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1.
5-Acyl-2-furancarboxaldehydes2arelmpol-tantIntermedlateslforsynthesizingnaturallyoccuTTingfuranoldfattyacidswhichhaveantloxldanteffectsandantlneoplastlcactlvltlesInbiologicalsystems-.Nakayamaela尸reportedsuccessfulhalodesllylatlonofethyls-trlm...  相似文献   

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The Cp2ZrCl2-catalyzed (Cp=5-C5H5) stereoselective cyclometalation of norbornenes and norbornadienes with AlEt3 was carried out. It led in one stage to the preparation of polycyclic aluminocyclopentanes (ACP). It was shown that the ACP synthesized can be converted into polycyclic thiophanes under the action of elementary sulfur.For previous communication, see [1].Institute of Chemistry, Bashkir Scientific Center, Ural Branch, Academy of Sciences, 450054 Ufa. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 386–391, February, 1992.  相似文献   

4.
Applying the TPD-MS with a high sensitivity of determination, the TPD spectrum of surface oxygen of V2O5/SiO2, V2O5-MoO3/SiO2 and V2O6-P2O5/SiO2 catalysts was obtained. The surface oxygen of these catalysts can be divided into three groups according to the desorption temperature. O2- desorbs mainly from 373K. to 423K, O- from 673K to 873K and O2- at above 873K. The activation energy and frequency factor of all the three kinds of oxygen species were calculated. Based on these results, the mechanism of oxygen desorption and the influence of P2O5 and MoO3 on the properties of oxygen supply of V2O5/SiO2 catalst were investigated. MoO3 and a small amount of P2Os increase the number of supplying oxygen and increase the activity of O- species. A large amount of P2O5 increases the number of supplying oxygen and restrains the activity of O- species.  相似文献   

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1 INTRODUCTION We once reported a CS bond cleavage reaction of (h5-C5Me5)Mo(StBu)3, which led to a Mo(IV) thio/thiolate complex (h5-C5Me5)MoS2(StBu)[1]. This reaction was facilitated by oxidants such as S8, gray selenium, and FeCl3[2]. The reaction with FeCl3 gave rise to a cubane cluster [(h5-C5Me5)2Mo2Fe2S4Cl2], which served as an excellent building block to construct various Mo/Fe/S clusters[2]. In this paper, we report the crystal structure of [(h5-C5Me5)2Mo2Fe…  相似文献   

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1 INTRODUCTION With the development of diode-pumped solid-sta- te lasers, the research to find more efficient materials for these lasers is gaining more importance. The luminescent materials host LnMgB5O10 may become potential solid-state laser materials[1, 2]. Nd3 -doped GdMg(BO2)5 as a potential diode-pumped laser crystal has been grown in our lab and characterized by a very strong absorption at near 808 nm and intense emission. Although the previous work repor- ted LaMg(BO2)5 with…  相似文献   

8.
Geoffrey T. Crisp 《合成通讯》2013,43(11-12):2117-2123
The palladium-catalysed coupling of 3,5 Di-O-p-toluoyl-5-iodo-2′ -deoxyuridine with functionalized and non-functionalized alkenylstannanes gave moderate to good yields of the corresponding 5-alkenyl-2 -deoxyuridines.  相似文献   

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5-Hydroxy-2-(2-phenylethyl)chromone(1) was synthesized from 2,6-dihydroxyacetophenone(7) obtained via four-steps resorcinol-reacting with phenylpropionic acid,the procedures involved are Baker-Venkataraman rearrangement and cyclization which are easy to conduct,the overall yield is 32%.  相似文献   

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The melting temperature, melting enthalpy, and specific heat capacities (C p) of 5′-deoxy-5′-iodo-2′,3′-O-isopropylidene-5-fluorouridine (DIOIPF) were measured using DSC-60 Differential Scanning Calorimetry. The melting temperature and melting enthalpy were obtained to be 453.80 K and 33.22 J g?1, respectively. The relationship between the specific heat capacity and temperature was obtained to be C p/J g?1 K?1 = 2.0261 – 0.0096T + 2 × 10?5 T 2 at the temperature range from 320.15 to 430.15 K. The thermal decomposition process was studied by the TG–DTA analyzer. The results showed that the thermal decomposition temperature of DIOIPF was above 487.84 K, and the decomposition process can be divided into three stages: the first stage is the decomposition of impurities, the mass loss in the second stage may be the sublimation of iodine and thermal decomposition process of the side-group C4H2O2N2F, and the third stage may be the thermal decomposition process of both the groups –CH3 and –CH2OCH2–. The obtained thermodynamic basic data are helpful for exploiting new synthetic method, engineering design, and commercial process of DIOIPF.  相似文献   

