- Conversion of Propanal to Pentan-3-one using Lanthanide Oxides
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The heterogeneous reaction between propanal vapour and rare-earth-metal oxides gives as major products pentan-3-one and carbon dioxide.Residence time investigations indicate that pentan-3-one and carbon dioxide are primary products.Deactivation and high-resolution electron microscopy studies support the hypothesis that surface participates in the reaction, and high oxygen mobilities in the oxide may allow defects to spread within the oxide.The carbon dioxide produced in the reaction poisons the lanthanum oxide leading to the faster deactivation and temperature-programmed desorption indicates the presence of a surface intermediate which decomposes to pentan-3-one and carbon dioxide.A mechanism is proposed in which the formation of pentan-3-one proceeds via surface-bound carboxylate species.Preliminary studies show that catalytic production of pentan-3-one can potentially be sustained by co-feeding water with propanal to the rare-earth-metal oxides.
- Claridge, John B.,Green, Malcolm L. H.,Tsang, Shik Chi,York, Andrew P. E.
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- Rational Design of a Metallocatalytic Cavitand for Regioselective Hydration of Specific Alkynes
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The synthesis of a functionalized supramolecular cavitand with inwardly oriented AuI and P=O moieties was explored, including its catalytic proclivity in the selective hydration of internal alkynes. The cavitand works as a supramolecular flask device: AuI coordinates to the triple bond, the P=O moiety connects with a H2O molecule, and the cavity favors folding of a single alkynyl side chain. Several tests of different substrate patterns indicated that the cavity was substrate specific, similar to enzymatic catalysis.
- Endo, Naoki,Inoue, Mami,Iwasawa, Tetsuo
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supporting information
p. 1136 - 1140
(2018/03/13)
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- Selective Catalytic Hydration of Alkynes in the Presence of Au-Cavitands: A Study in Structure–Activity Relationships
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The effects of the catalytic cavities in gold-functionalized cavitands in the hydration of internal alkynes have been studied. Variations on cavitand structures revealed the importance of two features that were studied: (1) flanking aromatic rings, and (2) an adjacent P=O moiety. The di-quinoxaline-spanned resorcin[4]arene system provides a well-defined compartment, in which a cationic Au ion activates an internal alkyne for conversion into a ketone by delivery of water that has also been activated, this time by a P=O moiety. We synthesized four variations on our parent cavitand. Variations of the cavitand walls include replacement of quinoxaline components with pyrazine or methylene units. Variation of the P=O center was accomplished with methylene or quinoxaline moieties. All variants displayed lower catalytic activity or selectivity, allowing us to confirm the significance both of an internal cavity and of an activation site for water.
- Inoue, Mami,Ugawa, Katto,Maruyama, Tomoyuki,Iwasawa, Tetsuo
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p. 5304 - 5311
(2018/09/12)
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- Study on the degradation mechanism and pathway of benzene dye intermediate 4-methoxy-2-nitroaniline: Via multiple methods in Fenton oxidation process
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Benzene dye intermediate (BDI) 4-methoxy-2-nitroaniline (4M2NA) wastewater has caused significant environmental concern due to its strong toxicity and potential carcinogenic effects. Reports concerning the degradation of 4M2NA by advanced oxidation process are limited. In this study, 4M2NA degradation by Fenton oxidation has been studied to obtain more insights into the reaction mechanism involved in the oxidation of 4M2NA. Results showed that when the 4M2NA (100 mg L-1) was completely decomposed, the TOC removal efficiency was only 30.70-31.54%, suggesting that some by-products highly recalcitrant to the Fenton oxidation were produced. UV-Vis spectra analysis based on Gauss peak fitting, HPLC analysis combined with two-dimensional correlation spectroscopy and GC-MS detection were carried out to clarify the degradation mechanism and pathway of 4M2NA. A total of nineteen reaction intermediates were identified and two possible degradation pathways were illustrated. Theoretical TOC calculated based on the concentration of oxalic acid, acetic acid, formic acid, and 4M2NA in the degradation process was nearly 94.41-97.11% of the measured TOC, indicating that the oxalic acid, acetic acid and formic acid were the main products. Finally, the predominant degradation pathway was proposed. These results could provide significant information to better understand the degradation mechanism of 4M2NA.
