- A novel and efficient alkyl radical trap in aqueous medium
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A simple water soluble diselenide derivative 1 shows radical scavenger properties towards alkyl and hydroxyl radicals (k3 (0°C)=6.8x108 M-1 s-1) in Fenton-type chemistry. The reaction rate between produced alkyl radicals 2 and the diselenide overwhelms self-termination and halogen transfer reactions.
- Barton, Derek H. R.,Jacob, Marc,Peralez, Eric
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- Photocatalytic Dehydrgenation of Aliphatic Alcohols by Aqueos Suspensions of Platinized Titanium Dioxide
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Photoirradiation (λex > 300 nm) of Ar-purged aqueos propan-2-ol solution gave hydrogen and acetone in the presence of platinum- and/or ruthenium dioxide-loaded TiO2.The photocatalytic activity of anatase TiO2 depended significantly on the amount of metal or metal oxide present; the effect on the activity increased in the order platinum black >> platinum powder > ruthenium dioxide.The photocatalytic activity of rutile TiO2 was negligible even when loaded with platinum black.The effective wavelengths for the photocatalytic dehydrogenation of propan-2-ol were below ca. 390 nm, in agreement with the u.v. absorption spectrum of anatase TiO2.In a similar way primary, secondary and tertiary aliphatic alcohols underwent photocatalytic oxidation, accompanied by hydrogen liberation, by platinized TiO2.The primary and secondary alcohols gave the corresponding carbonyl derivatives, while 2-methylpropan-2-ol and acetone gave dimeric products accompanied by stoichiometric hydrogen evolution.The initial rate of dehydrogenation in these photocatalytic systems was in proportion to the rate constants of hydrogen abstraction by hydroxyl radical in the homogeneous systems.
- Nishimoto, Sei-Ichi,Ohtani, Bunsho,Kagiya, Tsutomu
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- Method for Preparing Crosslinker Compound
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The present disclosure relates to a method for preparing a crosslinker compound in which a crosslinker compound capable of using for the production of a super absorbent polymer can be obtained in a higher yield by a simple manner. The crosslinker compound obtained by the above method can be used as a thermally decomposable crosslinker in the process of producing a super absorbent polymer.
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Paragraph 0064; 0067-0068
(2021/01/29)
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- 2,2,5,5-Tetramethyltetrahydrofuran (TMTHF): A non-polar, non-peroxide forming ether replacement for hazardous hydrocarbon solvents
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An inherently non-peroxide forming ether solvent, 2,2,5,5-tetramethyltetrahydrofuran (2,2,5,5-tetramethyloxolane), has been synthesized from readily available and potentially renewable feedstocks, and its solvation properties have been tested. Unlike traditional ethers, its absence of a proton at the alpha-position to the oxygen of the ether eliminates the potential to form hazardous peroxides. Additionally, this unusual structure leads to lower basicity compared with many traditional ethers, due to the concealment of the ethereal oxygen by four bulky methyl groups at the alpha-position. As such, this molecule exhibits similar solvent properties to common hydrocarbon solvents, particularly toluene. Its solvent properties have been proved by testing its performance in Fischer esterification, amidation and Grignard reactions. TMTHF's differences from traditional ethers is further demonstrated by its ability to produce high molecular weight radical-initiated polymers for use as pressure-sensitive adhesives.
- Byrne, Fergal,Forier, Bart,Bossaert, Greet,Hoebers, Charly,Farmer, Thomas J.,Clark, James H.,Hunt, Andrew J.
