Geometry optimization of p-C_(6)H_(4)-connected cyclo[20]carbon(p-C_(6)H_(4)-C_(20))was carried out at M062X/6-311G(d,p)level,three kinds of bond orders(Mayer,Laplacian,and Wiberg),electron-hole distributions,localize...Geometry optimization of p-C_(6)H_(4)-connected cyclo[20]carbon(p-C_(6)H_(4)-C_(20))was carried out at M062X/6-311G(d,p)level,three kinds of bond orders(Mayer,Laplacian,and Wiberg),electron-hole distributions,localized orbital locators(LOL),and infrared(IR)spectrum were also performed at the same level.Based on TD-DFT M062X/6-311G(d,p)method,the first 20 excited states and ultraviolet(UV)spectra of p-C_(6)H_(4)-C_(20) were calculated.Calculation results of π-electron delocalization analyses prove thatπ-electron delocalization of p-C_(6)H_(4)-C_(20) is more likely to occur on shorter C-C bonds rather than longer C-C bonds,and inside/outside of the ring plane rather than above/below the ring plane.Two absorption peaks of p-C_(6)H_(4)-C_(20) locate at about 319 nm and 236 nm,respectively.展开更多
Elucidating the confinement effect harbours tremendous significance for isobutane alkylation with C_(4) olefin.Herein,the confinement effect over zeolite catalysts was elucidated by combining DFT calculations,experime...Elucidating the confinement effect harbours tremendous significance for isobutane alkylation with C_(4) olefin.Herein,the confinement effect over zeolite catalysts was elucidated by combining DFT calculations,experiments(using the novel Beta zeolite exposing only external surfaces(Beta-E)and conventional Beta-I zeolite with both external and internal surfaces)and multi-techniques(e.g.,TGA-DTG,HRTEM,SEM and XRD).It is found that the main active sites for C_(4) alkylation reaction are located on internal surface rather than external surface.On the external surface,the hydride transfer reaction does not occur because the H-shared intermediate cannot be formed without the confinement effect.Moreover,the external surface has stronger selectivity for C_(4) olefin adsorption than isobutane,leading to enhanced oligomerization reactions.Therefore,the suitable micropore with confinement effect is essential for zeolite-catalyzed C_(4) alkylation.The atomic-scale insights of this work are of great referential importance to the design of highly effective zeolite catalyst.展开更多
This article refers to the results of small-scale and commercial tests on high-temperature cracking of C4 fraction in FCC unit to increase the propylene yield. The bench tests revealed that the conversion rate of C4 f...This article refers to the results of small-scale and commercial tests on high-temperature cracking of C4 fraction in FCC unit to increase the propylene yield. The bench tests revealed that the conversion rate of C4 fraction during high-temperature cracking reached 37.38 % and propylene yield was equal to 15.60 % with the conversion rate of C4 olefins equating around 50%. The results of commercial application showed that adoption of the technology for high-temperature cracking of C4 fraction in FCC unit had led to an increase of propylene yield by 2.16 % with no remarkable changes in the yields and properties of other products.展开更多
Aim To investigate the alkylation of 2-thiopyrimidine. Methods Treating the starting material 2-thiopyrimidine with chloromethyl ethers via a procedure of K2CO3 in DMF or with alkyl halide in CH3ONa-CH3OH at room temp...Aim To investigate the alkylation of 2-thiopyrimidine. Methods Treating the starting material 2-thiopyrimidine with chloromethyl ethers via a procedure of K2CO3 in DMF or with alkyl halide in CH3ONa-CH3OH at room temperature, to obtain the corresponding regioselective 2-S-allkyl pyrimidines. The products were determined by JH NMR, 2D NMR, IR and MS spectra. Results 2-S-alkyl-pyrimidines were regioselectively synthesized. Conclusion In different conditions with different alkyl halides, 2- thiouracil could be converted into the corresponding 2-S-alkylpyrimidines regioselectively.展开更多
The liquid phase alkylation of catechol with tert-butyl alcohol to produce4-tert-butyl catechol (4-TBC) was carried out over MCM-41, HZSM-5, H-exchanged montmorillonite andnovel acidic porous montmorillonite heterostr...The liquid phase alkylation of catechol with tert-butyl alcohol to produce4-tert-butyl catechol (4-TBC) was carried out over MCM-41, HZSM-5, H-exchanged montmorillonite andnovel acidic porous montmorillonite heterostructures (PMHs). Upon all catalysts tested, 4-TBC is themain product and 3-tert-butyl catechol (3-TBC) and 3,5-di-tert-butyl catechol are the sideproducts. The synthetic PMHs showed higher conversion of catechol and better selectivity to 4-TBCcompared to other solid acid catalysts tested. Over the PMHs derived from H-exchangedmontmorillonite through template extraction processes, the suitable reaction temperature is ca 410K, the ratio of catechol to tert-butyl alcohol is 1:2. Increasing the amount of catalyst (lowerweight hourly space velocity) can improve the conversion of catechol and influence the selectivityslightly. The reasonable reaction time is ca 8 h. The type and strength of acidity ofH-montmorillonite and PMH were determined by pyridine adsorption FT-IR and ammoniatemperature-programmed desorption techniques. The medium and strong acid sites are conducive toproducing 4-TBC and the weak acid sites to facilitating the 3-TBC formation. The differences betweenthe PMHs from calcination and those from extraction are attributed to proton migration and aciditychange in the gallery surface.展开更多
Resorcarens 1a-b (R'=Ph, p-MeOC6H4) were fully alkylated with alkyl iodides or bromides in TEBA/KOH/DMF solid-liquid PTC process with 63-82% yields, whereas the three calix[4]pyrroles 3a-b (2R= 2Me, (CH2)(4), (CH2...Resorcarens 1a-b (R'=Ph, p-MeOC6H4) were fully alkylated with alkyl iodides or bromides in TEBA/KOH/DMF solid-liquid PTC process with 63-82% yields, whereas the three calix[4]pyrroles 3a-b (2R= 2Me, (CH2)(4), (CH2)(5)) were alkylated with alkyl iodides in TBAB/ 50%NaOH/ CH2Cl2 liquid-liquid PTC system with lower yields (10-38%).展开更多
文摘Geometry optimization of p-C_(6)H_(4)-connected cyclo[20]carbon(p-C_(6)H_(4)-C_(20))was carried out at M062X/6-311G(d,p)level,three kinds of bond orders(Mayer,Laplacian,and Wiberg),electron-hole distributions,localized orbital locators(LOL),and infrared(IR)spectrum were also performed at the same level.Based on TD-DFT M062X/6-311G(d,p)method,the first 20 excited states and ultraviolet(UV)spectra of p-C_(6)H_(4)-C_(20) were calculated.Calculation results of π-electron delocalization analyses prove thatπ-electron delocalization of p-C_(6)H_(4)-C_(20) is more likely to occur on shorter C-C bonds rather than longer C-C bonds,and inside/outside of the ring plane rather than above/below the ring plane.Two absorption peaks of p-C_(6)H_(4)-C_(20) locate at about 319 nm and 236 nm,respectively.
