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991.
The infrared laser induced decomposition of mixtures of ethyl acetate and isopropyl bromide has been studied. The ratio of the yields of products ethylene and propylene, arising from the unimolecular decomposition reactions: ethyl acetate → ethylene + acetic acid, and isopropyl bromide → propylene + hydrogen bromide, were measured as a function of the ratio of ethyl acetate to isopropyl bromide and pressure of added helium. The results indicate clearly that in these systems non-equilibrium behavior is found up to the highest pressures used (about one atmosphere). A two level kinetic model is suggested which qualitatively explains the observations. 相似文献
992.
An approach was reported to synthesize silica hybridized ruthenium bipyridyl complex through amidation reaction by covalent attachment of bis(bipyridyl)-4,4'-dicarboxy-2,2'-bipyridyl-ruthenium to (3-aminopropyl)-triethoxysilane. The hybrid complex then was gelatinized through acid catalytic hydrolysis method and a sol-gel modified indium tin oxide electrode was prepared via spin coating technique. As prepared indium tin oxide electrode possesses good stability therein with excellent electrochemiluminescence behavior. 相似文献
993.
Koji Nakabayashi Masaki Kawano Prof. Dr. Tatsuhisa Kato Prof. Dr. Ko Furukawa Dr. Shin‐ichi Ohkoshi Prof. Dr. Toshiya Hozumi Dr. Makoto Fujita Prof. Dr. 《化学:亚洲杂志》2007,2(1):164-170
We show a new approach to manipulating the through‐space spin–spin interaction by utilizing the confined cavity of a self‐assembled M6L4 coordination cage. The coordination cage readily encapsulates stable organic radicals in solution, which brings the spin centers of the radicals closer to each other. In sharp contrast to the fact that the radical in solution in the absence of the cage is in a doublet state, in the presence of the cage through‐space spin–spin interaction is induced through cage‐encapsulation effects in solution as well as in the solid state, resulting in the triplet state of the complex. These results were confirmed by ESR spectroscopy and X‐ray crystallography. The quantity of triplet species generated by encapsulation in the cage increases with increasing affinity of the radicals to the cage. We estimated the affinity between several types of guests and the cage in solution by cyclic voltammetry. We also demonstrate that the through‐space interaction of organic radicals within the self‐assembled coordination cage can be controlled by external stimuli such as heat or pH. 相似文献
994.
Sulfonylation of alkenes through photoredox‐catalyzed functionalization of alkenes with thiourea dioxide under visible‐light irradiation is achieved. The reaction of alkenes, thiourea dioxide and electrophiles provides a green and efficient access to alkyl sulfones and sulfonamides. A broad reaction scope is presented with good functional group compatibility and excellent regioselectivity. A plausible mechanism involving a radical addition process with sulfur dioxide radical anion (SO2‐) derived from the oxidation of sulfur dioxide anion (SO22–) is proposed, which is supported by fluorescence quenching experiments. 相似文献
995.
Jia‐Xiang Yang Yu‐Peng Tian Qing‐Liang Liu Yong‐Shu Xie Hoong‐Kun Fun Suchada Chantrapromma Ibrahim Abdul Razak 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(1):m43-m44
In the title compound, [Fe(C5H5)(C16H12N3OS)], the 8‐aminoquinoline and acylthiourea moieties are almost planar. There are two perpendicular arrangements of the molecules in the crystal with slightly different conformations. The two cyclopentadienyl rings in each molecule are parallel and eclipsed. 相似文献
996.
Hans‐Dietrich Stachel Barbara Zimmer Eduard Eckl Katharina Semmlinger Wolfgang Weigand Ralf Wünsch Peter Mayer 《Helvetica chimica acta》2005,88(6):1208-1220
The 1,2‐dithiolosultam derivative 14 was obtained from the (α‐bromoalkylidene)propenesultam derivative 9 (Scheme 1). Regioselective cleavage of the two ester groups (→ 1b or 2b ) allowed the preparation of derivatives with different substituents at C(3) in the dithiole ring (see 27 and 28 ) as well as at C(6) in the isothiazole ring (see 17 – 21 ; Scheme 2). Curtius rearrangement of the 6‐carbonyl azide 21 in Ac2O afforded the 6‐acetamide 22 , and saponification and decarboxylation of the latter yielded ‘sulfothiolutin’ ( 30 ). Hydride reductions of two of the bicyclic sultams resulted in ring opening of the sultam ring and loss of the sulfonyl group. Thus the reduction of the dithiolosultam derivative 14 yielded the alkylidenethiotetronic acid derivative 33 (tetronic acid=furan‐2,4(3H,4H)‐dione), and the lactam‐sultam derivative 10 gave the alkylidenetetramic acid derivative 35 (tetramic acid=1,5‐dihydro‐4‐hydroxy‐2H‐pyrrol‐2‐one) (Scheme 3). Some of the new compounds ( 14, 22, 26 , and 30 ) exhibited antimycobacterial activity. The oxidative addition of 1 equiv. of [Pt(η2‐C2H4)L2] ( 36a , L=PPh3; 36b , L=1/2 dppf; 36c , L=1/2 (R,R)‐diop) into the S? S bond of 14 led to the cis‐(dithiolato)platinum(II) complexes 37a – c . (dppf=1,1′‐bis(diphenylphosphino)ferrocene; (R,R)‐diop={[(4R,5R)‐2,2‐demithyl‐1,3‐dioxolane‐4,5‐diyl]bis(methylene)}bis[diphenylphosphine]). 相似文献
997.
