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Uncatalyzed Reaction (uncatalyzed + reaction)
Selected AbstractsUncatalyzed Reaction of Silyl Ketene Acetals with Oxalyl Chloride: A Straightforward Preparation of Symmetrical Pulvinic Acids.CHEMINFORM, Issue 29 2005Benoit Heurtaux No abstract is available for this article. [source] Solvent- and catalyst-free reaction of (aminomethyl)phosphonates with epoxides: Synthesis of novel {[(2-hydroxyethyl)amino]methyl}phosphonatesHETEROATOM CHEMISTRY, Issue 5 2010Babak Kaboudin Uncatalyzed reaction of epoxides with (aminomethyl)phosphonates for the synthesis of novel {[(2-hydroxyethyl)amino]methyl}phosphonates is described. Treatment of (aminomethyl)phosphonates with epoxides without any catalyst and under solvent-free conditions gives novel {[(2-hydroxyethyl)amino]methyl}phosphonates. Using this method, a series of {[(2-hydroxyethyl)amino]methyl}phosphonates was synthesized in good yields. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:284,289, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20615 [source] Theoretical Study on Hetero-Diels,Alder Reaction of Butadiene with Benzaldehyde Catalyzed by Chiral InIII ComplexesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2010Xiuli Cao Abstract The mechanism of the hetero-Diels,Alder reaction of butadiene with benzaldehyde catalyzed by chiral N,N, -dioxide/In(OTf)3 complexes was studied theoretically by using density functional theory (DFT) and model system. The computational results indicate that the catalyzed reaction proceeded through a concerted mechanism via a highly zwitterionic transition state. The lowest energy barrier was 11.8 kJ,mol,1, which is 63.0 kJ,mol,1 lower than that of the uncatalyzed reaction. The results indicate that the endo approach is advantageous over the exo approach, because exo transitions states suffer from more steric hindrance than the endo transitions states as a result of interactions among the substrates, the trifluoromethanesulfonic group and the R4 groups of the ligand. The (S) configuration was observed predominantly over the (R) form, because there is no distinguishable repulsion between butadiene and the exo amino side or the endo amino side of the ligand. Besides, the interactions between the terminal hydrogen atoms of butadiene and the oxygen atoms of the trifluoromethanesulfonic group make the structure more stable. Thus, the experimental results were explained well by calculation of the chiral N,N, -dioxide/In(OTf)3 complex catalyzed hetero-Diels,Alder reaction at the molecular level. [source] Uncatalyzed and ruthenium(III)-catalyzed reaction of acidic chlorite with methylene violetINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 7 2003S. B. Jonnalagadda The kinetics and mechanism of the uncatalyzed and Ru(III)-catalyzed oxidation of methylene violet (3-amino-7-diethylamino-5-phenyl phenazinium chloride) (MV+) by acidic chlorite is reported. With excess concentrations of other reactants, both uncatalyzed and catalyzed reactions had pseudo-first-order kinetics with respect to MV+. The uncatalyzed reaction had first-order dependence on chlorite and H+ concentrations, but the catalyzed reaction had first-order dependence on both chlorite and catalyst, and a fractional order with respect to [H+]. The rate coefficient of the uncatalyzed reaction is (5.72 ± 0.19) M,2 s,1, while the catalytic constant for the catalyzed reaction is (22.4 ± 0.3) × 103 M,1 s,1. The basic stoichiometric equation is as follows: 2MV+ + 7ClO2, + 2H+ = 2P + CH3COOH + 4ClO2 + 3Cl,, where P+ = 3-amino-7-ethylamino-5-phenyl phenazinium-10-N-oxide. Stoichiometry is dependent on the initial concentration of chlorite present. Consistent with the experimental results, pertinent mechanisms are proposed. The proposed 15-step mechanism is simulated using literature; experimental and estimated rate coefficients and the simulated plots agreed well with the experimental curves. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 294,303, 2003 [source] Specific acid catalysis and Lewis acid catalysis of Diels,Alder reactions in aqueous mediaJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 3 2004Egid B. Mubofu Abstract A comparative study of specific acid catalysis and Lewis acid catalysis of Diels,Alder reactions between dienophiles (1, 4 and 6) and cyclopentadiene (2) in water and mixed aqueous media is reported. The reactions were performed in water with copper(II) nitrate as the Lewis acid catalyst whereas hydrochloric acid was employed for specific acid catalysis. At equimolar amounts of copper(II) nitrate and hydrochloric acid (0.01,M, for example) and under the same reaction conditions, the reaction rate for 1a with 2 is about 40 times faster with copper catalysis than with specific acid catalysis. Moreover, at 32°C and 0.01,M HCl, the reaction of 1b with 2 is about 21 times faster than the same uncatalyzed reaction in pure water under the same reaction conditions. The inverse solvent kinetic isotope effect shows that these Diels,Alder reactions undergo specific acid catalysis. Copyright © 2004 John Wiley & Sons, Ltd. [source] Fluoropolyethers end-capped by polar functional groups.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2002Abstract The kinetics of the dibutyltin dilaurate (DBTDL)-catalyzed urethane formation reactions of cyclohexyl isocyanate (CHI) with model monofunctional fluorinated alcohols and fluoropolyether diol Z-DOL H-1000 of various molecular weights (100,1084 g mol,1) in different solvents were studied. IR spectroscopy and chemical titration methods were used for measuring the rate of the total NCO disappearance at 30,60 °C. The effects of the reagents and DBTDL catalyst concentrations, the solvent and hydroxyl-containing compound nature, and the temperature on the reaction rate and mechanism were investigated. Depending on the initial reagent concentration and solvent, the reactions could be well described by zero-order, first-order, second-order, or more complex equations. The reaction mechanism, including the formation of intermediate ternary or binary complexes of reagents with the tin catalyst, could vary with the concentration and solvent and even during the reaction. The results were treated with a rate expression analogous to those used for enzymatic reactions. Under the explored conditions, the rate of the uncatalyzed reaction of fluorinated alcohols with CHI was negligible. Moreover, there was no allophanate formation, nor were there other side reactions, catalysis by urethane in the absence of DBTDL, or a synergetic effect in the presence of the tin catalyst. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3771,3795, 2002 [source] | ||||||||||