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p. 3671 - 3678
(2017/08/15)
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- An acetylenic condensation method for producing 2,5-dimethyl -2,5-hexane diol
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A disclosed method for producing 2,5-dimethyl-2,5-hexanediol by employing alkynylation condensation process comprises the following steps: (1) taking acetylene and acetone as raw materials to prepared a material solution containing hexynediol; (2) performing separation by employing a potassium hydroxide separation kettle; (3) sending the potassium hydroxide aqueous solution into a nickel alloy continuous evaporator for performing distillation condensation on the potassium hydroxide aqueous solution; (4) sending concentrated potassium hydroxide solution to an inorganic impurity separation apparatus to remove organic impurities; (5) sending the potassium hydroxide aqueous solution subjected to impurity removing to a cast iron evaporator, evaporating water away to form solid potassium hydroxide, then continuously heating to enable solid potassium hydroxide to be in a molten state, and then naturally cooling to perform recrystallization; and (7) cutting recrystallized potassium hydroxide into sheets by a slicer for cycle use as a catalyst raw material. Compared with the prior art, potassium hydroxide is subjected cyclic utilization, so that cost is saved.
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Paragraph 0028-0030
(2017/03/08)
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- EXPANSION OF RENEWABLE STEM CELL POPULATIONS
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Ex vivo and in vivo methods of expansion of renewable stem cells, expanded populations of renewable stem cells and their uses.
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Paragraph 0512
(2016/05/02)
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- Thermal decomposition of diethylketone cyclic triperoxide in polar solvents
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The thermolysis of diethylketone cyclic triperoxide (3,3,6,6,9,9-hexaethyl- 1,2,4,5,7,8-hexaoxacyclononane, DEKTP) was studied in different polar solvents (ethanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, and acetonitrile). The rate constant values (kd) are higher for reactions performed in secondary alcohols probably because of the possibility to form a cyclic adduct with the participation of the hydrogen atom bonded to the secondary carbon. The kinetic parameters were correlated with the physicochemical properties of the selected solvents. The products of the DEKTP thermal decomposition in different polar solvents support a radical-based decomposition mechanism. CSIRO 2014.
- Barreto, Gaston P.,Alvarez, Elida E.,Eyler, Gladys N.,Canizo, Adriana I.,Allegretti, Patricia E.
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p. 881 - 886
(2014/07/07)
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- Direct synthesis of 1,4-diols from alkenes by iron-catalyzed aerobic hydration and C-H hydroxylation
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Various 1,4-diols are easily accessible from alkenes through iron-catalyzed aerobic hydration. The reaction system consists of a user-friendly iron phthalocyanine complex, sodium borohydride, and molecular oxygen. Furthermore, the effect of additional ligands on the iron complex was examined for a model reaction. The second hydroxy group is installed by direct C(sp3)-H oxygenation, which is based on a [1,5] hydrogen shift process of a transient alkoxy radical that is formed by formal hydration of the olefin. One more hydroxy group: A method for the synthesis of 1,4-diols from simple alkenes has been developed. This unusual transformation entails an iron-catalyzed aerobic hydration and is achieved with convenient reagents, such as molecular oxygen. The formation of an intermediary alkoxy radical, which undergoes a [1,5] hydrogen shift, is likely to be essential for C(sp3)-H hydroxylation. Pc=phthalocyanine.
- Hashimoto, Takuma,Hirose, Daisuke,Taniguchi, Tsuyoshi
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supporting information
p. 2730 - 2734
(2014/03/21)
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- METHOD FOR PREPARING ACETYLENE ALCOHOLS AND THEIR SECONDARY PRODUCTS
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A process for preparing at least one unsaturated alcohol (B) comprises the steps (I) to (III) below: (I) reaction of at least one alkali metal hydroxide or alkaline earth metal hydroxide with at least one alcohol (A) in at least one organic solvent (L) to give a mixture (G-I) comprising at least the alcohol (A), the solvent (L) and an alkoxide (AL); (II) reaction of at least one carbonyl compound of the formula R-CO-R' with at least one alkyne of the formula R''-C≡C-H and the mixture (G-I) obtained in step (I) to give a mixture (G-II) comprising at least the alcohol (A), the solvent (L) and an unsaturated alcohol (B); (III) distillation of the mixture (G-II) obtained in step (II) to give the alcohol or alcohols (B) and a mixture (G-III) comprising the solvent (L) and the alcohol (A), wherein the solvent (L) obtained in step (III) and the alcohol (A) obtained in step (III) are recycled as a mixture to step (I).