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It is shown that (1,2,7-η3-2-Me-benzyl)(η5-C5H5)Mo(CO)2 exits in solution as one isomer which is fluxional, probably via (7-η1-2-Me-benzyl)((η5-C5H5)Mo(CO)2, with ΔG370 = 23.6 ± 1.0 kcal mol−1. In contrast, (1,2,7-η3-3-Me-benzyl)(η5-C5H5)Mo(CO)2 exits as two isomers at −20°C, which undergo interconversion at room temperature with ΔG 15.7 kcal mol−1. This dynamic process is an allyl rotation. It is probable that there is also a low energy [1,5]-sigmatropic shift.  相似文献   

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Uranium-carbon bond reactivity has been investigated with the bis(tethered silylalkyl) uranium metallocene (η5:κ1-C5Me4SiMe2CH2)2U, 1. Tert-butyl nitrile, tBuCN, inserts into both of the tethered U-C bonds to produce the bis(tethered ketimide) complex [η5:κ1-C5Me4SiMe2CH2C(tBu)N]2U, 2, which has unusually bent U-N-C bond angles. Carbon dioxide also inserts into both U-C bonds of 1 yielding the bis(tethered carboxylate) (C5Me4SiMe2CH2CO2)2U, 3. Neither PhCCPh nor PhCCH insert into the U-C bonds, but PhCCH cleaves the silylalkyl tethers in 1 to generate (C5Me4SiMe3)1? ligands in the complex (C5Me4SiMe3)2U(CCPh)2, 4.  相似文献   

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The crystallization kinetics of Cs2O–Fe2O3–P2O5 glasses containing 12.5–27 mol% Cs2O were studied by using differential scanning calorimetry under nonisothermal conditions. Strong dependence of activation energy with temperature was observed, indicating the complex nature of the crystallization process. The various crystallization products were identified by X-ray diffraction technique. CsFeP2O7 was found to be the major crystalline phase in all cases. The overall activation energy obtained by classical model-free kinetic method was compared with that of isoconversional method; and from the results, the dependence of activation energy on extent of reaction and average temperature was delineated.  相似文献   

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SynthesisandCrystalStructureof[(2,4-Me_2C_5H_5)_2NdC=CC_6H_5]_2ZHANGSuo-boandLIUJu-zheng(DepartmentofChemistry,JilinUniversit...  相似文献   

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1-Substituted 4-benzylidene-2-{-[3,5-di(tert-butyl)-4-hydroxyphenyl]vinyl}-4-benzylidene-2-imidazolin-5-ones have been synthesized by the interaction of azomethines and N-acylhydrazones (derivatives of 3,5-di(tert-butyl)-4-hydroxybenzaldehyde) with 4-benzylidene-2-methyloxazol-5-one. The acylation of 1,2-bis[3,5-di(tert-butyl)-4-hydroxybenzylideneamino]ethane with acid chlorides in acetonitrile in the presence of triethylamine leads to 1,3-diacyl-2-[3,5-di(tert-butyl)-4-hydroxyphenyl]imidazolidine.  相似文献   

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The processes of production of high purity nanopowders of niobium and tantalum pentoxide Ta2y Nb2(1–y)O5 with a low content of fluorine and Nb2O5 in low-temperature polymorph were studied. Ceramic samples were prepared from a charge of solid solutions LiTa y Nb1–y O3 and Li x Na1–x Ta y Nb1–y O3 synthesized using coprecipitated pentoxide Ta2y Nb2(1–y)O5. Therewith for solid solutions LixNa1–x Ta y Nb1–y O3 significantly larger values of high dielectric constant and ionic conductivity were achieved compared to the solid solutions obtained by using a mechanical mixture of Ta2O5 and Nb2O5. This converts solid solutions LixNa1–x Ta y Nb1–y O3 from acoustoelectronic and piezoelectric type of materials into the capacitor and ion-conductive type of solid materials.  相似文献   

18.
《Tetrahedron letters》1987,28(23):2623-2626
2′-5′,3′-5′ Linked triadenylates have been synthesized by direct bisadenylylation of adenosine 2′ and 3′ hydroxyls with an adenosine 5′-phosphorochloridite followed by oxidation.  相似文献   

19.
1,3-Dipolar cycloaddition reactions of ethyl 2-hydropolyfluoroalk-2-enoates (1) with some nitrones were described. The reaction of 3,4-dihydroisoquinoline N-oxide (2) with 1 took place readily in methylene chloride at room temperature to give the corresponding 5-fluoroalkylisoxazolidines regioselectively as a mixture of two diastereoisomers (trans and cis) in high yields, while longer reaction time and higher temperature were needed in the case of non-cyclic nitrones. Under similar conditions the reaction of quinoline N-oxide (14) with 1 did not give the expected adducts and a ring-opening product was obtained.  相似文献   

20.
Two new coenzyme B12 analogues, 2',5'-dideoxycytidylcobalamin (2a) and 2',5'-dide-oxyuridinylcobalamin (2b), and two others, 2',5'-dideoxyadenosylcobalamin (2c), and 5'-deoxy-thymidylcobalamin (2d) were prepared by an improved method. All the four analogues were investigated by UV-vis and 2D 1H NMR spectroscopy. The comparisons and discussion about their spectroscopic properties were done.  相似文献   

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