- Codimerization of butadiene and ethylene
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The catalytic system CoCl2/1,2-bis(diphenylphosphino)ethane/Et3Al, in 1,2-dichloroethane, shows high activity and selectivity for the production of cis-1,4-hexadiene from butadiene and ethylene. The temperature of reaction appears to be critical; between 80° and 110° cis-1,4-hexadiene is formed in high yield whereas below 80° more ethylene than butadiene is consumed, with the result that C8 compounds are produced. Above 110° 1,4-hexadiene is isomerized to 2,4-hexadiene. Ayield of 8 × 104 moles of 1,4-hexadiene per mole of CoCl2 has been obtained at a rate of formation of the diene of 8 mol · l-1 · h-1. The catalytically active species is probably an octahedral complex of a cobalt(I) hydride with Et3Al. A reaction scheme is proposed.
- Henrici-Olive,Olive
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Read Online
- Method for synthesizing diene compounds based on aldehyde-ketone condensation reaction
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The invention provides a method for synthesizing diene compounds based on an aldehyde-ketone condensation reaction. The method comprises the following steps: firstly, under the action of a condensation catalyst, performing a condensation reaction on ketone compounds and aldehyde compounds to obtain condensation products; then, under the action of a reduction catalyst, performing a reduction reaction on the condensation products obtained in the previous step to obtain reduction products; under the action of a catalyst, performing a dehydration reaction on the reduction products obtained in theprevious step to obtain the diene compounds. According to the method, ketone, aldehyde as well as homologues of ketone and aldehyde which are cheap and easy to obtain can be used as raw materials forsynthesizing the diene compounds such as butadiene, piperylene as well as homologues of butadiene and piperylene, experimental conditions are mild, the operation is simple, and a large-scale synthesisprospect is achieved.
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Paragraph 0185; 0191-0193
(2019/05/08)
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- SYNTHESIS OF PHEROMONES AND RELATED MATERIALS VIA OLEFIN METATHESIS
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Methods for preparation of olefins, including 8- and 11-unsaturated monoenes and polyenes, via transition metathesis-based synthetic routes are described. Metathesis reactions in the methods are catalyzed by transition metal catalysts including tungsten-, molybdenum-, and ruthenium-based catalysts. The olefins include insect pheromones useful in a number of agricultural applications.
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Paragraph 0110
(2018/09/12)
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- Ring Opening of Biomass-Derived Cyclic Ethers to Dienes over Silica/Alumina
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We show that cyclic ethers, such 2-methyltetrahydrofuran (2-MTHF), can undergo dehydration to produce pentadienes over SiO2/Al2O3. The catalyst exhibited reversible deactivation due to coke deposition, with the yield to pentadienes decreasing from 68% to 52% at 623 K over 58 h time on stream. A reaction network for 2-MTHF dehydration was proposed on the basis of the results of space time studies. Pentadienes can be produced directly by a concerted hydride shift and dehydration of carbenium intermediates or indirectly through dehydration of pentanal and pentenol. Reaction kinetics studies were performed at temperatures ranging from 573 to 653 K and 2-MTHF partial pressures from 0.21 to 2.51 kPa. The apparent activation energy barrier for 2-MTHF conversion to pentadienes and the reaction rate order for ring opening were determined to be 74 kJ mol-1 and 0.24, respectively, indicating strong interaction between 2-MTHF and the SiO2/Al2O3 surface. Other solid acids such as γ-Al2O3, H-ZSM-5, and Al-Sn-Beta were found to be active for 2-MTHF dehydration to pentadienes. The rate of ring opening decreased in the order 2,5-dimethyltetrahydrofuran > 2-MTHF > tetrahydropyran > tetrahydrofuran. Over SiO2/Al2O3, the dehydration of 2,5-dimethyltetrahydrofuran resulted in 75% yield to hexadiene isomers. (Figure Presented).
- Kumbhalkar, Mrunmayi D.,Buchanan, J. Scott,Huber, George W.,Dumesic, James A.
