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31.
P. Hazot J. P. Chapel C. Pichot A. Elaissari T. Delair 《Journal of polymer science. Part A, Polymer chemistry》2002,40(11):1808-1817
Monodisperse, thermosensitive poly(N‐ethyl methacrylamide) microgel particles were prepared by the batch precipitation/emulsion polymerization of water‐soluble N‐ethyl methacrylamide and the hydrophobic crosslinker ethylene glycol dimethacrylate initiated by potassium persulfate. Particular attention was paid to the effect of the crosslinker agent on the polymerization process (kinetics, conversion, and water‐soluble oligomer content). Particles were characterized in terms of their size distribution and swelling capacity. A polymerization mechanism for the water‐soluble monomer and non‐water‐soluble crosslinker is proposed and discussed on the basis of a combination of both emulsion and precipitation polymerization processes. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1808–1817, 2002 相似文献
32.
Dan Donescu Sever Serban Kristiana Gosa Cristian Petcu 《Central European Journal of Chemistry》2005,3(1):10-27
The possibility to prepare hybrids made by poly(vinyl acetate) (PVAc), poly(methyl methacrylate) (PMMA) and/or poly(ethyl
acrylate) (PEtA) with TiO2 was studied. The processes of polymer formation-radical polymerization and sol-gel process for inorganic network —were achieved
simultaneously. Due to a high reactivity of titanium isopropoxide (TIP) in the sol-gel process, a complexant comonomer, allyl
acetoacetate (AlAcAc), was used. Covalent bonds between polymer and inorganic chains were obtained by addition of trialkoxysilane
derivates with vinyl (VTES) or methacryloyl (MPTS) groups. The presence of TIP inhibits the radical polymerization of vinyl
acetate (VAc). The PVAc-TiO2 hybrids were produced by the sol-gel process of TIP in the presence of pre-obtained PVAc. Except for VTES and MPTS, trialkoxysilane
derivates with methyl (MeTES), octyl (OTES) and phenyl (PTES) groups were used. The thermal stability of hybrids is strongly
affected by TiO2 presence and by the type of trialkoxysilane derivates. The thermal stability of PVAc hybrids decreases in the presence of
TiO2 inorganic network. The glass transition temperature of polymers increases in the presence of the inorganic network. 相似文献
33.
V. Slavinska Dz. Sile G. Rozenthal G. Maurops J. Popelis M. Katkevich V. Stonkus E. Lukevics 《Chemistry of Heterocyclic Compounds》2006,42(5):570-573
The hydrogenation of ethyl 4-R-2,4-dioxobutyrates (R = phenyl, 2-furyl) at 5% Pt/Al2O3 catalyst, modified with cinchonidine, and at palladium black was investigated. The former had low activity under the conditions
we tested. The main products during the hydrogenation of these compounds at palladium black are ethyl 4-R-2-hydroxy-4-oxobutyrates.
The yield of the phenyl derivative amounts to 68.5%, while the yield of the corresponding 2-furyl derivative amounts to 97%.
In the last case ethyl 2-hydroxy-4-oxo-4-(2-tetrahydrofuryl)butyrate was detected as impurity. The optimum conditions for
the formation of ethyl 2-hydroxy-4-phenylbutyrate (yield 88.2%) were determined.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 655–659, May, 2006. 相似文献
34.
G. Glöckner 《Chromatographia》1987,23(7):517-524
Summary Prerequisite of quantitative evaluation in chromatography is equivalence of sample composition and detector signal. This includes
complete retention and proper elution of all sample constituents. In polymer HPLC, complete retention requires a poor starting
eluent, a sufficiently active column, and a low ratio of injection volume to column volume. On small pore columns, insufficient
retention caused the polymer to elute either in the interstitial volume (sample exclusion), together with the sample solvent,
or immediately after the solvent plug.Stat-copoly(styrene/ethyl methacrylate) samples are more difficultly retained thanstat-copoly(styrene/acrylonitrile) specimes. With the former copolymer it could be shown that incomplete retention did not cause
sample demixing. In order to gain complete retention, non-exclusion HPLC of polymers should be performed with columns whose
solvent volume is at least 50 times as large as the injection volume. This consequence is of practical importance in chromatographic
cross-fractionation where rather large volumes of SEC eluate are injected into the apparatus for gradient HPLC. 相似文献
35.
以乙基紫为活性物质的聚氯乙烯膜氰化亚金电极的研制和应用 总被引:3,自引:0,他引:3
以碱性染料为活性物质制备20余种不同组分PVC膜Au(CN)2^-电极,确定较佳膜组成为乙基紫0.99%,邻苯二甲酸二丁酯69.2%,PVC粉29.8%。该电极对Au(CN)2^-浓度在5.0×10^-7 ̄1.0×10^-2mol/L范围内接近能斯特响应;斜率为55.7mV(30℃)。稳定性与选择性较好。该电极制备简单,使用方便,已成功用于氰化镀金液中金的测定。 相似文献
36.
A. V. Kurkin V. V. Nesterov A. V. Karchava M. A. Yurovskaya 《Chemistry of Heterocyclic Compounds》2003,39(11):1466-1477
A new approach has been proposed to the synthesis of indole derivatives containing a chiral substituent at the nitrogen atom, comprizing Fischer indolization of phenylhydrazines with a chiral substituent at the -nitrogen atom. The initial hydrazines were obtained by the alkylation (Mitsunobu reaction applying optically active esters of lactic acid) of anilines containing an electron-accepting substituent at the amino group. Subsequent removal of the activating acceptor grouping was realized by nitrosation of the chiral secondary aniline followed by reduction of the corresponding N-nitroso compound. 相似文献
37.
38.
1INTRODUCTIONPolarizedketenedithioacetalshavebeenex-tensivelyusedasbuildingblocksinorganicsyn-thesis,especiallyinthesynthesisofheterocycliccompounds[1~6].Pyrazoleanditsderivativesrepre-sentoneofthemostactiveclassesofcompoundspossessingwidespectraofbiologicalactivities.Overthepastfewyears,considerableevidenceshavebeenaccumulatedtodemonstratetheefficacyofpyrazolederivatives,suchasantibacterial[7],fun-gicidal[8],herbicidal[9],insecticidal[10]andotherbiologicalactivities[11,12].Uptonow,alarg… 相似文献
39.
L. G. Voskressensky T. N. Borisova L. N. Kulikova A. V. Varlamov 《Chemistry of Heterocyclic Compounds》2007,43(7):913-918
The interaction of 7-trifluoroacetyltetrahydropyrrolo[1,2-c]pyrimidine with acetylenedicarboxylic ester (DMAD) and ethyl propiolate
in acetonitrile and alcohols has been studied. It was established that DMAD splits pyrrolopyrimidine at the aminal fragment
in acetonitrile and methanol with the formation of 1-H-and 2-(N-dimethoxycarbonylvinyl-N-methyl)aminoethyl-1-methoxymethyl-3-methyl-5-trifluoroacetylpyrroles.
In acetonitrile ethyl propiolate splits pyrrolopyrimidine both at the aminal fragment and at the C(3)-N(2) bond (Hofmann reaction), but in ethanol only at the C(3)-N(2) bond with the formation of 2-propenylpyrroles.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1082–1087, July, 2007. 相似文献
40.