4538-51-6Relevant academic research and scientific papers
Poly(THF-co-cyano ethylene oxide): Cyano Ethylene Oxide (CEO) Copolymerization with THF Leading to Multifunctional and Water-Soluble PolyTHF Polyelectrolytes
Christ, Eva-Maria,Herzberger, Jana,Montigny, Mirko,Tremel, Wolfgang,Frey, Holger
, p. 3681 - 3695 (2016)
Cyano-functional polyether copolymers based on THF were prepared via cationic ring-opening copolymerization of THF with cyano ethylene oxide (CEO). The CEO content of poly(tetrahydrofuran) (polyTHF) based copolymers varied from 3.3 to 29.3%, and molecular weights ranged from 5100 to 31900 g·mol-1 with Mw/Mn in the range of 1.31 to 1.74 (SEC in THF, PS standards). The polymerization was conducted with methyl trifluoromethanesulfonate (MeOTf) as an initiator. Kinetic studies concerning incorporation of both monomers were performed via NMR spectroscopy. The cyano groups at the poly(THF-co-CEO) copolymers enable direct access to amino (polyTHF-NH2) and carboxyl groups (polyTHF-COOH) in facile one-step procedures, respectively. The modified copolymers were characterized via NMR, MALDI-ToF mass, and FT-IR spectroscopy. Thermal properties of the materials were studied via differential scanning calorimetry (DSC), demonstrating a gradual decrease of the melting points with increasing amount of CEO in the copolymers (from 30 °C for 3.3% CEO to 21 °C for 8.4% CEO). After postmodification to carboxylic acid groups the melting points decrease from 26 to 18 °C in the series of copolymers. Contact angles of water on thin films of the polymers can be tuned in a wide range from 72.7° to 17.8° by varying the CEO fraction as well as by postmodification. Crystallization studies of CaCO3 with water-soluble polyTHF-COOH revealed the composition-dependent inhibition of calcite growth, with crystallite size in the mineralization process being controlled by the amount of carboxylic acid groups at the poly(THF) copolymers.
Efficient epoxidation of electron-deficient alkenes with hydrogen peroxide catalyzed by [γ-PW10O38V2(μ-OH) 2]3-
Kamata, Keigo,Sugahara, Kosei,Yonehara, Kazuhiro,Ishimoto, Ryo,Mizuno, Noritaka
scheme or table, p. 7549 - 7559 (2011/08/03)
A divanadium-substituted phosphotungstate, [γ-PW10O 38V2(μ-OH)2]3- (I), showed the highest catalytic activity for the H2O2-based epoxidation of allyl acetate among vanadium and tungsten complexes with a turnover number of 210. In the presence of I, various kinds of electron-deficient alkenes with acetate, ether, carbonyl, and chloro groups at the allylic positions could chemoselectively be oxidized to the corresponding epoxides in high yields with only an equimolar amount of H2O2 with respect to the substrates. Even acrylonitrile and methacrylonitrile could be epoxidized without formation of the corresponding amides. In addition, I could rapidly (min) catalyze epoxidation of various kinds of terminal, internal, and cyclic alkenes with H;bsubesubbsubesub& under the stoichiometric conditions. The mechanistic, spectroscopic, and kinetic studies showed that the I-catalyzed epoxidation consists of the following three steps: 1) The reaction of I with H;bsubesubbsubesub& leads to reversible formation of a hydroperoxo species [I;circbsubesubbsubesubbsubesubcirccircbsupesup& (II), 2) the successive dehydration of II forms an active oxygen species with a peroxo group [ 2:2-O2)]3- (III), and 3) III reacts with alkene to form the corresponding epoxide. The kinetic studies showed that the present epoxidation proceeds via III. Catalytic activities of divanadium-substituted polyoxotungstates for epoxidation with H 2O2 were dependent on the different kinds of the heteroatoms (i.e., Si or P) in the catalyst and I was more active than [γ-SiW10O38V2(μ-OH)2] 4-. On the basis of the kinetic, spectroscopic, and computational results, including those of [γ-SiW10O38V 2(μ-OH)2]4-, the acidity of the hydroperoxo species in II would play an important role in the dehydration reactivity (i.e., k3). The largest k3 value of I leads to a significant increase in the catalytic activity of I under the more concentrated conditions. Copyright
Chromium Silicalite-2 (CrS-2): an Efficient Catalyst for the Chemoselective Epoxidation of Alkenes with TBHP
Joseph, Reni,Sasidharan, M.,Kumar, R.,Sudalai, A.,Ravindranathan, T.
, p. 1341 - 1342 (2007/10/02)
Chromium-containing medium-pore molecular sieve (Si/Cr > 140) having MEL (CrS-2) topology efficiently catalyses the chemoselective epoxidation of various olefins to the corresponding epoxides using 70percent tert-butyl hydroperoxide (TBHP) as an oxidant.
Chemistry of α-Aminonitriles. Formation of 2-Oxoethyl Phosphates ('Glycolaldehyde Phosphates') from rac-Oxiranecarbonitrile and on (Formal) Constitutional Relationships between 2-Oxoethyl Phosphates and Oligo(hexo- and pentopyranosyl)nucleotide Backbones
Pitsch, Stefan,Pombo-Villar, Esteban,Eschenmoser, Albert
, p. 2251 - 2285 (2007/10/02)
Oxiranecarbonitrile in basic aqueous solution at room temperature reacts regioselectively with inorganic phosphate to give the cyanohydrin of 2-oxoethyl phosphate ('glycolaldehyde phosphate'), a source of (the hydrate of) the free aldehyde, preferably in the presence of formaldehyde.In aqueous phosphate solution buffered to nearly neutral pH, oxiranecarbonitrile produces the phosphodiester of glycolaldehyde as its bis-cyanohydrin in good yield.In contrast to mono- and dialkylation, trialkylation of phosphate with oxiranecarbonitrile is difficult, and the triester derivative is highly sensitive to hydrolysis.Glycolaldehyde phosphate per se is of prebiotic interest, since it had been shown to aldomerize in basic aqueous solution regioselectively to rac-hexose 2,4,6-triphosphates and- in the presence of formaldehyde - mainly to rac-pentose 2,4-diphosphates with, under appropriate conditions, rac-ribose 2,4-diphosphate as the major reaction product.However, the question as to whether oxiranecarbonitrile itself has the potential of having been a prebiological natural constituent remains unanswered.Backbone structures of hexopyranosyl-oligonucleotides with phosphodiester linkages specifically between the positions 6'->4',6'->2', or 4'->2' of the sugar residues can formally be derived via the (hypothetical) aldomerization pathway, a combinatorial intermolecular aldomerization of glycolaldehyde phosphate and bis(glycolaldehyde)phosphodiester in a 1:1 ratio.The constitutional relationships revealed by this synthetic analysis has played a decisive role as a selection criterion in the pursuit of our experimental studies toward a chemical etiology of the natural nucleic acids' structure.The Discussion in this paper delineates how the analysis contributed to the conception of the structure of p-RNA.The English Footnotes to Schemes 1-11 provi de an extension of this summary.