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Page/Page column 14-15
(2008/06/13)
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- Sonolysis of tert-butyl alcohol in aqueous solution
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A product study of the sonolysis of the volatile substrate t-butanol in aqueous solution indicates that substrate decomposition is practically completely determined, even at concentrations as low as millimolar, by oxidative pyrolysis going on in the gas phase within the collapsing cavitational bubble. OH-Radical-induced reactions in solution are insignificant since the volatility of this substrate, its gas-phase concentration within the bubble enhanced by a certain degree of hydrophobicity, causes OH radicals generated thermolytically from water vapour to be intercepted before they can reach the aqueous phase. The nature of the products, as well as the t-butanol-concentration dependence of the product yields, can be qualitatively explained on the basis of the t-butanol-pyrolysis mechanism. Kinetic considerations involving the relative yields of the pyrolysis products ethane, ethylene and acetylene lead to an estimate of a value of 3600 K for the average pyrolysis temperature at a t-butanol bulk concentration of 10-3 molar.
- Tauber, Armin,Mark, Gertraud,Schuchmann, Heinz-Peter,Von Sonntag, Clemens
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p. 1129 - 1135
(2007/10/03)
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- Continuous production process of tertiary alcohols by radical addition of secondary alcohols to alkenes
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A process is disclosed for producing tertiary alcohols by radical addition of secondary alcohols to alkenes. The reaction is carried out as a continuous process in the presence of an organic peroxide as a radical initiator and during a mean contact time of the reaction mixture of up to a maximum of 1 hour.
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- Dimethyldioxirane reactions: Rate acceleration due to intramolecular H-bonding
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Absolute rate studies were carried out on a series of C - H insertion reactions of dimethyldioxirane (1a). The substrates were chosen so that the distance between a single tertiary C - H bond and an OH group could be varied. The measured rate constants indicate that a rate acceleration occurs when the distance between the reacting C - H bond and the OH group permits intramolecular H-bonding stabilization of the transition state. A similar study in related compounds without the OH group showed no effect of chain length on the rate of the C - H insertion reaction. A related study of the epoxidation reaction of la also found an increased rate when chain length permitted intramolecular H-bonding by an OH group.
- Murray, Robert W.,Gu, Hong
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p. 751 - 758
(2007/10/03)
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- The Synthesis of Glycols by Mercury-Photosensitized Alcohol Dehydrodimerization
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A variety of alcohols can be dehydrodimerized to give 1,2-diols on a multigram scale at 1 atm pressure and reflux temperature on photolysis (254 nm) in the presence of a trace of Hg vapor.Initial C-H bond breaking is followed by recombination of the resulting α-centered radicals, which normally leads to C-C bond formation α to oxygen.The reaction rate and selectivity can be increased by operating at lower temperatures under H2, in which case H atoms replace Hg* as the principal abstracting reagent and H atom abstraction from the α-CH bond leads directly to the α-C-centered radical.Under H atom conditions, unsaturated alcohols also react, in which case diols other than the 1,2-isomer can be formed selectively.The product can be rationalized on the basis of H atom addition to the C=C double bond to give the most stable radical which then dimerizes.For the special case of t-BuOH, H atom abstraction from the t-BuOH β-CH group under H atom conditions leads to the β-centered radical, which dimerizes to the 1,4-diol.Radical disproportionation accounts for some of the byproducts observed.The following previously unknown C-H bond strengths (kcal/mol) were determined from the results, assuming the literature BDE for the α-C-H of 2-propanol (91.0 +/-1.0); n-butanol, 92.8 +/- 1.0( α), 95.2 +/- 1.0 (β), and 94.3 +/- 1.0 (γ); n-propanol, 93.1 +/- 1.0 (α), and 95.0 +/- 1.0 (β), respectively.
- Lee, Jesse C.,Boojamra, Constantine G.,Crabtree, Robert H.
