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31.
Mark S. Daskin Ali E. Haghani Mandar Khanal Chryssi Malandraki 《Annals of Operations Research》1989,18(1):113-139
The level of aggregation is critical in discrete location analyses as it affects the level of data collection required, computation times and the usefulness of the analyses. We examine the effects of three alternative nodal aggregation schemes on (i) the model's solution times, (ii) the locational decisions indicated by the maximum covering model, (iii) the coverage provided by the aggregate solutions compared with the optimal solutions, and (iv) the coverage predicted by the aggregate model compared with the coverage that results from using the aggregate model's facility sites and the disaggregate demands. The results suggest that considerable aggregation can be tolerated without incurring large errors in total coverage, but that location errors are introduced at moderate levels of aggregation. The magnitude of these errors is significantly affected by the aggregation scheme employed. 相似文献
32.
Th. Kappe E. Ziegler M. Ali A. Chirazi 《Monatshefte für Chemie / Chemical Monthly》1969,100(1):142-145
Zusammenfassung Perimidon (1) reagiert mit monosubstit. Malonsäure-trichlorphenylestern (2) bei 250° zu 9-Hydroxy-5,7-dioxo-4,5-dihydro-7H-pyrido[1,2,3-cd]perimidinen (3), die durch saure Hydrolyse zu 10-Amino-4-hydroxy-benzo[h]carbostyrilen (4) gespalten werden.
Syntheses of heterocycles, CXXII: Reaction of perimidone with reactive malonates
Perimidone (1) reacts with monosubstituted 2.4.6-trichlorophenyl malonates at 250° to 9-hydroxy-5.7-dioxo-4.5-dihydro-7H-pyrido[1.2.3-cd]perimidines (3), which are cleaved by acid yielding 10-amino-4-hydroxy-benzo[h]quinolin-2-ones (4).相似文献
33.
BIOLOGICAL ACTIVITIES OF PHTHALOCYANINES-X. SYNTHESES AND ANALYSES OF SULFONATED PHTHALOCYANINES 总被引:5,自引:0,他引:5
Hasrat Ali Réjean Langlois J. Richard Wagner Nicole Brasseur Benoit Paquette Johan E. VAN Lier 《Photochemistry and photobiology》1988,47(5):713-717
Abstract— Synthetic methods to obtain selectively sulfonated metallo phthalocyanines are compared. Both condensation and direct sulfonation procedures lead to mixtures of mono- to tetrasulfonated products which are resolved by reverse phase liquid chromatography in buffered aqueous-methanol. The proportion of sulfonated derivatives is examined as a function of the starting reagents in the case of the condensation method, and as a function of the temperature and reaction time in the case of the direct sulfonation procedure. The number of sulfonate groups per phthalocyanine molecule is determined by oxidative degradation of the phthalocyanine ring followed by quantitative chromatographic analysis of the sulfophthalamide and phthalamide fragments. 相似文献
34.
A straightforward and effective procedure for the conversion of benzylic, allylic and aliphatic alcohols to the corresponding iodides using Ph3P/I2 under solvent-free conditions using microwave irradiation is reported. 相似文献
35.
BinaS. Siddiqui M.Nadeem Kardar S.Tariq Ali Shazia Khan 《Helvetica chimica acta》2003,86(6):2164-2169
A new obtusafuran derivative, lawsonicin ( 1 ), and a new naphthaquinone, lawsonadeem ( 2 ), along with a known constituent, vomifoliol ( 3 ), were isolated from the aerial parts of Lawsonia alba and characterized by chemical transformation and spectroscopic experiments, including 2D‐NMR techniques. 相似文献
36.
37.
The new compound, Na[(Mo2
VO4)(pte)(OMe)(MeOH)2] (pte = anion of 6-acetonylisoxanthopterin), has been prepared using the redox non-innocent title ligand in MeOH–H2O, and characterized by elemental analysis and physico-chemical methods including e.s.m.s., i.r., u.v.–vis. and 1H-n.m.r. spectra. Rate constants data (1.4 × 10–3 s–1 at 300 K) for its oxygen atom transfer with dimethyl sulphoxide tally with those of synthetic analogue systems reported earlier by different authors. The negative activation entropy (–206.3 J mol–1 deg–1) is consistent with an associative mechanism for this reaction. 相似文献
38.
Mohammad Ali Bigdeli Abbas Rahmati Hossein Abbasi-Ghadim Gholam Hossein Mahdavinia 《Tetrahedron letters》2007,48(26):4575-4578
Aromatic amines have been synthesized efficiently from enamines using SnCl4 and SbCl5 in CH2Cl2 at room temperature. 相似文献
39.
Relative rates of solvolysis of some N-triorganosilylanilines in mixtures of ethanol and aqueous potassium hydroxide have been determined, with results as follows. (i) For XC6H4NHSiEt3 compounds in MeOH (5 vol) + aq. alkali (2 vol) at 50°: (X =) H, 1.0;p-Me, 0.80;p-OMe, 0.83;m-Me, 0.90; o-Me, 0.87; p-SMe, 1.90; p-F, 1.7; p-Cl, 2.8; o-Cl, 14; m-Cl, 4.2; m-NO2, 18; p-CN, ca. 43; p-NO2, ca. 120. (ii) For PhNHSi(C6H4Y)3 compounds in MeOH (10 vol) + aq. alkali (1 vol) at 50°: (Y =) H, 1.0; p-OMe, 0.12; p-Cl, ca. 32; m-Cl, ca. 84. (iii) For PhNHSiR3 compounds in MeOH (5 vol) + aq. alkali (2 vol) : (R3 =) Et3, 1.0; Et2Me, 18 (at 30°); Me2-i-Pr, 8 (at 30°);Me2-t-Bu, 0.012 (at 50°);i-Pr3, 0.006 (at 50°). In series (i) the relative rates correlate with σ, or where appropriate σ?-constants, with a ? value of 1.6. It is suggested that in the transition state of the rate-determining step the OSi bond is fully formed, or almost so, the SiN bond approximately 20—50% broken, and the bond between the nitrogen atom and a proton from the solvent ca. 10—30% formed. 相似文献
40.
Mohammad Ali Zolfigol Iraj Mohammadpoor-BaltorkDavood Habibi BiBi Fatemeh MirjaliliAbdolhamid Bamoniri 《Tetrahedron letters》2003,44(44):8165-8167
Primary and secondary trimethylsilyl ethers were converted to their corresponding ethers in the presence Nafion-H® with good to excellent yields under mild and heterogeneous conditions. 相似文献