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931.
A study was made on the inhibition by some 3,3′- and 4,4′-disubstituted azobenzenes of the polymerization of vinylacetate initiated by azoisobutyronitrile at 50°. The inhibitory effects of these substances can be attributed to their ability to engage in radical addition giving a less reactive hydrazyl type radical. The mechanism of the inhibition has been established by ESR and kinetic (stoichiometric) measurements. The value of k5/k2 (characteristic of the reactivity of an inhibitor) was determined for 9 substituents. The radical reactivity of the aromatic azo group was decreased by electron donor substituents and increased by electron acceptors. The substituent effect can be well interpreted by the Hammett equation; the value of the reaction constant was ? = +0.53. 相似文献
932.
V. S. Yuminov S. V. Kartsov V. L. Maksimov M. D. Bargamova A. V. Fokin 《Russian Chemical Bulletin》1989,38(4):845-849
Conclusions Perfluoro-2,4-dimethyl-2-fluorocarbonyl-1,3-dioxolane reacts with sodium carbonate to give perfluoro-2-methylene-2-methyl-1,3-dioxolane. Under the reaction conditions, the latter dimerizes to perfluoro-2-(2,4-dimethyl-1,3-dioxolan-2-ylmethylene)-4-methyl-1,3-dioxolane, and on treatment with CsF is converted into perfluoromethyl-(1,3-dioxolany-2-yl)ketone.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 938–942, April, 1989. 相似文献
933.
A. N. Vinnichenko N. I. Shtemenko V. S. Vedenko G. N. Tumanov L. P. Glushko R. V. Kashenkova 《Chemistry of Natural Compounds》1988,24(3):302-305
It has been established that the change in the composition of the total lipids and the fall in the fatty acid content depend on the initial maize genotype. A decrease in the amount of unsaponifiable substances in the grain of mutants is accompanied by qualitative changes in the composition regardless of the nature of the genotype.Scientific-Research Institute of Biology Dnepropetrovsk State university. Translated from Khimiya Prirodnykh Soedinenii. No. 3. pp. 360–363. May–June, 1988. 相似文献
934.
The compounds 1,1,1-trichloro-2,4-pentanedione, Cu(II)tca2, Co(II)tca2, Mn(II)tca2, Al(III)tca3, Cr(III)tca3 and Fe(III)tca3 (tca?1,1,1-trichloro-2,4-pentanedionato, [CCl3COCHCOCH3]?) have been prepared and their mass spectra have been obtained. The mass spectral results have been compared with findings for comparable fluorinated and nonhalogenated compounds. Comparisons are made in terms of internal redox reactions and hard and soft acid base theory. Rearrangement of chloride from ligand to metal accompanied by the elimination of CO or other neutral even electron fragments emerges as an important reaction for the ions of these compounds. While the internal redox reactions characteristic of all previous β-diketonate complex mass spectra still occur, their importance appears reduced to some degree by the facility of the chlorine rearrangement. 相似文献
935.
Khilya V. P. Kupchevskaya I. P. Salikhova A. I. Grishko L. G. Babichev F. S. Kirillova L. G. 《Chemistry of Heterocyclic Compounds》1977,13(9):948-953
Condensation of 2-pyridylacetonitrile with polyphenols gave the corresponding -(2-pyridyl)-acetophenones, which were converted to the pyridine analogs of natural isoflavones and to 3-pyridylchromones with methyl, trifluoromethyl, and ethoxycarbonyl groups in the 2 position. The antimicrobial activity of 3-pyridylchromones and their reaction with alkylating and acylating agents and phosphorus pentasulfide were investigated.See [1] for communication V.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1180–1185, September, 1977. 相似文献
936.
[reaction: see text]. Polymer-bound chiral electrophilic selenium reagents have been developed and applied to stereoselective selenenylation reactions of various alkenes. Different cleavage protocols allow further functionalization of the addition products leading to improvements in selenium-based solid-phase chemistry. 相似文献
937.
A. Boughriet C. Cordier L. Deram B. Ouddane H. Chamley M. Wartel 《Fresenius' Journal of Analytical Chemistry》1995,352(3-4):341-353
A study of managanese and iron associated with particulate matter in seawaters derived from the English Channel (and North Sea). Sequential extraction procedures have been used to identify geochemical processes that govern Mn and Fe coprecipitation/accumulation/distribution in different particulate phases (carbonate; Fe-Mn(hydr)oxides; organic matter and residual phase). The oxidation states of Mn and Fe, some mechanisms of bonding and the magnetic characteristics of particles have been investigated by Mössbauer spectroscopy, electron spin resonance(ESR) spectroscopy, and mass susceptibility balance. The effect of pH and redox potential on stability of different dissolved and particulate Mn species was also examined. In the these calcareous seawaters, manganese (II) is predominantly bound to the carbonate phase (calcite) in the form of MnxCa1-xCO3. However the persistent occurrence of Mn in oxidation states > 2 in these particles has suggested the existence of manganese(III) in the polymeric FeOOH structures as an intermediate entity during Mn(II) oxidation in the sea. The activity coefficient of the entity MnOOH in FeOOH has been evaluated and p-pH diagrams of Mn have been proposed under marine conditions. 相似文献
938.
Institute of Biochemistry, Academy of Sciences of the Georgian Republic, Tbilisi, and Samara Medical Institute, Russia. Translated
from Khimiya Prirodnykh Soedinenii, No. 6, pp. 821–822, November–December, 1994. 相似文献
939.
The extraction of the V(V)-BPHA complex into chloroform and benzene was investigated using48V tracer produced from the45V reaction using the Variable Energy Cyclotron, Calcutta. A neutron activation analysis procedure for the estimation of vanadium in gallium metal samples based on the extraction of V(V)-BPHA complex into benzene is given. 相似文献
940.
L. A. Chetkina A. N. Sobolev V. K. Bel'skii V. E. Zavodnik I. G. Arzamanova Ya. V. Gurvich O. F. Starikova 《Journal of Structural Chemistry》1991,32(5):766-768
L. Ya. Karpov Scientific-Research Physicochemical Institute. Scientific-Research Institute of Rubber and Latex Goods. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 5, pp. 162–164, September–October, 1991. 相似文献