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1.
N. Fazeli F. Afshar Taromi 《Journal of polymer science. Part A, Polymer chemistry》2003,41(1):135-142
The basis of the two‐step in–in method is as follows: star polymers with poly(divinyl benzene) cores, synthesized by the arm‐first method, include many unreacted double bonds in their core, and these double bonds can be attacked by the carbanions of some monomers such as styrene and dienes. In this work, linear polyisoprene chains were used to attack the double bonds existing in the poly(divinyl benzene) cores of polystyrene star polymers, so that a heteroarm star polymer with polystyrene and polyisoprene arms was synthesized. It was later well characterized with size exclusion chromatography, light scattering, viscometry, UV spectroscopy, dynamic mechanical thermal analysis, and 1H NMR. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 135–142, 2003 相似文献
2.
S. V. Koroteev D. S. Ermekov Z. V. Todres A. D. Malievskii 《Russian Chemical Bulletin》1992,41(1):60-64
Reaction of cis-,-dinitrostilbene (substrate) with morpholine (reagent) in n-hexane leads to cis--nitro--morpholinostilbene (end product). The process is of first order with respect to the substrate and second order with respect to the reagent. Possible reaction mechanisms are analyzed, and it is established that the following are most probable on the basis of kinetic patterns and stereochemistry: development of a charge transfer complex having a hydrogen bond between the substrate nitro group and reagent amino group; reaction of the complex with a second reagent molecule and formation of a carbanion (this stage determines the overall reaction rate); and detachment of a nitrite ion from the nitrocarbanion and its protonation to form the end product.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. A. N. Nesmeyanov Institute of Heteroorganic Compound, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 78–83, January, 1992. 相似文献
3.
Johannes Smid 《Journal of polymer science. Part A, Polymer chemistry》2004,42(15):3655-3667
The discovery and implications of the existence of two kinds of ion pairs in solutions of carbanion salts is described. Also discussed are the factors controlling tight–loose ion pair equilibrium: the nature of the carbanion and its counterion, temperature, pressure, solvent, and cation‐complexing additives. A few examples are presented of the effect of these ionic species on the mechanisms of anionic polymerization and proton transfer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3655–3667, 2004 相似文献
4.
Fabio BonaLuisella De Vitis Saverio FlorioLudovico Ronzini Luigino Troisi 《Tetrahedron》2003,59(9):1381-1387
2-Chloroalkylthiazolyllithiums, prepared by deprotonating the 2-chloroalkylthiazoles with n-BuLi at −78°C in THF, add to ketones or imines affording in ‘one-pot’ oxiranes and aziridines in a Z stereoselective manner. 相似文献
5.
Bicyclic sulfonamides were synthesized from 4-alkenyl N-alkenylsulfonyl l-prolines using a ring-closure metathesis reaction. Three types of bicyclic sulfonamides varying in the size of the second ring (5,5; 5,6; 5,7) were synthesized. A sulfonamide counterpart of an indolizidinone 2-carboxylic acid was synthesized and evaluated for its activity against the enzyme thrombin. 相似文献
6.
M. Veiderma T. Kaljuvee R. Knubovets M. Pôldme K. Tônsuaadu 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):125-128
Abstract The mechanisms of thermal transformations in different types of natural phosphates and their mixtures with H3PO4 and Na2CO3 are discussed. 相似文献
7.
Jordanka Petrova Snejana Momchilova Nikolay G. Vassilev 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):45-52
Abstract The interaction of Li-diethylbenzylphosphonate 1-Li with aldehydes 2 is studied at different reaction conditions, the corresponding β-hydroxyethanephosphonate 3 being isolated. It is found that in these cases the aldol stage of the HWE reaction is not stereoselective or threo isomers predominate. The elimination stage leads only to trans-alkene due to the electron and steric influence of the substituents at the phosphorus atom. 相似文献
8.
Chengye Yuan Jiachang Yao Shusen Li 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):21-27
Abstract For the evaluation of the structural effect of electrophiles on the regioselectivity of ambident anions, the reaction of phosphoryl allylic carbanion with p-substituted benzaldehydes was investigated. 相似文献
9.
《中国化学快报》2020,31(7):1911-1913
An efficient protocol for the synthesis of asymmetric 1,3-diketones was reported through diacylation of 1,1-diborylalkanes using two different acyl sources. In this transformation, an enolate boron species was initially formed by introducing an acyl group, then it was trapped by another acyl group to form 1,3-diketone. This method not only provided the gateway to obtain a series of 1,3-diketones, but also afforded an operationally simple and efficient access to pyrazoles and isoxazoles. 相似文献
10.
Jordanka Petrova Nikolai G. Vassilev Marko Kirilov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):457-463
Abstract The reaction of the lithium derivative of diethyl ester of phenylmethanephosphonic acid (1-Li) with alkanones, cycloalkanones, alkylaryl and diarylketones 2s-b is studied at -70°C in THF. The corresponding adducts-diethyl esters of l-phenyl-2,2-dialkyl(phenyl)-2-hydroxyethanephosphonic acids 3s-h are isolated, their yields being usually higher at short reaction time. The olefination of 3-Li as well as of 3 (both by thermolysis or in acidic media) proceeds in low degree, while in the case of 3-Na the yields of alkenes 4 are good. The relative configurations of 3b. 31 and 3g are determined by IR and NMR-spectra, as well as by their stereospecific olefination. “Threo”-stereoselectivity of the addition stage of the reaction of 1-Li with 2b, 21 and 2g is observed, the “threo”/“erythro” ratio remaining independent on the reaction time. 相似文献