≈8000 mlswP/（g-cat.h）, the specific HDS activity of thiophene reached 3.29 mmolc4H4S/（s.molMo）, which was 1.32 times as high as that （2.49 mmolc4H4S/（s.molMo）） of the AC-based counterpart, and was 2.47 times as high as that （1.33 mmolc4H4S/（s-molMo）） of the catalysts supported by AC with the respective optimal MoaCol-loading amount, 16.90%Mo3Co1/AC. Analogous reaction-chemical behaviours were also observed in the case of pyrrole HDN. It was experimentally found that using the CNTs in place of AC as support of the catalyst caused little change in the apparent activation energy for the thiophene HDS or pyrrole HDN reaction, but led to a significant increase in the concentration of catalytically active Mo-species （Mo^4＋） at the surface of the functioning catalyst. On the other hand, H2-TPD measurements revealed that the CNT-supported catalyst could reversibly adsorb a greater amount of hydrogen under atmospheric pressure at temperatures ranging from room temperature to about 673 K. This unique feature would help to generate microenvironments with higher stationarystate concentration of active hydrogen-adspecies at the surface of the functioning catalyst. Both factors mentioned above were favorable to increasing the rate of thiophene HDS and pyrrole HDN reactions.

Synthesis and Non-linear Optical(NLO) Properties of a Series of Alkoxysilane Derivative Chromophores

1 Introduction Nonlinear optical materials（NLO） have drawn a great intrest of some scholars and scientists in the last dacades because of their tremendous potential application in optoelectronic. The fabrication of efficient optoelectron devices is a challenging task because such systems need to meet the stringentable requirements for high optical quality and large and sustainable electro-optical（EO） response. In pursuit of NLO materials with excellent optoelectronic property,

Wet Desulfurization of High-Sulfur Petroleum Coke Improved via Pre-calcination,H_(2)O_(2) Treatment,and Ultrasound

This work reports an improved method for the wet desulfurization of high-sulfur petroleum coke(petcoke)powder based on the combination of pre-calcination,H_(2)O_(2),and ultrasound.The results demonstrated that over 45%of the sulfur atoms were efficiently removed from Tianjin coke and Qilu coke(particle size<0.1 mm)by pre-calcination at 800℃ for 6 h followed by desulfurization with HNO3(8 mol/L)and H_(2)O_(2)(2 mol/L)solution at a reaction temperature of 60℃,a reaction time of 6 h,a liquid-to-solid ratio of 10 mL/g,and a 40 kHz ultrasonic power of 400 W.In addition,the specific surface area of the petcoke particles increased from 0.7 to 301.49 m^(2)/g.After desulfurization,the pore size distribution of the petcoke particles was more concentrated on micropores compared with the samples prior to petcoke treatment.Reactive force field molecular dynamics simulation results indicated that HNO_(3) continuously oxidized the carbon atoms adjacent to sulfur atoms in the petcoke macromolecules and promoted sulfur removal from petcoke via the cleavage of C-S bonds.The sulfur transformation mechanism can be summarized as follows:thiophene sulfur→branched chain carbon sulfur→CO_(2)S→C_(2)O_(2)S→C_(2)O_(3)NS→C_(2)O_(4)S→CO_(2)S.

Adsorption desulfurization of model gasoline by metal–organic framework Ni3（BTC）2

This work presented the synthesis of Ni-based metal-organic framework material with a paddle-wheel structure Ni3(BTC)2 (Ni-BTC) and its application in thiophene (TP) adsorption from gasoline distillate by batch method. Adsorption isotherms of TP, cyclohexene, and toluene in cyclohexane onto Ni-BTC were conducted at 298-308 K to interpret the different effect of cyclohexene and toluene on TP adsorption. The results showed that, compared w让h cyclohexene, toluene addition in model gasoline led to a more evident decline in sulfur capacity of Ni-BTC, which is opposite to isostructural HKUST-1. The adsorption isotherms of TP, cyclohexene and toluene fit Langmuir model, S-type model and Temkin model well, respectively, indicating that the adsorption mechanisms of TP and the two competitors are different from one another The adsorption capacities on Ni-BTC followed the order of cyclohexene < toluene < TP at the same equilibrium concentrations, implying the order of the adsorption affinities, which is in good agreement with the different extent of influence by the two competitors. The enthalpy of TP adsorption on Ni-BTC was estimated to be -80.01 kj/mol, almost twice that on HKUST-1. The poor reusability of Ni-BTC in batch experiment, which is owing to its sensitivity to the air, can be prevented from regenerating used Ni-BTC in fixed-bed reactor by N2 flow. The difference between Ni-BTC and HKUST-1 in maximum adsorption capacity (q0),△H of TP adsorption, and stability demonstrates that the central metal in isostructural MOFs plays a key role in adjusting the desulfurization performance, which may open up a potential avenue for the development of MOF-based adsorbents with superior desulfurization performance.