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p. 3895 - 3900
(2007/10/02)
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- Photochemical dimerization of organic compounds
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At least one of selectivity and reaction rate of photosensitized vapor phase dimerizations, including dehydrodimerizations, hydrodimerizations and cross-dimerizations of saturated and unsaturated organic compounds is improved by conducting the dimerization in the presence of hydrogen or nitrous oxide.
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- Friedel-Crafts alkylation of pyrene in carbon disulfide; 1H NMR spectroscopy of pyrene derivatives
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Friedel-Crafts alkylation of pyrene with 2,5-dichloro-2,5-dimethylhexane and 2,4-dichloro-2,4-dimethylpentane in carbon disulfide yields 7,7,10,10-tetramethyl-7,8,9,10-tetrahydrobenzopyrene and 7,7,9,9-tetramethyl-8,9-dihydro-7H-cyclopentapyrene, respectively, both in 99percent yield.Alkylation with 1,4-dichlorobutane, followed by aromatization, yields benzopyrene in a facile two-step synthesis in 8percent yield.A mechanism is proposed which rationalizes the fact that only one ring of pyrene undergoes substitution.The 1H-1H NMR coupling constants of the pyrene derivatives are discussed.
- Rodenburg, L.,Block, R. de,Erkelens, C.,Lugtenburg, J.,Cornelisse, J.
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p. 529 - 535
(2007/10/02)
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- Cyclodehydration of Non-aromatic Diols on Al(III)-Montmorillonite Clay: Reactivity and Mechanism
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Al(III)-Montmorillonite-catalysed reactions of non-aromatic diols and butane-1,4-dithiol into the corresponding heterocyclic compounds are described.Experiments with S-(+)-pentane-1,4-diol indicate a mechanism involving competitive protonation of the primary and secondary hydroxy groups, followed by SN2 displacement of water to form the cyclic product.A comparison of the relative catalytic efficiencies of Al(III)-montmorillonite and the corresponding alumina pillared clay suggests that the performance of the former is superior in the above acid-catalysed reactions.
- Kotkar, Dilip,Mahajan, Satish W.,Mandal, Arun K.,Ghosh, Pushpito K.
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p. 1749 - 1752
(2007/10/02)
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- PHOTOCATALYTIC DEGRADATION AND DIMERIZATION OF t-BUTYL ALCOHOL BY AQUEOUS SUSPENSION OF PLATINIZED TITANIUM DIOXIDE
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Photoirradiation (λex > 300 nm) of argon-purged aqueous suspension of platinized TiO2 containing t-butyl alcohol at 27 +/- 3 deg C led to the formation of hydrogen, methane, and ethane in the gas phase, and acetone, t-pentyl alcohol (PntOH), and 2,5-dimethylhexane-2,5-diol (2,5-DH) in the solution phase.While TiO2 without Pt showed little activity, the product yields increased linearly upon increasing the amount of Pt loading up to 10 wtpercent.The increasing concentrations of ButOH on the TiO2 surface.The acetone formation predominated in the presence of either oxygen or silver salt.Product distributions obtained by the γ-irradiation under N2O-saturated conditions and by treatment with Fenton's reagent were similar to that of the photocatalytic reaction by platinized TiO2.
- Nishimoto, Sei-ichi,Ohtani, Bunsho,Shirai, Hiroshi,Kagiya, Tsutomu
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p. 661 - 666
(2007/10/02)
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- Photocatalytic Carbon-Carbon Bond Formation with Concurrent Hydrogen Evolution on Colloidal Zinc Sulphide
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In the photocatalytic system containing colloidal ZnS, water, and organic substrates such as triethylamine, tetrahydrofuran, or methanol, oxidative carbon-carbon bond formation occurs with efficient reductive H2 evolution, to give the dimeric products 2,3-bis(diethylamino)butane, 2,2'-bitetrahydrofuryl, or ethylene glycol, respectively.
- Yanagida, Shozo,Azuma, Takayuki,Kawakami, Horishi,Kizumoto, Hirotoshi,Sakurai, Hiroshi
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