Virgil Percec Anatoliy V. Popov Ernesto Ramirez‐Castillo 《Journal of polymer science. Part A, Polymer chemistry》2005,43(2):287-295
The single‐electron‐transfer/degenerative‐chain‐transfer mediated living radical polymerization (SET–DTLRP) of vinyl chloride (VC) in H2O/tetrahydrofuran at 25 °C catalyzed by thiourea dioxide [(NH2)2C?SO2] is reported. This polymerization occurs only in the presence of a basic sodium bicarbonate (NaHCO3) buffer and the electron‐transfer cocatalyst octyl viologen. The resulting poly(vinyl chloride) (PVC) has a number‐average molecular weight of 1500–7000 and a weight‐average molecular weight/number‐average molecular weight ratio of 1.5. This PVC does not contain detectable amounts of structural defects and has both active chloroiodomethyl and inactive chloromethyl chain ends. Because of possible side reactions caused by the primary sulfoxylate anion (SO), the catalytic activity of (NH2)2C?SO2 in the SET–DTLRP of VC is lower than that of the single‐electron‐transfer agent sodium dithionite. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 287–295, 2005 相似文献
998.
M. Mora M. E. Castro A. Nio F. J. Melendez C. Muoz‐Caro 《International journal of quantum chemistry》2005,103(1):25-33
This work presents an analysis of the equivalence of MP2 and DFT (B3LYP functional) conformational populations. As a test case, we select three cholinergic agents (trans‐nicotine, acetylcholine, and the nicotinic analgesic ABT‐594), where the minima on the conformational energy hypersurfaces expand a large range of energies (~0–30 kJ mol?1). From energetic and structural data obtained in vacuo at the MP2 and B3LYP/cc‐pVDZ levels, we build conformational partition functions, including the effect of the conformational kinetic energy and the rotovibrational coupling. Our results at a physiological temperature (37°C) show qualitative agreement in all cases. Quantitative agreement, however, is only found for trans‐nicotine and ABT‐594. In the first case, energy minima differ by <0.2 kJ mol?1. Therefore, the equivalence of structural results translates in the equivalence of the conformational distribution. For ABT‐594, the minima are separated by as much as 8.0 kJ mol?1, and the conformational energy determines the conformational distribution. In this case, the slight relative variation of conformational energy, between B3LYP and MP2, does not affect the population, since the secondary minima are high in energy and very low in population. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
999.
Jin‐Jun Wang Kimiaki Imafuku Yong Key Shim Gui‐Ji Jiang 《Journal of heterocyclic chemistry》2005,42(5):835-840
Methyl E/Z‐pyropheophorbide‐a 131‐ketoximes 2a,b and their O‐acetyl derivatives 3a,b were oxidized with osmium(VIII) oxide to give aldehydes 4a,b and 5a,b , respectively. The Wittig reactions of the aldehyde chlorines 4a,b and 5a,b with benzyltriphenylphosphonium chloride were performed to form the corresponding methyl (31E/Z,131E/Z)‐32‐phenylpyropheophorbide‐a 131‐ketoximes 6aa‐bb and their O‐acetyl derivatives 7aa‐bb ; hydrolysis of these ketoximes 6aa,ba and 6ab,bb in formic acid produced methyl (E/Z)‐32‐phenylpyropheophorbide‐a's 8a,b . 相似文献
1000.
Jordi de Mier‐Vinu ngel M. Montaa Virtudes Moreno María J. Prieto 《无机化学与普通化学杂志》2005,631(11):2054-2061
Two 1,4‐diamine ligands were synthesized having 1,2‐bis(aminomethyl)‐cyclohexane and 1,2‐bis(aminomethyl)‐benzene structures. The two ligands have different electron density in the six‐membered ring: a cyclohexane versus a phenyl ring. The organic synthesis of the ligands was carried out by synthetic pathways of seven and four steps, respectively, starting from 1,2,3,6‐tetrahydrophthalic anhydride and diethyl phthalate. The coordination of platinum to these ligands afforded platinum(II) complexes which are analogue to the clinical drug cisplatin but form a seven‐membered chelate ring. The interaction of the platinum compounds with DNA was studied in order to know the relationship between the electron density of ligands and their capability to chelate DNA, by using three techniques: Circular Dichroism, Agarose Gel Electrophoresis and Atomic Force Microscopy. The degree of interaction of both compounds with DNA was slightly different, but both complexes showed a cisplatin‐like behaviour and are promising candidates to follow an extensive study of their cytotoxic activity. 相似文献