- Guo, Ying,Xue, Qiang,Cui, Kangping,Zhang, Jia,Wang, Hui,Zhang, Huanzhen,Yuan, Fang,Chen, Honghan
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p. 10764 - 10775
(2018/03/26)
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- Regioselective Isomerization of 2,3-Disubstituted Epoxides to Ketones: An Alternative to the Wacker Oxidation of Internal Alkenes
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We report an alternative pathway to the Wacker oxidation of internal olefins involving epoxidation of trans-alkenes followed by a mild and highly regioselective isomerization to give the major ketone isomers in 66-98% yield. Preliminary kinetics and isotope labeling studies suggest epoxide ring opening as the turnover limiting step in our proposed mechanism. A similar catalytic system was applied to the kinetic resolution of select trans-epoxides to give synthetically useful selectivity factors of 17-23 for benzyl-substituted substrates.
- Lamb, Jessica R.,Mulzer, Michael,Lapointe, Anne M.,Coates, Geoffrey W.
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p. 15049 - 15054
(2015/12/08)
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- CONVERSION OF OXYGENATES TO HYDROCARBON FUELS BY DEOXYGENATION
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Oxygenates from biomass, particularly hydroxyl-substituted C2-plus hydrocarbons, are treated for removal of some or all of their oxygen atoms and for chain lengthening by carbon-carbon coupling in a single reaction medium in the gas phase over a solid catalyst.
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Page/Page column 32-33
(2011/10/10)
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- Pheromone synthesis. Part 243: Synthesis and biological evaluation of (3R,13R,1′S)-1′-ethyl-2′-methylpropyl 3,13-dimethylpentadecanoate, the major component of the sex pheromone of Paulownia bagworm, Clania variegata, and its stereoisomers
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All of the four stereoisomers of (1′S)-1′-ethyl-2′-methylpropyl 3,13-dimethylpentadecanoate, the major component of the female sex pheromone of Clania variegata, were synthesized by employing olefin cross metathesis as the key reaction and starting from (R)- or (S)-2-methyl-1-butanol, (R)- or (S)-citronellal, and (S)-2-methyl-3-pentanol. Their bioassay revealed the (3R,13R,1′S)-isomer as the bioactive one, whose more efficient synthesis was achieved in two different ways by employing Wittig reaction as the key step.
- Mori, Kenji,Tashiro, Takuya,Zhao, Boguang,Suckling, David M.,El-Sayed, Ashraf M.
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experimental part
p. 2642 - 2653
(2010/05/18)
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- Silica-supported HgSO4/H2SO4: A convenient reagent for the hydration of alkynes under mild conditions
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The silica-supported aqueous-phase catalyst (SAPC) approach has proven convenient for efficiently performing the hydration of alkynes with HgSO 4/H2SO4 to give the corresponding carbonyl compounds in dichloromethane under mild conditions. The use of this solid reagent significantly improves the reaction work-up as it merely involves filtering and evaporating the solvent.
- Mello, Rossella,Alcalde-Aragonés, Ana,González-Nú?ez, María Elena
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scheme or table
p. 4281 - 4283
(2010/09/07)
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- Synthesis of all the four stereoisomers of (1′S)-1-ethyl-2-methylpropyl 3,13-dimethylpentadecanoate, the major component of the sex pheromone of Paulownia bagworm, Clania variegata
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All the four stereoisomers of (1′S)-1-ethyl-2-methylpropyl 3,13-dimethylpentadecanoate, the major component of the sex pheromone of Clania variegata, were synthesized by starting from (R)- or (S)-2-methylbutan-1-ol, (R)- or (S)-citronellal, and (S)-2-methylpentan-3-ol. Olefin cross metathesis was employed as the key reaction.
- Mori, Kenji,Tashiro, Takuya
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scheme or table
p. 3266 - 3269
(2009/09/05)
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- Liquid-phase isomerization of saturated and unsaturated epoxides
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The liquid-phase isomerization of a variety of epoxides was studied using a complex catalyst system based on magnesium bromide and dimethylformamide. The data obtained elucidate the mechanism of the liquid-phase isomerization and show the range of oxygen-containing compounds which can be prepared through this reaction.
