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91.
92.
D. Tirzite A. Krauze A. Zubareva G. Tirzitis G. Duburs 《Chemistry of Heterocyclic Compounds》2002,38(7):795-800
The alkylation of 3-cyano-1,4-dihydropyridine-2(3H)-thiones or the condensation of an aromatic aldehyde, cyanothioacetamide, acetylacetone, and methyl iodide in the presence of piperidine has given a series of novel 5-acetyl-2-alkylthio-4-aryl-6-methyl-1,4-dihydropyridine-3-carboxylic acid nitriles. A compound was obtained from 3,5-di(tert-butyl)-4-hydroxybenzaldehyde in the molecule of which were combined the active part of the antioxidant ionol and a 1,4-dihydropyridine ring. It was found that, among the compounds synthesized, the highest antiradical activity occurred in a compound having two hydroxyl groups in the 4-phenyl substituent. 相似文献
93.
Ahmed M. Mkadmh 《International journal of quantum chemistry》2020,120(23):e26393
Different isomers of N5+ were modeled at DFT(PBE0)/aug-cc-pV(Q + d)Z, and their ground(transition) state characteristics were assessed through frequency calculations. Single-point energies were accomplished at PBE0/aug-cc-pV(5 + d)Z. Nonlinear optical susceptibilities (NLO) of isomers were accomplished using Firefly, while the linear optical invariant was examined using the finite-field method, Firefly, and modified dipole field tensor in the presence of two different screening factors. The excited states, singlets and triplets, of were modeled at the CIS and CIS(D) and then their optical parameters were estimated at TDFT(PBE0)/aug-cc-pV(Q + d)Z using Firefly. The singlet is found the most stable isomer, with the inversional rate constant larger than that of the Cs isomer and high energy barrier with the triplet counterpart. Isomers 2 , 3 , and 4 are found local minima, while 5 and 6 are saddle points: transition states between equivalent invertomers. Energy calculations of the singlet and triplet isomers were in excellent agreement with the literature. An excellent correlation is found between the average polarizability and the impulse factor. Substantial variations were found between the singlet and triplet excited states in terms of energy, geometry, and optical properties from one side and with from the other side. Reactivity indices showed that N1 and N5 are the optimum nucleophilic and electrophilic reactivity sites. 相似文献
94.
Fedushkin IL Morozov AG Rassadin OV Fukin GK 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(19):5749-5757
Compounds [Sr(dpp-bian)(thf)4] (2), [Ba(dpp-bian)(dme)2.5] (3) and [Mg(dtb-bian)(thf)2] (4) (dpp-bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene; dtb-bian = 1,2-bis[(2,5-di-tert-butylphenyl)imino]acenaphthene) were prepared by reduction of dpp-bian and dtb-bian with an excess of metallic Mg, Sr, or Ba in THF or DME. Reactions of [Mg(dpp-bian)(thf)3], 3, and 4 with diphenylacetonitrile gave keteniminates [Mg(dpp-bianH)(NCCPh2)(thf)2] (5), [Mg(dtb-bianH)(NCCPh2)(thf)2] (6), and [Ba(dpp-bianH)(NCCPh2)(dme)2] (7), respectively. The reaction of 2 with CH3C[triple chemical bond]N in THF gave [{Sr(dpp-bianH)[N(H)C(CH3)C(H)CN](thf)}2] (8). The compounds 2, 3, 5-8 were characterized by elemental analysis, and IR and NMR spectroscopy. Molecular structures of 2, 3, 7, and 8 were determined by single-crystal X-ray diffraction. In contrast to reactions of alkali-metal reagents, magnesium amides, or yttriumalkyls with alpha-H acidic nitriles, which are accompanied by an amine or an alkane elimination, the reactions of [Mg(dpp-bian)(thf)3] (1), 2, 3, and 4 with such nitriles proceeded with formation of Mg, Sr, and Ba keteniminates and simultaneous protonation of one nitrogen atom of the bian ligand. The NMR spectroscopic data obtained for complex 5 indicated that in solution the amino hydrogen atom underwent the fast (on the NMR timescale) shuttle transfer between both nitrogen atoms of the dpp-bianH ligand. 相似文献
95.
The texture of Cr2O3-K2O/Al2O3catalysts containing oxides of rare earth elements (REE) was studied. The catalysts are used for the synthesis of 2-methylthiophene by the reaction of H2S with n-pentane or piperilene. The heterocyclization of n-pentane is a consecutive reaction involving a step of dehydrogenation of initial hydrocarbon. At this step the texture of the catalyst affects the yield of 2-methylthiophene. The yield of 2-methylthiophene obtained from piperilene and I2S is independent of the catalyst texture. 相似文献
96.
A. V. Kazakova N. D. Kushch L. I. Buravov E. B. Yagubskii S. V. Simonov L. V. Zorina S. S. Khasanov R. P. Shibaeva E. Canadell J. Yamada M. Umemiya 《Russian Chemical Bulletin》2007,56(1):49-55
New radical cation salts based on 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene (BDA-TTP) with copper(II) metal complex anions, β-(BDA-TTP)4Cu2Cl6 and (BDA-TTP)2CuCl4, were synthesized and structurally characterized. Single crystals were prepared by electrochemical oxidation of BDA-TTP under
galvanostatic conditions. X-ray diffraction study demonstrated that the salts have a layered structure, in which the conducting
BDA-TTP layers alternate with the [Cu2Cl6]2− or [CuCl4]2− anions. Both salts show the semiconductor-type temperature dependence of the conductivity.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 48–54, January, 2007. 相似文献
97.
