- Photochemical Activation of a Hydroxyquinone-Derived Phenyliodonium Ylide by Visible Light: Synthetic and Mechanistic Investigations
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We have identified and extensively investigated the photochemical activation and reaction of a hydroxyquinone-derived phenyliodonium ylide in the presence of visible light using experiment and theory. These studies revealed that in its photoexcited state this iodonium is capable of facilitating a range of single-electron transfer (SET) processes, including hydrogen atom transfer (HAT), a Povarov-type reaction, and atom-transfer radical addition chemistry. Where possible, we have employed density functional theory (DFT) to develop a more complete understanding of these photoinduced synthetic transformations.
- Jalali, Mona,Ho, Curtis C.,Fuller, Rebecca O.,Lucas, Nigel T.,Ariafard, Alireza,Bissember, Alex C.
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- Preparation method of 4-cyclopentene-1,3-diketone
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The invention relates to a preparation method of 4-cyclopentene-1,3-diketone. The invention provides the preparation method of the 4-cyclopentene-1,3-diketone, which has the characteristics of small catalyst dosage, easiness in separation, economy, greenness, environmental protection, high product yield and the like. The preparation method comprises the following steps: 1) mixing a reaction substrate, a reaction solvent, an oxidant and a catalyst in a reactor according to a certain ratio, carrying out a heating reaction in a closed manner at a certain reaction temperature, and then cooling toroom temperature to obtain a 4-cyclopentene-1, 3-diketone reaction solution; and 2) centrifuging the reaction solution, carrying out reduced pressure distillation, recovering the reaction solvent to obtain a crude product, adding water to dissolve the crude product, extracting with an extractant at 0-4 DEG C, and recovering the extractant under reduced pressure to obtain the white acicular crystal4-cyclopentene-1, 3-diketone. Byproducts are few, the conversion rate exceeds 99%, and the selectivity is greater than 98%. The purity of the separated, recrystallized and purified product is higherthan 99.9%. The method has a relatively high industrialization prospect.
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Paragraph 0075-0084
(2020/06/30)
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- Polymer pyrolysis and oxidation studies in a continuous feed and flow reactor: Cellulose and polystyrene
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A dual-zone, continuous feed tubular reactor is developed to assess the potential for formation of products from incomplete combustion in thermal oxidation of common polymers. Solid polymer (cellulose or polystyrene) is fed continuously into a volatilization oven where it fragments and vaporizes. The gas-phase polymer fragments flow directly into a second, main flow reactor to undergo further reaction. Temperatures in the main flow reactor are varied independently to observe conditions needed to convert the initial polymer fragments to CO2 and H2O. Combustion products are monitored at main reactor temperatures from 400 to 850 °C and at 2.0-s total residence time with four on-line GC/FIDs; polymer reaction products and intermediates are further identified by GC/MS analysis. Analysis of polymer decomposition fragments at 400 °C encompasses complex oxygenated and aromatic hydrocarbon species, which range from high-molecular-weight intermediates of ca. 300 amu, through intermediate mass ranges down to C1 and C2 hydrocarbons, CO, and CO2. Approximately 41 of these species are positively identified for cellulose and 52 for polystyrene. Products from thermal oxidation of cellulose and polystyrene are shown to achieve complete combustion to CO2 and H2O at a main reactor temperature of 850 °C under fuel-lean equivalence ratio and 2.0-s reaction time. A dual-zone, continuous feed tubular reactor is developed to assess the potential for formation of products from incomplete combustion in thermal oxidation of common polymers. Solid polymer (cellulose or polystyrene) is fed continuously into a volatilization oven where it fragments and vaporizes. The gas-phase polymer fragments flow directly into a second, main flow reactor to undergo further reaction. Temperatures in the main flow reactor are varied independently to observe conditions needed to convert the initial polymer fragments to CO2 and H2O. Combustion products are monitored at main reactor temperatures from 400 to 850°C and at 2.0-s total residence time with four on-line GC/FIDs; polymer reaction products and intermediates are further identified by GC/MS analysis. Analysis of polymer decomposition fragments at 400°C encompasses complex oxygenated and aromatic hydrocarbon species, which range from high-molecular-weight intermediates of ca. 300 amu, through intermediate mass ranges down to C1 and C2 hydrocarbons, CO, and CO2. Approximately 41 of these species are positively identified for cellulose and 52 for polystyrene. Products from thermal oxidation of cellulose and polystyrene are shown to achieve complete combustion to CO2 and H2O at a main reactor temperature of 850°C under fuel-lean equivalence ratio and 2.0-s reaction time.
- Park, Byung-Ik,Bozzelli, Joseph W.,Booty, Michael R.,Bernhard, Mary J.,Mesuere, Karel,Pettigrew, Charles A.,Shi, Ji-Chun,Simonich, Staci L.
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p. 2584 - 2592
(2007/10/03)
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- A regioselective synthesis of 4-methyl-1-pyrindan-5-one
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The enamine 7 reacts with crotonic aldehyde in the presence of p-toluenesulphonic acid via the intermediate 8 to yield regioselectively the unknown title compound 9. In alkaline medium, 9 is also formed from 7 and acetylacetaldehyde dimethyl acetal as well as small amounts of 11 and 12; under acidic conditions, however, mixtures of the regioisomers 9/9a are obtained in poor yield. 9a can be separated by fractional crystallisation of the hydrochlorides. Corresponding to 7 the homologous enamine 13 and acetylacetaldehyde acetal by alkaline catalysis gives the 4-methyltetrahydroquinolinone 1, respectively. Improved experimental details for an efficient preparation of the starting compounds 3 and 4 are given.
- Reimann,Poschl
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p. 589 - 592
(2007/10/02)
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- The Chemistry of 2-Oxido-3-phenyliodonio-1,4-benzoquinones: Transformation to 2-Cyclopentene-1,4-diones and Cycloadditions
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The conversion of substituted 2-hydroxy-1,4-benzoquinones, 1, to 2-cyclopentene-1,4-diones, 3 is effected by thermolysis of their iodonium zwitterions, 2.Some cycloadditions through 2 are also described.
- Papoutsis, Ioannis,Spyroudis, Spyros,Varvoglis, Anastasios
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p. 8449 - 8452
(2007/10/02)
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- FLASH-THERMOLYSIS OF METHYLENEPHTALIDE AND 3-METHYLENE-2-COUMARANONE
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The synthesis and flash-thermolysis of methylenephtalide 1 and 3-methylene-2-coumaranone 2 are reported.At high temperatures ( 1000 deg C) these two isomeric lactones do not extrude CO2 but give rise to new clean thermal rearrangements.
- Bloch, R.,Orvane, P.
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p. 3597 - 3600
(2007/10/02)
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