- Mechanistic studies of the copolymerization reaction of aziridines and carbon monoxide to produce poly-β-peptoids
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The coupling of carbon monoxide and aziridines has been shown to be selective for comonomer-alternating enchainment in the presence of PhCH 2C(O)Co(CO)4 to afford poly-β-peptoids. In this article, we have investigated the mechanistic aspects of the reaction of CO and N-butylaziridine by means of in situ infrared spectroscopy employing CH 3C(O)Co(CO)3L (L = PPh3 (1) and P(otolyl) 3 (2)) as precatalysts. Precatalyst 1 exists in solution under catalytic conditions as an equilibrium mixture of 1 and CH3C(O)Co(CO) 4, and affords both poly-β-butylalanoid and the corresponding lactam. By way of contrast, precatalyst 2 which possesses the sterically bulky and labile P(o-tolyl)3 ligand, affords only the acyl cobalt tetracarbonyl species in solution during catalysis with concomitant selective production of the copolymer. Kinetic studies conducted with precatalyst 2 showed the coupling reaction to have a first order dependence on catalyst, a first order dependence on N-butylaziridine, and only a slight dependence on the concentration of CO over the pressure range 17-69 bar. The working mechanistic model for the copolymerization reaction involves first aziridine insertion into the cobalt-acyl bond, rate determining ring opening by the cobaltate species, followed by the migratory CO insertion.
- Darensbourg, Donald J.,Phelps, Andrea L.,Le Gall, Nathalie,Jia, Li
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- Synthesis and characterization of novel ionic liquids: N-substituted aziridinium salts
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Ionic liquids based on three-membered ring aziridinium cations have been synthesized for the first time using a straightforward synthetic route. N-butyl-N-methylaziridinium bis(trifluoromethanesulfonyl)imide, N-propyl-N-ethylaziridinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-[2-(2-methoxyethoxy)ethyl]aziridinium bis(trifluoromethanesulfonyl) imide, N-butyl-N-methylaziridinium dicyanamide, and N-butyl-N-ethylaziridinium dicyanamide were thus obtained in good yields and satisfactory purity and fully characterized.
- Duriska, Martin B.,Grondin, Joseph,Servant, Laurent,Birot, Marc,Deleuze, Herve
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p. 652 - 657
(2012/08/27)
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- Acid-Catalyzed Decomposition of 1-Alkyltriazolines: A Mechanistic Study
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1-Alkyltriazolines are five-membered cyclic triazenes containing the unusual Z-configuration for the triazene moiety.The hydrolytic decomposition of these compounds in aqueous or mixed acetonitrile-aqueous buffers leads predominantly to the formation of the corresponding 1-alkylaziridines and lesser amounts of 2-(alkylamino)ethanols, alkylamines, and acetaldehyde.The latter two products presumably result from hydrolysis of a rearrangement produkt, N-ethylidenealkylamine.Neither the nature of the 1-alkyl group nor the pH of the medium greatly influences the product distribution, although decomposition in purely aqueous buffers slightly reduces the aziridine yields.The rate of hydrolysis of 1-alkyltriazolines is about twice as fast as that of the analogous acyclic 1,3,3-trialkyltriazenes and varies in the order tert-butyl > isopropyl > ethyl > butyl > methyl > propyl > benzyl.The mechanism of the decomposition is specific acid-catalyzed (A1) involving rapid reversible protonation followed by rate-limiting formation of a 2-(alkylamino)ethyldiazonium ion.The slopes of the log kobs versus pH plots are near -1.0.The solvent deuterium isotope effect, kH2O/kD2O, is in all cases methyl > ethyl.
- Smith, Richard H.,Wladkowski, Brian D.,Taylor, Jesse E.,Thompson, Erin J.,Pruski, Brunon,et al.
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p. 2097 - 2103
(2007/10/02)
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- Process for the production of high energy materials
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A process for the production of a high energy nitrate ester involves reacting, in an inert organic solvent, a heterocyclic compound, selected from oxiranes, oxetanes, N-substituted aziridines and N-substituted azetidines, with either N2 O4 or N2 O5, and when the compound is reacted with N2 O4, oxidizing the O- or N-nitrate substituents or substituent in the product to O- or N-nitrate substituent or substituents. The remaining ring carbon atoms on the heterocyclic compound may be substituted or unsubstituted. Preferred substituent groups for the C and/or N ring atoms on the compound include alkyl, cyanoalkyl, haloalkyl, nitroalkyl, and substituted aryl. Several novel nitrate ester are also provided, including nitrated derivatives of polybutadiene, in which between 1% and 25% of the carbon atoms in the polymer are substituted by vicinal nitrate ester (--ONO2) groups.
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