Deacon GB Delbridge EE Evans DJ Harika R Junk PC Skelton BW White AH 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(5):1193-1204
Sodium and potassium tetrakis(3,5-di-tert-butylpyrazolato)lanthanoidate(III) complexes [M[Ln(tBu(2)pz)(4)]] have been prepared by reaction of anhydrous lanthanoid trihalides with alkali metal 3,5-di-tert-butylpyrazolates at 200-300 degrees C, and a 1,2,4,5-tetramethylbenzene flux for M=K. On extraction with toluene (or occasionally directly from the reaction tube) the following complexes were isolated: [Na(PhMe)[Ln(tBu(2)pz)(4)]] (1 Ln; 1 Ln=1 Tb, 1 Ho, 1 Er, 1 Yb), [K(PhMe)[Ln(tBu(2)pz)(4)]].2 PhMe (2 Ln; 2 Ln=2 La, 2 Sm, 2 Tb, 2 Ho, 2 Yb, 2 Lu), [Na[Ln(tBu(2)pz)(4)]](n) (3 Ln; 3 Ln=3 La, 3 Tb, 3 Ho, 3 Er, 3 Yb), [K[Ln(tBu(2)pz)(4)]](n) (4 Ln; 4 Ln=4 La, 4 Nd, 4 Sm, 4 Tb, 4 Ho, 4 Er, 4 Yb, 4 Lu), with the last two classes generally being obtained by loss of toluene from 1 Ln or 2 Ln, and [Na(tBu(2)pzH)[Ln(tBu(2)pz)(4)]].PhMe (5 Ln; 5 Ln=5 Nd, 5 Er, 5 Yb). Extraction with 1,2-dimethoxyethane (DME) after isolation of 2 Ho yielded [K(dme)[Ho(tBu(2)pz)(4)]] (6 Ho). X-ray crystal structures of 1 Ln (=1 Tb, 1 Ho; P2(1)/c), 2 Ln (=2 La, 2 Sm, 2 Tb, 2 Yb, 2 Lu; Pnma), 3,4 Ln (=3 La, 3 Er, 4 Sm; P2(1)/m), and 5 Ln (=5 Nd, 5 Er, and 5 Yb; P1) show each group to be isomorphous regardless of the size of the Ln(3+) ion. All complexes contain eight-coordinate [Ln(eta(2)-tBu(2)pz)(4)] units. These are further linked to the alkali metal by bridging through two (1,2,5 Ln) or three (3,4 Ln) tBu(2)pz groups which show striking coordination versatility. Sodium is coordinated by an eta(4)-PhMe, a micro-eta(2):eta(2)-tBu(2)pz, and a micro-eta(4)(Na):eta(2)(Ln)-tBu(2)pz ligand in 1 Ln, and by one eta(1)-tBu(2)pzH and two micro-eta(3)(Na):eta(2)(Ln) ligands in 5 Ln. By contrast, potassium has one eta(6)-PhMe and two micro-eta(5)(K):eta(2)(Ln) ligands in 2 Ln. Classes 3,4 Ln form polymeric chains with the alkali metal bonded by two micro-eta(3)(NNC-M):eta(2)(Ln)-tBu(2)pz ligands within [MLn(tBu(2)pz)(4)] units which are joined together by eta(1)(C)-tBu(2)pz-Na, K linkages. 相似文献
98.
Ti-47Al-1.2Ce合金显微组织及稀土相 总被引:8,自引:2,他引:8
TiA1金属间化合物以其低密度 ,高比强度和比弹性模量 ,良好的抗蠕变及抗氧化能力等特点 ,已成为航天、航空、能源及汽车工业极具竞争力的高温结构材料。虽然TiAl基合金有众多优点 ,但仍存在室温塑性较低、成形性差、性能不平衡等问题 ,还需要深入研究TiAl基合金的合金化及制备工艺等方面技术 ,以此来控制并改善合金的显微组织 ,提高TiAl基合金的综合性能[1~ 4 ] 。合金化是改善TiAl基合金显微组织和性能的重要途径之一 ,通常添加的合金元素有V ,Cr ,Nb ,W ,Mo ,Si ,B等[5~ 7] 。稀土元素一般被用来细化材料… 相似文献
99.
100.
负载稀土型酸活化膨润土的酯化催化活性 总被引:7,自引:0,他引:7
负载稀土型酸活化膨润土的酯化催化活性李永绣,冯天泽,胡平贵,何小彬,辜子英,廖荣辉(南昌大学化学系南昌330047)关键词稀土,膨润土,催化酯化可用稀土、膨润土单独作酯化催化剂,但活性不高[1~3]。本文将稀土用离子交换的方法负载到酸活化膨润土中,寻... 相似文献