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1.
N-Substituted 3- and 4-formylpyrroles have been obtained by hydroformamination of 2,5-dimethoxy-2,5-dihydrofurans in the presence of HRh(CO)(PPh3)3.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1837–1840, August, 1990.  相似文献   

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Spontaneous homopolymerization of 2,5-dimethylene-2,5-dihydrofuran (DDF) was studied. The polymerization rates in two different initial monomer concentrations of DDF were analyzed with the first-order and second-order kinetics, and the homopolymerization of DDF was found to obey the first-order kinetics. The Arrhenius plot of the apparent rate constants at 30, 40, 50, and 60° gave an overall activation energy of 68.0 kJ/mol for the polymerization of DDF. From the comparison of the apparent rate constants at –78° and the time (the so-called half-life time) to decrease in half the monomer concentration for DDF with the corresponding values for p-xylylene (QM), DDF was found to be a less reactive monomer than QM. The copolymerizations of DDF with vinyl monomers such as acrylonitrile (AN), α-chloroacrylonitrile (CIAN), diethyl fumarate (DEF), and fumaronitrile (FN) were carried out in chloroform at 50° in the presence of AIBN to obtain the monomer reactivity ratios r1(DDF) = 30.0 ± 3.0 and r2 (AN) = 0 for the DDF-AN system, r1 (DDF) = 1.55 ± 0.2 and r2(CIAN) = 0 for the DDF-CIAN system, r1(DDF) = 3.88 ± 0.2 and r2(DEF) = 0 for the DDF-DEF system, and r1(DDF) = 2.41 ± 0.1 and r2 (FN) = 0 for the DDF-FN system, respectively. As the monomer reactivity ratios of r2 for all systems were zero, Q and e values of DDF were calculated from the combination of two r1 (DDF) values of any two copolymerization systems to be the 7.64 to 6.63 ×1021 range for Q and the –0.70 to –6.31 range for e, indicating that DDF is a highly conjugative and electron-donating monomer. © 1995 John Wiley & Sons, Inc.  相似文献   

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2,5-Dimethylene-2,5-dihydrofuran (3), generated flash pyrolitically, underwent di- and trimerization reactions to give cyclic dimer and trimer. Compound 3 was trapped with methanol, ethanol, bromine, acetic acid, thiophenol and oxygen. Results from trapping experiments suggest that the diradical form of 3 is involved.  相似文献   

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The title compound was prepared, characterized, and on thermal decomposition at 100°C in the presence of a chlorine atom trap was found to give acetone, 1,2-dichloroethane, and 4-chloro-2-methyl-2-butanol.  相似文献   

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Itis shown that 2,5-dimethoxy-2,5-dihydrofurans enter into 1,3-dipolar cycloaddition with benzonitrile N-oxides and with diphenylnitrilimines to form derivatives of 1,3-dimethoxy-6-phenyl-1,3,3a,6a-tetrahydrofuro[3,4-d]isoxazole and 1,3-dimethoxy-4,6-diphenyl-1,3,3a,-6a-tetrahydrofuro[3,4-d]pyrazole, respectively.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 150–151, February, 1971.  相似文献   

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From hydroxyhydroperoxides II and III a new bicyclic system, namely the 5,6-dioxabicyclo[2.1.1]hexane VII is obtained by photolysis or by protic acids. Epimer epoxides IV and XI are obtained on reaction with triethylamine.  相似文献   

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Alkylation of 5-aminotetrazole with 2,5-dimethylhexane-2,5-diol in perchloric acid was found to proceed on an endocyclic nitrogen atom as well as on the amino group, giving 5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-4H-tetrazolo[1,5-a][1,3]diazepine. Under analogous conditions, 3-amino-1,2,4-triazole undergoes cycloalkylation of the neighboring N1 and N2 atoms of the heterocycle resulting in 1-amino-5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-[1,2,4]triazolo[1,2-a]pyridazinium perchlorate. The crystal structures of the products were determined by single crystal X-ray analysis.  相似文献   

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2,5-Dimethoxy-2,5-dihydrofuran (DDF) reacts with dichloroketene to give 7,9-dimethoxy-3,3,5,5-tetrachloro-8-oxabicyclo[4,3,0]-noan-2,4-dione (I), and methyl chloro-(2,5-dihydro-5-methoxy-2-furanylidene) acetate (II). The reactions of 2,5-dihydrofuran and 2,5-dimethoxy-tetrahydrofuran with dichloroketene were also-studied for comparison. Compound II was derived from the insertion of a molecule of dichloroketene into the C-O bond of DDF with subsequent dehydrochlorination. Compound I resulted from the cycloaddition of two molecules of dichloroketene to the C=C bond of DDF. A mechanism involving a 1,5-dipolar intermediate is proposed to account for this novel reaction.  相似文献   

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By analysis of the products from the protolytic cleavage of methyl 3-(2,5-dialkoxy-2,5-dihydro-2-furyl)propionate (I) in the presence of mixed nucleophiles and investigation of their mutual transformations the main paths in the dissociation of the protonated molecule of (I), with the formation of both linear cleavage products (derivatives of 1,4-diketones and 4-ketopimelic acid) and furylcarbinol derivatives, were determined.Latvian Institute of Organic Synthesis. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 190–197, February, 1997.  相似文献   

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[structure: see text] Syntheses of differently substituted 2,5-diarylthiophenes and 2,5-diarylthiazoles are carried out with the palladium-catalyzed C-H substitution reaction using AgF as an activator. Remarkably strong photoluminescence is observed in 2,5-diarylthiophene. Differences between the physical properties of liquid crystalline characteristics and cyclic voltammograms of thiophene and thiazole are also studied.  相似文献   

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Kei Kobayashi 《Tetrahedron》2006,62(41):9548-9553
Syntheses of 2,5-diarylthiazole and 2,5-diarylthiophene derivatives bearing ethynylene and thienylene spacers are performed. With the methods for coupling reactions of terminal alkynes and at the CH bond of heteroaromatic compounds, which we have developed, five kinds of thiazole and thiophene derivatives 3-7 are prepared. Spectroscopic characteristics of 3-7 are also measured.  相似文献   

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Russian Journal of General Chemistry -  相似文献   

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