- Mel'nik,Khvatova,Moskvichev,Srednev,Egorova
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p. 167 - 169
(2007/10/03)
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- n-pentane carbonylation with CO on sulfated zirconia: An in situ solid-state 13C NMR study
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Using 13C CP/MAS NMR, the first evidence has been obtained for n-pentane carbonylation with carbon monoxide into C6 aldehydes, ketones and carboxylic acids on a sulfated zirconia catalyst.
- Luzgin,Stepanov,Shmachkova,Kotsarenko
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- Superacid-catalyzed selective formation-rearrangement of isoalkanes with carbon monoxide to branched ketones
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Efficient high octane oxygenate additives for gasoline, that is, branched aliphatic ketones, are the products of the title reaction of isoalkanes with carbon monoxide. Isobutane, for example, gives methyl isopropyl ketone in 91% yield and 93% selectivity (see scheme). The reaction gives no branched carboxylic acids, showing it to be independent of Koch carbonylation. The intriguing reaction is suggested to proceed through initial electrophilic C-H bond substitution by the formyl cation (or its protosolvated form), followed by rearrangement.
- Olah, George A.,Prakash, G. K. Surya,Mathew, Thomas,Marinez, Eric R.
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p. 2547 - 2548
(2007/10/03)
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- Fine particulate matter (PM) and organic speciation of fireplace emissions
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This paper presents a summary of fireplace particle size and organic speciation data gathered to date in an ongoing project. Tests are being conducted in a residential wood combustion (RWC) laboratory on three factory- built fireplaces. RWC wood smoke particles 10 μm (PM10) consist primarily of a mixture of organic compounds that have condensed into droplets; therefore, the size distribution and total mass are influenced by temperature of the sample during its collection. During the series 1 tests (15 tests), the dilution tunnel used to cool and dilute the stack gases gave an average mixed gas temperature of 47.3 °C and an average dilution ratio of 4.3. Averages for the PM2.5 (particles 2.5 μm) and PM10 fractions were 74 and 84%, respectively. For the series 2 tests, the dilution tunnel was modified, reducing the average mixed gas temperatures to 33.8 °C and increasing the average dilution ratio to 11.0 in tests completed to date. PM2.5 and PM10 fractions were 83 and 91%, respectively. Since typical winter time mixed gas temperatures would usually be less than 10 °C, these size fraction results (even from the series 2 tests) probably represent the lower bound; the PM10 and PM2.5 size fractions might be higher at typical winter temperatures. The particles collected on the first stage (cutpoint ? 11.7 μm) were light gray and appeared to include inorganic ash. Particles collected on the remainder of the stages were black and appeared to be condensed organics because there was noticeable lateral bleeding of the collected materials into the filter substrate. Total particulate emission rates ranged from 10.3 to 58.4 g/h; corresponding emission factors ranged from 3.3 to 14.9 g/kg of dry wood burned. A wide range of Environmental Protection Agency (EPA) Method 8270 semivolatile organic compounds were found in the emissions; of the 17 target compounds quantified, major constituents are phenol, 2-methylphenol, 4- methylphenol, 2,4-dimethylphenol, and naphthalene. An account is given on fireplace particle size and organic speciation data gathered to date in an ongoing project. Total particulate matter emission rates and the results of analyses for semivolatile organics in the emissions are discussed.
- Purvis, Carol R.,Mccrillis, Robert C.,Kariher, Peter H.
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p. 1653 - 1658
(2007/10/03)
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- Elemental fluorine. Part 7. New oxidation methodology
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Reaction of fluorine with water in the presence of acids provides new oxidants for 'in-situ' oxidation of ketones. Direct reaction of fluorine with anhydrous alcohols and 1,2-diols provides simple methodology for oxidation to corresponding secondary ketones or α-hydroxy ketones.
- Chambers, Richard D.,Hutchinson, John,Sandford, Graham,Shah, Aneela,Vaughan, Julian F. S.
