Regio and stereoselective synthesis of substituted dihydrofurans were accomplished by eeric ammonium nitrate mediated oxidative cycloaddition of 1,3-dicarbonyls to β-aryl-α,β-unsaturated ketones in moderate yields.
Low-valent titanium reagent prepared in situ from TiCl_4 and Zn was employed to induce the intramolecular coupling of nitro group with carbonyl group to give substituted hydroxyl pyrrolines, pyrroles and lactam in goo...Low-valent titanium reagent prepared in situ from TiCl_4 and Zn was employed to induce the intramolecular coupling of nitro group with carbonyl group to give substituted hydroxyl pyrrolines, pyrroles and lactam in good yields.展开更多
Aging of a solid composite propellant containing HTPB/AP/AL was performed in order to validate the conformance of the accelerated aging data to the Arrhenius law. The main objective of the work was to examine the infl...Aging of a solid composite propellant containing HTPB/AP/AL was performed in order to validate the conformance of the accelerated aging data to the Arrhenius law. The main objective of the work was to examine the influence of the aziridine bonding agents family on the propellant aging. Aging of the prepared propellant samples was conducted as follows: 1. Four samples, one free of bonding agents, and three containing aziridine based bonding agents MAPO,HX-752, MAT4 were aged at 65°C. 2. Another four samples based on HX-752, MAT4 with different curing agents were aged at 65°C. The measured mechanical properties of the free bonding agent propellant samples were very far from the specifications and this illustrates the importance of the bonding agents in both the preparation and the aging phases.The prepared bonding agent 'MAT4' gave remarkable improvements of the mechanical properties comparing with HX-752 and MAPO. The aziridine bonding agents family inhibited the rate of decomposition of the propellant during the aging periods and supported the propellant matrix against decomposition at the elevate temperatures. Using of HMDI as curing agent gave slight better mechanical properties to the IPDI.展开更多
Under neat conditions,an efficient method for synthesis of imidoesters has been developed using cyanatobenzenes and dicarbonyl compounds.Nucleophilic addition spontaneously occurred between the two kinds of materials ...Under neat conditions,an efficient method for synthesis of imidoesters has been developed using cyanatobenzenes and dicarbonyl compounds.Nucleophilic addition spontaneously occurred between the two kinds of materials at room temperature with yields of up to 90%.A mechanism directed towards to the imidoester formation has been proposed.展开更多
The microwave-assisted substitution of β-dicarbonyl compounds with secondary alcohols has been achieved efficiently, using very cheap fluoroboric acid （HBF4） as the catalyst. For various β-dicarbonyl compounds and...The microwave-assisted substitution of β-dicarbonyl compounds with secondary alcohols has been achieved efficiently, using very cheap fluoroboric acid （HBF4） as the catalyst. For various β-dicarbonyl compounds and a series of secondary alcohols, the direct substitution gives high yields after only 5 min of microwave irradiation.展开更多
Based on the absorption property of a diazine that can be formed by reaction of glyoxal and 3-methyl-2-benzothiazolinone hydrazone(MBTH)in the Ultravioletvisible(UV-vis)spectral region,a HPLC method was developed for ...Based on the absorption property of a diazine that can be formed by reaction of glyoxal and 3-methyl-2-benzothiazolinone hydrazone(MBTH)in the Ultravioletvisible(UV-vis)spectral region,a HPLC method was developed for the determination of glyoxal in acetaldehyde solution.Glyoxal was derivatised from MBTH and the derivatives(diazine)were analyzed by HPLC for identification and quantification.The determination was performed on a ZORBAX Eclipse XDB-C18 column(4.6250 mm,5 mm)at 35℃ with an injection volume of 10 mL,using a mixture of acetonitrile-water solvent(99∶5,v∶v)as a mobile phase with a flow rate of 0.8 mL·min^(–1).The proper derivative reaction conditions were the temperature of 70℃,MBTH to carbonyl molar ratio of 12,and reaction time of 110 min.The glyoxal diazine was a yellow dye with a maximum molar absorptivity at 401 nm and its retention time was 5.2 min under optimal HPLC conditions.The standard curve for glyoxal had a strong linear relationship with a regression coefficient(R2=0.999)in the range of 0.002–0.020 g·L^(–1).The analysis of glyoxal in an oxidising solution gave accurate results with a relative standard deviation(RSD)value of 0.55%.The average relative recovery was 102%.This efficient HPLC technique is also proposed for detecting other dicarbonyl compounds besides glyoxal.展开更多
ESR method was used to elucidate the mechanism of the reactions of alkyl,allyl or benzyl halides with dicyclopentadienyldicarbonyl titanium.The paramagnetic intermediates of the reac- tions were identified during the ...ESR method was used to elucidate the mechanism of the reactions of alkyl,allyl or benzyl halides with dicyclopentadienyldicarbonyl titanium.The paramagnetic intermediates of the reac- tions were identified during the course of the reactions.The reaction mechanism based on ESR find- ings and the products analyses is postulated to operate on radical pathways.When alkyl halides were used to react with the organometallic compound 1,the intermediate found was[Cp_2Ti(CO)X](C), and the main product was identified to be dicyclopentadienyl-acyl-halo titanium(3),an insertion of TiCO into R-X,i.e.[Cp_2Ti-C(O)R]X.When allyl or benzyl halidcs were used,the intermediate found was[Cp_2TiX](B),and the main products were identified to be the dicyclopentadienyl titanium dihalides and the coupling products of allyl or benzyl groups.展开更多
文摘Regio and stereoselective synthesis of substituted dihydrofurans were accomplished by eeric ammonium nitrate mediated oxidative cycloaddition of 1,3-dicarbonyls to β-aryl-α,β-unsaturated ketones in moderate yields.
