- STUDY OF PHASE TRANSFER CATALYSIS BY LAYERED SCINTILLATION METHOD.
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The static and kinetic feature of the reaction of sodium cyanide with 1-bromoalkanes in the presence of various phase transfer catalysts was investigated in the oil/water system by using a layered scintillation method and the mechanism of catalytic action was discussed. From the measurement of equilibrium constants for both reactions of hexadecyltrimethylammonium cyanide with 1-bromooctane and of sodium cyanide with hexadecyltrimethylammonium bromide in organic phase, it was pointed out that the latter reaction was responsible for the advance of overall reaction. It is also found that majority of the phase transfer catalysts exist in the oil phase.
- Hideshima,Morinaga,Kimizuka
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- Physical Organic Studies on Bimolecular Reactions in Reversed Micelles: Addition of Cyanide Ion to the N-Methyl-3-carbamoylpyridinium Ion in Hexadecyltrimethylammonium Bromide Reversed Micelles
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The bimolecular reaction of cyanide (CN-) ion with N-methyl-3-carbamoylpyridinium (S+) ion, in the water pool of the reversed-micellar system water/ hexadecyltrimethylammonium bromide (HTAB)/ chloroform-isooctane (3:2, v/v) has been studied at various temperatures (15-40 deg C) by measuring spectrophotometrically the decrease of the absorption due to S+ (265 nm) and the increase of the absorption due to the addition product (340 nm).The results of the reaction series were examined throughout with respect to the molar ratio of water to HTAB, R.Since the rate and equilibrium constants of the bimolecular reaction are affected by the method in which the concentrations of reactants are defined or by fixing the extent of reaction space, the water pool is assumed to be the sole reaction space and the rate and equilibrium constants in the water pool, k2w and Kw, which are based on the modified concentrations of the reaction species, have been evaluated.It is found that terms of k2w and Kw, the smaller the value of R, the more the addition reaction is enhanced.From the relationships between Kw and k2w vs. temperature, the standard and activation enthalpies of reaction, ΔH and ΔH, respectively, have been calculated.The behavior of ΔH and ΔH as well as Kw and k2w is found to differ in reactions which have R below and above ca.3.To explain the enhancement of the reaction due to the specific field effect of the water pool and the retardation of the reaction due to electrostatic interactions among S+ ions, the involvement of CN- and HTAB ions is proposed.The differing behaviour in the reactions is more clearly manifested in the thermodynamic and kinetic diagrams of enthalpy vs. entropy, which give separate plots corresponding to R both below and above ca.3.In addition, the effect of varying the CN- ion concentration is discussed and is found to be consistent with the situation described above.
- Goto, Ayako,Kishimoto, Hiroshi
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- STUDIES ON as-TRIAZINE DERIVATIVES. VII. RESEMBLANCE BETWEEN as-TRIAZINES AND QUINAZOLINES IN NUCLEOPHILIC ADDITION-ELIMINATION REACTIONS.
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Alike 4-chloroquinazoline, 5-chloro-1,2,4-triazines (as-triazines) reacted with aromatic aldehydes in the presence of 1,3-dimethylbenzimidazolium iodide under basic conditions to give 5-aroyl-as-triazines.The Grignard reaction of 5-cyano-as-triazine with arylmagnesium bromides failed to give any significant product.Some analogy of as-triazines with quinazolines, in their chemical properties, was additionally investigated.