基金supported by the National Natural Science Foundation of China(21978325,21776312,21908186)the Independent Innovation Foundation of Qingdao(17-1-1-18-jch)+1 种基金the Fundamental Research Funds for the Central Universities(18CX02014A)the Fundamental Research Funds for the Central Universities and the Opening Fund of State Key Laboratory of Heavy Oil Processing(SKLOP202003002).
文摘Elucidating the confinement effect harbours tremendous significance for isobutane alkylation with C_(4) olefin.Herein,the confinement effect over zeolite catalysts was elucidated by combining DFT calculations,experiments(using the novel Beta zeolite exposing only external surfaces(Beta-E)and conventional Beta-I zeolite with both external and internal surfaces)and multi-techniques(e.g.,TGA-DTG,HRTEM,SEM and XRD).It is found that the main active sites for C_(4) alkylation reaction are located on internal surface rather than external surface.On the external surface,the hydride transfer reaction does not occur because the H-shared intermediate cannot be formed without the confinement effect.Moreover,the external surface has stronger selectivity for C_(4) olefin adsorption than isobutane,leading to enhanced oligomerization reactions.Therefore,the suitable micropore with confinement effect is essential for zeolite-catalyzed C_(4) alkylation.The atomic-scale insights of this work are of great referential importance to the design of highly effective zeolite catalyst.
文摘This article refers to the results of small-scale and commercial tests on high-temperature cracking of C4 fraction in FCC unit to increase the propylene yield. The bench tests revealed that the conversion rate of C4 fraction during high-temperature cracking reached 37.38 % and propylene yield was equal to 15.60 % with the conversion rate of C4 olefins equating around 50%. The results of commercial application showed that adoption of the technology for high-temperature cracking of C4 fraction in FCC unit had led to an increase of propylene yield by 2.16 % with no remarkable changes in the yields and properties of other products.
基金National Nature Science Foundation of China(NO.20172007).
文摘Aim To investigate the alkylation of 2-thiopyrimidine. Methods Treating the starting material 2-thiopyrimidine with chloromethyl ethers via a procedure of K2CO3 in DMF or with alkyl halide in CH3ONa-CH3OH at room temperature, to obtain the corresponding regioselective 2-S-allkyl pyrimidines. The products were determined by JH NMR, 2D NMR, IR and MS spectra. Results 2-S-alkyl-pyrimidines were regioselectively synthesized. Conclusion In different conditions with different alkyl halides, 2- thiouracil could be converted into the corresponding 2-S-alkylpyrimidines regioselectively.
基金Supported by the National Natural Science Foundation of China (No. 20376075) the Natural Science Foundation of Zhejiang Province (No. 201057).
文摘The liquid phase alkylation of catechol with tert-butyl alcohol to produce4-tert-butyl catechol (4-TBC) was carried out over MCM-41, HZSM-5, H-exchanged montmorillonite andnovel acidic porous montmorillonite heterostructures (PMHs). Upon all catalysts tested, 4-TBC is themain product and 3-tert-butyl catechol (3-TBC) and 3,5-di-tert-butyl catechol are the sideproducts. The synthetic PMHs showed higher conversion of catechol and better selectivity to 4-TBCcompared to other solid acid catalysts tested. Over the PMHs derived from H-exchangedmontmorillonite through template extraction processes, the suitable reaction temperature is ca 410K, the ratio of catechol to tert-butyl alcohol is 1:2. Increasing the amount of catalyst (lowerweight hourly space velocity) can improve the conversion of catechol and influence the selectivityslightly. The reasonable reaction time is ca 8 h. The type and strength of acidity ofH-montmorillonite and PMH were determined by pyridine adsorption FT-IR and ammoniatemperature-programmed desorption techniques. The medium and strong acid sites are conducive toproducing 4-TBC and the weak acid sites to facilitating the 3-TBC formation. The differences betweenthe PMHs from calcination and those from extraction are attributed to proton migration and aciditychange in the gallery surface.
文摘Resorcarens 1a-b (R'=Ph, p-MeOC6H4) were fully alkylated with alkyl iodides or bromides in TEBA/KOH/DMF solid-liquid PTC process with 63-82% yields, whereas the three calix[4]pyrroles 3a-b (2R= 2Me, (CH2)(4), (CH2)(5)) were alkylated with alkyl iodides in TBAB/ 50%NaOH/ CH2Cl2 liquid-liquid PTC system with lower yields (10-38%).