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p. 15833 - 15842
(2007/10/03)
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- Variable regiochemistry in the stoichiometric and catalytic hydroamination of alkynes by imidozirconium complexes caused by an unusual dependence of the rate law on alkyne structure and temperature
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We have investigated the regiochemistry of the stoichiometric and catalytic hydroamination of disubstituted alkynes by imidozirconium complexes. The addition of alkynes to Cp2Zr=NR occurred regioselectively to give metallacycles 2, with the larger alkyne substituent RL located α to the metal center. Hydrolysis of the metallacycles then gave enamines and their tautomeric imines which were the net result of anti-Markovnikov addition to the alkyne. The size of the R group on the imido ligand and the size of the alkyne were influential in determining the degree of regioselectivity. By utilizing Cp2(THF)Zr=NR to generate Cp2Zr=NR at room temperature and Cp2Zr(R′)(NHR) to generate Cp2Zr=NR at high temperature, it was determined that the thermodynamic and kinetic regioselectivities were nearly identical for dialkylacetylenes. In contrast, for 1-phenylpropyne, the thermodynamic regioselectivity was found to be greater than the kinetic regioselectivity. The regioselectivity was found to be invariant from -6 to 45°C in the addition of both 4-methyl-2-pentyne and 2-hexyne to Cp2(THF)Zr=NAr. However, a significant erosion of regioselectivity was observed when 2-hexyne and 4-methyl-2-pentyne were catalytically hydroaminated by Cp2Zr(NHAr)2 at 120°C. A kinetic study of the catalytic reaction suggested that the reason for this erosion was that the protonation step in the catalytic cycle (k3[amine]) was slower than the cycloreversion of the stereoisomeric metallacycles to alkyne and Cp2Zr=NAr (k-2) (the step that leads to regioequilibration). Because the protonation is selective for the metallacycle in which the smaller substituent is located at the position adjacent to the metal center, it counters the regioselectivity of the cycloaddition. This was an unexpected result because (1) an earlier study showed that k3 [amine] was larger than k-2 for the addition of diphenylacetylene to Cp2Zr=NR at both 25°C and the catalytic reaction temperature (95°C in this case) and (2) in the present work, it was demonstrated that k3 [amine] was also larger than k-2 for dialkylacetylenes at 25°C. It was concluded that the relative magnitudes of the rate constants k3 (protonation) and k-2 (reversion) must vary with temperature more dramatically in the dialkylacetylene + Cp2Zr=NR reaction than in the diarylacetylene + Cp2Zr=NR reaction. This was confirmed by direct competition experiments carried out at 25, 60, and 100°C. We believe that the cycloreversion step k-2 is characterized by both a larger ΔH? and a larger ΔS? than protonation because the former is a unimolecular and the latter a bimolecular reaction.
- Baranger, Anne M.,Walsh, Patrick J.,Bergman, Robert G.
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p. 2753 - 2763
(2007/10/02)
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- EFFECT OF STERIC FACTORS ON THE EQUILIBRIUM IN THE FORMATION OF TERT-BUTYLPEROXY KETALS FROM ALIPHATIC KETONES
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The equilibrium in the formation of tert-butylperoxy ketals from aliphatic ketones and tert-butyl hydroperoxide is determined by the steric factors of the substituents at the carbonyl group of the ketones.The dependence of the equilibrium constant on the steric parameters of the substituents is described by the Taft equation log K/KO = δΣEs0 with δ = 1.37 (r = 0.970).
- Antonovskii, V. L.,Fedorova, E. V.,Shtivel', N. E.,Emelin, Yu. D.
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p. 704 - 706
(2007/10/02)
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- THE SYNTHETIC UTILITY OF DIOXYPHOSPHORANES IN ORGANIC SYNTHESIS
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Diethoxytriphenylphosphorane, DTPP, prepared by reaction of triphenylphosphine and diethyl peroxide, is a "hydrolytically active" dioxyphosphorane which promotes mild and efficient cyclodehydration of diols to cyclic ethers in neutral media.Simple 1,2-, 1,4-, and 1,5-diols afford good yields of the cyclic ethers but 1,3-propanediol and 1,6-hexanediol give mainly 3-ethoxy-1-propanol and 6-ethoxy-1-hexanol, respectively, with DTPP.Tri- and tetra-substituted 1,2-diols afford the relatively stable 1,3,2-dioxaphospholanes in the presence of DTPP and the reaction conditions dictate whether epoxides, ketones, or allylic alcohols are obtained.