文摘Low-valent titanium reagent prepared in situ from TiCl_4 and Zn was employed to induce the intramolecular coupling of nitro group with carbonyl group to give substituted hydroxyl pyrrolines, pyrroles and lactam in good yields.
文摘Aging of a solid composite propellant containing HTPB/AP/AL was performed in order to validate the conformance of the accelerated aging data to the Arrhenius law. The main objective of the work was to examine the influence of the aziridine bonding agents family on the propellant aging. Aging of the prepared propellant samples was conducted as follows: 1. Four samples, one free of bonding agents, and three containing aziridine based bonding agents MAPO,HX-752, MAT4 were aged at 65°C. 2. Another four samples based on HX-752, MAT4 with different curing agents were aged at 65°C. The measured mechanical properties of the free bonding agent propellant samples were very far from the specifications and this illustrates the importance of the bonding agents in both the preparation and the aging phases.The prepared bonding agent 'MAT4' gave remarkable improvements of the mechanical properties comparing with HX-752 and MAPO. The aziridine bonding agents family inhibited the rate of decomposition of the propellant during the aging periods and supported the propellant matrix against decomposition at the elevate temperatures. Using of HMDI as curing agent gave slight better mechanical properties to the IPDI.
基金the National Natural Science Foundation of China (Nos.21372265 and 61271059)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,the Natural Science Foundation Project of CQ CSTC (Nos.CSTC2013jcyjA0217 and CSTC2010BB4086)the Fundamental Research Funds for the Central Universities(Nos.CQDXWL2013-Z012 and CDJZR-14225502)
文摘Under neat conditions,an efficient method for synthesis of imidoesters has been developed using cyanatobenzenes and dicarbonyl compounds.Nucleophilic addition spontaneously occurred between the two kinds of materials at room temperature with yields of up to 90%.A mechanism directed towards to the imidoester formation has been proposed.
基金Project supported by the National Natural Science Foundation of China （No. 20902020）, the Shanghai Pujiang Talent Program （No. 09PJ1403500） and the Fundamental Research Funds for the Central Universities.
文摘The microwave-assisted substitution of β-dicarbonyl compounds with secondary alcohols has been achieved efficiently, using very cheap fluoroboric acid （HBF4） as the catalyst. For various β-dicarbonyl compounds and a series of secondary alcohols, the direct substitution gives high yields after only 5 min of microwave irradiation.
基金Financial support by the China Petroleum and Chemical Corporation is gratefully acknowledged.
文摘Based on the absorption property of a diazine that can be formed by reaction of glyoxal and 3-methyl-2-benzothiazolinone hydrazone(MBTH)in the Ultravioletvisible(UV-vis)spectral region,a HPLC method was developed for the determination of glyoxal in acetaldehyde solution.Glyoxal was derivatised from MBTH and the derivatives(diazine)were analyzed by HPLC for identification and quantification.The determination was performed on a ZORBAX Eclipse XDB-C18 column(4.6250 mm,5 mm)at 35℃ with an injection volume of 10 mL,using a mixture of acetonitrile-water solvent(99∶5,v∶v)as a mobile phase with a flow rate of 0.8 mL·min^(–1).The proper derivative reaction conditions were the temperature of 70℃,MBTH to carbonyl molar ratio of 12,and reaction time of 110 min.The glyoxal diazine was a yellow dye with a maximum molar absorptivity at 401 nm and its retention time was 5.2 min under optimal HPLC conditions.The standard curve for glyoxal had a strong linear relationship with a regression coefficient(R2=0.999)in the range of 0.002–0.020 g·L^(–1).The analysis of glyoxal in an oxidising solution gave accurate results with a relative standard deviation(RSD)value of 0.55%.The average relative recovery was 102%.This efficient HPLC technique is also proposed for detecting other dicarbonyl compounds besides glyoxal.
基金Supported by the National Natural Science Foundation of China.
文摘ESR method was used to elucidate the mechanism of the reactions of alkyl,allyl or benzyl halides with dicyclopentadienyldicarbonyl titanium.The paramagnetic intermediates of the reac- tions were identified during the course of the reactions.The reaction mechanism based on ESR find- ings and the products analyses is postulated to operate on radical pathways.When alkyl halides were used to react with the organometallic compound 1,the intermediate found was[Cp_2Ti(CO)X](C), and the main product was identified to be dicyclopentadienyl-acyl-halo titanium(3),an insertion of TiCO into R-X,i.e.[Cp_2Ti-C(O)R]X.When allyl or benzyl halidcs were used,the intermediate found was[Cp_2TiX](B),and the main products were identified to be the dicyclopentadienyl titanium dihalides and the coupling products of allyl or benzyl groups.