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p. 5248 - 5256
(2017/08/17)
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- Synthesis and characterization of tridentate schiff base derivative of indenyl lanthanoid chloride tetrahydrofuranate complexes for catalytic applications
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Four kinds of novel lanthanocene complexes were synthesized in reasonable yield by the reaction of equimolar quantity of sodium salt of tridentate Schiff base [N-(2-methoxyphenyl)salicylideneimine] with indenyl lanthanoid dichloride tetrahydrofuranate in tetrahydrofuran. All the complexes after purification were characterized by MS and EA, respectively. These complexes isomerized successfully the 1,5- hexadiene into a mixture of products such as 1,4-hexadiene, 2,4-hexadiene,1,3-hexadiene, methylenecyclopentane and methylcyclopentene. Similarly they also proved effective for the polymerization of methylmethacrylate (MMA), 56.45 % yield and high molecular weight (355 × 103).
- Yousaf, Muhammad,Zahoor, Ameer Fawad,Anjum, Anbreen,Bokhari, Tanveer Hussain,Ali, Kulsoom Ghulam,Purveen, Bushra,Naheed, Shazia,Jabbar, Abdul,Ahmad, Hafiz Badaruddin
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p. 518 - 520
(2013/02/22)
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- CATALYTIC DEHYDRATION OF ALCOHOLS AND ETHERS OVER A TERNARY MIXED OXIDE
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A ternary V—Ti—P mixed oxide is shown to catalytically dehydrate 2-methyl-tetrahydrofuran in high conversion to give piperylene, in good yield. Volatile products collected from this reaction contain piperylene in concentrations as high as 80 percent by weight. Dehydration of glycerol to acrolein in high conversion and moderate selectivity is also demonstrated. The catalyst is also shown to dehydrate other alcohols and ether substrates. The catalyst is resistant to deactivation and maintains activity between runs.
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Paragraph 0043; 0046
(2013/03/28)
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- Vapor-phase catalytic dehydration of terminal diols
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Vapor-phase catalytic reactions of several terminal diols were investigated over several rare earth oxides, such as Sc2O3, Y 2O3, CeO2, Yb2O3, and Lu2O3. Sc2O3 showed selective catalytic activity in the dehydration of terminal diols with long carbon chain, such as 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol, to produce the corresponding unsaturated alcohols. In the dehydration of 1,6-hexanediol, 5-hexen-1-ol was produced with selectivity over 60 mol%, together with by-products such as ε-caprolactone and oxacycloheptane. In the dehydration of 1,10-decanediol, 9-decen-1-ol was produced with selectivity higher than 70 mol%. In addition to Sc 2O3, heavy rare earth oxides such as Lu2O 3 as well as monoclinic ZrO2 showed moderate selectivity in the dehydration of the terminal diols.
- Abe, Katsutoshi,Ohishi, Yusuke,Okada, Takuto,Yamada, Yasuhiro,Sato, Satoshi
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experimental part
p. 419 - 424
(2012/02/03)
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- Synthesis of derivatives of lanthanocene complexes for the isomerization of 1,5-hexadiene
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the title complexes were prepared by the reaction of tris(cyclopentadienyl) lanthanides [Ln = Sm, Dy or Er] and tris(cyclopentadienyl)- yttirium with tridentate Schiff base, N-(2-methoxyphenyl)salicylidineamine in THF under argon at ambient temperature and were characterized by elemental analysis and spectroscopic techniques (MS and IR). These lanthanides complexes were applied for the isomerization of 1,5- hexadiene. The isomerization resulted into a mixture of 1,4-hexadiene and methylenecyclopentane as intermediate and 2,4-hexadiene and methylcyclopentene as end products. The ratio of the linear to the cyclic product in the reaction is dependent upon amount of catalyst used.