- Robinson, Philip L.,Kelly, Jeffery W.,Evans, Slayton A.
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- Diethoxytriphenylphosphorane: A Mild, Regioselective Cyclodehydrating Reagent for Conversion of Diols to Cyclic Ethers. Stereochemistry, Synthetic Utility, and Scope
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Diethoxytriphenylphosphorane, Ph3P(OEt)2, prepared by reaction of triphenylphosphine and diethyl peroxide, is a "hydrolytically active" dioxyphosphorane which promotes mild cyclodehydration (40-110 deg C) of diols to cyclic ethers in neutral media.The regioselectivity in the closure of (S)-(+)-propane-1,2-diol and (R)-(-)-pentane-1,4-diol with Ph3P(OEt)2 is high (81-82 percent) while the cyclodehydration of (S)-(+)-phenylethane-1,2-diol gives racemized (+/-)-styrene oxide.Simple 1,2-, 1,4-, and 1,5-diols afford good yields of the cyclic ethers but 1,3-propanediol and 1,6-hexanediol give mainly 3-ethoxy-1-propanol and 6-ethoxy-1-hexanol, respectively with Ph3P(OEt)2.Tri- and tetra-substituted 1,2-diols afford the relatively stable 1,3,2-dioxaphospholanes (or ?-dioxyphosphoranes) in the presence of Ph3P(OEt)2, and, depending on conditions, the 1,3,2-dioxaphospholanes are selectively converted to epoxides, ketones or allylic alcohols.The carbonyl compounds arise from 1,2-hydride and 1,2-methyl migrations; the allylic alcohols are derived from thermolytic eliminations. trans-1,2-Cyclohexanediols afford essentially quantitative yields (>95 percent) of the cyclohexene oxides while cis-1,2-cyclohexanediol gives the stable 1,3,2-dioxaphospholane with Ph3P(OEt)2 which decomposes under thermal conditions to cyclohexanone (90 percent).Ph3P(OEt)2 is extremely useful for conversion of "sensitive" 1,2-diols to acidic and /or thermally labile epoxides as demonstrated by the quantitative conversion of 9,10-dihydro-trans-9,10-phenanthrenediol to 9,10-dihydrophenanthrene oxide and 2α,10-pinanediol to 2α,10-epoxypinane.
- Robinson, Philip L.,Barry, Carey N.,Kelly, Jeffery W.,Evans, Slayton A.
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p. 5210 - 5219
(2007/10/02)
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- SUBSTITUTION OF THE HYDROXYL GROUP IN ACETYLENIC ALCOHOLS BY HYDROGEN
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Tertiary α-alkynols containing at least one phenyl group at the acetylenic carbon atom are reduced by trialkyl- and triarylsilanes in the presence of trifluoroacetic acid to the corresponding acetylene hydrocarbons.
- Libman, N. M.,Shandybina, O. N.
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p. 2290 - 2293
(2007/10/02)
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- GENERAL RELATIONSHIPS IN THE OPENING OF THE OXIRANE RING DURING CLEAVAGE OF GLYCIDIC ACIDS
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By investigation of the decarboxylation of 2,3-epoxy derivatives of acids with various structures it was shown that contrary to the existing theory about the essential opening of the β (C-O) bond in the oxirane ring there are many structural types of 2,3-epoxypropionic acids, in which opening of the α (C-O) bond in the oxirane ring occurs during decarboxylation.It was also shown that these two possible reaction paths can also arise during the decarboxylation of one 2,3-epoxypropionic acid.On the basis of the obtained data a general relationship is developed for theopening of the oxirane ring during the decarboxylation of 2,3-epoxypropionic acids with any structure, and this makes it possible to predict the structure of the obtained carbonyl compound.