- Konno, Shoetsu,Ohba, Setsuya,Sagi, Mataichi,Yamanaka, Hiroshi
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p. 1243 - 1246
(2007/10/02)
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- Monooxygen Donation Potential of 4a-Hydroperoxyflavins As Compared with Those of a Percarboxylic Acid and Other Hydroperoxides. Monooxygen Donation to Olefin, Tertiary Amine, Alkyl Sulfide, and Iodide Ion
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The reaction of the hydroxyperoxides diphenylhydroperoxyacetonitrile (4), methyl diphenylhydroperoxyacetate (5), and 5',6',7',8'-tetrahydro-4a'-hydroperoxy-3'-methylspiro-4'(3'H)-one (6) with I-, thioxane, and N,N-dimethylbenzylamine (DMBA) are first order in both hydroperoxide and substrate.For both 5 and 6, I3- is produced in 100percent yield.Product analysis for the reaction of 4, 5, and 6 with thioxane and DMBA established that the hydroxyperoxides are converted to the corresponding alcohols and that thioxane sulfoxide and N,N-dimethylbenzylamine N-oxide are formed.The reactions are quantitative.The reaction of 4 with I- proved to be complicated.The alcohol generated from 4 is the cyanohydrin of benzophenone.The dissociation of the benzophenone cyanohydrin product is competitive with I3- formation so that CN- produced in the dissociation reacts with I3- to yield ICN.Kinetic and thermodynamic analyses have provided the pertinent rate and equilibrium constants associated with the overall time course for reaction of 4 with I-.The second-order rate constant for the reaction of m-chloroperbenzoic acid (1) with I- has been determined and the second-order rate constant for reaction of 1 with thioxane was obtained from experiments in which thioxane and I- were employed as competitive substrates.The second-order rate constants for reaction of 1, 4, 5, and 6 with I-, thioxane, and DMBA were compared with like constants for the reactions of 4a-hydroperoxy-5-ethyl-3-methyllumiflavin (2), 1-carba-1-deaza-4a-hydroperoxy-5-ethyl-3-methyllumiflavin (3), t-BuOOH (7), and H2O2 (8).A log - log plot of the rate constants for monooxygen transfer from hydroperoxides to thioxane (kS) and to DMBA (kN) was found to be linear and of slope 1.0.The best line for the plot of log kS vs. the log of the rate constants for reactions with I- (kI) was of slope 1.1.The points for m-chloroperbenzoic acid were found to fit the log kS vs. log KI plot.These results show that the second-order rate constants for reactions of I-, thioxane, and DMBA are of like dependence on the electronic and steric characteristics of the hydroperoxides and percarboxylic acid 1.A linear free energy plot correlates the log of the second-order rate constants vs. pKa of YOH for oxygen transfer from YOOH = 1, 2, 4, 5, 7, and 8 (βlg = -0.6).In these reactions the 4a-hydroperoxyflavin 2 is the most efficient monooxygen donor of the hydroperoxides investigated, being 103 - 106 more reactive than t-BuOOH and ca. 103 less reactive than the peracid 1.The kinetics of epoxidation of 2,3-dimethyl-2-butene by the hydroperoxides 2 - 6 were invesigated by following both hydroperoxide disappearance and product formation.The results of these investigations, which include further reaction of epoxide with hydroperoxide to provide pinacol and 2,3-dimethyl-1-buten-3-ol, are discussed.Evidence for epoxidation of 2,3-dimethyl-2-butene ...
- Bruice, Thomas C.,Noar, J. Barry,Ball, Sheldon S.,Venkataram, U. V.
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p. 2452 - 2463
(2007/10/02)
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- CYCLIZATION OF HYDROXYIMINO-β-DICARBONYL COMPOUNDS WITH KETONES UNDER THE INFLUENCE OF ALKALI-METAL ALKOXIDES
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Investigation of the condensation of hydroxyimino-β-dicarbonyl compounds with acetone in the presence of sodium ethoxide by a spectrophotometric methods showed that the accumulation rate of 3,5-dimethyl-2-nitrosophenol in the reaction of hydroxyiminoacetylacetone with acetone increases with increase in the sodium ethoxide concentration.In the transition to arylated hydroxyimino-β-diketones p-nitrosophenols are formed exclusively and the reaction rate decreases, but increase in the electron-withdrawing characteristics of the substituent in the benzene ring of the hydroxyimino-β-dicarbonyl compound leads to an increase in the cyclization rate.For the case of the condensation of hydroxyiminoacetylacetone with acetone and methyl ethyl ketone an increase was found in the ratio of the para and ortho isomers of the nitrosophenols with decrease in the radius of the alkali metal, with substitution of potassium ethoxide by the alkoxides of tertiary alcohols, and with the use of solvents not containing hydroxyl group ( DMSO ).On the basis of the obtained data an improved preparative method was developed for the synthesis of p-nitrosophenols.A series of 2,3,5-trialkylnitrosophenols and previously unobtainable 3,5-di(aryl)heterylnitrosophenols were obtained.
- Belyaev, E. Yu.,El'tsov, A. V.,Kochetkov, B. B.,Orlovskaya, N. F.,Tovbis, M. S.
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p. 1299 - 1304
(2007/10/02)
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