- Yousaf, Muhammad,Zahoor, Ameer Fawad,Ali, Kulsoom G.,Ahmad, Hafiz Badaruddin,Qian, Yanlong
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experimental part
p. 4969 - 4975
(2012/07/28)
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- Schiff base derivative of cyclooctatetraenyl lanthanoid/NaH catalytic systems for the isomerization of 1,5-hexadiene
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The different types of the tridentate Schiff base {N-(2-methoxyphenyl)- salicylideneamine} derivative of lanthnoid cyclooctatetraenyl complexes [COTLn Schiff base 2THF (Ln = Sm, Eu, Gd and Er)] along with NaH are proved to be a versatile tool for the isomerization of 1,5-hexadiene. The isomerization resulted a mixture of products such as 1,4-hexadiene, 1,3-hexadiene, 2,4-hexadiene, methylenecyclopentane and methylcyclopentene. Among these 1,4-hexadiene and methylenecyclopentane were the end products while 1,3-hexadiene, 2,4-hexadiene and methylcyclopetene were the intermediates. From the results it is assumed that radius of the metal is an important factor in determining the catalytic efficiency of the complexes.
- Yousaf, Muhammad,Ali, Kulsoom Ghulam,Parveen, Bushra,Jabbar, Abdul,Ahmad, Hafiz Badaruddin,Ma, Hiyan
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scheme or table
p. 5254 - 5260
(2012/07/28)
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- Specific features of ethylene codimerization with butadiene and isoprene in the presence of systems based on iron acetylacetonate and organoaluminum compounds
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The influence of different factors on the kinetics and selectivity of ethylene codimerization with butadiene and isoprene catalyzed by FeAA3 + AIR3 systems in aromatic solvents was studied. The main products of these transformations were octa- and decatrienes, the codimers of ethylene with butadiene. The reactions between FeAA3 and AlEt3 were studied in model conditions. The data on the yield and composition of gaseous products, as well as the structure of intermediates, were obtained. The assumption that active centers in ethylene codimerization and copolymerization with butadiene and isoprene are alkyl and hydride forms of univalent iron and complexes of zero-valent iron was proved. The scheme of the process suggesting the linear codimerization of ethylene with 1,3-dienes and isomerization of 1,4-hexadiene as a degenerated polymerization with univalent iron hydride as an active center was discussed in detail. The alternative mechanism of ethylene codimerization with 1,3-dienes in the presence of zero-valent iron complexes via the formation of a five-membered iron cycle was also discussed.
- Belova,Matkovskii
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p. 110 - 120
(2007/10/03)
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- COORDINATION AND CATALYTIC REACTIONS OF UNSATURATED COMPOUNDS: IV.* INTERPRETATION OF THE MECHANISM OF EPOXIDATION OF ETHYLENE BY SULFUR DIOXIDE
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Sulfur dioxide reacts with ethylene (but not with higher 1-alkenes) under conditions of heterogeneous catalysis at 300-400 deg C to form ethylene oxide and sulfur together with other products.The epoxidation evidently results from complex formation between the ethylene, sulfur dioxide, and catalyst with subsequent colligation of the C-S bonds, ring enlargement through insertion of an oxygen atom at one of these bonds, and elimination of SO from the unstable cyclic sulfinate.Elemental sulfur is formed in all the secondary transformations (during the decomposition of SO and the reduction of SO2 by the oxirane).
- Devekki, A. V.,Koshelev, Yu. V.,Malov, Yu. I.
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p. 829 - 834
(2007/10/02)
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- Cope Rearrangements of Donor Substituted 1,5-Hexadienes
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Alkoxy, alkylthio, and dialkylamino groups in position 3 of 1,5-hexadiene and in position 2 of 3,3-dimethyl-1,5-hexadiene have rather small effects on the Cope rearrangement (maximum rate acceleration by a factor of 60; maximum ΔEa = 5,5 kcal/mol = 23 kJ/mol).The pattern of substituent effects is more consistent with a diradicaloid mechanism than with a concerted sigmatropic rearrangement.
- Dollinger, Michael,Henning, Wolfgang,Kirmse, Wolfgang
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p. 2309 - 2325
(2007/10/02)
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- Etude des transformations catalytiques sur alumine de β-tetrahydrofurylmethanols
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The products obtained by treatment of β-tetrahydrofurylmethanols at 310-330 deg C, using alumina as catalyst are studied.The nature of the products-furans, tetrahydrofurans, aliphatic and cyclic dienes-shows that beside the simple dehydration side reactions take place leading, as the case may be, to dehydrogenation, raduction, ring opening and fragmentation.
- Infarnet, Yves,Accary, Armand,Huet, Jean
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p. 261 - 266
(2007/10/02)
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