- Kuroyan, R. A.,Markosyan, A. I.,Engoyan, A. P.,Vartanyan, S. A.
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p. 1709 - 1714
(2007/10/02)
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- CHLORINATION AND CYCLODEHYDRATION OF 1,2-DIOLS WITH THE "TRIPHENYLPHOSPHINE-TETRACHLOROMETHANE-POTASSIUM CARBONATE" REAGENT
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The yields of the epoxides obtained from the reaction of 1,2-diols with the "triphenylphosphine-tetrachloromethane-potassium carbonate reagent" range from 27-85percent depending on the relative concentration of triphenylphosphine and diol.In the absence of heterogeneous potassium carbonate, reactions of 1,2-diols with triphenylphosphine-tetrachloromethane give largely 1,2-chlorohydrins.
- Barry, Carey N.,Evans, Slayton A.
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p. 661 - 664
(2007/10/02)
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- The Allopolarization Principle and its Applications, VI. The Alkylation of Enolate Anions: Polarity and Regioselectivity
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The O/C methylation ratio in the reaction of sodium enolates with dimethylsulfate depends on the polar (electronic) effect of substituents.The relative ?-charge density Px/y = lx/ly can be used as a measure for the polarity of ambifunctional anions; in case of enolate anions PO/C = lO/lC.The change of the regioselectivity Sf = log QO/QC in the alkylation of enolates is a function of a change in the polarity PO/C; ΔSf=f(ΔPx/y).The polar effect of substituents influences the charge control during the alkylation process via a change of the polarity of the enolate system: The higher the polarity of the anion, the stronger the charge control and the higher the yield of enol ether (O-alkylation). - Keywords: Alkylation, Enolate Anions
- Gompper, Rudolf,Vogt, Hans-Hubert,Wagner, Hans-Ulrich
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p. 1644 - 1652
(2007/10/02)
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- The Allopolarization Principle and its Applications, IV. Substituent Effects in the Methylation of Enolate Anions
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The ratio of O- and C-methylated products in the reaction of the sodium salts of acetophenones 1, propiophenones 3, phenylacetones 5, β-dicarbonyl compounds 12, α-cyanocarbonyl compounds 13, acetaldehyde, propionaldehyde, and diethylketone with dimethyl sulfate, methyl iodide, and trimethyl phosphate in HMPTA has been determined with regard to the effect of substituents.In some cases the influence of solvents, concentration and temperature has also been studied.
- Gompper, Rudolf,Vogt, Hans-Hubert
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p. 2866 - 2883
(2007/10/02)
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- Desamination of β- and γ-Amino Alcohols
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Nitrous acid deaminations of the β-amino alcohols 2 and 12 afford 1,2 diols as well as ketones by pinacolic rearrangement.Both types of products arise with predominant inversion of configuration.Stereochemical studies and isotopic labeling reveal that formation of the diols involves an oxygen shift, presumably via oxirane intermediates.Deamination of the γ-amino alcohol 37 induces, in part, sequential rearrangements to give products also obtained from 12, but in different proportions and enantiomeric purities.Conformational control provides a reasonable explanation of our results.
- Guenther, Bernd-Rainer,Kirmse, Wolfgang
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p. 518 - 532
(2007/10/02)
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- Manufacture of 2,6,6-trimethyl-cyclohex-2-en-1-one
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2,6,6-Trimethyl-cyclohex-2-en-1-one is manufactured by reacting ethyl isopropyl ketone with acrolein in an organic solvent in the presence of a strong organic acid at from 40° to 150° C.
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- Cardioglycoside derivatives of the strophanthidin type, a process for their manufacture and medicinal preparations containing these compounds
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Cyclic acetals or ketals of cardioglycosides derived from k-strophanthidin or strophanthidol are more readily absorbed by the stomach and intestine than the parent cardioglycoside. The acetals are produced by reaction of the parent cardioglycoside, e.g., strophanthidindigitoxide, with an aldehyde or ketone, or the corresponding acetal or ketal, in the presence of an acid condensation catalyst, to produce the k-strophanthidin derivative optionally followed by reduction to the strophanthidiol derivative.
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